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Update and organize the content on Deployments (#14861)

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shavidissa
2019-07-02 13:10:29 -07:00
committed by Kubernetes Prow Robot
parent b692fddd32
commit 0f4543b94b
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content/en/docs/concepts/workloads/controllers/deployment.md
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@@ -17,10 +17,10 @@ weight: 30
A _Deployment_ controller provides declarative updates for [Pods](/docs/concepts/workloads/pods/pod/) and A _Deployment_ controller provides declarative updates for [Pods](/docs/concepts/workloads/pods/pod/) and
[ReplicaSets](/docs/concepts/workloads/controllers/replicaset/). [ReplicaSets](/docs/concepts/workloads/controllers/replicaset/).
You describe a _desired state_ in a Deployment object, and the Deployment controller changes the actual state to the desired state at a controlled rate. You can define Deployments to create new ReplicaSets, or to remove existing Deployments and adopt all their resources with new Deployments. You describe a _desired state_ in a Deployment, and the Deployment controller changes the actual state to the desired state at a controlled rate. You can define Deployments to create new ReplicaSets, or to remove existing Deployments and adopt all their resources with new Deployments.
{{< note >}} {{< note >}}
You should not manage ReplicaSets owned by a Deployment. All the use cases should be covered by manipulating the Deployment object. Consider opening an issue in the main Kubernetes repository if your use case is not covered below. Do not manage ReplicaSets owned by a Deployment. Consider opening an issue in the main Kubernetes repository if your use case is not covered below.
{{< /note >}} {{< /note >}}
{{% /capture %}} {{% /capture %}}
@@ -54,11 +54,11 @@ In this example:
In this case, you simply select a label that is defined in the Pod template (`app: nginx`). In this case, you simply select a label that is defined in the Pod template (`app: nginx`).
However, more sophisticated selection rules are possible, However, more sophisticated selection rules are possible,
as long as the Pod template itself satisfies the rule. as long as the Pod template itself satisfies the rule.
{{< note >}} {{< note >}}
`matchLabels` is a map of {key,value} pairs. A single {key,value} in the `matchLabels` map The `matchLabels` field is a map of {key,value} pairs. A single {key,value} in the `matchLabels` map
is equivalent to an element of `matchExpressions`, whose key field is "key", the operator is "In", is equivalent to an element of `matchExpressions`, whose key field is "key" the operator is "In",
and the values array contains only "value". The requirements are ANDed. and the values array contains only "value".
All of the requirements, from both `matchLabels` and `matchExpressions`, must be satisfied in order to match.
{{< /note >}} {{< /note >}}
* The `template` field contains the following sub-fields: * The `template` field contains the following sub-fields:
@@ -67,81 +67,67 @@ In this example:
the Pods run one container, `nginx`, which runs the `nginx` the Pods run one container, `nginx`, which runs the `nginx`
[Docker Hub](https://hub.docker.com/) image at version 1.7.9. [Docker Hub](https://hub.docker.com/) image at version 1.7.9.
* Create one container and name it `nginx` using the `name` field. * Create one container and name it `nginx` using the `name` field.
* Open port `80` so that the container can send and accept traffic.
To create this Deployment, run the following command: Follow the steps given below to create the above Deployment:
Before you begin, make sure your Kubernetes cluster is up and running.
1. Create the Deployment by running the following command:
{{< note >}}
You may specify the `--record` flag to write the command executed in the resource annotation `kubernetes.io/change-cause`. It is useful for future introspection.
For example, to see the commands executed in each Deployment revision.
{{< /note >}}
```shell ```shell
kubectl apply -f https://k8s.io/examples/controllers/nginx-deployment.yaml kubectl apply -f https://k8s.io/examples/controllers/nginx-deployment.yaml
``` ```
{{< note >}} 2. Run `kubectl get deployments` to check if the Deployment was created. If the Deployment is still being created, the output is similar to the following:
You may specify the `--record` flag to write the command executed in the resource annotation `kubernetes.io/change-cause`. It is useful for future introspection, for example to see the commands executed in each Deployment revision.
{{< /note >}}
Next, run `kubectl get deployments`. The output is similar to the following:
```shell ```shell
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 3 0 0 0 1s nginx-deployment 3 0 0 0 1s
``` ```
When you inspect the Deployments in your cluster, the following fields are displayed: When you inspect the Deployments in your cluster, the following fields are displayed:
* `NAME` lists the names of the Deployments in the cluster. * `NAME` lists the names of the Deployments in the cluster.
* `DESIRED` displays the desired number of _replicas_ of the application, which * `DESIRED` displays the desired number of _replicas_ of the application, which you define when you create the Deployment. This is the _desired state_.
you define when you create the Deployment. This is the _desired state_.
* `CURRENT` displays how many replicas are currently running. * `CURRENT` displays how many replicas are currently running.
* `UP-TO-DATE` displays the number of replicas that have been updated to achieve * `UP-TO-DATE` displays the number of replicas that have been updated to achieve the desired state.
the desired state. * `AVAILABLE` displays how many replicas of the application are available to your users.
* `AVAILABLE` displays how many replicas of the application are available to
your users.
* `AGE` displays the amount of time that the application has been running. * `AGE` displays the amount of time that the application has been running.
Notice how the values in each field correspond to the values in the Deployment specification: Notice how the number of desired replicas is 3 according to `.spec.replicas` field.
* The number of desired replicas is 3 according to `.spec.replicas` field.
* The number of current replicas is 0 according to the `.status.replicas` field.
* The number of up-to-date replicas is 0 according to the `.status.updatedReplicas` field.
* The number of available replicas is 0 according to the `.status.availableReplicas` field.
To see the Deployment rollout status, run `kubectl rollout status deployment.v1.apps/nginx-deployment`. This command returns the following output:
3. To see the Deployment rollout status, run `kubectl rollout status deployment.v1.apps/nginx-deployment`. The output is similar to this:
```shell ```shell
Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated...
deployment.apps/nginx-deployment successfully rolled out deployment.apps/nginx-deployment successfully rolled out
``` ```
Run the `kubectl get deployments` again a few seconds later: 4. Run the `kubectl get deployments` again a few seconds later. The output is similar to this:
```shell ```shell
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 3 3 3 3 18s nginx-deployment 3 3 3 3 18s
``` ```
Notice that the Deployment has created all three replicas, and all replicas are up-to-date (they contain the latest Pod template) and available.
Notice that the Deployment has created all three replicas, and all replicas are up-to-date (they contain the 5. To see the ReplicaSet (`rs`) created by the Deployment, run `kubectl get rs`. The output is similar to this:
latest Pod template) and available (the Pod status is Ready for at least the value of the Deployment's `.spec.minReadySeconds` field).
To see the ReplicaSet (`rs`) created by the deployment, run `kubectl get rs`:
```shell ```shell
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-deployment-75675f5897 3 3 3 18s nginx-deployment-75675f5897 3 3 3 18s
``` ```
Notice that the name of the ReplicaSet is always formatted as `[DEPLOYMENT-NAME]-[RANDOM-STRING]`. The random string is Notice that the name of the ReplicaSet is always formatted as `[DEPLOYMENT-NAME]-[RANDOM-STRING]`. The random string is
randomly generated and uses the pod-template-hash as a seed. randomly generated and uses the pod-template-hash as a seed.
To see the labels automatically generated for each pod, run `kubectl get pods --show-labels`. The following output is returned: 6. To see the labels automatically generated for each Pod, run `kubectl get pods --show-labels`. The following output is returned:
```shell ```shell
NAME READY STATUS RESTARTS AGE LABELS NAME READY STATUS RESTARTS AGE LABELS
nginx-deployment-75675f5897-7ci7o 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453 nginx-deployment-75675f5897-7ci7o 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453
nginx-deployment-75675f5897-kzszj 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453 nginx-deployment-75675f5897-kzszj 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453
nginx-deployment-75675f5897-qqcnn 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453 nginx-deployment-75675f5897-qqcnn 1/1 Running 0 18s app=nginx,pod-template-hash=3123191453
``` ```
The created ReplicaSet ensures that there are three `nginx` Pods.
The created ReplicaSet ensures that there are three `nginx` Pods running at all times.
{{< note >}} {{< note >}}
You must specify an appropriate selector and Pod template labels in a Deployment (in this case, You must specify an appropriate selector and Pod template labels in a Deployment (in this case,
@@ -162,18 +148,20 @@ and in any existing Pods that the ReplicaSet might have.
## Updating a Deployment ## Updating a Deployment
{{< note >}} {{< note >}}
A Deployment's rollout is triggered if and only if the Deployment's pod template (that is, `.spec.template`) A Deployment's rollout is triggered if and only if the Deployment's Pod template (that is, `.spec.template`)
is changed, for example if the labels or container images of the template are updated. Other updates, such as scaling the Deployment, do not trigger a rollout. is changed, for example if the labels or container images of the template are updated. Other updates, such as scaling the Deployment, do not trigger a rollout.
{{< /note >}} {{< /note >}}
Suppose that you now want to update the nginx Pods to use the `nginx:1.9.1` image Follow the steps given below to update your Deployment:
instead of the `nginx:1.7.9` image.
1. Let's update the nginx Pods to use the `nginx:1.9.1` image instead of the `nginx:1.7.9` image.
```shell ```shell
kubectl --record deployment.apps/nginx-deployment set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 kubectl --record deployment.apps/nginx-deployment set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1
``` ```
The output is similar to this:
``` ```
image updated deployment.apps/nginx-deployment image updated
``` ```
Alternatively, you can `edit` the Deployment and change `.spec.template.spec.containers[0].image` from `nginx:1.7.9` to `nginx:1.9.1`: Alternatively, you can `edit` the Deployment and change `.spec.template.spec.containers[0].image` from `nginx:1.7.9` to `nginx:1.9.1`:
@@ -181,51 +169,57 @@ Alternatively, you can `edit` the Deployment and change `.spec.template.spec.con
```shell ```shell
kubectl edit deployment.v1.apps/nginx-deployment kubectl edit deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment edited deployment.apps/nginx-deployment edited
``` ```
To see the rollout status, run: 2. To see the rollout status, run:
```shell ```shell
kubectl rollout status deployment.v1.apps/nginx-deployment kubectl rollout status deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated...
```
or
```
deployment.apps/nginx-deployment successfully rolled out deployment.apps/nginx-deployment successfully rolled out
``` ```
After the rollout succeeds, you may want to `get` the Deployment: Get more details on your updated Deployment:
```shell * After the rollout succeeds, you can view the Deployment by running `kubectl get deployments`.
kubectl get deployments The output is similar to this:
```
``` ```
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 3 3 3 3 36s nginx-deployment 3 3 3 3 36s
``` ```
The number of up-to-date replicas indicates that the Deployment has updated the replicas to the latest configuration. * Run `kubectl get rs` to see that the Deployment updated the Pods by creating a new ReplicaSet and scaling it
The current replicas indicates the total replicas this Deployment manages, and the available replicas indicates the
number of current replicas that are available.
You can run `kubectl get rs` to see that the Deployment updated the Pods by creating a new ReplicaSet and scaling it
up to 3 replicas, as well as scaling down the old ReplicaSet to 0 replicas. up to 3 replicas, as well as scaling down the old ReplicaSet to 0 replicas.
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-deployment-1564180365 3 3 3 6s nginx-deployment-1564180365 3 3 3 6s
nginx-deployment-2035384211 0 0 0 36s nginx-deployment-2035384211 0 0 0 36s
``` ```
Running `get pods` should now show only the new Pods: * Running `get pods` should now show only the new Pods:
```shell ```shell
kubectl get pods kubectl get pods
``` ```
The output is similar to this:
``` ```
NAME READY STATUS RESTARTS AGE NAME READY STATUS RESTARTS AGE
nginx-deployment-1564180365-khku8 1/1 Running 0 14s nginx-deployment-1564180365-khku8 1/1 Running 0 14s
@@ -233,22 +227,24 @@ nginx-deployment-1564180365-nacti 1/1 Running 0 14s
nginx-deployment-1564180365-z9gth 1/1 Running 0 14s nginx-deployment-1564180365-z9gth 1/1 Running 0 14s
``` ```
Next time you want to update these Pods, you only need to update the Deployment's pod template again. Next time you want to update these Pods, you only need to update the Deployment's Pod template again.
Deployment can ensure that only a certain number of Pods may be down while they are being updated. By Deployment ensures that only a certain number of Pods are down while they are being updated. By default,
default, it ensures that at least 25% less than the desired number of Pods are up (25% max unavailable). it ensures that at least 25% of the desired number of Pods are up (25% max unavailable).
Deployment can also ensure that only a certain number of Pods may be created above the desired number of Deployment also ensures that only a certain number of Pods are created above the desired number of Pods.
Pods. By default, it ensures that at most 25% more than the desired number of Pods are up (25% max surge). By default, it ensures that at most 25% of the desired number of Pods are up (25% max surge).
For example, if you look at the above Deployment closely, you will see that it first created a new Pod, For example, if you look at the above Deployment closely, you will see that it first created a new Pod,
then deleted some old Pods and created new ones. It does not kill old Pods until a sufficient number of then deleted some old Pods, and created new ones. It does not kill old Pods until a sufficient number of
new Pods have come up, and does not create new Pods until a sufficient number of old Pods have been killed. new Pods have come up, and does not create new Pods until a sufficient number of old Pods have been killed.
It makes sure that number of available Pods is at least 2 and the number of total Pods is at most 4. It makes sure that at least 2 Pods are available and that at max 4 Pods in total are available.
* Get details of your Deployment:
```shell ```shell
kubectl describe deployments kubectl describe deployments
``` ```
The output is similar to this:
``` ```
Name: nginx-deployment Name: nginx-deployment
Namespace: default Namespace: default
@@ -287,7 +283,6 @@ Events:
Normal ScalingReplicaSet 19s deployment-controller Scaled up replica set nginx-deployment-1564180365 to 3 Normal ScalingReplicaSet 19s deployment-controller Scaled up replica set nginx-deployment-1564180365 to 3
Normal ScalingReplicaSet 14s deployment-controller Scaled down replica set nginx-deployment-2035384211 to 0 Normal ScalingReplicaSet 14s deployment-controller Scaled down replica set nginx-deployment-2035384211 to 0
``` ```
Here you see that when you first created the Deployment, it created a ReplicaSet (nginx-deployment-2035384211) Here you see that when you first created the Deployment, it created a ReplicaSet (nginx-deployment-2035384211)
and scaled it up to 3 replicas directly. When you updated the Deployment, it created a new ReplicaSet and scaled it up to 3 replicas directly. When you updated the Deployment, it created a new ReplicaSet
(nginx-deployment-1564180365) and scaled it up to 1 and then scaled down the old ReplicaSet to 2, so that at (nginx-deployment-1564180365) and scaled it up to 1 and then scaled down the old ReplicaSet to 2, so that at
@@ -297,20 +292,20 @@ in the new ReplicaSet, and the old ReplicaSet is scaled down to 0.
### Rollover (aka multiple updates in-flight) ### Rollover (aka multiple updates in-flight)
Each time a new deployment object is observed by the Deployment controller, a ReplicaSet is created to bring up Each time a new Deployment is observed by the Deployment controller, a ReplicaSet is created to bring up
the desired Pods if there is no existing ReplicaSet doing so. Existing ReplicaSet controlling Pods whose labels the desired Pods. If the Deployment is updated, the existing ReplicaSet that controls Pods whose labels
match `.spec.selector` but whose template does not match `.spec.template` are scaled down. Eventually, the new match `.spec.selector` but whose template does not match `.spec.template` are scaled down. Eventually, the new
ReplicaSet will be scaled to `.spec.replicas` and all old ReplicaSets will be scaled to 0. ReplicaSet is scaled to `.spec.replicas` and all old ReplicaSets is scaled to 0.
If you update a Deployment while an existing rollout is in progress, the Deployment will create a new ReplicaSet If you update a Deployment while an existing rollout is in progress, the Deployment creates a new ReplicaSet
as per the update and start scaling that up, and will roll over the ReplicaSet that it was scaling up previously as per the update and start scaling that up, and rolls over the ReplicaSet that it was scaling up previously
-- it will add it to its list of old ReplicaSets and will start scaling it down. -- it will add it to its list of old ReplicaSets and start scaling it down.
For example, suppose you create a Deployment to create 5 replicas of `nginx:1.7.9`, For example, suppose you create a Deployment to create 5 replicas of `nginx:1.7.9`,
but then updates the Deployment to create 5 replicas of `nginx:1.9.1`, when only 3 but then update the Deployment to create 5 replicas of `nginx:1.9.1`, when only 3
replicas of `nginx:1.7.9` had been created. In that case, Deployment will immediately start replicas of `nginx:1.7.9` had been created. In that case, the Deployment immediately starts
killing the 3 `nginx:1.7.9` Pods that it had created, and will start creating killing the 3 `nginx:1.7.9` Pods that it had created, and starts creating
`nginx:1.9.1` Pods. It will not wait for 5 replicas of `nginx:1.7.9` to be created `nginx:1.9.1` Pods. It does not wait for the 5 replicas of `nginx:1.7.9` to be created
before changing course. before changing course.
### Label selector updates ### Label selector updates
@@ -323,56 +318,62 @@ all of the implications.
In API version `apps/v1`, a Deployment's label selector is immutable after it gets created. In API version `apps/v1`, a Deployment's label selector is immutable after it gets created.
{{< /note >}} {{< /note >}}
* Selector additions require the pod template labels in the Deployment spec to be updated with the new label too, * Selector additions require the Pod template labels in the Deployment spec to be updated with the new label too,
otherwise a validation error is returned. This change is a non-overlapping one, meaning that the new selector does otherwise a validation error is returned. This change is a non-overlapping one, meaning that the new selector does
not select ReplicaSets and Pods created with the old selector, resulting in orphaning all old ReplicaSets and not select ReplicaSets and Pods created with the old selector, resulting in orphaning all old ReplicaSets and
creating a new ReplicaSet. creating a new ReplicaSet.
* Selector updates -- that is, changing the existing value in a selector key -- result in the same behavior as additions. * Selector updates changes the existing value in a selector key -- result in the same behavior as additions.
* Selector removals -- that is, removing an existing key from the Deployment selector -- do not require any changes in the * Selector removals removes an existing key from the Deployment selector -- do not require any changes in the
pod template labels. No existing ReplicaSet is orphaned, and a new ReplicaSet is not created, but note that the Pod template labels. Existing ReplicaSets are not orphaned, and a new ReplicaSet is not created, but note that the
removed label still exists in any existing Pods and ReplicaSets. removed label still exists in any existing Pods and ReplicaSets.
## Rolling Back a Deployment ## Rolling Back a Deployment
Sometimes you may want to rollback a Deployment; for example, when the Deployment is not stable, such as crash looping. Sometimes, you may want to rollback a Deployment; for example, when the Deployment is not stable, such as crash looping.
By default, all of the Deployment's rollout history is kept in the system so that you can rollback anytime you want By default, all of the Deployment's rollout history is kept in the system so that you can rollback anytime you want
(you can change that by modifying revision history limit). (you can change that by modifying revision history limit).
{{< note >}} {{< note >}}
A Deployment's revision is created when a Deployment's rollout is triggered. This means that the A Deployment's revision is created when a Deployment's rollout is triggered. This means that the
new revision is created if and only if the Deployment's pod template (`.spec.template`) is changed, new revision is created if and only if the Deployment's Pod template (`.spec.template`) is changed,
for example if you update the labels or container images of the template. Other updates, such as scaling the Deployment, for example if you update the labels or container images of the template. Other updates, such as scaling the Deployment,
do not create a Deployment revision, so that you can facilitate simultaneous manual- or auto-scaling. do not create a Deployment revision, so that you can facilitate simultaneous manual- or auto-scaling.
This means that when you roll back to an earlier revision, only the Deployment's pod template part is This means that when you roll back to an earlier revision, only the Deployment's Pod template part is
rolled back. rolled back.
{{< /note >}} {{< /note >}}
Suppose that you made a typo while updating the Deployment, by putting the image name as `nginx:1.91` instead of `nginx:1.9.1`: * Suppose that you made a typo while updating the Deployment, by putting the image name as `nginx:1.91` instead of `nginx:1.9.1`:
```shell ```shell
kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment image updated deployment.apps/nginx-deployment image updated
``` ```
The rollout will be stuck. * The rollout gets stuck. You can verify it by checking the rollout status:
```shell ```shell
kubectl rollout status deployment.v1.apps/nginx-deployment kubectl rollout status deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
Waiting for rollout to finish: 1 out of 3 new replicas have been updated... Waiting for rollout to finish: 1 out of 3 new replicas have been updated...
``` ```
Press Ctrl-C to stop the above rollout status watch. For more information on stuck rollouts, * Press Ctrl-C to stop the above rollout status watch. For more information on stuck rollouts,
[read more here](#deployment-status). [read more here](#deployment-status).
You will see that the number of old replicas (nginx-deployment-1564180365 and nginx-deployment-2035384211) is 2, and new replicas (nginx-deployment-3066724191) is 1. * You see that the number of old replicas (`nginx-deployment-1564180365` and `nginx-deployment-2035384211`) is 2, and new replicas (nginx-deployment-3066724191) is 1.
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-deployment-1564180365 3 3 3 25s nginx-deployment-1564180365 3 3 3 25s
@@ -380,11 +381,13 @@ nginx-deployment-2035384211 0 0 0 36s
nginx-deployment-3066724191 1 1 0 6s nginx-deployment-3066724191 1 1 0 6s
``` ```
Looking at the Pods created, you will see that 1 Pod created by new ReplicaSet is stuck in an image pull loop. * Looking at the Pods created, you see that 1 Pod created by new ReplicaSet is stuck in an image pull loop.
```shell ```shell
kubectl get pods kubectl get pods
``` ```
The output is similar to this:
``` ```
NAME READY STATUS RESTARTS AGE NAME READY STATUS RESTARTS AGE
nginx-deployment-1564180365-70iae 1/1 Running 0 25s nginx-deployment-1564180365-70iae 1/1 Running 0 25s
@@ -394,14 +397,17 @@ nginx-deployment-3066724191-08mng 0/1 ImagePullBackOff 0 6s
``` ```
{{< note >}} {{< note >}}
The Deployment controller will stop the bad rollout automatically, and will stop scaling up the new The Deployment controller stops the bad rollout automatically, and stops scaling up the new
ReplicaSet. This depends on the rollingUpdate parameters (`maxUnavailable` specifically) that you have specified. ReplicaSet. This depends on the rollingUpdate parameters (`maxUnavailable` specifically) that you have specified.
Kubernetes by default sets the value to 25%. Kubernetes by default sets the value to 25%.
{{< /note >}} {{< /note >}}
* Get the description of the Deployment:
```shell ```shell
kubectl describe deployment kubectl describe deployment
``` ```
The output is similar to this:
``` ```
Name: nginx-deployment Name: nginx-deployment
Namespace: default Namespace: default
@@ -446,11 +452,13 @@ To fix this, you need to rollback to a previous revision of Deployment that is s
### Checking Rollout History of a Deployment ### Checking Rollout History of a Deployment
First, check the revisions of this deployment: Follow the steps given below to check the rollout history:
1. First, check the revisions of this Deployment:
```shell ```shell
kubectl rollout history deployment.v1.apps/nginx-deployment kubectl rollout history deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployments "nginx-deployment" deployments "nginx-deployment"
REVISION CHANGE-CAUSE REVISION CHANGE-CAUSE
@@ -458,17 +466,19 @@ REVISION CHANGE-CAUSE
2 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true 2 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
3 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true 3 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true
``` ```
`CHANGE-CAUSE` is copied from the Deployment annotation `kubernetes.io/change-cause` to its revisions upon creation. You could specify the`CHANGE-CAUSE` message by:
`CHANGE-CAUSE` is copied from the Deployment annotation `kubernetes.io/change-cause` to its revisions upon creation. You can specify the`CHANGE-CAUSE` message by:
* Annotating the Deployment with `kubectl annotate deployment.v1.apps/nginx-deployment kubernetes.io/change-cause="image updated to 1.9.1"` * Annotating the Deployment with `kubectl annotate deployment.v1.apps/nginx-deployment kubernetes.io/change-cause="image updated to 1.9.1"`
* Append the `--record` flag to save the `kubectl` command that is making changes to the resource. * Append the `--record` flag to save the `kubectl` command that is making changes to the resource.
* Manually editing the manifest of the resource. * Manually editing the manifest of the resource.
To further see the details of each revision, run: 2. To see the details of each revision, run:
```shell ```shell
kubectl rollout history deployment.v1.apps/nginx-deployment --revision=2 kubectl rollout history deployment.v1.apps/nginx-deployment --revision=2
``` ```
The output is similar to this:
``` ```
deployments "nginx-deployment" revision 2 deployments "nginx-deployment" revision 2
Labels: app=nginx Labels: app=nginx
@@ -486,21 +496,24 @@ deployments "nginx-deployment" revision 2
``` ```
### Rolling Back to a Previous Revision ### Rolling Back to a Previous Revision
Follow the steps given below to rollback the Deployment from the current version to the previous version, which is version 2.
Now you've decided to undo the current rollout and rollback to the previous revision: 1. Now you've decided to undo the current rollout and rollback to the previous revision:
```shell ```shell
kubectl rollout undo deployment.v1.apps/nginx-deployment kubectl rollout undo deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment deployment.apps/nginx-deployment
``` ```
Alternatively, you can rollback to a specific revision by specifying it with `--to-revision`: Alternatively, you can rollback to a specific revision by specifying it with `--to-revision`:
```shell ```shell
kubectl rollout undo deployment.v1.apps/nginx-deployment --to-revision=2 kubectl rollout undo deployment.v1.apps/nginx-deployment --to-revision=2
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment deployment.apps/nginx-deployment
``` ```
@@ -510,17 +523,21 @@ For more details about rollout related commands, read [`kubectl rollout`](/docs/
The Deployment is now rolled back to a previous stable revision. As you can see, a `DeploymentRollback` event The Deployment is now rolled back to a previous stable revision. As you can see, a `DeploymentRollback` event
for rolling back to revision 2 is generated from Deployment controller. for rolling back to revision 2 is generated from Deployment controller.
2. Check if the rollback was successful and the Deployment is running as expected, run:
```shell ```shell
kubectl get deployment nginx-deployment kubectl get deployment nginx-deployment
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 3 3 3 3 30m nginx-deployment 3 3 3 3 30m
``` ```
3. Get the description of the Deployment:
```shell ```shell
kubectl describe deployment nginx-deployment kubectl describe deployment nginx-deployment
``` ```
The output is similar to this:
``` ```
Name: nginx-deployment Name: nginx-deployment
Namespace: default Namespace: default
@@ -572,17 +589,19 @@ You can scale a Deployment by using the following command:
```shell ```shell
kubectl scale deployment.v1.apps/nginx-deployment --replicas=10 kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment scaled deployment.apps/nginx-deployment scaled
``` ```
Assuming [horizontal pod autoscaling](/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/) is enabled Assuming [horizontal Pod autoscaling](/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/) is enabled
in your cluster, you can setup an autoscaler for your Deployment and choose the minimum and maximum number of in your cluster, you can setup an autoscaler for your Deployment and choose the minimum and maximum number of
Pods you want to run based on the CPU utilization of your existing Pods. Pods you want to run based on the CPU utilization of your existing Pods.
```shell ```shell
kubectl autoscale deployment.v1.apps/nginx-deployment --min=10 --max=15 --cpu-percent=80 kubectl autoscale deployment.v1.apps/nginx-deployment --min=10 --max=15 --cpu-percent=80
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment scaled deployment.apps/nginx-deployment scaled
``` ```
@@ -591,62 +610,70 @@ deployment.apps/nginx-deployment scaled
RollingUpdate Deployments support running multiple versions of an application at the same time. When you RollingUpdate Deployments support running multiple versions of an application at the same time. When you
or an autoscaler scales a RollingUpdate Deployment that is in the middle of a rollout (either in progress or an autoscaler scales a RollingUpdate Deployment that is in the middle of a rollout (either in progress
or paused), then the Deployment controller will balance the additional replicas in the existing active or paused), the Deployment controller balances the additional replicas in the existing active
ReplicaSets (ReplicaSets with Pods) in order to mitigate risk. This is called *proportional scaling*. ReplicaSets (ReplicaSets with Pods) in order to mitigate risk. This is called *proportional scaling*.
For example, you are running a Deployment with 10 replicas, [maxSurge](#max-surge)=3, and [maxUnavailable](#max-unavailable)=2. For example, you are running a Deployment with 10 replicas, [maxSurge](#max-surge)=3, and [maxUnavailable](#max-unavailable)=2.
* Ensure that the 10 replicas in your Deployment are running.
```shell ```shell
kubectl get deploy kubectl get deploy
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 10 10 10 10 50s nginx-deployment 10 10 10 10 50s
``` ```
You update to a new image which happens to be unresolvable from inside the cluster. * You update to a new image which happens to be unresolvable from inside the cluster.
```shell ```shell
kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:sometag kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:sometag
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment image updated deployment.apps/nginx-deployment image updated
``` ```
The image update starts a new rollout with ReplicaSet nginx-deployment-1989198191, but it's blocked due to the * The image update starts a new rollout with ReplicaSet nginx-deployment-1989198191, but it's blocked due to the
`maxUnavailable` requirement that you mentioned above. `maxUnavailable` requirement that you mentioned above. Check out the rollout status:
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-deployment-1989198191 5 5 0 9s nginx-deployment-1989198191 5 5 0 9s
nginx-deployment-618515232 8 8 8 1m nginx-deployment-618515232 8 8 8 1m
``` ```
Then a new scaling request for the Deployment comes along. The autoscaler increments the Deployment replicas * Then a new scaling request for the Deployment comes along. The autoscaler increments the Deployment replicas
to 15. The Deployment controller needs to decide where to add these new 5 replicas. If you weren't using to 15. The Deployment controller needs to decide where to add these new 5 replicas. If you weren't using
proportional scaling, all 5 of them would be added in the new ReplicaSet. With proportional scaling, you proportional scaling, all 5 of them would be added in the new ReplicaSet. With proportional scaling, you
spread the additional replicas across all ReplicaSets. Bigger proportions go to the ReplicaSets with the spread the additional replicas across all ReplicaSets. Bigger proportions go to the ReplicaSets with the
most replicas and lower proportions go to ReplicaSets with less replicas. Any leftovers are added to the most replicas and lower proportions go to ReplicaSets with less replicas. Any leftovers are added to the
ReplicaSet with the most replicas. ReplicaSets with zero replicas are not scaled up. ReplicaSet with the most replicas. ReplicaSets with zero replicas are not scaled up.
In our example above, 3 replicas will be added to the old ReplicaSet and 2 replicas will be added to the In our example above, 3 replicas are added to the old ReplicaSet and 2 replicas are added to the
new ReplicaSet. The rollout process should eventually move all replicas to the new ReplicaSet, assuming new ReplicaSet. The rollout process should eventually move all replicas to the new ReplicaSet, assuming
the new replicas become healthy. the new replicas become healthy. To confirm this, run:
```shell ```shell
kubectl get deploy kubectl get deploy
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx-deployment 15 18 7 8 7m nginx-deployment 15 18 7 8 7m
``` ```
The rollout status confirms how the replicas were added to each ReplicaSet.
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-deployment-1989198191 7 7 0 7m nginx-deployment-1989198191 7 7 0 7m
@@ -655,68 +682,77 @@ nginx-deployment-618515232 11 11 11 7m
## Pausing and Resuming a Deployment ## Pausing and Resuming a Deployment
You can pause a Deployment before triggering one or more updates and then resume it. This will allow you to You can pause a Deployment before triggering one or more updates and then resume it. This allows you to
apply multiple fixes in between pausing and resuming without triggering unnecessary rollouts. apply multiple fixes in between pausing and resuming without triggering unnecessary rollouts.
For example, with a Deployment that was just created: * For example, with a Deployment that was just created:
Get the Deployment details:
```shell ```shell
kubectl get deploy kubectl get deploy
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
nginx 3 3 3 3 1m nginx 3 3 3 3 1m
``` ```
Get the rollout status:
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-2142116321 3 3 3 1m nginx-2142116321 3 3 3 1m
``` ```
Pause by running the following command: * Pause by running the following command:
```shell ```shell
kubectl rollout pause deployment.v1.apps/nginx-deployment kubectl rollout pause deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment paused deployment.apps/nginx-deployment paused
``` ```
Then update the image of the Deployment: * Then update the image of the Deployment:
```shell ```shell
kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment image updated deployment.apps/nginx-deployment image updated
``` ```
Notice that no new rollout started: * Notice that no new rollout started:
```shell ```shell
kubectl rollout history deployment.v1.apps/nginx-deployment kubectl rollout history deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployments "nginx" deployments "nginx"
REVISION CHANGE-CAUSE REVISION CHANGE-CAUSE
1 <none> 1 <none>
``` ```
* Get the rollout status to ensure that the Deployment is updates successfully:
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-2142116321 3 3 3 2m nginx-2142116321 3 3 3 2m
``` ```
You can make as many updates as you wish, for example, update the resources that will be used: * You can make as many updates as you wish, for example, update the resources that will be used:
```shell ```shell
kubectl set resources deployment.v1.apps/nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi kubectl set resources deployment.v1.apps/nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment resource requirements updated deployment.apps/nginx-deployment resource requirements updated
``` ```
@@ -724,20 +760,21 @@ deployment.apps/nginx-deployment resource requirements updated
The initial state of the Deployment prior to pausing it will continue its function, but new updates to The initial state of the Deployment prior to pausing it will continue its function, but new updates to
the Deployment will not have any effect as long as the Deployment is paused. the Deployment will not have any effect as long as the Deployment is paused.
Eventually, resume the Deployment and observe a new ReplicaSet coming up with all the new updates: * Eventually, resume the Deployment and observe a new ReplicaSet coming up with all the new updates:
```shell ```shell
kubectl rollout resume deployment.v1.apps/nginx-deployment kubectl rollout resume deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment resumed deployment.apps/nginx-deployment resumed
``` ```
* Watch the status of the rollout until it's done.
```shell ```shell
kubectl get rs -w kubectl get rs -w
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-2142116321 2 2 2 2m nginx-2142116321 2 2 2 2m
@@ -754,17 +791,18 @@ nginx-2142116321 0 1 1 2m
nginx-2142116321 0 1 1 2m nginx-2142116321 0 1 1 2m
nginx-2142116321 0 0 0 2m nginx-2142116321 0 0 0 2m
nginx-3926361531 3 3 3 20s nginx-3926361531 3 3 3 20s
``` ```
* Get the status of the latest rollout:
```shell ```shell
kubectl get rs kubectl get rs
``` ```
The output is similar to this:
``` ```
NAME DESIRED CURRENT READY AGE NAME DESIRED CURRENT READY AGE
nginx-2142116321 0 0 0 2m nginx-2142116321 0 0 0 2m
nginx-3926361531 3 3 3 28s nginx-3926361531 3 3 3 28s
``` ```
{{< note >}} {{< note >}}
You cannot rollback a paused Deployment until you resume it. You cannot rollback a paused Deployment until you resume it.
{{< /note >}} {{< /note >}}
@@ -800,6 +838,7 @@ successfully, `kubectl rollout status` returns a zero exit code.
```shell ```shell
kubectl rollout status deployment.v1.apps/nginx-deployment kubectl rollout status deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
Waiting for rollout to finish: 2 of 3 updated replicas are available... Waiting for rollout to finish: 2 of 3 updated replicas are available...
deployment.apps/nginx-deployment successfully rolled out deployment.apps/nginx-deployment successfully rolled out
@@ -830,6 +869,7 @@ lack of progress for a Deployment after 10 minutes:
```shell ```shell
kubectl patch deployment.v1.apps/nginx-deployment -p '{"spec":{"progressDeadlineSeconds":600}}' kubectl patch deployment.v1.apps/nginx-deployment -p '{"spec":{"progressDeadlineSeconds":600}}'
``` ```
The output is similar to this:
``` ```
deployment.apps/nginx-deployment patched deployment.apps/nginx-deployment patched
``` ```
@@ -843,7 +883,7 @@ attributes to the Deployment's `.status.conditions`:
See the [Kubernetes API conventions](https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#typical-status-properties) for more information on status conditions. See the [Kubernetes API conventions](https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#typical-status-properties) for more information on status conditions.
{{< note >}} {{< note >}}
Kubernetes will take no action on a stalled Deployment other than to report a status condition with Kubernetes takes no action on a stalled Deployment other than to report a status condition with
`Reason=ProgressDeadlineExceeded`. Higher level orchestrators can take advantage of it and act accordingly, for `Reason=ProgressDeadlineExceeded`. Higher level orchestrators can take advantage of it and act accordingly, for
example, rollback the Deployment to its previous version. example, rollback the Deployment to its previous version.
{{< /note >}} {{< /note >}}
@@ -861,6 +901,7 @@ insufficient quota. If you describe the Deployment you will notice the following
```shell ```shell
kubectl describe deployment nginx-deployment kubectl describe deployment nginx-deployment
``` ```
The output is similar to this:
``` ```
<...> <...>
Conditions: Conditions:
@@ -872,7 +913,7 @@ Conditions:
<...> <...>
``` ```
If you run `kubectl get deployment nginx-deployment -o yaml`, the Deployment status might look like this: If you run `kubectl get deployment nginx-deployment -o yaml`, the Deployment status is similar to this:
``` ```
status: status:
@@ -939,6 +980,7 @@ returns a non-zero exit code if the Deployment has exceeded the progression dead
```shell ```shell
kubectl rollout status deployment.v1.apps/nginx-deployment kubectl rollout status deployment.v1.apps/nginx-deployment
``` ```
The output is similar to this:
``` ```
Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated...
error: deployment "nginx" exceeded its progress deadline error: deployment "nginx" exceeded its progress deadline
@@ -949,7 +991,7 @@ $ echo $?
### Operating on a failed deployment ### Operating on a failed deployment
All actions that apply to a complete Deployment also apply to a failed Deployment. You can scale it up/down, roll back All actions that apply to a complete Deployment also apply to a failed Deployment. You can scale it up/down, roll back
to a previous revision, or even pause it if you need to apply multiple tweaks in the Deployment pod template. to a previous revision, or even pause it if you need to apply multiple tweaks in the Deployment Pod template.
## Clean up Policy ## Clean up Policy
@@ -962,9 +1004,7 @@ Explicitly setting this field to 0, will result in cleaning up all the history o
thus that Deployment will not be able to roll back. thus that Deployment will not be able to roll back.
{{< /note >}} {{< /note >}}
## Use Cases ## Canary Deployment
### Canary Deployment
If you want to roll out releases to a subset of users or servers using the Deployment, you If you want to roll out releases to a subset of users or servers using the Deployment, you
can create multiple Deployments, one for each release, following the canary pattern described in can create multiple Deployments, one for each release, following the canary pattern described in
@@ -982,10 +1022,10 @@ A Deployment also needs a [`.spec` section](https://git.k8s.io/community/contrib
The `.spec.template` and `.spec.selector` are the only required field of the `.spec`. The `.spec.template` and `.spec.selector` are the only required field of the `.spec`.
The `.spec.template` is a [pod template](/docs/concepts/workloads/pods/pod-overview/#pod-templates). It has exactly the same schema as a [Pod](/docs/concepts/workloads/pods/pod/), except it is nested and does not have an The `.spec.template` is a [Pod template](/docs/concepts/workloads/pods/pod-overview/#pod-templates). It has exactly the same schema as a [Pod](/docs/concepts/workloads/pods/pod/), except it is nested and does not have an
`apiVersion` or `kind`. `apiVersion` or `kind`.
In addition to required fields for a Pod, a pod template in a Deployment must specify appropriate In addition to required fields for a Pod, a Pod template in a Deployment must specify appropriate
labels and an appropriate restart policy. For labels, make sure not to overlap with other controllers. See [selector](#selector)). labels and an appropriate restart policy. For labels, make sure not to overlap with other controllers. See [selector](#selector)).
Only a [`.spec.template.spec.restartPolicy`](/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy) equal to `Always` is Only a [`.spec.template.spec.restartPolicy`](/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy) equal to `Always` is
@@ -998,7 +1038,7 @@ allowed, which is the default if not specified.
### Selector ### Selector
`.spec.selector` is an required field that specifies a [label selector](/docs/concepts/overview/working-with-objects/labels/) `.spec.selector` is an required field that specifies a [label selector](/docs/concepts/overview/working-with-objects/labels/)
for the Pods targeted by this deployment. for the Pods targeted by this Deployment.
`.spec.selector` must match `.spec.template.metadata.labels`, or it will be rejected by the API. `.spec.selector` must match `.spec.template.metadata.labels`, or it will be rejected by the API.
@@ -1009,9 +1049,9 @@ from `.spec.template` or if the total number of such Pods exceeds `.spec.replica
Pods with `.spec.template` if the number of Pods is less than the desired number. Pods with `.spec.template` if the number of Pods is less than the desired number.
{{< note >}} {{< note >}}
You should not create other pods whose labels match this selector, either directly, by creating You should not create other Pods whose labels match this selector, either directly, by creating
another Deployment, or by creating another controller such as a ReplicaSet or a ReplicationController. If you another Deployment, or by creating another controller such as a ReplicaSet or a ReplicationController. If you
do so, the first Deployment thinks that it created these other pods. Kubernetes does not stop you from doing this. do so, the first Deployment thinks that it created these other Pods. Kubernetes does not stop you from doing this.
{{< /note >}} {{< /note >}}
If you have multiple controllers that have overlapping selectors, the controllers will fight with each If you have multiple controllers that have overlapping selectors, the controllers will fight with each
@@ -1062,8 +1102,8 @@ total number of Pods running at any time during the update is at most 130% of de
`.spec.progressDeadlineSeconds` is an optional field that specifies the number of seconds you want `.spec.progressDeadlineSeconds` is an optional field that specifies the number of seconds you want
to wait for your Deployment to progress before the system reports back that the Deployment has to wait for your Deployment to progress before the system reports back that the Deployment has
[failed progressing](#failed-deployment) - surfaced as a condition with `Type=Progressing`, `Status=False`. [failed progressing](#failed-deployment) - surfaced as a condition with `Type=Progressing`, `Status=False`.
and `Reason=ProgressDeadlineExceeded` in the status of the resource. The deployment controller will keep and `Reason=ProgressDeadlineExceeded` in the status of the resource. The Deployment controller will keep
retrying the Deployment. In the future, once automatic rollback will be implemented, the deployment retrying the Deployment. In the future, once automatic rollback will be implemented, the Deployment
controller will roll back a Deployment as soon as it observes such a condition. controller will roll back a Deployment as soon as it observes such a condition.
If specified, this field needs to be greater than `.spec.minReadySeconds`. If specified, this field needs to be greater than `.spec.minReadySeconds`.