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Merge pull request #368 from janetkuo/canary-deployment

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Teach how to run canary deployments
This commit is contained in:
Brian Grant
2016-04-27 07:51:36 -07:00
parent d13fa9a1de 74ae94d43d
commit bc4fec4ad8
2 changed files with 38 additions and 11 deletions
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docs/user-guide/deployments.md
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Note: A paused Deployment cannot be scaled at this moment, and we will add this feature in 1.3 release, see [issue #20853](https://github.com/kubernetes/kubernetes/issues/20853). You cannot rollback a paused Deployment either, and you should resume a Deployment first before doing a rollback.
## Use Cases
### Canary Deployment
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 [managing resources](/docs/user-guide/managing-deployments/#canary-deployments).
## Writing a Deployment Spec
As with all other Kubernetes configs, a Deployment needs `apiVersion`, `kind`, and
docs/user-guide/managing-deployments.md
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## Canary deployments
Another scenario where multiple labels are needed is to distinguish deployments of different releases or configurations of the same component. For example, it is common practice to deploy a *canary* of a new application release (specified via image tag) side by side with the previous release so that the new release can receive live production traffic before fully rolling it out. For instance, a new release of the guestbook frontend might carry the following labels:
```yaml
labels:
app: guestbook
tier: frontend
track: canary
```
and the primary, stable release would have a different value of the `track` label, so that two sets of pods would not overlap:
Another scenario where multiple labels are needed is to distinguish deployments of different releases or configurations of the same component. It is common practice to deploy a *canary* of a new application release (specified via image tag in the pod template) side by side with the previous release so that the new release can receive live production traffic before fully rolling it out.
For instance, you can use a `track` label to differentiate different releases.
The primary, stable release would have a `track` label with value as `stable`:
```yaml
name: frontend
replicas: 3
...
labels:
app: guestbook
tier: frontend
track: stable
...
image: gb-frontend:v3
```
The frontend service would span both sets of replicas by selecting the common subset of their labels, omitting the `track` label:
and then you can create a new release of the guestbook frontend that carries the `track` label with different value (i.e. `canary`), so that two sets of pods would not overlap:
```yaml
name: frontend-canary
replicas: 1
...
labels:
app: guestbook
tier: frontend
track: canary
...
image: gb-frontend:v4
```
The frontend service would span both sets of replicas by selecting the common subset of their labels (i.e. omitting the `track` label), so that the traffic will be redirected to both applications:
```yaml
selector:
@@ -162,6 +177,11 @@ The frontend service would span both sets of replicas by selecting the common su
tier: frontend
```
You can tweak the number of replicas of the stable and canary releases to determine the ratio of each release that will receive live production traffic (in this case, 3:1).
Once you're confident, you can update the stable track to the new application release and remove the canary one.
For a more concrete example, check the [tutorial of deploying Ghost](https://github.com/kelseyhightower/talks/tree/master/kubecon-eu-2016/demo#deploy-a-canary).
## Updating labels
Sometimes existing pods and other resources need to be relabeled before creating new resources. This can be done with `kubectl label`.