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Minor Fixes - Style Guide, Numbered Lists (#9934)

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Cody Clark
2018-08-20 13:47:30 -07:00
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content/en/docs/tutorials/stateful-application/cassandra.md
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--- ---
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This tutorial shows you how to develop a native cloud [Cassandra](http://cassandra.apache.org/) deployment on Kubernetes. In this example, a custom Cassandra `SeedProvider` enables Cassandra to discover new Cassandra nodes as they join the cluster. This tutorial shows you how to develop a native cloud [Cassandra](http://cassandra.apache.org/) deployment on Kubernetes. In this example, a custom Cassandra *SeedProvider* enables Cassandra to discover new Cassandra nodes as they join the cluster.
`StatefulSet`s make it easier to deploy stateful applications within a clustered environment. For more information on the features used in this tutorial, see the [`StatefulSet`](/docs/concepts/workloads/controllers/statefulset/) documentation. *StatefulSets* make it easier to deploy stateful applications within a clustered environment. For more information on the features used in this tutorial, see the [*StatefulSet*](/docs/concepts/workloads/controllers/statefulset/) documentation.
**Cassandra on Docker** **Cassandra on Docker**
The `Pod`s in this tutorial use the [`gcr.io/google-samples/cassandra:v13`](https://github.com/kubernetes/examples/blob/master/cassandra/image/Dockerfile) The *Pods* in this tutorial use the [`gcr.io/google-samples/cassandra:v13`](https://github.com/kubernetes/examples/blob/master/cassandra/image/Dockerfile)
image from Google's [container registry](https://cloud.google.com/container-registry/docs/). image from Google's [container registry](https://cloud.google.com/container-registry/docs/).
The Docker image above is based on [debian-base](https://github.com/kubernetes/kubernetes/tree/master/build/debian-base) The Docker image above is based on [debian-base](https://github.com/kubernetes/kubernetes/tree/master/build/debian-base)
and includes OpenJDK 8. and includes OpenJDK 8.
@@ -30,17 +30,17 @@ By using environment variables you can change values that are inserted into `cas
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* Create and validate a Cassandra headless [`Service`](/docs/concepts/services-networking/service/). * Create and validate a Cassandra headless [*Service*](/docs/concepts/services-networking/service/).
* Use a [`StatefulSet`](/docs/concepts/workloads/controllers/statefulset/) to create a Cassandra ring. * Use a [StatefulSet](/docs/concepts/workloads/controllers/statefulset/) to create a Cassandra ring.
* Validate the [`StatefulSet`](/docs/concepts/workloads/controllers/statefulset/). * Validate the [StatefulSet](/docs/concepts/workloads/controllers/statefulset/).
* Modify the [`StatefulSet`](/docs/concepts/workloads/controllers/statefulset/). * Modify the [StatefulSet](/docs/concepts/workloads/controllers/statefulset/).
* Delete the [`StatefulSet`](/docs/concepts/workloads/controllers/statefulset/) and its [`Pod`s](/docs/concepts/workloads/pods/pod/). * Delete the [StatefulSet](/docs/concepts/workloads/controllers/statefulset/) and its [Pods](/docs/concepts/workloads/pods/pod/).
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{{% capture prerequisites %}} {{% capture prerequisites %}}
To complete this tutorial, you should already have a basic familiarity with [`Pod`s](/docs/concepts/workloads/pods/pod/), [`Service`s](/docs/concepts/services-networking/service/), and [`StatefulSet`s](/docs/concepts/workloads/controllers/statefulset/). In addition, you should: To complete this tutorial, you should already have a basic familiarity with [Pods](/docs/concepts/workloads/pods/pod/), [Services](/docs/concepts/services-networking/service/), and [StatefulSets](/docs/concepts/workloads/controllers/statefulset/). In addition, you should:
* [Install and Configure](/docs/tasks/tools/install-kubectl/) the `kubectl` command-line tool * [Install and Configure](/docs/tasks/tools/install-kubectl/) the *kubectl* command-line tool
* Download [`cassandra-service.yaml`](/examples/application/cassandra/cassandra-service.yaml) * Download [`cassandra-service.yaml`](/examples/application/cassandra/cassandra-service.yaml)
and [`cassandra-statefulset.yaml`](/examples/application/cassandra/cassandra-statefulset.yaml) and [`cassandra-statefulset.yaml`](/examples/application/cassandra/cassandra-statefulset.yaml)
@@ -54,7 +54,7 @@ To complete this tutorial, you should already have a basic familiarity with [`Po
### Additional Minikube Setup Instructions ### Additional Minikube Setup Instructions
{{< caution >}} {{< caution >}}
**Caution:** [Minikube](/docs/getting-started-guides/minikube/) defaults to 1024MB of memory and 1 CPU. Running Minikube with the default resource configuration may result in insufficient resource errors during this tutorial. To avoid these errors, we recommend running Minikube with 5 GB of memory and 4 CPUs: **Caution:** [Minikube](/docs/getting-started-guides/minikube/) defaults to 1024MB of memory and 1 CPU. Running Minikube with the default resource configuration results in insufficient resource errors during this tutorial. To avoid these errors, start Minikube with the folllowing settings:
```shell ```shell
minikube start --memory 5120 --cpus=4 minikube start --memory 5120 --cpus=4
@@ -66,14 +66,14 @@ minikube start --memory 5120 --cpus=4
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## Creating a Cassandra Headless Service ## Creating a Cassandra Headless Service
A Kubernetes [`Service`](/docs/concepts/services-networking/service/) describes a set of [`Pod`s](/docs/concepts/workloads/pods/pod/) that perform the same task. A Kubernetes [Service](/docs/concepts/services-networking/service/) describes a set of [Pods](/docs/concepts/workloads/pods/pod/) that perform the same task.
The following `Service` is used for DNS lookups between Cassandra `Pod`s and clients within the Kubernetes cluster. The following `Service` is used for DNS lookups between Cassandra Pods and clients within the Kubernetes cluster.
{{< codenew file="application/cassandra/cassandra-service.yaml" >}} {{< codenew file="application/cassandra/cassandra-service.yaml" >}}
1. Launch a terminal window in the directory you downloaded the manifest files. 1. Launch a terminal window in the directory you downloaded the manifest files.
1. Create a `Service` to track all Cassandra `StatefulSet` nodes from the `cassandra-service.yaml` file: 1. Create a Service to track all Cassandra StatefulSet nodes from the `cassandra-service.yaml` file:
```shell ```shell
kubectl create -f https://k8s.io/examples/application/cassandra/cassandra-service.yaml kubectl create -f https://k8s.io/examples/application/cassandra/cassandra-service.yaml
@@ -81,7 +81,7 @@ The following `Service` is used for DNS lookups between Cassandra `Pod`s and cli
### Validating (optional) ### Validating (optional)
Get the Cassandra `Service`. Get the Cassandra Service.
```shell ```shell
kubectl get svc cassandra kubectl get svc cassandra
@@ -98,16 +98,16 @@ Service creation failed if anything else is returned. Read [Debug Services](/doc
## Using a StatefulSet to Create a Cassandra Ring ## Using a StatefulSet to Create a Cassandra Ring
The `StatefulSet` manifest, included below, creates a Cassandra ring that consists of three `Pod`s. The StatefulSet manifest, included below, creates a Cassandra ring that consists of three Pods.
{{< note >}} {{< note >}}
**Note:** This example uses the default provisioner for Minikube. Please update the following `StatefulSet` for the cloud you are working with. **Note:** This example uses the default provisioner for Minikube. Please update the following StatefulSet for the cloud you are working with.
{{< /note >}} {{< /note >}}
{{< codenew file="application/cassandra/cassandra-statefulset.yaml" >}} {{< codenew file="application/cassandra/cassandra-statefulset.yaml" >}}
1. Update the `StatefulSet` if necessary. 1. Update the StatefulSet if necessary.
1. Create the Cassandra `StatefulSet` from the `cassandra-statefulset.yaml` file: 1. Create the Cassandra StatefulSet from the `cassandra-statefulset.yaml` file:
```shell ```shell
kubectl create -f https://k8s.io/examples/application/cassandra/cassandra-statefulset.yaml kubectl create -f https://k8s.io/examples/application/cassandra/cassandra-statefulset.yaml
@@ -115,7 +115,7 @@ The `StatefulSet` manifest, included below, creates a Cassandra ring that consis
## Validating The Cassandra StatefulSet ## Validating The Cassandra StatefulSet
1. Get the Cassandra `StatefulSet`: 1. Get the Cassandra StatefulSet:
```shell ```shell
kubectl get statefulset cassandra kubectl get statefulset cassandra
@@ -128,9 +128,9 @@ The `StatefulSet` manifest, included below, creates a Cassandra ring that consis
cassandra 3 0 13s cassandra 3 0 13s
``` ```
The `StatefulSet` resource deploys `Pod`s sequentially. The `StatefulSet` resource deploys Pods sequentially.
1. Get the `Pod`s to see the ordered creation status: 1. Get the Pods to see the ordered creation status:
```shell ```shell
kubectl get pods -l="app=cassandra" kubectl get pods -l="app=cassandra"
@@ -144,7 +144,7 @@ The `StatefulSet` manifest, included below, creates a Cassandra ring that consis
cassandra-1 0/1 ContainerCreating 0 8s cassandra-1 0/1 ContainerCreating 0 8s
``` ```
Please note that it may take several minutes for all three `Pod`s to deploy. Once they are deployed, the same command returns: It can take several minutes for all three Pods to deploy. Once they are deployed, the same command returns:
``` ```
NAME READY STATUS RESTARTS AGE NAME READY STATUS RESTARTS AGE
@@ -174,7 +174,7 @@ The `StatefulSet` manifest, included below, creates a Cassandra ring that consis
## Modifying the Cassandra StatefulSet ## Modifying the Cassandra StatefulSet
Use `kubectl edit` to modify the size of a Cassandra `StatefulSet`. Use `kubectl edit` to modify the size of a Cassandra StatefulSet.
1. Run the following command: 1. Run the following command:
@@ -205,11 +205,11 @@ Use `kubectl edit` to modify the size of a Cassandra `StatefulSet`.
replicas: 3 replicas: 3
``` ```
2. Change the number of replicas to 4, and then save the manifest. 1. Change the number of replicas to 4, and then save the manifest.
The `StatefulSet` now contains 4 `Pod`s. The `StatefulSet` now contains 4 Pods.
1. Get the Cassandra `StatefulSet` to verify: 1. Get the Cassandra StatefulSet to verify:
```shell ```shell
kubectl get statefulset cassandra kubectl get statefulset cassandra
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Deleting or scaling a `StatefulSet` down does not delete the volumes associated with the `StatefulSet`. This ensures safety first: your data is more valuable than an auto purge of all related StatefulSet resources. Deleting or scaling a StatefulSet down does not delete the volumes associated with the StatefulSet. This setting is for your safety because your data is more valuable than automatically purging all related StatefulSet resources.
{{< warning >}} {{< warning >}}
**Warning:** Depending on the storage class and reclaim policy, deleting the `PersistentVolumeClaim`s may cause the associated volumes to also be deleted. Never assume you’ll be able to access data if its volume claims are deleted. **Warning:** Depending on the storage class and reclaim policy, deleting the *PersistentVolumeClaims* may cause the associated volumes to also be deleted. Never assume you’ll be able to access data if its volume claims are deleted.
{{< /warning >}} {{< /warning >}}
1. Run the following commands (chained together into a single command) to delete everything in the Cassandra `StatefulSet`: 1. Run the following commands (chained together into a single command) to delete everything in the Cassandra `StatefulSet`:
@@ -241,7 +241,7 @@ Deleting or scaling a `StatefulSet` down does not delete the volumes associated
&& kubectl delete pvc -l app=cassandra && kubectl delete pvc -l app=cassandra
``` ```
1. Run the following command to delete the Cassandra `Service`. 1. Run the following command to delete the Cassandra Service.
```shell ```shell
kubectl delete service -l app=cassandra kubectl delete service -l app=cassandra
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* Learn how to [Scale a `StatefulSet`](/docs/tasks/run-application/scale-stateful-set/). * Learn how to [Scale a StatefulSet](/docs/tasks/run-application/scale-stateful-set/).
* Learn more about the [`KubernetesSeedProvider`](https://github.com/kubernetes/examples/blob/master/cassandra/java/src/main/java/io/k8s/cassandra/KubernetesSeedProvider.java) * Learn more about the [*KubernetesSeedProvider*](https://github.com/kubernetes/examples/blob/master/cassandra/java/src/main/java/io/k8s/cassandra/KubernetesSeedProvider.java)
* See more custom [Seed Provider Configurations](https://git.k8s.io/examples/cassandra/java/README.md) * See more custom [Seed Provider Configurations](https://git.k8s.io/examples/cassandra/java/README.md)
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