112 lines
4.1 KiB
Markdown
112 lines
4.1 KiB
Markdown
---
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title: Federated Deployment
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content_template: templates/task
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---
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{{% capture overview %}}
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{{< note >}}
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{{< include "federation-current-state.md" >}}
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{{< /note >}}
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This guide explains how to use Deployments in the Federation control plane.
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Deployments in the federation control plane (referred to as "Federated Deployments" in
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this guide) are very similar to the traditional [Kubernetes
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Deployment](/docs/concepts/workloads/controllers/deployment/) and provide the same functionality.
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Creating them in the federation control plane ensures that the desired number of
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replicas exist across the registered clusters.
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{{< feature-state for_k8s_version="1.5" state="alpha" >}}
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Some features
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(such as full rollout compatibility) are still in development.
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{{% /capture %}}
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{{% capture prerequisites %}}
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* {{< include "federated-task-tutorial-prereqs.md" >}}
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* You should also have a basic
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[working knowledge of Kubernetes](/docs/setup/pick-right-solution/) in
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general and [Deployments](/docs/concepts/workloads/controllers/deployment/) in particular.
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{{% /capture %}}
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{{% capture steps %}}
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## Creating a Federated Deployment
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The API for Federated Deployment is compatible with the
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API for traditional Kubernetes Deployment. You can create a Deployment by sending
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a request to the federation apiserver.
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You can do that using [kubectl](/docs/user-guide/kubectl/) by running:
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``` shell
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kubectl --context=federation-cluster create -f mydeployment.yaml
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```
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The `--context=federation-cluster` flag tells kubectl to submit the
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request to the Federation apiserver instead of sending it to a Kubernetes
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cluster.
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Once a Federated Deployment is created, the federation control plane will create
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a Deployment in all underlying Kubernetes clusters.
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You can verify this by checking each of the underlying clusters, for example:
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``` shell
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kubectl --context=gce-asia-east1a get deployment mydep
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```
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The above assumes that you have a context named 'gce-asia-east1a'
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configured in your client for your cluster in that zone.
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These Deployments in underlying clusters will match the federation Deployment
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_except_ in the number of replicas and revision-related annotations.
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Federation control plane ensures that the
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sum of replicas in each cluster combined matches the desired number of replicas in the
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Federated Deployment.
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### Spreading Replicas in Underlying Clusters
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By default, replicas are spread equally in all the underlying clusters. For example:
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if you have 3 registered clusters and you create a Federated Deployment with
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`spec.replicas = 9`, then each Deployment in the 3 clusters will have
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`spec.replicas=3`.
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To modify the number of replicas in each cluster, you can specify
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[FederatedReplicaSetPreference](https://github.com/kubernetes/federation/blob/{{< param "githubbranch" >}}/apis/federation/types.go)
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as an annotation with key `federation.kubernetes.io/deployment-preferences`
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on Federated Deployment.
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## Updating a Federated Deployment
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You can update a Federated Deployment as you would update a Kubernetes
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Deployment; however, for a Federated Deployment, you must send the request to
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the federation apiserver instead of sending it to a specific Kubernetes cluster.
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The federation control plane ensures that whenever the Federated Deployment is
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updated, it updates the corresponding Deployments in all underlying clusters to
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match it. So if the rolling update strategy was chosen then the underlying
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cluster will do the rolling update independently and `maxSurge` and `maxUnavailable`
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will apply only to individual clusters. This behavior may change in the future.
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If your update includes a change in number of replicas, the federation
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control plane will change the number of replicas in underlying clusters to
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ensure that their sum remains equal to the number of desired replicas in
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Federated Deployment.
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## Deleting a Federated Deployment
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You can delete a Federated Deployment as you would delete a Kubernetes
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Deployment; however, for a Federated Deployment, you must send the request to
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the federation apiserver instead of sending it to a specific Kubernetes cluster.
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For example, you can do that using kubectl by running:
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```shell
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kubectl --context=federation-cluster delete deployment mydep
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```
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{{% /capture %}}
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