88 lines
3.0 KiB
Markdown
88 lines
3.0 KiB
Markdown
---
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title: Federated ConfigMap
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---
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This guide explains how to use ConfigMaps in a Federation control plane.
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* TOC
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{:toc}
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## Prerequisites
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This guide assumes that you have a running Kubernetes Cluster
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Federation installation. If not, then head over to the
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[federation admin guide](/docs/admin/federation/) to learn how to
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bring up a cluster federation (or have your cluster administrator do
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this for you).
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Other tutorials, such as Kelsey Hightower's
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[Federated Kubernetes Tutorial](https://github.com/kelseyhightower/kubernetes-cluster-federation),
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might also help you create a Federated Kubernetes cluster.
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You should also have a basic
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[working knowledge of Kubernetes](/docs/getting-started-guides/) in
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general and [ConfigMaps](/docs/user-guide/ConfigMaps/) in particular.
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## Overview
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Federated ConfigMaps are very similar to the traditional [Kubernetes
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ConfigMaps](/docs/user-guide/configmap/) and provide the same functionality.
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Creating them in the federation control plane ensures that they are synchronized
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across all the clusters in federation.
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## Creating a Federated ConfigMap
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The API for Federated ConfigMap is 100% compatible with the
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API for traditional Kubernetes ConfigMap. You can create a ConfigMap 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 myconfigmap.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 ConfigMap is created, the federation control plane will create
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a matching ConfigMap 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 configmap myconfigmap
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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 ConfigMaps in underlying clusters will match the Federated ConfigMap.
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## Updating a Federated ConfigMap
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You can update a Federated ConfigMap as you would update a Kubernetes
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ConfigMap; however, for a Federated ConfigMap, 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 ConfigMap is
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updated, it updates the corresponding ConfigMaps in all underlying clusters to
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match it.
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## Deleting a Federated ConfigMap
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You can delete a Federated ConfigMap as you would delete a Kubernetes
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ConfigMap; however, for a Federated ConfigMap, 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 configmap
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```
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Note that at this point, deleting a Federated ConfigMap will not delete the
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corresponding ConfigMaps from underlying clusters.
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You must delete the underlying ConfigMaps manually.
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We intend to fix this in the future.
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