bd196ea49c
v2: Resolve issues from comments, fix bugs in update-demo example, rename files for clarity, add turn-down steps. v3: Add more set commands, clean up rest of env var checks.
113 lines
3.6 KiB
Markdown
113 lines
3.6 KiB
Markdown
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Live update example
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This example demonstrates the usage of Kubernetes to perform a live update on a running group of pods.
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### Step Zero: Prerequisites
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This example assumes that you have forked the repository and [turned up a Kubernetes cluster](https://github.com/GoogleCloudPlatform/kubernetes-new#contents):
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```shell
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$ cd kubernetes
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$ hack/dev-build-and-up.sh
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```
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This example also assumes that you have [Docker](http://docker.io) installed on your local machine.
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It also assumes that `$DOCKER_HUB_USER` is set to your Docker user id. We use this to upload the docker images that are used in the demo.
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You may need to open the firewall for port 8080 using the [console][cloud-console] or the `gcutil` tool. The following command will allow traffic from any source to instances tagged `kubernetes-minion`:
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```shell
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$ gcutil addfirewall --allowed=tcp:8080 --target_tags=kubernetes-minion kubernetes-minion-8080
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```
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### Step Zero: Build the image
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```shell
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$ cd examples/update-demo
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$ ./0-build-images.sh
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```
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### Step One: Turn up the UX for the demo
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```shell
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$ ./1-run-web-proxy.sh &
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```
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This can sometimes spew to the output so you could also run it in a different terminal.
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Now visit the the [demo website](http://localhost:8001/static). You won't see anything much quite yet.
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### Step Two: Run the controller
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Now we will turn up two replicas of an image. They all serve on port 8080, mapped to internal port 80
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```shell
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$ ./2-create-replication-controller.sh
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```
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After these pull the image (which may take a minute or so) you'll see a couple of squares in the UI detailing the pods that are running along with the image that they are serving up. A cute little nautilus.
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### Step Three: Try resizing the controller
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Now we will increase the number of replicas from two to four:
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```shell
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$ ./3-scale.sh
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```
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If you go back to the [demo website](http://localhost:8001/static/index.html) you should eventually see four boxes, one for each pod.
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### Step Four: Update the docker image
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We will now update the docker image to serve a different image by doing a rolling update to a new Docker image.
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```shell
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$ ./4-rolling-update
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```
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The rollingUpdate command in kubecfg will do 2 things:
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1. Update the template in the replication controller to the new image (`$DOCKER_HUB_USER/update-demo:kitten`)
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2. Kill each of the pods one by one. It'll let the replication controller create new pods to replace those that were killed.
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Watch the UX, it will update one pod every 10 seconds until all of the pods have the new image.
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### Step Five: Bring down the pods
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```shell
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$ ./5-down.sh
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```
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This will first 'stop' the replication controller by turning the target number of replicas to 0. It'll then delete that controller.
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[cloud-console]: https://console.developer.google.com
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### Step Six: Cleanup
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To turn down a Kubernetes cluster:
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```shell
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$ cd ../.. # Up to kubernetes.
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$ cluster/kube-down.sh
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```
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### Image Copyright
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Note that he images included here are public domain.
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* [kitten](http://commons.wikimedia.org/wiki/File:Kitten-stare.jpg)
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* [nautilus](http://commons.wikimedia.org/wiki/File:Nautilus_pompilius.jpg)
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