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change kinflate to kustomize
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Jingfang Liu
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demos/mySql.md
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239
demos/mySql.md
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# Demo: MySql
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This example takes some off-the-shelf k8s resources
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designed for MySQL, and customizes them to suit a
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production scenario.
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In the production environment we want:
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- MySQL resource names to be prefixed by 'prod-'.
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- MySQL resources to have 'env: prod' labels.
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- MySQL to use persistent disk for storing data.
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### Download resources
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Download `deployment.yaml`, `service.yaml` and
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`secret.yaml`. These are plain k8s resources files one
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could add to a k8s cluster to run MySql.
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<!-- @makeMySQLDir @test -->
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```
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DEMO_HOME=$(mktemp -d)
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cd $DEMO_HOME
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# Get MySQL configs
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for f in service secret deployment ; do \
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wget https://raw.githubusercontent.com/kinflate/mysql/master/emptyDir/$f.yaml ; \
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done
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```
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### Initialize a manifest
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A _manifest_ groups these resources together.
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Create one:
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<!-- @initApp @test -->
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```
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cd $DEMO_HOME
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kustomize init
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```
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You should now have a file called `kustomize.yaml`:
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<!-- @catMan @test -->
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```
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cat $DEMO_HOME/kustomize.yaml
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```
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containing something like:
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> ```
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> apiVersion: manifest.k8s.io/v1alpha1
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> kind: Manifest
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> metadata:
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> name: helloworld
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> # description: helloworld does useful stuff.
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> namePrefix: some-prefix
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> # Labels to add to all objects and selectors.
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> # These labels would also be used to form the selector for apply --prune
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> # Named differently than “labels” to avoid confusion with metadata for this object
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> objectLabels:
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> app: helloworld
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> objectAnnotations:
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> note: This is a example annotation
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> resources:
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> - deployment.yaml
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> - service.yaml
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> # There could also be configmaps in Base, which would make these overlays
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> configmaps: []
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> # There could be secrets in Base, if just using a fork/rebase workflow
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> secrets: []
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> recursive: true
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> ```
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### Add the resources to the manifest
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<!-- @addResources @test -->
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```
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cd $DEMO_HOME
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kustomize edit add resource secret.yaml
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kustomize edit add resource service.yaml
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kustomize edit add resource deployment.yaml
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cat kustomize.yaml
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```
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`kustomize.yaml`'s resources section should contain:
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> ```
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> apiVersion: manifest.k8s.io/v1alpha1
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> ....
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> resources:
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> - secret.yaml
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> - service.yaml
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> - deployment.yaml
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> ```
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### Name Customization
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Arrange for the MySQL resources to begin with prefix
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_prod-_ (since they are meant for the _production_
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environment):
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<!-- @customizeLabel @test -->
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```
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cd $DEMO_HOME
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kustomize edit set nameprefix 'prod-'
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cat kustomize.yaml
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```
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`kustomize.yaml` should have updated value of namePrefix field:
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> ```
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> apiVersion: manifest.k8s.io/v1alpha1
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> ....
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> namePrefix: prod-
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> objectAnnotations:
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> note: This is a example annotation
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> ```
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This `namePrefix` directive adds _prod-_ to all
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resource names.
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<!-- @genNamePrefixConfig @test -->
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```
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kustomize build $DEMO_HOME
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```
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The output should contain:
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> ```
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> apiVersion: v1
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> data:
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> password: YWRtaW4=
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> kind: Secret
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> metadata:
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> ....
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> name: prod-mysql-pass-d2gtcm2t2k
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> ---
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> apiVersion: v1
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> kind: Service
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> metadata:
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> ....
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> name: prod-mysql
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> spec:
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> ....
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> ---
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> apiVersion: apps/v1beta2
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> kind: Deployment
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> metadata:
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> ....
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> name: prod-mysql
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> spec:
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> selector:
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> ....
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> ```
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### Label Customization
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We want resources in production environment to have
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certain labels so that we can query them by label
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selector.
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`kustomize` does not have `set label` command to add
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label, but we can edit `kustomize.yaml` file under
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`prod` directory and add the production labels under
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`objectLabels` fields as highlighted below.
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<!-- @customizeLabels @test -->
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```
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sed -i 's/app: helloworld/app: prod/' \
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$DEMO_HOME/kustomize.yaml
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```
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At this point, running `kustomize build` will
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generate MySQL configs with name-prefix 'prod-' and
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labels `env:prod`.
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### Storage customization
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Off the shelf MySQL uses `emptyDir` type volume, which
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gets wiped away if the MySQL Pod is recreated, and that
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is certainly not desirable for production
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environment. So we want to use Persistent Disk in
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production. kustomize lets you apply `patches` to the
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resources.
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<!-- @createPatchFile @test -->
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```
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cat <<'EOF' > $DEMO_HOME/persistent-disk.yaml
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apiVersion: apps/v1beta2 # for versions before 1.9.0 use apps/v1beta2
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kind: Deployment
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metadata:
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name: mysql
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spec:
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template:
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spec:
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volumes:
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- name: mysql-persistent-storage
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emptyDir: null
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gcePersistentDisk:
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pdName: mysql-persistent-storage
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EOF
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```
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Specify the patch file in the manifest:
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<!-- @specifyPatch @test -->
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```
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cat <<'EOF' >> $DEMO_HOME/kustomize.yaml
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patches:
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- persistent-disk.yaml
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EOF
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```
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Lets break this down:
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- In the first step, we created a YAML file named
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`persistent-disk.yaml` to patch the resource defined
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in deployment.yaml
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- Then we added `persistent-disk.yaml` to list of
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`patches` in `kustomize.yaml`. `kustomize build`
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will apply this patch to the deployment resource with
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the name `mysql` as defined in the patch.
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The output of the following command can now be applied
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to the cluster (i.e. piped to `kubectl apply`) to
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create the production environment.
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<!-- @finalInflation @test -->
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```
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kustomize build $DEMO_HOME # | kubectl apply -f -
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```
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