Add springboot example demo
This commit is contained in:
Jingfang Liu
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@ -8,3 +8,6 @@ These demos are covered by presubmit tests.
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* [mysql](mySql.md) - Create a mySql production
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* [mysql](mySql.md) - Create a mySql production
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configuration from scratch.
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configuration from scratch.
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* [springboot](springboot.md) - Create a Spring Boot application production
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configuration from scratch.
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@ -0,0 +1,350 @@
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# Demo: SpringBoot
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In this tutorial, you will learn - how to use `kinflate` to customize a basic Spring Boot application's
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k8s configuration for production use cases.
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In the production environment we want to customize the following:
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- add application specific configuration for this Spring Boot application
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- configure prod DB access configuration
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- resource names to be prefixed by 'prod-'.
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- resources to have 'env: prod' labels.
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- JVM memory to be properly set.
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- health check and readiness check.
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### Download resources
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Download `deployment.yaml`, `service.yaml`. These are plain k8s resources files one
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could add to a k8s cluster to run sbdemo.
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<!-- @makeSpringBootDir @test -->
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```
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DEMO_HOME=$(mktemp -d)
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cd $DEMO_HOME
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# Get SpringBoot configs
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for f in service deployment; do \
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wget https://raw.githubusercontent.com/kinflate/example-springboot/master/$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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kinflate init
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```
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The above step will create a `kinflate` configuration file called `Kube-manifest.yaml` in current directory.
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<!-- @catMan @test -->
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```
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cat $DEMO_HOME/Kube-manifest.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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> configMapGenerator: []
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> # There could be secrets in Base, if just using a fork/rebase workflow
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> secretGenerator: []
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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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kinflate edit add resource service.yaml
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kinflate edit add resource deployment.yaml
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cat Kube-manifest.yaml
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```
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`Kube-manifest.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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> - service.yaml
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> - deployment.yaml
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> ```
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### Add configmap to the manifest
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<!-- @addConfigMap @test -->
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```
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cd $DEMO_HOME
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wget https://raw.githubusercontent.com/kinflate/example-springboot/master/application.properties
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kinflate edit add configmap demo-configmap --from-file application.properties
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cat Kube-manifest.yaml
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```
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`Kube-manifest.yaml`'s configMapGenerator section should contain:
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> ```
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> configMapGenerator:
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> - files:
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> - application.properties
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> name: demo-configmap
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> kind: Manifest
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> ```
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### Customize configmap
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We want to add database credentials for the prod environment. In general, these credentials can be put into the file `application.properties`.
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However, for some cases, we want to keep the credentials in a different file and keep application specific configs in `application.properties`.
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With this clear separation, the credentials and application specific things can be managed and maintained flexibly by different teams.
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For example, application developers only tune the application configs in `application.properties` and operation teams or SREs
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only care about the credentials.
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For Spring Boot application, we can set an active profile through the environment variable `spring.profiles.active`. Then
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the application will pick up an extra `application-<profile>.properties` file. With this, we can customize the configmap in two
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steps. Add an environment variable through the patch and add a file to the configmap.
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<!-- @customizeConfigMap @test -->
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```
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cat <<EOF >$DEMO_HOME/patch.yaml
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apiVersion: apps/v1beta2
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kind: Deployment
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metadata:
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name: sbdemo
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spec:
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template:
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spec:
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containers:
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- name: sbdemo
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env:
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- name: spring.profiles.active
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value: prod
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EOF
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cat <<EOF >>$DEMO_HOME/Kube-manifest.yaml
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patches:
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- patch.yaml
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EOF
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cat <<EOF >$DEMO_HOME/application-prod.properties
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spring.jpa.hibernate.ddl-auto=update
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spring.datasource.url=jdbc:mysql://<prod_database_host>:3306/db_example
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spring.datasource.username=root
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spring.datasource.password=admin
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EOF
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kinflate edit add configmap demo-configmap --from-file application-prod.properties
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cat Kube-manifest.yaml
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```
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`Kube-manifest.yaml`'s configMapGenerator section should contain:
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> ```
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> configMapGenerator:
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> - files:
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> - application.properties
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> - application-prod.properties
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> name: demo-configmap
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> kind: Manifest
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> ```
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### Name Customization
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Arrange for the 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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kinflate edit set nameprefix 'prod-'
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cat Kube-manifest.yaml
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```
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`Kube-manifest.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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kinflate 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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> ....
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> kind: ConfigMap
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> metadata:
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> ....
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> name: prod-demo-configmap-7746248cmc
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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-sbdemo
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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-sbdemo
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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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`kinflate` does not have `edit set label` command to add
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label, but we can edit `Kube-manifest.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/Kube-manifest.yaml
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```
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At this point, running `kinflate 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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### Download Patch for JVM memory
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When a Spring Boot application is deployed in a k8s cluster, the JVM is running inside a container. We want to set memory limit for the container and make sure
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the JVM is aware of that limit. In K8s deployment, we can set the resource limits for containers and inject these limits to
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some environment variables by downward API. When the container starts to run, it can pick up the environment variables and
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set JVM options accordingly.
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Download the patch `memorylimit_patch.yaml`. It contains the memory limits setup.
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<!-- @downloadPatch @test -->
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```
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cd $DEMO_HOME
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wget https://raw.githubusercontent.com/kinflate/example-springboot-instances/master/production/memorylimit_patch.yaml
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cat memorylimit_patch.yaml
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```
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The output contains
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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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> name: sbdemo
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> spec:
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> template:
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> spec:
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> containers:
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> - name: sbdemo
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> resources:
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> limits:
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> memory: 1250Mi
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> requests:
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> memory: 1250Mi
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> env:
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> - name: MEM_TOTAL_MB
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> valueFrom:
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> resourceFieldRef:
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> resource: limits.memory
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> ```
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### Download Patch for health check
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We also want to add liveness check and readiness check in the production environment. Spring Boot application
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has end points such as `/actuator/health` for this. We can customize the k8s deployment resource to talk to Spring Boot end point.
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Download the patch `healthcheck_patch.yaml`. It contains the liveness probes and readyness probes.
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<!-- @downloadPatch @test -->
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```
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cd $DEMO_HOME
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wget https://raw.githubusercontent.com/kinflate/example-springboot-instances/master/production/healthcheck_patch.yaml
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cat healthcheck_patch.yaml
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```
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The output contains
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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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> name: sbdemo
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> spec:
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> template:
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> spec:
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> containers:
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> - name: sbdemo
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> livenessProbe:
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> httpGet:
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> path: /actuator/health
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> port: 8080
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> initialDelaySeconds: 10
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> periodSeconds: 3
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> readinessProbe:
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> initialDelaySeconds: 20
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> periodSeconds: 10
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> httpGet:
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> path: /actuator/info
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> port: 8080
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> ```
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### Add patch to Manifest
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Currently `kinflate` doesn't provide a command to add a file as a patch, but we can edit the file `Kube-manifest.yaml` to
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include this patch.
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<!-- @addPatch @test -->
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```
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mv $DEMO_HOME/Kube-manifest.yaml $DEMO_HOME/tmp.yaml
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sed '/patches:$/{N;s/- patch.yaml/- patch.yaml\n- memorylimit_patch.yaml\n- healthcheck_patch.yaml/}' $DEMO_HOME/tmp.yaml >& $DEMO_HOME/Kube-manifest.yaml
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```
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`Kube-manifest.yaml` should have patches field:
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> ```
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> patches
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> - patch.yaml
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> - memorylimit_patch.yaml
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> - healthcheck_patch.yaml
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> ```
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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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<!-- @finalBuild @test -->
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```
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kinflate build $DEMO_HOME # | kubectl apply -f -
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```
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