Platform Capability Building Workshop - OpenShift

Prerequisites

• Git
• OpenShift CLI (Downloading Source)
  • Download

  cd ~/downloads && wget https://github.com/openshift/origin/releases/download/v3.11.0/openshift-origin-client-tools-v3.11.0-0cbc58b-linux-64bit.tar.gz

  • Uncompress file and add in PATH

  mkdir ~/openshift-cli
  cd ~/downloads && tar xvf openshift-origin-client-tools-v3.11.0-0cbc58b-linux-64bit.tar.gz -C ~/openshift-cli --strip-components 1

  • Add oc in PATH. You can either

  export PATH=#USER_HOME#/openshift-cli:$PATH

Workshop -- part 1

Basic check before we get started

oc login https://oc.tlk.im:443 --token=#TOKEN#

oc projects

oc new-project #PROJECT_NAME#

oc status

Deploy first application on OpenShift

S2I builder image

What this repo is created for? By comparing to traditional pipeline way of build,

1. Build docker image
2. Build application
3. Run application

How Source-to-Image works

For example, to create a reproducible build pipeline for Tomcat (the popular Java webserver) and Maven:

1. Create a builder image containing OpenJDK and Tomcat that expects to have a WAR file injected
2. Create a second image that layers on top of the first image Maven and any other standard dependencies, and expects to have a Maven project injected
3. Invoke source-to-image using the Java application source and the Maven image to create the desired application WAR
4. Invoke source-to-image a second time using the WAR file from the previous step and the initial Tomcat image to create the runtime image

Follow Springboot S2I README.md to import S2I builder image into the online catalog.

Note: only continue next step only when builder image is created successfully. You can check from web console.

Build service with S2I builder image

Before creating any service, you need to fork a repo under your account from https://github.com/#YOUR_ACCOUNT#/openshift-workshop.git.

Now let's create a zipkin server application.

There are two ways. Either to create via oc,

oc new-app -f openshift/zipkin-server/build-deployment-config.yaml \
    -p PROJECT_NAME=#PROJECT_NAME# \ 
    -p APP_NAME=zipkin-server \
    -p GIT_SOURCE_URL=https://github.com/#YOUR_ACCOUNT#/openshift-workshop.git \
    -p GIT_SOURCE_REF=master \
    -p APP_PORT=9000 \
    -p APP_ENV=dev

new-app command creates a build configuration, which itself creates a new application image from source code. It typically also creates deployment configuration to deploy the new image, and a service to provide load-balanced access to the deployment running your image.

or to create via the web console as below,

Start the build to get service running

oc get buildconfig

oc start-build zipkin-server

Access service

Creating a Service first,

oc expose dc/zipkin-server --name=zipkin-server -l app=zipkin-server

Then create a Route,

oc expose svc/zipkin-server --name=zipkin-server --hostname=#PROJECT_NAME#.apps.tlk.im --port=9000 -l app=zipkin-server

It will expose zipkin-server service to hostname you specify.

Now you are able to access zipkin server via URL http://#PROJECT_NAME#.apps.tlk.im.

Deploy service with CI/CD pipeline

Create service from template

oc create -f openshift/service/template.yaml

Upload template to projects.

Once template gets uploaded, you can deploy service by the OpenShift stored template,

oc process api-services-template \
    -p PROJECT_NAME=#PROJECT_NAME# \ 
        -p APP_NAME=zipkin-server \
        -p GIT_SOURCE_URL=https://github.com/#YOUR_ACCOUNT#/openshift-workshop.git \
        -p GIT_SOURCE_REF=master \
        -p APP_PORT=9000 \
        -p APP_ENV=dev | oc create -f -

Jenkins slave

oc create -f openshift/jenkins/buildconfig/gradle-centos7.yaml

oc start-build jenkins-slave-gradle-centos7

Access the service

Go to http://#PROJECT_NAME#.apps.tlk.im/product-service/products/123

Make some change to application

Opens file ProductController and make a change to the code. Then commit and push your change.

Now manually start the build to eventually trigger the new deployment,

oc start-build product-service

Auto triggering

• Define your Secret before actually doing it.

  oc create -f openshift/service/github-webhook-secret.yaml

• Update BuildConfig to allow auto build triggering when there is new change is checked in codebase.

  Edit the BuildConfig for product-service by,

  oc edit template api-services-template

  Update BuildConfig by adding another trigger.

  triggers: 
    - type: "GitHub"
      github:
        secretReference: 
          name: "service-webhook-secret"

• Copy Webhook url from OpenShift console

  oc describe bc/product-service

• Config Webhook in github

  • Go to Settings of repo https://github.com/#YOUR_ACCOUNT#/openshift-workshop.git

  • Click Webhooks item to add Webhook

  • Paste the webhook URL in field Payload URL, select application/json in Content type field, click disable ssl verification

  • Github will test the webhook automatically, if succeed, it will place a green mark before the url.

To verify the auto triggering, make another change to ProductController then commit and push the change to check.

Unfortunately you can not verify when the OpenShift access has networking limit.

CI/CD Model

Best practices

Use of Labels

oc delete all --selector="app=zipkin-server"

Template on OpenShift

oc process -f zipkin-server-template.yaml | oc create -f -

To create objects by giving pre-defined template.

oc create -f openshift/service/template.yaml

To upload template to projects.

oc process api-services-template \
    -p PROJECT_NAME=#PROJECT_NAME# \ 
        -p APP_NAME=zipkin-server \
        -p GIT_SOURCE_URL=https://github.com/#YOUR_ACCOUNT#/openshift-workshop.git \
        -p GIT_SOURCE_REF=master \
        -p APP_PORT=9000 \
        -p APP_ENV=dev | oc delete -f - 

Workshop -- part 2

Rollback

To get information about all available revisions of your application,

oc rollout history dc/product-service

You can view details specific to a revision by using the --revision flag,

oc rollout history dc/product-service --revision=3

Given you are very sure which revision you want to rollback, now you can,

1. rollback to the last successful deployed revision of your configuration,

   oc rollout undo dc/product-service

   A new replication controller will be started. If no revision is specified with --to-revision, then the last successfully deployed revision will be used.

2. Rollback to specific revision of DeploymentConfiguration,

   oc rollout undo dc/product-service --to-revision=2

   If revision is specified with --to-revision, the specific revision of deployment will be used.

Scale up & down

Scale up and down via CLI like below,

oc scale dc/product-service --replicas=2

Verify either from Web console or from CLI by oc describe service #SERIVCE_NAME#

oc scale dc/product-service --replicas=1

Scale down to 1 to reset.

Auto-Scaling

By default, pods consume unbounded node resources. Therefore in terms of steps,

1. Resource limits on pods

   resources:
     limits:
       cpu: 100m
     requests:
       cpu: 100m

2. Configure autoscaler

   oc autoscale dc/product-service --min 1 --max 10 --cpu-percent=10

3. To verify the change,

   ab -n 1000 -c 100 http://##

Deployment strategies

Rolling strategy

Slowly replaces instances of previous version of application with the instances of new version of the application. All rolling deployments in OpenShift are canary deployments.

Use this strategy when,

• no downtime during application update
• application supports having old code and new code running at the same time

Recreate strategy

Lifecycle hooks are supported for injecting code into the deployment process. Use this strategy when,

• must run migrations or date transformations before you new code starts
• do not support having new and old version of applications running at the same time
• want to use volume which is not supported being shared between multiple replicas

This way incurs downtime becuase for a brief period no instaces of application are running

Custom strategy

Apparently, this strategy allows you define your own process of deployment.

Blue-Green deployment

Involves running two versions of application at the same time and moving traffic from the in-production version (green version) to the newer version (the blue version). You can implement it either by

• rolling strategy
• switch services in a route

A/B deployment

It lets you try new version of application in a limited way in the production environment. With full control of portion of requests to each version of application, as testing progresses you can increase the fraction of requests to the new version and ultimately stop using the old version.

By configurating Route object, we can achieve that.

Logging & Monitoring

A quick showcase.

Go to HOWTO.md for how to configure and build the projects.