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testFlask-Jenkins

Sample Jenkins Pipeline for a Flask Python Application on Openshift

testFlask-Jenkins

Sample Jenkins Pipeline for a Flask Python Application
Application will show how we can use Jenkins to deploy/test a flask application running on openshift, the Application being used is testFlask
Environment variables used in Commands have samples in the sample_env file.
So this example assumes a pipeline scenario where there is a running production application represented by our Production Project ‘NAMESPACE_PROD’ and at build time we deploy the same exact infrastructure in our devlopment project ‘NAMESPACE_DEV’ and test, when all satisfied we promote our dev image to production which is automatically deployed based on a trigger on the imagestream.

prerequisites

OCP Version >= 4.11

Steps to Run

Source Environment Variables

eval "$(curl https://raw.githubusercontent.com/MoOyeg/testFlask/master/sample_env)"

Create a Jenkins namespace
oc new-project $JENKINS_NAMESPACE

Create Jenkins either with storage or without

With Storage

oc process -f ./jenkinsdeploytemplates/jenkins-persistent-deployment.yaml | oc apply -f - -n $JENKINS_NAMESPACE

Without Storage

oc process -f ./jenkinsdeploytemplates/jenkins-ephemeral-deployment.yaml | oc apply -f - -n $JENKINS_NAMESPACE

We used Openshift Oauth, so confirm you can login to Jenkins with the credentials you used to log into openshift

To get the route for the Jenkins login url

oc get route jenkins -n $JENKINS_NAMESPACE -o jsonpath='{ .spec.host }'

Open the URL in a browser and login
Create prod and test projects for your pipeline and add permissions for the jenkins Service Account to be able to build on thos projects

Create Projects

oc new-project $NAMESPACE_DEV

oc new-project $NAMESPACE_PROD

Add Permissions for Jenkins service account to Projects

oc policy add-role-to-user edit system:serviceaccount:$JENKINS_NAMESPACE:jenkins -n $NAMESPACE_DEV 

oc policy add-role-to-user edit system:serviceaccount:$JENKINS_NAMESPACE:jenkins -n $NAMESPACE_PROD

Add Permissions for Default service account in jenkins namespace to Projects

oc policy add-role-to-user edit system:serviceaccount:$JENKINS_NAMESPACE:default -n $NAMESPACE_DEV

oc policy add-role-to-user edit system:serviceaccount:$JENKINS_NAMESPACE:default -n $NAMESPACE_PROD

Run Installation Steps for Application - You can skip this step, pipeline will still run but wont show how to replace promoted application.

Create Jenkins Slave for Python
The Jenkins slave will be used to run the jenkins pipeline, while not necessary to always create your own slave as Openshift comes out of the box with some, I am using this example to show you can build yours and if you have dependencies to test or build your application you can add them into your image.I am using the Dockerfile above to build my image, because the image uses an image in registry.redhat.io remember to create a service account, create a service account secret and link that secret to your builder service account in Jenkins, please see https://access.redhat.com/documentation/en-us/openshift_container_platform/3.11/html/configuring_clusters/install-config-configuring-red-hat-registry
Also you might not be able to build this image if your cluster is not entitled, please do this at cloud.redhat.com. If you have redhat subscriptions but have not entitled your cluster you can use this process to pass your entitlement into the BuildConfig, see https://docs.openshift.com/container-platform/4.4/builds/running-entitled-builds.html
To build a jenkins image without a subscription please read https://github.com/openshift/jenkins.
- Pass DockerFile Value into Variable(Openshift Subscription Required)
  
  If you have access to RedHat catalog
```
export BASE_IMAGE=registry.redhat.io/openshift4/ose-jenkins-agent-base:v4.10.0
```
  else:
  - If you do not have access you can try this option
    export BASE_IMAGE=image-registry.openshift-image-registry.svc:5000/openshift/jenkins-agent-base:latest
    then create dockerfile with image
    export PYTHON_DOCKERFILE=$(curl https://raw.githubusercontent.com/MoOyeg/testFlask-Jenkins/master/Dockerfile | envsubst )
- Build Slave Image in Jenkins Project
  oc new-build --strategy=docker -D="$PYTHON_DOCKERFILE" --name=python-jenkins -n $JENKINS_NAMESPACE

Create Our BuildConfig with our buildstrategy as Pipeline

We can create our BuildConfig below

echo """
apiVersion: build.openshift.io/v1
kind: BuildConfig
metadata:
  name: "$APP_NAME-pipeline"
  namespace: $JENKINS_NAMESPACE
spec:
  source:
    git:
      ref: master
      uri: 'https://github.com/MoOyeg/testFlask-Jenkins.git'
    type: Git
  strategy:
    type: "JenkinsPipeline"
    jenkinsPipelineStrategy:
      jenkinsfilePath: Jenkinsfile
""" | oc create -f -

Pass our variables to our pipeline, they will show up as parameters in jenkins**

Set environment variables on BuildConfig

  oc set env bc/$APP_NAME-pipeline \
--env=JENKINS_NAMESPACE=$JENKINS_NAMESPACE \
--env=REPO="https://github.com/MoOyeg/testFlask.git" \
--env=BRANCH=master \
--env=DEV_PROJECT=$NAMESPACE_DEV --env=APP_NAME=$APP_NAME \
--env=MYSQL_USER=$MYSQL_USER --env=MYSQL_PASSWORD=$MYSQL_PASSWORD \
--env=APP_CONFIG=$APP_CONFIG --env=APP_MODULE=$APP_MODULE \
--env=MYSQL_HOST=$MYSQL_HOST --env=MYSQL_DATABASE=$MYSQL_DATABASE --env=PROD_PROJECT=$NAMESPACE_PROD -n $JENKINS_NAMESPACE

Start build in Jenkins

We can start build using

oc start-build $APP_NAME-pipeline -n $JENKINS_NAMESPACE

Log into Jenkins to follow the build, you can use the route provided earlier
Build has approval stage to simulate approval, we need to accept that to move forward
We can confirm that prod version got updated with new application image
This pipeline can also be triggered with a a code change via a webhook

We can add a webhook by

oc set triggers bc/$APP_NAME-pipeline --from-github -n $JENKINS_NAMESPACE

Use PodTemplates and Volumes for Pipeline

Create PodTemplates

PodTemplatesprovide a way to define the Pod Instance to run that will run the build process.Example here requires the use of a Storage Class that supports dynamic provisioning.
This pipeline shows an example of how to provision a dynamic volume and share it between the workspace and a pod within the pipline steps. This Pipeline requires that you provide elevated privileged to the Jenkins serviceaccount to allow dynamic provisioning of the pvc.
For this Example RWX is required for storage class

Export your StorageClass Values, see example below:

export SC_NAME=sc-efs
export PV_SIZE=300Mi
export ACCESS_MODE=ReadWriteMany

Create PodTemplates to use your above storage values

envsubst '$SC_NAME $PV_SIZE $ACCESS_MODE' < ./podtemplates/podtemplate-dynamic-volume-rwx.yaml | oc create -n $JENKINS_NAMESPACE -f -

envsubst '$SC_NAME $PV_SIZE $ACCESS_MODE' < ./podtemplates/podtemplate-python-inherit-dynamic-volume.yaml | oc create -n $JENKINS_NAMESPACE -f -

This example shares workspace volume with application builds, Since the PVC can only exist in one namespace we will build in JENKINS_NAMESPACE. Let’s add our application secret
```
oc create secret generic my-secret --from-literal=MYSQL_USER=$MYSQL_USER --from-literal=MYSQL_PASSWORD=$MYSQL_PASSWORD -n $JENKINS_NAMESPACE
```
Depending on how your cluster is configured you might need to apply RBAC permissions to allow Jenkins Agent use volumes.
```
 oc apply -k ./rbac
```

You can manually create the pipeline object in Jenkins. Use the Jenkinsfile-with-volume(preferred) OR you can also use a Buildconfig.

echo """
apiVersion: build.openshift.io/v1
kind: BuildConfig
metadata:
  name: "$APP_NAME-pipeline-volume"
  namespace: $JENKINS_NAMESPACE
spec:
  source:
    git:
      ref: master
      uri: 'https://github.com/MoOyeg/testFlask-Jenkins.git'
    type: Git
  strategy:
    type: "JenkinsPipeline"
    jenkinsPipelineStrategy:
      jenkinsfilePath: Jenkinsfile-with-volume
""" | oc create -f -

oc set env bc/$APP_NAME-pipeline-volume \
--env=JENKINS_NAMESPACE=$JENKINS_NAMESPACE \
--env=REPO="https://github.com/MoOyeg/testFlask.git" \
--env=BRANCH="master" \
--env=DEV_PROJECT=$NAMESPACE_DEV --env=APP_NAME=$APP_NAME \
--env=APP_CONFIG=$APP_CONFIG --env=APP_MODULE=$APP_MODULE \
--env=MYSQL_USER=$MYSQL_USER --env=MYSQL_PASSWORD=$MYSQL_PASSWORD \
--env=MYSQL_HOST=$MYSQL_HOST --env=MYSQL_DATABASE=$MYSQL_DATABASE --env=PROD_PROJECT=$NAMESPACE_PROD -n $JENKINS_NAMESPACE