data-loader-job.yaml

# By Sharon Campbell, Ken Simon, and Joe Beda for Heptio
# one-time Job that executes the /tmp/mysql-sakila-data-loader.sh script
# from another container copy of our PHP image
# this is how we get initial data for our database
# we use https://dev.mysql.com/doc/sakila/en/ as the database in our demo

apiVersion: batch/v1
# https://kubernetes.io/docs/concepts/jobs/run-to-completion-finite-workloads/
kind: Job
metadata:
  name: mysql-data-loader-with-timeout
  labels:
    "heptio.com/example": lamp
spec:
  # https://kubernetes.io/docs/concepts/jobs/run-to-completion-finite-workloads/#job-termination-and-cleanup
  activeDeadlineSeconds: 100
  template:
    metadata:
      name: mysql-data-loader
    spec:
      # this creates a temporary container just to run this Job
      containers:
      - name: mysql-data-loader
        # deploys this custom PHP image from Docker Hub
        # https://hub.docker.com/r/heptio/example-php-dbconnect/
        # this is the same PHP image we use to create the PHP Deployment in php.yaml
        # it could be a completely different image, though, if our script was in its own image
        # it's just convenient to have our PHP app and our data loader script packaged together
        # make sure the host image for your script has any utilities the script needs
        # like curl and mysql-client, in our case
        image: heptio/example-php-dbconnect
        # env sets environment variables in the container
        # exactly like environment variables set from the command line
        env:
          # The PHP image will configure an environment variable with the value of MYSQL_USER...
          - name: MYSQL_USER
            # rather than embed sensitive details in this config
            # we reference another Kubernetes object
            # in this case, the Secret with the name: mysql-credentials            
            valueFrom:
              secretKeyRef:
                name: mysql-credentials
                # references the user key-value pair from the mysql-credentials Secret
                key: user
          # ... and a password of the value of MYSQL_PASSWORD ...
          - name: MYSQL_PASSWORD
            valueFrom:
              secretKeyRef:
                name: mysql-credentials
                key: password
          # ... and the MYSQL_HOST mysql.default.svc.cluster.local
          # which comes from the Service with the name mysql in the mysql.yaml file
          - name: MYSQL_HOST
            value: mysql.default.svc.cluster.local
        # you can replace /tmp/mysql-sakila-data-loader.sh
        # with a link to your own script in your image 
        command: ["/tmp/mysql-sakila-data-loader.sh"]
      # if running /tmp/mysql-sakila-data-loader.sh returns a non-zero exit status
      # the Job will be considered a failure, and this Job will run again
      # restartPolicy: OnFailure ensures this Job will keep attempting to load our data
      # until it completes successfully
      # so if this Job tries to run before the PHP server is up, or before the MySQL server is up
      # or before the Secret is created, this Job will keep trying to complete
      # the mysql-sakila-data-loader.sh script itself has "set -o errexit"
      # so if any commands the script itself launches fail, the whole script returns nonzero
      restartPolicy: OnFailure