DevOps / OpenShift

Triple Treat with OpenShift

Introduction

Let’s carry on with The Kitchen Cake with OpenShift and bake up an application that showcases a multi-container tiered architecture with persistent storage. Web client PHP application calls REST service calls a Database. All on a local workstation environment. Yum, just ask Milky. This lab is another in the OpenShift MiniLabs series.

milky

Objective

This lab will step you through setting up the Cat-of-the-Day https://github.com/StefanoPicozzi/cotd.git application to take the shape as per the schematic below. Incidentally, doing so will also showcase the capability to setup various frameworks and tools and services in a local lab environment within OpenShift (without using a virtual machines) which remains isolated from interfering with your local Operation System configuration. And save the accompanying OpenShift system state as a named profile which can be recovered later.

cotd2item

Setup

Initial Attempt

This tutorial assumes you have completed the OpenShift MiniLabs installation procedure. Then refresh before continuing.

Repeat Attempt

To reset your environment to repeat this tutorial do the following:

$ cd ~/containersascode
$ ./oc-cluster-wrapper/oc-cluster up containersascode
$ oc login -u developer - p developer
$ oc delete project client
$ oc delete project rest
$ oc login -u system:admin
$ oc delete pv cotdvolume
$ oc delete pv mysqlvolume
$ rm -rf ~/containersascode/volumes/cotdvolume
$ rm -rf ~/containersascode/volumes/mysqlvolume

Instructions

Create the COTD Client Web Application

$ cd ~/containersascode
$ oc login -u developer -p developer
$ oc new-project client --display-name='Client' --description='Client'
$ oc project client
$ oc new-app --name='cotd' -l name='cotd' php~https://github.com/StefanoPicozzi/cotd.git
$ oc expose service cotd --name=cotd -l name='cotd'
$ oc status

Create  COTD Persistent Volume

We are going to map the images directory to a persistent local store . In this way we can easily change and add images to our item list. So let’s first create the pv needed. Replace the $HOME by your fully expanded path name, e.g. /usr/johndoe.

$ cd ~/containersascode
$ oc login -u system:admin 
$ oc get pv 
$ oc create -f - << EOF!
apiVersion: v1
kind: PersistentVolume
metadata:
  name: cotdvolume
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Recycle
  hostPath:
    path: $HOME/containerascode/volumes/cotdvolume
EOF!

$ oc get pv

Set Up the COTD Volume Claim

$ oc login -u developer -p developer
$ oc project client

$ oc set volume dc/cotd --add \
   --overwrite \
   --name=images \
   --type=persistentVolumeClaim \
   --mount-path=/opt/app-root/src/data/images \
   --claim-size=100Mi \
   --claim-name=cotdclaim \
   --containers=cotd

$ cd ~/containersascode/cotd/data/images
$ ls -lasi
$ cp -r * ~/containersascode/volumes/cotdvolume

Verify cotd Persistence

Visit the local file system location of your cotdvolume and then change a few of the, e.g. cat images. Verify the change is reflected as expected when stepping through the items at: http://cotd-client.127.0.0.1.xip.io/item.php

Create  MySQL Persistent Volume

We are going to back the CakePHP MySQL service with a persistent storage claim.  So let’s create the pv needed. Replace the $HOME by your fully expanded path name, e.g. /usr/johndoe.

$ cd ~/containersascode
$ oc login -u system:admin 
$ oc get pv 

$ oc create -f - << EOF!
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysqlvolume
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
    - ReadWriteMany
  persistentVolumeReclaimPolicy: Recycle
  hostPath:
    path: $HOME/containerascode/volumes/mysqlvolume
EOF!

$ oc get pv

Create the Items REST Service

Let’s create a CakePHP REST application using a persistent mysql template. The template includes the instructions to claim the volume.

$ oc login -u system:admin
$ oc project openshift
$ docker pull registry.access.redhat.com/rhscl/php-70-rhel7
$ docker pull registry.access.redhat.com/rhscl/mysql-57-rhel7
$ oc import-image php:7.0 --from=registry.access.redhat.com/rhscl/php-70-rhel7 --confirm
$ oc import-image mysql:5.7 --from=registry.access.redhat.com/rhscl/mysql-57-rhel7 --confirm

$ cd ~/containersascode 
$ oc login -u developer -p developer 
$ oc new-project rest --display-name='Items REST Service' --description='Items REST Service' 
$ oc project rest 

$ oc create -f https://raw.githubusercontent.com/StefanoPicozzi/items/master/openshift/templates/cakephp-mysql-persistent.json 

$ oc create -f https://raw.githubusercontent.com/openshift/cakephp-ex/master/openshift/templates/cakephp-mysql-persistent.json

$ oc new-app --template=cakephp-mysql-persistent -p NAME='items' -p SOURCE_REPOSITORY_URL=https://github.com/StefanoPicozzi/items.git -p DATABASE_USER=user -p DATABASE_PASSWORD=password 
$ oc status

 

Populate the MySQL Database

$ cd ~/containersascode
$ oc login -u developer -p developer
$ oc project rest
$ export PODID=`oc get pods -n rest --no-headers=true | grep mysql | cut -f 1 -d ' '`
$ oc port-forward $PODID 3306:3306

Now launch your favourite database administration tool, such as e.g. MySQL Workbench and create a new connection with attributes as per below. Click to connect and you are good to go.

Name: Items
Connection method: Standard (TCP/IP)
Hostname: 127.0.0.1
Port: 3306
Username: user
Password: password

You can then create the items table and populate the database by a copy/paste of the sql instructions as supplied at: https://github.com/StefanoPicozzi/items/tree/master/etc.

Verify MySQL Persistence

Go the https://127.0.0.1:8443/console/project/rest/overview page and scale down and scale up the mysql container. Then visit the REST CakePHP page for Items at http://items-rest.127.0.0.1.xip.io/ and verify that the database remains populated as before.

screen-shot-2016-12-02-at-2-43-01-pm

Wire up cotd to items

The cotd application will look for a REST service as a data source if the environment variable SERVICE is set (refer data/rest.php). SERVICE takes the value of the IP address of the items REST service. In our case it will be a 172.x.y.z address as this local cluster instance does not have a DNS service defined. Update the environment variable as follow which will trigger a redeploy of cotd. ( In an upcoming MiniLab we will revise this design element to leverage a microservice framework. )

$ cd ~/containersascode
$ oc login -u developer -p developer
$ export PODID=`oc get service -n rest --no-headers=true | grep items | cut -c 11-25`
$ oc project client
$ oc env dc/cotd SERVICE=$PODID SELECTOR=cats

Verify Success

Using the REST CakePHP tool at: http://items-rest.127.0.0.1.xip.io/ change around the ranks of two of the items, e.g. swap around ranks for items 1 and 5. Now click the Home button back at: http://cotd-client.127.0.0.1.xip.io/item.php and verify that the ordering has changed as expected.

Screen Shot 2016-12-06 at 2.32.09 pm.png

Trivia

For the latest in OpenShift developments keep checking https://blog.openshift.com. A list of curated OpenShift resources can be inspected at OpenShift Resources

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