Background

As an exercise I had run WordPress via a Docker Compose file locally and then within Azure (I would not recommend this for “production” systems, this was merely an intellectual exercise and I based my ideas on this article amongst other.

Running containers within Azure is a little confusing for the beginner as, typical for Microsoft, there are many ways to do the same thing and I noted that it is possible to run multiple containers with a YAML file as opposed to a Docker Compose file.

So I created a YAML file which mirrored my Compose file and tried to run it

az container create --resource-group mygroup --dns-name-label myyaml  --file deploy-wp.yaml

With a YAML file:

apiVersion: 2021-09-01
location: uksouth
name: wordpress-group
type: Microsoft.ContainerInstance/containerGroups
properties:
  containers:
    - name: wordpress
      properties:
        image: wordpress:6.4
        resources:
          requests:
            cpu: 1
            memoryInGb: 1.5        
        ports:
          - port: 80
        environmentVariables:
          - name: WORDPRESS_DB_HOST
            value: db
          - name: WORDPRESS_DB_USER
            value: wordpressuser
          - name: WORDPRESS_DB_PASSWORD
            value: wordpresspass
          - name: WORDPRESS_DB_NAME
            value: wordpressdb
    - name: mysql
      properties:

        image: mysql:8.0.27
        resources:
          requests:
            cpu: 1
            memoryInGb: 1.5        
        ports:
          - port: 3306
          - port: 33060
        environmentVariables:
          - name: MYSQL_ROOT_PASSWORD
            value: rootpass
          - name: MYSQL_DATABASE
            value: wordpressdb
          - name: MYSQL_USER
            value: wordpressuser
          - name: MYSQL_PASSWORD
            value: wordpresspass
  osType: Linux
  ipAddress:
    type: Public
    dnsNameLabel: testwordpress
    ports:
      - protocol: tcp
        port: 80
      - protocol: tcp
        port: 3306
      - protocol: tcp
        port: 33060

The containers started and I could read the logs via

az container logs –resource-group mygroup –name wordpress-group –container-name wordpress
az container logs –resource-group mygroup –name wordpress-group –container-name mysql

I could also get the FQDN of wordpress via

az container show --resource-group mygroup --name wordpress-group  --query "{FQDN:ipAddress.fqdn,ProvisioningState:provisioningState}" --out table

The Problem

I then browsed to the port 80 endpoint for the WordPress container (URL obtained from the Azure portal) and….Error….wordpress could not connect to the database

The Solution

After much head scratching and searching I found an article that suggested using 127.0.0.1 for the “db name” in the yaml file

          - name: WORDPRESS_DB_HOST
            value: 127.0.0.1:3306