Pipeline requirements - nginx/php stack - service link

[b2p-fred]

I have a specific pipeline configuration where i need to have some inter services communication. Indeed, I need to use a nginx / php-fpm stack for my Symfony application and the Nginx service uses the PHP service as an upstream.

As such, I need to know (and use) the PHP service name (or IP address) for the Nginx configuration in an environment variable.

Here is my pipeline code:

version: v1.0
name: deploy-backend
description: Deploy the application backend
jobs:
- job: Setup the application package
  steps:
  - artifactDownload:
      path: Download installable package
      pattern: epr-backend-api
      tag: '{{.cds.version}}'
  - script:
    - # Test that I get my application home page
    - curl -X GET http://nginx-api:80
    - echo "Result $?"
  requirements:
  - model: epr-PHP
  - service:
      name: mailer
      value: '{{.cds.proj.DOCKER_REGISTRY}}{{.cds.proj.DOCKER_REGISTRY_PREFIX}}epr-backend_mailer:{{.cds.proj.IMAGE_TAG_MAILER}} APP_ENV={{.cds.env.APP_ENV}}'
  - service:
      name: mariadb
      value: '{{.cds.proj.DOCKER_REGISTRY}}{{.cds.proj.DOCKER_REGISTRY_PREFIX}}epr-backend_db:{{.cds.proj.IMAGE_TAG_DB}} APP_ENV={{.cds.env.APP_ENV}} MARIADB_ALLOW_EMPTY_ROOT_PASSWORD=false MARIADB_ROOT_PASSWORD={{.cds.env.DATABASE_ROOT_PASSWORD}} MARIADB_DATABASE={{.cds.env.DATABASE_NAME}} MARIADB_USER={{.cds.env.DATABASE_USER}} MARIADB_PASSWORD={{.cds.env.DATABASE_PASSWORD}}'
  - service:
      name: nginx-api
      value: '{{.cds.proj.DOCKER_REGISTRY}}{{.cds.proj.DOCKER_REGISTRY_PREFIX}}epr-backend_nginx:{{.cds.proj.IMAGE_TAG_NGINX}} HOSTNAME=nginx-api APP_ENV={{.cds.env.APP_ENV}} NGINX_PHP_UPSTREAM_HOST=php-api NGINX_PHP_UPSTREAM_PORT=9000 NGINX_PHP_UPSTREAM_COMMENT=n/a'
  - service:
      name: php-api
      value: '{{.cds.proj.DOCKER_REGISTRY}}{{.cds.proj.DOCKER_REGISTRY_PREFIX}}epr-backend_php:{{.cds.proj.IMAGE_TAG_PHP}} HOSTNAME=php-fpm APP_ENV={{.cds.env.APP_ENV}}'

With this configuration the nginx-api service fails to start because it cannot reach the php-api container.
When I replace php-api with 127.0.0.1 (or 172.17.0.1, or any pingable ip address) in the NGINX_PHP_UPSTREAM_HOST environment variable, the nginx-api starts correctly but my curl script fails because of a bad gateway.

Is there a solution to have the real address (or better, the hostname) of my php-api service container ?

**[edit]**indeed, one solution to get the service container hostname would be to be able to use the worker model name as a variable; see #5988