Backstage

This pack contains a service job that runs Backstage in a single Nomad client. It currently supports being run by the Docker driver.

It has 2 tasks:

• Backstage: (reference) the open platform for building developer portals;
• PostgreSQL: (reference) the persistent database used by Backstage.

Setup:

• Service-to-service communication is handled by Nomad;
• PostgreSQL's state is persisted with Nomad Host Volumes.

Requirements

Clients that expect to run this job require:

• Nomad >= 1.4.0 (because the pack use Nomad Variables)
• Docker volumes to be enabled within their Docker plugin stanza, due to the usage of Nomad's host volume:

plugin "docker" {
  config {
    volumes {
      enabled = true
    }
  }
}

• Host volume to be enabled in the client configuration (the host volume directory - /var/lib/postgres - must be created in advance):

client {
  host_volume "backstage-postgres" {
    path      = "/var/lib/postgres"
    read_only = false
  }
}

Customizing the Docker images

The 2 docker images can be replaced by using their variable names:

• postgresql_task_image
• backstage_task_image

Example:

$ nomad-pack run backstage --var backstage_task_image="ghcr.io/backstage/backstage:1.7.1"

Pack Usage

Prerequisite

Create a variable specification file:

# spec.nv.hcl
path = "nomad/jobs/backstage"

items {
  # Mandatory variables
  postgres_user = "your_postgres_username"
  postgres_password = "your_postgres_password"

  #Optional variables
  github_token = "your_github_token"
}

The default docker image for Backstage is configured to use GitHub in order to locate entities (see GitHub integration), so you will need to define a variable to store your GitHub token.

If you use another integration in your custom image, Azure DevOps for instance, you will need to define a variable for it (e.g. azure_token = "your_ado_token").

To set your variables in your Nomad instance, execute the following command:

$ nomad var put @spec.nv.hcl

Variables

• job_name (string) - The name to use as the job name which overrides using the pack name
• datacenters (list of strings) - A list of datacenters in the region which are eligible for task placement
• region (string) - The region where jobs will be deployed
• postgresql_group_nomad_service_name (string) - The nomad service name for the PostgreSQL application
• postgresql_task_image (string) - PostgreSQL's Docker image (must include the tag)
• postgresql_task_volume_path (string) - The volume's absolute path in the host to be used by PostgreSQL
• postgresql_task_resources (object, number number) - The resources to assign to the PostgreSQL service
• backstage_group_nomad_service_name (string) - The nomad service name for the Backstage application
• backstage_task_image (string) - Backstage's Docker image (must include the tag)
• backstage_task_nomad_vars (map of string) - Backstage's nomad variables (see below for the details)
• backstage_task_resources (object, number number) - The resources to assign to the Backstage service

Custom Nomad Variables

If you need to use other Nomad variables than postgres_user and postgres_password with this pack, you will need to pass them to backstage_task_nomad_vars.

backstage_task_nomad_vars = [
  {
    key = "AZURE_TOKEN"
    value = "azure_token"
  },
  {
    key = "YOUR_SECRET_ENV_VAR"
    value = "your_nomad_var_key"
  }
]