docker-auth

Docker Authentication

This module serves as a post-bootstrap addon for the Core Module. It allows you to configure Nomad clients to authenticate with private Docker registries.

This is intended to be used alongside the core.

Pre-requisites

You must have Terraformed the core module first. In addition, you must have at least initialised and unsealed the Vault servers.

You must also provision this with the aws-auth module. You must give the nomad_client token role in aws-auth the docker_auth policy.

You can use both modules in the same Terraform module to provision to satisfy the requirements. For example:

module "docker_auth" {
    source = "..."

    # ...
}

module "aws_auth" {
    source = "..."

    # ...

    # Attach policy to allow creation of tokens for Nomad servers
    nomad_client_policies = ["...", "${module.docker_auth.policy_name}"]
}

Vault Provider

Refer to the documentation on the Terraform Vault provider for details on how you can provide a Vault token for this Terraform operation. In general, you might want to do this with a Root token.

Consul Provider

Refer to the documentation on how to configure the ACL token for the provider if needed.

Vault Token

Instead of generating a Vault Token by hand while configuring Nomad, we instead choose to configure Vault to enable the AWS authentication method so that Nomad servers instance will be able to retrieve a token on first boot purely by authenticating with Vault via their Instance Profile.

What this module does

This module first provisions two policies and token roles in Vault.

Policies

• nomad_server_policy: This policy allows the token holder to create a periodic token with the nomad_cluster_policy using the nomad_server token role.
• nomad_cluster_policy: This policy allows Nomad to create child tokens for jobs that require it.

Roles

• nomad_server: This allows the creation of a token that is passed to Nomad for Nomad to create child tokens for use with jobs using the nomad_cluster role.
• nomad_cluster: This role is used by Nomad servers to create child tokens for use with jobs.

Tokens

Using a source token obtained from the aws-auth module that has the nomad_server_policy, we can create a new nomad_cluster token using the nomad_cluster role.

The nomad_cluster token will then be passed to Nomad servers for Nomad to manage. This token will be used by Nomad servers to create child tokens for use with jobs.

Integration with Core module

After you have applied this module, a key will be set in Consul's KV store. The default user_data scripts of the Core's Nomad servers and clients will check for the presence of this key in Consul to configure themselves accordingly. Refer to the Core module's documentation on how to update your Nomad cluster.

Inputs and Outputs

Refer to INOUT.md