terraform-docker-mirror

This Terraform module ensures that a source Docker image is mirrored to the specified Docker registry, copying image source_prefix/image_name:image-tag to dest_prefix/image_name:image_tag.

It requires a Terraform Docker Provider to be configured, as well as a Docker daemon running on the Terraform-local machine. Note you may need to setup authentication or run docker login to access private registries.

Motivations

Prepare images for Cloud Run

Google Cloud Run requires images to pulled from the Google Container Registry (GCR) registries at gcr.io. One can use this module to mirror from their alternate Docker infrastructure to GCR.

Docker on GCP Private Network

If one uses Docker on a private network on the Google Cloud (GCP/GKE), the nodes will not be able to pull from the Docker Hub Registry. However, the nodes can pull from the Google Container Registry (GCR). Thus, mirroring the registries will facilitate the nodes' access to images. This module enables this to be managed with Terraform.

How It Works

This module works by first creating a docker_image resource, which pulls the "source" image to the Docker provider. That pull will trigger a local-exec provisioner which performs a tag and docker push to the destination registry.

Terraform Version Compatibility

Version v0.1.0 of terraform-docker-mirror supports Terraform 0.11 and earlier.

Version v0.2.0, v0.3.0, and v0.3.1 support Terraform 0.12.

Version v0.4.0 and later support Terraform 0.13.

If unspecified, Terraform uses the latesst master.

You can specify the version with the source attribute, like so:

module "docker-mirror-vault" {
  source = "github.com/neomantra/terraform-docker-mirror?ref=v0.4.0"
  ...
}

Example

The following will mirror the HashiCorp Vault image (vault:1.0.3) to the GCR registry for my-gcp-project:

module "docker-mirror-vault" {
  source        = "github.com/neomantra/terraform-docker-mirror?ref=v0.4.0"
  image_name    = "vault"
  image_tag     = "1.0.3"
  dest_prefix   = "us.gcr.io/my-gcp-project"
}

Example with source_prefix, copying openresty/openresty:xenial to us.gcr.io/my-gcp-project/openresty:xenial:

module "docker-mirror-resty" {
  source        = "github.com/neomantra/terraform-docker-mirror?ref=v0.4.0"
  image_name    = "vault"
  image_tag     = "1.0.3"
  source_prefix = "openresty"
  dest_prefix   = "us.gcr.io/my-gcp-project"
}

License

Authored by Evan Wies.

Copyright (c) 2019-2020 Neomantra BV.

Released under the MIT License, see LICENSE.