Copy images between repositories

You can use the gcrane tool to copy images between Docker repositories in Artifact Registry.

You can also use the tool to copy images from Container Registry to Artifact Registry.

Before you begin

Verify the following requirements:

You have created the target Docker repository in Artifact Registry for the images you are copying.
You have the required permissions:
- Artifact Registry Reader (roles/storage.objectViewer) or a role with equivalent permissions for the repository you are copying from.
- Artifact Registry Writer (roles/artifactregistry.writer) or a role with equivalent permissions for the target repository.

Overview

The gcrane tool simplifies copying across repositories with support for:

Copying sets of images with a single command, including all images under a specified path or all images stored on multi-regional host in your project.
Skipping image layers that are already uploaded.

Removing unused images

Removing unused images before you performing a copy operation can help you to reduce storage costs.

A number of tools are available to identify and automate removal of images that you no longer need. For example, the gcr-cleaner tool helps you to find and remove old images based on different criteria. The gcr-cleaner tool is not an official Google product.

For more information about setting up and using the tool, see the gcr-cleaner documentation.

Setting up gcrane

You can run gcrane from the following environments:

Compute Engine instance - Use this option if you have a larger number of containers to copy.

Costs: Instance uptime for the Compute Engine VM. If the VM instance is in a different location than the source repository, network egress charges might apply for the images you copy.
Cloud Shell - An option for copying small sets of about 40GB or less. Since the gcrane tool skips uploading image layers that are already uploaded, this limit is for new data that you are copying.

Copying larger repositories might cause Cloud Shell to disconnect after the request timeout period of 10 minutes.

Costs: If the Cloud Shell instance is in a different location than the source repository, network egress charges might apply for the images you copy. You cannot chose the location of a Cloud Shell session. To check the location of the current session, run the command:
```
curl metadata/computeMetadata/v1/instance/zone
```

We recommend using the latest version of the gcrane tool to take advantage of all available features and enhancements. The setup instructions in the following sections include steps to download the latest version.

To check the version of an existing gcrane installation, run the command:

gcrane version

Setting up Compute Engine

To copy images with gcrane from a Compute Engine VM instance:

Create a VM instance. To minimize costs, create the instance in the same location as the registry you are copying from.
By default, the VM instance is associated with the default service account and has permissions to pull images. You must change the access scope so that the VM instance can push images.
1. Stop the VM instance. See Stopping an instance.
2. Change the access scope with the command:
```
gcloud compute instances set-service-account INSTANCE --scopes=storage-rw
```
  Replace INSTANCE with the name of the VM instance.
3. Restart the VM instance. See Starting a stopped instance.
Connect to the VM instance using SSH.

Run the following command to download gcrane.

curl -L \
https://github.com/google/go-containerregistry/releases/latest/download/go-containerregistry_Linux_x86_64.tar.gz \
-o go-containerregistry.tar.gz

Run the following commands to make the gcrane command executable.

tar -zxvf go-containerregistry.tar.gz
chmod +x gcrane
sudo mv gcrane /usr/local/bin/

Run the command gcrane --help to verify the installation.

You are now ready to copy images. To continue:

Setting up Cloud Shell

Open a Cloud Shell window.

Open Cloud Shell
Set the default project. Replace PROJECT with the ID of project where Container Registry and Artifact Registry are installed
```
gcloud config set project PROJECT
```

Run the following command to download the gcrane tool.

curl -L \
https://github.com/google/go-containerregistry/releases/latest/download/go-containerregistry_Linux_x86_64.tar.gz \
-o go-containerregistry.tar.gz

Run the following commands to make the gcrane command executable.

tar -zxvf go-containerregistry.tar.gz
chmod +x gcrane
sudo mv gcrane /usr/local/bin/

Run the command gcrane --help to verify the installation.

You are now ready to copy images. To continue:

Setting up a local machine

Download gcrane from the GitHub repository. For example, the following command downloads the Linux x86-64 distribution from the command line.

curl -L \
https://github.com/google/go-containerregistry/releases/latest/download/go-containerregistry_Linux_x86_64.tar.gz \
-o go-containerregistry.tar.gz

Run the following commands to make the gcrane command executable. The commands assume that the downloaded file is named go-containerregistry.tar.gz.
```
tar -zxvf go-containerregistry.tar.gz
chmod +x gcrane
sudo mv gcrane /usr/local/bin/
```
Run the command gcrane --help to verify the installation.

You are now ready to copy images. To continue:

Identifying images to copy

After you have installed the gcrane tool, you can list the existing images in the source repository to find the ones you want to copy.

To list existing images, run the command:

gcrane ls LOCATION-docker.pkg.dev/PROJECT/REPOSITORY

To list tags an image has, run the command:

gcrane ls LOCATION-docker.pkg.dev/PROJECT/IMAGE

To list images recursively under a specific path, run the command:

gcrane ls -r LOCATION-docker.pkg.dev/PROJECT/PATH

For each of the commands:

Replace LOCATION with the location of the repository.
Replace PROJECT with the project ID.
Replace PATH with the path to copy.

See Copying images for the commands to copy your images.

Copying images

You can copy individual images or sets of images with the gcrane cp command.

To copy a single image, run the command:

gcrane cp LOCATION1-docker.pkg.dev/PROJECT1/REPOSITORY1/IMAGE1 \
LOCATION2-docker.pkg.dev/PROJECT2/REPOSITORY2/IMAGE2

To copy images recursively under a specific path in a repository, run the command:

gcrane cp -r LOCATION1-docker.pkg.dev/PROJECT1/REPOSITORY1/IMAGE1/PATH1 \
LOCATION2-docker.pkg.dev/PROJECT2/REPOSITORY2/IMAGE2/PATH2

To copy all images in a repository, run the command:

gcrane cp -r LOCATION1-docker.pkg.dev/PROJECT1/REPOSITORY1 \
LOCATION2-docker.pkg.dev/PROJECT2/REPOSITORY2

Replace the following values:

LOCATION1 is the location of the source repository.
LOCATION2 is the location of the target repository.
PROJECT1 is the Google Cloud project ID associated with the source repository.
PROJECT2 is the Google Cloud project ID associated with the target repository.
REPOSITORY1 is the name of the source repository.
REPOSITORY2 is the name of the target repository.
IMAGE1 is the image that you want to copy.
IMAGE2 is the name for the image in the target repository.

Examples

The following command copies my-image:tag1 from the repository repo1 to the repository repo2 within the same project and region.

gcrane cp us-west1-docker.pkg.dev/my-project/repo1/my-image:tag1 \
us-west1-docker.pkg.dev/my-project/repo2/my-image:tag1

The following command recursively copies all images under test-images/testing in the repository repo1 to the same path under the repository repo2.

gcrane cp -r us-west1-docker.pkg.dev/my-project/repo1/test-images/testing \
us-west1-docker.pkg.dev/my-project/repo2/test-images/testing

The following command copies all images from the repository my-repo in the project dev-project to the repository my-repo in another project called prod-project.

gcrane cp -r us-west1-docker.pkg.dev/dev-project/my-repo \
us-west1-docker.pkg.dev/prod-project/my-repo