Pull Container Images Using ctr
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In this containerd challenge, you'll need to pull images from different container registries using the ctr command.
Let's start with a simple one - pull an nginx image from Docker Hub.
Hint 1
Unlike with the docker command, you can't just run ctr pull nginx.
The ctr command has a subcommand for working with images.
Try ctr image --help to see how to use it.
Hint 2
The ctr image pull command takes a fully-qualified image reference as an argument.
The famous docker run nginx is actually a shorthand for docker run docker.io/library/nginx:latest.
Try adapting this sacred knowledge to ctr image pull.
Docker Hub is not the only container registry supported by containerd.
Let's try pulling an image from another source - Google Container Registry (GCR) - gcr.io/distroless/static-debian12 is a good candidate.
Hint 3
Getting a cryptic failed to resolve reference: object required error?
Make sure you're using the fully-qualified image reference, including the tag!
To solidify your knowledge, let's try pulling an image from one more registry - the GitHub Container Registry (GHCR). This time, you'll need to come up with the image example yourself.
Hint 4
A fully-qualified image reference consists of three parts:
the registry domain, the repository path, and the tag.
For example, in gcr.io/distroless/static-debian12:nonroot,
the domain is gcr.io, the repository path is distroless/static-debian12,
and the tag is nonroot.
Hint 5
The GitHub Container Registry domain is ghcr.io.
Hint 6
On GHCR, the image repository path is typically the same as the code repository path.
For example, images of the github.com/openfaas/faas-netes project are hosted at ghcr.io/openfaas/faas-netes.