Working with Images
Rancher Desktop provides the ability to build, push, and pull images via the NERDCTL project and the Docker CLI.
Note, both nerdctl
and docker
are put into the path automatically. This occurs during the installer on Windows, and upon first run on macOS and Linux.
General Usage​
Using either tool requires Rancher Desktop to be running with the appropriate container runtime. For nerdctl
, use the containerd runtime. For docker
, use the Moby runtime.
You can learn about all of the command options and display the help documentation by running:
- nerdctl
- docker
nerdctl -h
Unlike Docker, containerd features its own namespaces. By default, nerdctl images are stored in the default
namespace. If you want your images available for use by Kubernetes, use the --namespace k8s.io
or -n k8s.io
CLI argument. You can also switch to a namespace called default
or any other name using the option --namespace <NAMESPACE_NAME>
. Note that nerdctl namespaces are separate and independent from Kubernetes and kubectl
namespaces.
docker --help
Listing Images​
To see the images currently available, run the following command:
- nerdctl
- docker
nerdctl images
docker images
Building Images​
- nerdctl
- docker
Building images has a similar feel to existing tools. For example, consider
running nerdctl
from a directory with a Dockerfile
where the Dockerfile
is
using a scratch image.
nerdctl build .
[+] Building 0.1s (4/4) FINISHED
=> [internal] load build definition from Dockerfile
=> => transferring dockerfile: 31B
=> [internal] load .dockerignore
=> => transferring context: 2B
=> [internal] load build context
=> => transferring context: 33B
=> CACHED [1/1] ADD anvil-app /
nerdctl
has options for tagging at the same time as building and other options you've
come to expect.
nerdctl build -t TAG .
To build an image for use with Kubernetes, specify the k8s.io
namespace as follows:
nerdctl build -n k8s.io .
Consider running docker
from a directory with a Dockerfile
where the Dockerfile
is
using a scratch image.
docker build .
Sending build context to Docker daemon 13.93MB
Step 1/5 : FROM some-repo/some-image
---> e57ace221dff
...
---> fd984c4cbf97
Successfully built fd984c4cbf97
docker
has options for tagging at the same time as building and other options you've
come to expect.
docker build -t TAG .
Building Local Images​
In order to demonstrate the steps to build local images and run apps, a sample nodejs app is provided within the Rancher Desktop docs repository. To get started, clone the repository and cd into assets/express-sample
in a terminal.
Run the following command to build image from Dockerfile:
- nerdctl
- docker
nerdctl --namespace k8s.io build -t expressapp:v1.0 .
docker build -t expressapp:v1.0 .
Run the following command to run container:
kubectl run --image expressapp:v1.0 expressapp
kubectl port-forward pods/expressapp 3000:3000
Note: When adding the latest
tag, be sure to also specify the following:
imagePullPolicy: Never
Tagging Images​
If you want to tag an existing image you've built you can use the following command:
- nerdctl
- docker
nerdctl tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
Removing Images​
To remove an image, run the following command:
- nerdctl
- docker
nerdctl rmi IMAGE
docker rmi IMAGE