Pushing images

comparing 5 ways to push your image into a minikiube cluster.

Comparison table for different methods

The best method to push your image to minikube depends on the container-runtime you built your cluster with (the default is docker). Here is a comparison table to help you choose:

Method Supported Runtimes Performance
docker-env command only docker good
podman-env command only cri-o good
cache add command all ok
registry addon all ok
minikube ssh all best
  • note1 : the default container-runtime on minikube is ‘docker’.
  • note2 : ‘none’ driver (bare metal) does not need pushing image to the cluster, as any image on your system is already available to the kuberentes.

1. Pushing directly to the in-cluster Docker daemon (docker-env)

When using a container or VM driver (all drivers except none), you can reuse the Docker daemon inside minikube cluster. this means you don’t have to build on your host machine and push the image into a docker registry. You can just build inside the same docker daemon as minikube which speeds up local experiments.

To point your terminal to use the docker daemon inside minikube run this:

eval $(minikube docker-env)

now any ‘docker’ command you run in this current terminal will run against the docker inside minikube cluster.

so if you do the following commands, it will show you the containers inside the minikube, inside minikube’s VM or Container.

docker ps

now you can ‘build’ against the docker inside minikube. which is instantly accessible to kubernetes cluster.

docker build -t my_image .

To verify your terminal is using minikuber’s docker-env you can check the value of the environment variable MINIKUBE_ACTIVE_DOCKERD to reflect the cluster name.

Tip 1: Remember to turn off the imagePullPolicy:Always (use imagePullPolicy:IfNotPresent or imagePullPolicy:Never) in your yaml file. Otherwise Kubernetes won’t use your locally build image and it will pull from the network.

Tip 2: Evaluating the docker-env is only valid for the current terminal. By closing the terminal, you will go back to using your own system’s docker daemon.

Tip 3: In container-based drivers such as Docker or Podman, you will need to re-do docker-env each time you restart your minikube cluster.

more information on docker-env

2. Push images using ‘cache’ command.

From your host, you can push a Docker image directly to minikube. This image will be cached and automatically pulled into all future minikube clusters created on the machine

minikube cache add alpine:latest

The add command will store the requested image to $MINIKUBE_HOME/cache/images, and load it into the minikube cluster’s container runtime environment automatically.

Tip 1 : If your image changes after your cached it, you need to do ‘cache reload’.

minikube refreshes the cache images on each start. however to reload all the cached images on demand, run this command :

minikube cache reload

Tip 2 : if you have multiple clusters, the cache command will load the image for all of them.

To display images you have added to the cache:

minikube cache list

This listing will not include the images minikube’s built-in system images.

minikube cache delete <image name>

For more information, see:

3. Pushing directly to in-cluster CRI-O. (podman-env)

This is similar to docker-env but only for CRI-O runtime. To push directly to CRI-O, configure podman client on your host using the podman-env command in your shell:

eval $(minikube podman-env)

You should now be able to use podman client on the command line on your host machine talking to the podman service inside the minikube VM:

podman-remote help

Note: On Linux the remote client is called “podman-remote”, while the local program is called “podman”.

podman help

Note: On macOS the remote client is called “podman”, since there is no local “podman” program available.

podman help

Note: On Windows the remote client is called “podman”, since there is no local “podman” program available.

Remember to turn off the imagePullPolicy:Always (use imagePullPolicy:IfNotPresent or imagePullPolicy:Never), as otherwise Kubernetes won’t use images you built locally.

4. Pushing to an in-cluster using Registry addon

For illustration purpose, we will assume that minikube VM has one of the ip from subnet. If you have not overridden these subnets as per networking guide, you can find out default subnet being used by minikube for a specific OS and driver combination here which is subject to change. Replace with appropriate values for your environment wherever applicable.

Ensure that docker is configured to use as insecure registry. Refer here for instructions.

Ensure that is enabled as insecure registry in minikube. Refer here for instructions..

Enable minikube registry addon:

minikube addons enable registry

Build docker image and tag it appropriately:

docker build --tag $(minikube ip):5000/test-img .

Push docker image to minikube registry:

docker push $(minikube ip):5000/test-img

5. Building images inside of minikube using SSH

Use minikube ssh to run commands inside the minikube node, and run the docker build directly there. Any command you run there will run against the same daemon that kubernetes cluster is using.

docker build

For more information on the docker build command, read the Docker documentation (docker.com).

For Podman, use:

sudo podman build

For more information on the podman build command, read the Podman documentation (podman.io).

to exit minikube ssh and come back to your terminal type:

Last modified June 17, 2020: Able to run sucessfully (0a309f9c5)