kustomize-docker

Docker image for systems using Kustomize and kubectl.

Included additions beyond base Apline:

• Kustomize 5.2.1
• Kubectl 1.23.17
• AWS 1.29.82
• sops 3.8.1
• envsubst

Working directory is set to /working/ if you need to mount files.

Usage

On docker

If you're making up your own workflow, the image is on Docker Hub.

End-to-end Usage

Using the commands shown below, a complete deploy can be run by piping the output of each into the others:

# envsubst for plain sh using docker. Passes all exported variables off to docker
ENV=$(env | grep = | grep -v '^_' | sed 's/\([^=]*\)=.*/ -e \1 /' | tr -d '\n')

docker run --rm -i \
    $ENV \
    -w /working/ \
    -v "$(pwd):/working/" \
    benjjefferies/kustomize-docker \
    kustomize build /working/overlays/$OVERLAY \
| docker run --rm -i \
    $ENV \
    benjjefferies/kustomize-docker \
    envsubst \
| docker run --rm -i \
    -v "$KUBECONFIG:/root/.kube/config" \
    benjjefferies/kustomize-docker \
    kubectl apply -f -

envsubst

Envsubst may be useful in building deploy-specific Kustomize overlays. A general pattern for this is:

# envsubst for plain sh using docker. Passes all exported variables off to docker
ENV=$(env | grep = | grep -v '^_' | sed 's/\([^=]*\)=.*/ -e \1 /' | tr -d '\n')

docker run --rm -i \
    $ENV \
    benjjefferies/kustomize-docker \
    envsubst \
    < input_file.yaml \
    > output_file.yaml

kustomize

If $OVERLAY is the name of the overlay to use and your current working directory is the base of your Kustomize files:

ENV=$(env | grep = | grep -v '^_' | sed 's/\([^=]*\)=.*/ -e \1 /' | tr -d '\n')
docker run --rm -i \
    $ENV \
    -w /working/ \
    -v "$(pwd):/working/" \
    benjjefferies/kustomize-docker \
    kustomize build /working/overlays/$OVERLAY

Note that all kustomization.yamls, resources, patches, etc must be under the working directory or the container will not be able to access them.

We also include all the local environment variables in the kustomize run because configMap and secret generators might do things like "echo $ENV_VAR" and we want that to work.

kubectl

If $KUBECONFIG is the path to your K8s configuration file (this is the default variable named used by Gitlab's CI):

docker run --rm -i \
    -v "$KUBECONFIG:/root/.kube/config" \
    benjjefferies/kustomize-docker \
    kubectl apply -f - \
    < input_file.yaml

AWS

To get .kube/config in AWS EKS you can use the aws-cli.

docker run --rm -i \
    -e AWS_ACCESS_KEY_ID $AWS_ACCESS_KEY_ID \
    -e AWS_SECRET_ACCESS_KEY $AWS_SECRET_ACCESS_KEY \
    benjjefferies/kustomize-docker \
    aws eks --region $region update-kubeconfig --name $eks-cluster-name

If you're going to be doing any kubectl cping, don't forget to add the appropriate volumes.