For development and testing purposes, sometimes its useful to build images locally and push them directly to a Kubernetes cluster.

This can be achieved by running a docker registry in the cluster and using a special repo prefix such as "127.0.0.1:5000/" that will be seen as an insecure registry url.

Start/Stop private registry in cluster

start private registry

./start-docker-private-registry

stop private registry

./stop-docker-private-registry

Registry access

Access the registry via port forwarding

Use the docker-private-registry pod to forward the port

./port-forward-registry

Then use the address/port

127.0.0.1:5000

Test the registry

Check if the registry catalog can be accessed and the ability to push an image.

(set -x && curl -X GET http://127.0.0.1:5000/v2/_catalog && docker pull busybox && docker tag busybox 127.0.0.1:5000/busybox && docker push 127.0.0.1:5000/busybox)

Example Build and Deployment

cd example

# build and push the image to the registry
make build_image && make push_to_registry

# create a simple deployment
make create_deployment

# check details of the deployed pod to ensure its using the built image
make describe_pod

Troubleshooting

• Check the Insecure Registries list

  Log into each node in the cluster and ensure that the docker daemon is running with the right "Insecure Registries' list.

  docker info|grep -i -A5 'Insecure Registries'

• Docker for Mac issue

  You may see an error like the following

  Get http://127.0.0.1:5000/v2/: dial tcp 127.0.0.1:5000: getsockopt: connection refused
  

  Since docker is running in a VM on the mac, its not possible to directly use "127.0.0.1:5000".
  Use socat running in a container as a workaround.

  docker run --rm --privileged \
      --pid=host gsunner/ubuntu-socat \
      nsenter -t 1 -u -n -i socat TCP-LISTEN:5000,fork TCP:docker.for.mac.host.internal:5000