distribution/docs/insecure.md

Insecure Registry

While it's highly recommended to secure your registry using a TLS certificate issued by a known CA, you may alternatively decide to use self-signed certificates, or even use your registry over plain http.

You have to understand the downsides in doing so, and the extra burden in configuration.

Deploying a plain HTTP registry

⚠️ it's not possible to use an insecure registry with basic authentication

This basically tells Docker to entirely disregard security for your registry.

1. edit the file /etc/default/docker so that there is a line that reads: DOCKER_OPTS="--insecure-registry myregistrydomain.com:5000" (or add that to existing DOCKER_OPTS)
2. restart your Docker daemon: on ubuntu, this is usually service docker stop && service docker start

Pros:

• easy to configure

Cons:

• very insecure
• you have to configure every docker daemon that wants to access your registry

Using self-signed certificates

⚠️ using this along with basic authentication requires to also trust the certificate into the OS cert store for some versions of docker

Generate your own certificate:

mkdir -p certs && openssl req \
  -newkey rsa:4096 -nodes -sha256 -keyout certs/domain.key \
  -x509 -days 365 -out certs/domain.crt

Be sure to use the name myregistrydomain.com as a CN.

Stop and restart your registry.

Then you have to instruct every docker daemon to trust that certificate. This is done by copying the domain.crt file to /etc/docker/certs.d/myregistrydomain.com:5000/ca.crt (don't forget to restart docker after doing so).

Stop and restart all your docker daemons.

Pros:

• more secure than the insecure registry solution

Cons:

• you have to configure every docker daemon that wants to access your registry

Failing...

Failing to configure docker and trying to pull from a registry that is not using TLS will result in the following message:

FATA[0000] Error response from daemon: v1 ping attempt failed with error:
Get https://myregistrydomain.com:5000/v1/_ping: tls: oversized record received with length 20527. 
If this private registry supports only HTTP or HTTPS with an unknown CA certificate,please add 
`--insecure-registry myregistrydomain.com:5000` to the daemon's arguments.
In the case of HTTPS, if you have access to the registry's CA certificate, no need for the flag;
simply place the CA certificate at /etc/docker/certs.d/myregistrydomain.com:5000/ca.crt