distribution/docs/authentication.md

Authentication

While running an unrestricted registry is certainly ok for development, secured local networks, or test setups, you should probably implement access restriction if you plan on making your registry available to a wider audience or through public internet.

The Registry supports two different authentication methods to get your there:

• direct authentication, through the use of a proxy
• delegated authentication, redirecting to a trusted token server

The first method is recommended for most people as the most straight-forward solution.

The second method requires significantly more investment, and only make sense if you want to fully configure ACLs and more control over the Registry integration into your global authorization and authentication systems.

Direct authentication through a proxy

With this method, you implement basic authentication in a reverse proxy that sits in front of your registry.

Since the Docker engine uses basic authentication to negotiate access to the Registry, securing communication between docker engines and your proxy is absolutely paramount.

While this model gives you the ability to use whatever authentication backend you want through a secondary authentication mechanism implemented inside your proxy, it also requires that you move TLS termination from the Registry to the proxy itself.

Below is a simple example of secured basic authentication (using TLS), using nginx as a proxy.

### Requirements

You should have followed entirely the basic deployment guide.

If you have not, please take the time to do so.

At this point, it's assumed that:

• you understand Docker security requirements, and how to configure your docker engines properly
• you have installed Docker Compose
• you have a domain.crt and domain.key files, for the CN myregistrydomain.com (or whatever domain name you want to use)
• these files are located inside the current directory, and there is nothing else in that directory
• it's HIGHLY recommended that you get a certificate from a known CA instead of self-signed certificates
• be sure you have stopped and removed any previously running registry (typically docker stop registry && docker rm registry)

Setting things up

Read again the requirements.

Ready?

Run the following:

mkdir auth
mkdir data

# This is the main nginx configuration you will use
cat <<EOF > auth/registry.conf
upstream docker-registry {
  server registry:5000;
}

server {
  listen 443 ssl;
  server_name myregistrydomain.com;

  # SSL
  ssl_certificate /etc/nginx/conf.d/domain.crt;
  ssl_certificate_key /etc/nginx/conf.d/domain.key;

  # disable any limits to avoid HTTP 413 for large image uploads
  client_max_body_size 0;

  # required to avoid HTTP 411: see Issue #1486 (https://github.com/docker/docker/issues/1486)
  chunked_transfer_encoding on;

  location /v2/ {
    # Do not allow connections from docker 1.5 and earlier
    # docker pre-1.6.0 did not properly set the user agent on ping, catch "Go *" user agents
    if (\$http_user_agent ~ "^(docker\/1\.(3|4|5(?!\.[0-9]-dev))|Go ).*\$" ) {
      return 404;
    }

    # To add basic authentication to v2 use auth_basic setting plus add_header
    auth_basic "registry.localhost";
    auth_basic_user_file /etc/nginx/conf.d/registry.password;
    add_header 'Docker-Distribution-Api-Version' 'registry/2.0' always;

    proxy_pass                          http://docker-registry;
    proxy_set_header  Host              \$http_host;   # required for docker client's sake
    proxy_set_header  X-Real-IP         \$remote_addr; # pass on real client's IP
    proxy_set_header  X-Forwarded-For   \$proxy_add_x_forwarded_for;
    proxy_set_header  X-Forwarded-Proto \$scheme;
    proxy_read_timeout                  900;
  }
}
EOF

# Now, create a password file for "testuser" and "testpassword"
echo 'testuser:$2y$05$.nIfPAEgpWCh.rpts/XHX.UOfCRNtvMmYjh6sY/AZBmeg/dQyN62q' > auth/registry.password

# Alternatively you could have achieved the same thing with htpasswd
# htpasswd -Bbc auth/registry.password testuser testpassword

# Copy over your certificate files
cp domain.crt auth
cp domain.key auth

# Now create your compose file

cat <<EOF > docker-compose.yml
nginx:
  image: "nginx:1.9"
  ports:
    - 5043:443
  links:
    - registry:registry
  volumes:
    - `pwd`/auth/:/etc/nginx/conf.d

registry:
  image: registry:2
  ports:
    - 127.0.0.1:5000:5000
  environment:
    REGISTRY_STORAGE_FILESYSTEM_ROOTDIRECTORY: /data
  volumes:
    - `pwd`/data:/data
EOF

Starting and stopping

That's it. You can now:

• docker-compose up -d to start your registry
• docker login myregistrydomain.com:5043 (using testuser and testpassword)
• docker tag ubuntu myregistrydomain.com:5043/toto
• docker push myregistrydomain.com:5043/toto

Docker still complains about the certificate?

That's certainly because you are using a self-signed certificate, despite the warnings.

If you really insist on using these, you have to trust it at the OS level.

Usually, on Ubuntu this is done with:

cp auth/domain.crt /usr/local/share/ca-certificates/myregistrydomain.com.crt
update-ca-certificates

... and on RedHat with:

cp auth/domain.crt /etc/pki/ca-trust/source/anchors/myregistrydomain.com.crt
update-ca-trust

Now:

• service docker stop && service docker start (or any other way you use to restart docker)
• docker-compose up -d to bring your registry up

Token-based delegated authentication

This is advanced.

You will find background information here, configuration information here.

Beware that you will have to implement your own authentication service for this to work (though there exist third-party open-source implementations).

Manual Set-up

If you'd like to manually configure your HTTP server, here are a few requirements that are absolutely necessary for the docker client to be able to interface with it:

• Each response needs to have the header "Docker-Distribution-Api-Version registry/2.0" set, even (especially) if there is a 401 or 404 error response. Make sure using cURL that this header is provided. Note: If you're using Nginx, this functionality is only available since 1.7.5 using the "always" add_header directive, or when compiling with the "more_set_headers" module.

• A large enough maximum for client body size, preferrably unlimited. Because images can be pretty big, the very low default maximum size of most HTTP servers won't be sufficient to be able to upload the files.

• Support for chunked transfer encoding.