acme-companion is a lightweight companion container for nginx-proxy.

It handles the automated creation, renewal and use of SSL certificates for proxied Docker containers through the ACME protocol.

Required read if you use the latest version : the v2.0.0 release of this project mark the switch of the ACME client used by the Docker image from simp.le to acme.sh. This switch result in some backward incompatible changes, so please read this issue and the updated docs for more details before updating your image. The single most important change is that the container now requires a volume mounted to /etc/acme.sh in order to persist ACME account keys and SSL certificates. The last tagged version that uses simp_le is v1.13.1.

Features:

• Automated creation/renewal of Let's Encrypt (or other ACME CAs) certificates using acme.sh.
• Let's Encrypt / ACME domain validation through http-01 challenge only.
• Automated update and reload of nginx config on certificate creation/renewal.
• Support creation of Multi-Domain (SAN) Certificates.
• Creation of a Strong Diffie-Hellman Group at startup.
• Work with all versions of docker.

Requirements:

• Your host must be publicly reachable on both port 80 and 443.
• Check your firewall rules and do not attempt to block port 80 as that will prevent http-01 challenges from completing.
• For the same reason, you can't use nginx-proxy's HTTPS_METHOD=nohttp.
• The (sub)domains you want to issue certificates for must correctly resolve to the host.
• Your DNS provider must answer correctly to CAA record requests.
• If your (sub)domains have AAAA records set, the host must be publicly reachable over IPv6 on port 80 and 443.

Basic usage (with the nginx-proxy container)

Three writable volumes must be declared on the nginx-proxy container so that they can be shared with the acme-companion container:

• /etc/nginx/certs to store certificates and private keys (readonly for the nginx-proxy container).
• /etc/nginx/vhost.d to change the configuration of vhosts (required so the CA may access http-01 challenge files).
• /usr/share/nginx/html to write http-01 challenge files.

Additionally, a fourth volume must be declared on the acme-companion container to store acme.sh configuration and state: /etc/acme.sh.

Please also read the doc about data persistence.

Example of use:

Step 1 - nginx-proxy

Start nginx-proxy with the three additional volumes declared:

$ docker run --detach \
    --name nginx-proxy \
    --publish 80:80 \
    --publish 443:443 \
    --volume certs:/etc/nginx/certs \
    --volume vhost:/etc/nginx/vhost.d \
    --volume html:/usr/share/nginx/html \
    --volume /var/run/docker.sock:/tmp/docker.sock:ro \
    nginxproxy/nginx-proxy

Binding the host docker socket (/var/run/docker.sock) inside the container to /tmp/docker.sock is a requirement of nginx-proxy.

Step 2 - acme-companion

Start the acme-companion container, getting the volumes from nginx-proxy with --volumes-from:

$ docker run --detach \
    --name nginx-proxy-acme \
    --volumes-from nginx-proxy \
    --volume /var/run/docker.sock:/var/run/docker.sock:ro \
    --volume acme:/etc/acme.sh \
    --env "DEFAULT_EMAIL=mail@yourdomain.tld" \
    nginxproxy/acme-companion

The host docker socket has to be bound inside this container too, this time to /var/run/docker.sock.

Albeit optional, it is recommended to provide a valid default email address through the DEFAULT_EMAIL environment variable, so that Let's Encrypt can warn you about expiring certificates and allow you to recover your account.

Step 3 - proxied container(s)

Once both nginx-proxy and acme-companion containers are up and running, start any container you want proxied with environment variables VIRTUAL_HOST and LETSENCRYPT_HOST both set to the domain(s) your proxied container is going to use.

VIRTUAL_HOST control proxying by nginx-proxy and LETSENCRYPT_HOST control certificate creation and SSL enabling by acme-companion.

Certificates will only be issued for containers that have both VIRTUAL_HOST and LETSENCRYPT_HOST variables set to domain(s) that correctly resolve to the host, provided the host is publicly reachable.

$ docker run --detach \
    --name your-proxied-app \
    --env "VIRTUAL_HOST=subdomain.yourdomain.tld" \
    --env "LETSENCRYPT_HOST=subdomain.yourdomain.tld" \
    nginx

The containers being proxied must expose the port to be proxied, either by using the EXPOSE directive in their Dockerfile or by using the --expose flag to docker run or docker create.

If the proxied container listen on and expose another port than the default 80, you can force nginx-proxy to use this port with the VIRTUAL_PORT environment variable.

Example using Grafana (expose and listen on port 3000):

$ docker run --detach \
    --name grafana \
    --env "VIRTUAL_HOST=othersubdomain.yourdomain.tld" \
    --env "VIRTUAL_PORT=3000" \
    --env "LETSENCRYPT_HOST=othersubdomain.yourdomain.tld" \
    --env "LETSENCRYPT_EMAIL=mail@yourdomain.tld" \
    grafana/grafana

Repeat Step 3 for any other container you want to proxy.

Additional documentation

Please check the docs section.