A Docker image to automatically request and renew SSL/TLS certificates from Let's Encrypt using certbot and the Webroot or Cloudflare DNS method for domain validation. This image is also capable of sending a HUP signal to Docker container(s) running a web server in order to use the freshly minted certificates.

Based on the quay.io/letsencrypt/letsencrypt base image and inspired by kvaps/letsencrypt-webroot. Modified for Cloudflare DNS support by Logicer

For ease of auditability, this version is simplified with configuration removed or generalized.

Contents:

• Usage
  • Webroot
  • Cloudflare DNS
• Optional features
  • Reload server configuration
  • Copy certificates to another directory
  • Customize webroot path
  • Change the check frequency
  • Change DNS propagation delay
• Configuration

Verify domain ownership by hosting a file. The webroot method works on any server hosting the website on port 80 or 443.

The webroot method assumes a web server is set up to serve ACME challenge files. For example, using Nginx:

location '/.well-known/acme-challenge' {
  root /var/www;
}

Your server container should be configured to be able use certificates retrieved by certbot. The certificates can be found at /etc/letsencrypt/live/example.com or be copied to a directory of your choice (see below). For example, using Nginx:

ssl_certificate     /etc/letsencrypt/live/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

Run this image:

docker run -d
  -e 'DOMAINS=example.com www.example.com' \
  -e [email protected] \
  -e SERVER_CONTAINER=nginx \
  -e WEBROOT_PATH=/var/www \
  -e CERTS_PATH=/etc/nginx/certs \
  -e CHECK_FREQ=7 \
  -v /tmp/letsencrypt:/var/www \
  -v /etc/nginx/certs:/etc/nginx/certs \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v /etc/letsencrypt:/etc/letsencrypt \
  -v /var/log/letsencrypt/:/var/log/letsencrypt \
  -v /var/lib/letsencrypt:/var/lib/letsencrypt \
  logicer16/auto-letsencrypt

Docker compose:

version: '2'

services:
  nginx:
    image: nginx
    volumes:
      - certs:/etc/nginx/certs
      - /tmp/letsencrypt/www:/tmp/letsencrypt/www
    ports:
      - "80:80"
      - "443:443"
    restart: unless-stopped

  letsencrypt:
    image: logicer16/auto-letsencrypt
    volumes:
      - /tmp/letsencrypt/www:/tmp/letsencrypt/www
      - certs:/etc/nginx/certs
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/letsencrypt:/etc/letsencrypt
      - /var/log/letsencrypt/:/var/log/letsencrypt
      - /var/lib/letsencrypt:/var/lib/letsencrypt
    environment:
      - DOMAINS=example.com www.example.com
      - [email protected]
      - SERVER_CONTAINER=nginx
      - WEBROOT_PATH=/tmp/letsencrypt/www
      - CERTS_PATH=/etc/nginx/certs
      - CHECK_FREQ=7
    restart: unless-stopped
    depends_on:
      - nginx

  volumes:
    certs:

The container will attempt to request and renew SSL/TLS certificates for the specified domains and automatically repeat the renew process periodically (default is every 30 days).

Verify domain ownership through a DNS record. The Cloudflare DNS requires the domain's primary DNS provider to be Cloudflare. By verifying through DNS, wildcard (*.example.com) certificates can also be created.

For certbot to create the required DNS reocrd, it needs to authenticate with an API Token (recomended) or a Global API Key (not recommended). Follow these instructions to create the credential and save it to a .ini file. This file must be bound to this image at the path specified by CLOUDFLARE_CREDENTIALS.

Your server container should be configured to be able use certificates retrieved by certbot. The certificates can be found at /etc/letsencrypt/live/example.com or be copied to a directory of your choice (see below). For example, using Nginx:

ssl_certificate     /etc/letsencrypt/live/example.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

Run this image:

docker run -d
  -e 'DOMAINS=*.example.com' \
  -e [email protected] \
  -e CLOUDFLARE_CREDENTIAL=/cloudflare-credential.ini \
  -e CLOUDFLARE_PROPAGATION_SECONDS=10 \
  -e SERVER_CONTAINER=nginx \
  -e CERTS_PATH=/etc/nginx/certs \
  -e CHECK_FREQ=7 \
  -v /etc/nginx/certs:/etc/nginx/certs \
  -v ./cloudflare-credential.ini:/cloudflare-credential.ini \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v /etc/letsencrypt:/etc/letsencrypt \
  -v /var/log/letsencrypt/:/var/log/letsencrypt \
  -v /var/lib/letsencrypt:/var/lib/letsencrypt \
  logicer16/auto-letsencrypt

Docker compose:

version: '2'

services:
  nginx:
    image: nginx
    volumes:
      - certs:/etc/nginx/certs
    ports:
      - "443:443"
    restart: unless-stopped

  letsencrypt:
    image: logicer16/auto-letsencrypt
    volumes:
      - certs:/etc/nginx/certs
      - ./cloudflare-credential.ini:/cloudflare-credential.ini
      - /var/run/docker.sock:/var/run/docker.sock
      - /etc/letsencrypt:/etc/letsencrypt
      - /var/log/letsencrypt/:/var/log/letsencrypt
      - /var/lib/letsencrypt:/var/lib/letsencrypt
    environment:
      - DOMAINS=*.example.com
      - [email protected]
      - CLOUDFLARE_CREDENTIAL=/cloudflare-credential.ini
      - CLOUDFLARE_PROPAGATION_SECONDS=10
      - SERVER_CONTAINER=nginx
      - CERTS_PATH=/etc/nginx/certs
      - CHECK_FREQ=7
    restart: unless-stopped
    depends_on:
      - nginx

  volumes:
    certs:

The container will attempt to request and renew SSL/TLS certificates for the specified domains and automatically repeat the renew process periodically (default is every 30 days).

To automatically reload the server configuration to use the new certificates, provide the container name(s) to the environment variable SERVER_CONTAINER and pass through the Docker socket to this container: -v /var/run/docker.sock:/var/run/docker.sock. The image will send a HUP signal to the specified container(s). multiple containers can be specified by seperating them by spaces. Container labels can also be used with SERVER_CONTAINER_LABEL.

Provide a directory path to the CERTS_PATH environment variable if you wish to copy the certificates to another directory. You may wish to do this in order to avoid exposing the entire /etc/letsencrypt/ directory to your web server container.

To configure the webroot path use the WEBROOT_PATH environment variable. The default is /var/www.

Provide a number to the CHECK_FREQ environment variable to adjust how often it attempts to renew a certificate. The default is 30 days. Please note certbot is configured to keep matching certificates until one is due for renewal, avoiding unnecessary renewals.

Provide a number to the CLOUDFLARE_PROPAGATION_SECONDS environment variable to adjust the number of seconds to wait before verifying the DNS record. The default is 10 seconds.