docker-letsencrypt-cron

Create and automatically renew website SSL certificates using the letsencrypt free certificate authority, and its client certbot.

This image will renew your certificates every 2 months, and place the lastest ones in the /certs folder in the container, and in the ./certs folder on the host.

Setup

In docker-compose.yml, change the environment variables:

• DOMAINS: a space separated list of domains for which you want to generate certificates.
• EMAIL: where you will receive updates from letsencrypt.
• CONCAT: true or false on whether you want to concatenate the certificate's full chain with the private key (required for e.g. haproxy), or keep the two files separate (required for e.g. nginx or apache).

ACME Validation challenge

To authenticate the certificates, the you need to pass the ACME validation challenge. This requires requests made on port 80 to your.domain.com/.well-known/ to be forwarded to this container.

The recommended way to use this image is to set up your reverse proxy to automatically forward requests for the ACME validation challenges to this container.

Haproxy example

If you use a haproxy reverse proxy, you can add the following to your configuration file in order to pass the ACME challenge.

frontend http
  bind *:80
  acl letsencrypt_check path_beg /.well-known

  use_backend certbot if letsencrypt_check

backend certbot
  server certbot certbot:80 maxconn 32

Nginx example

If you use nginx as a reverse proxy, you can add the following to your configuration file in order to pass the ACME challenge.

upstream certbot_upstream{
  server certbot:80;
}

server {
  listen              80;
  location '/.well-known/acme-challenge' {
    default_type "text/plain";
    proxy_pass http://certbot_upstream;
  }
}

Usage

docker-compose up -d

The first time you start it up, you may want to run the certificate generation script immediately:

docker exec certbot sh -c "/run_certbot.sh"

At 3AM, on the 1st of every odd month, a cron job will start the script, renewing your certificates.

More information

Find out more about letsencrypt: https://letsencrypt.org

Certbot github: https://github.com/certbot/certbot

Changelog

0.2

• Upgraded to use certbot client
• Changed image to use alpine linux

0.1

• Initial release