docker-nginx-auto-ssl

The simpliest solution to add SSL cert to your site

Docker image for automatic generation of SSL certs using Let's encrypt and Open Resty, with reasonable SSL settings, HTTP/2 and WebSockets support out-of-the-box. You can specify allowed domains and simple proxies using ENV variables, and easily override nginx.conf to your needs.

This is possible thanks to OpenResty and lua-resty-auto-ssl.

Image status: used in production. Some backward-compatible changes may be added in the future.

Usage

Quick start to generate and auto-renew certs for your blog / application:

# replace these values
export DOMAIN=yourdomain.com
export APP_ADDRESS=localhost:8080

# install docker first, and then run following command
docker run -d \
  --name nginx-auto-ssl \
  --restart on-failure \
  --network host \
  -e ALLOWED_DOMAINS="$DOMAIN" \
  -e SITES="$DOMAIN=$APP_ADDRESS" \
  -v ssl-data:/etc/resty-auto-ssl \
  valian/docker-nginx-auto-ssl

# display logs from container, to check if everything is fine.
docker logs nginx-auto-ssl

Docker-compose example:

# docker-compose.yml
version: '2'
services:
  nginx:
    image: valian/docker-nginx-auto-ssl
    restart: on-failure
    ports:
      - 80:80
      - 443:443
    volumes:
      - ssl_data:/etc/resty-auto-ssl
    environment:
      ALLOWED_DOMAINS: 'yourdomain.com'
      SITES: 'yourdomain.com=myapp:80'
  
  # your application, listening on port specified in `SITES` env variable
  myapp:
    image: nginx

volumes:
  ssl_data:

start using

docker-compose up -d

Both cases will work when request to yourdomain.com will reach just-deployed nginx (so when it will be running on your server, with correctly defined DNS entry).

Available configuration options:

Variable	Example	Description
ALLOWED_DOMAINS	(www|api).example.com, example.com, ([a-z]+.)?example.com	Regex pattern of allowed domains. Internally, we're using ngx.re.match. By default we accept all domains
DIFFIE_HELLMAN	true	Force regeneration of dhparam.pem. If not specified, default one is used.
SITES	db.com=localhost:5432; *.app.com=localhost:8080, _=localhost:8080	Shortcut for defining multiple proxies, in form of domain1=endpoint1; domain2=endpoint2. Default template for proxy is here. Name _ means default server, just like in nginx configuration
FORCE_HTTPS	true, false	If true, automatically adds location to resty-server-http.conf redirecting traffic from http to https. true by default.
LETSENCRYPT_URL	https://acme-v02.api.letsencrypt.org/directory, https://acme-staging-v02.api.letsencrypt.org/directory	Let's Encrypt server URL to use
RESOLVER_ADDRESS	8.8.8.8, 127.0.0.53	DNS resolver used for OCSP stapling. 8.8.8.8 by default. To disable ipv6 append ipv6=off, eg 8.8.8.8 ipv6=off
STORAGE_ADAPTER	file, redis	Location to store generated certificates. Best practice is redis in order to avoid I/O blocking in OpenResty and make the certs available across multiple containers (for a load balanced environment) . file by default
REDIS_HOST	hostname, ip address	The redis host name to use for cert storage. Required if STORAGE_ADAPTER=redis
REDIS_PORT	port number	The redis port number. 6379 by default
REDIS_DB	db_number	The Redis database number used by lua-resty-auto-ssl to save certificates. 0 by default
REDIS_KEY_PREFIX	some-prefix	Prefix all keys stored in Redis with this string. '' by default

If you want to proxy multiple sites (probably the most common case, that's why I've made it possible to achieve without custom configuration):

docker run -d \
  --name nginx-auto-ssl \
  --restart on-failure \
  -p 80:80 \
  -p 443:443 \
  -e ALLOWED_DOMAINS=example.com \
  -e SITES='example.com=localhost:5432;*.example.com=localhost:8080' \
  valian/docker-nginx-auto-ssl

Customization

Includes from /etc/nginx/conf.d/*.conf

Additional server blocks are automatically loaded from /etc/nginx/conf.d/*.conf. If you want to provide your own configuration, you can either use volumes or create custom image.

Example server configuration (for example, named server.conf)

server {
  listen 443 ssl default_server;
  
  # remember about this line!
  include resty-server-https.conf;

  location / {
    proxy_pass http://app;
  }
  
  location /api {
    proxy_pass http://api;
  }
}

Volumes way

# instead of $PWD, use directory with your custom configurations
docker run -d \
  --name nginx-auto-ssl \
  --restart on-failure \
  -p 80:80 \
  -p 443:443 \
  -v $PWD:/etc/nginx/conf.d
  valian/docker-nginx-auto-ssl

Custom image way

FROM valian/docker-nginx-auto-ssl

# instead of . use directory with your configurations
COPY . /etc/nginx/conf.d

docker build -t docker-nginx-auto-ssl .
docker run [YOUR_OPTIONS] docker-nginx-auto-ssl

Using $SITES with your own template

You have to override /usr/local/openresty/nginx/conf/server-proxy.conf either using volume or custom image. Basic templating is implemented for variables $SERVER_NAME and $SERVER_ENDPOINT.

Example template:

server {
  listen 443 ssl;
  server_name $SERVER_NAME;

  include resty-server-https.conf;

  location / {
    proxy_pass http://$SERVER_ENDPOINT;
  }
}

Your own nginx.conf

If you have custom requirements and other customization options are not enough, you can easily provide your own configuration.

Example Dockerfile:

FROM valian/docker-nginx-auto-ssl

COPY nginx.conf /usr/local/openresty/nginx/conf/

Minimal working nginx.conf:

events {
  worker_connections 1024;
}

http {
  
  # required
  include resty-http.conf;

  server {
    listen 443 ssl;
    
    # required
    include resty-server-https.conf;
    
    # you should add your own locations here    
  }

  server {
    listen 80 default_server;
    
    # required
    include resty-server-http.conf;
  }
}

Minimal nginx.conf with support for $SITES and conf.d includes

events {
  worker_connections 1024;
}

http {

  include resty-http.conf;

  server {
    listen 80 default_server;
    include resty-server-http.conf;
  }
  
  # you can insert your blocks here or inside conf.d
  
  include /etc/nginx/conf.d/*.conf;
}

Build and run it using

docker build -t docker-nginx-auto-ssl .
docker run [YOUR_OPTIONS] docker-nginx-auto-ssl

How does it work?

A short walktrough of what's going on here.

• The docker entrypoint is responsible for preparing a location block for each site declared in SITES env variable. This file is used as a template.
• when request comes to port 80, it's by default redirected to 443 (HTTP -> HTTPS redirection)
• when request comes to port 443, HTTPS certificate is resolved by lua code (relevant file in this repo and source code from lua-resty-auto-ssl). If certificate exists for a given domain and is valid, it's returned. Otherwise, a process of generating new certificate starts. It's initialized here and uses https://github.com/dehydrated-io/dehydrated for all the Let's Encrypt-related communication. It starts challenge process, prepares files for challenge and receives certificates. All of that is done in a couple of seconds, while the original request waits for the response.
• challenge files are prepared and served under /.well-known/acme-challenge/ (relevant file from this repo and source code from lua-resty-auto-ssl)

There's more to it, eg locks across all workers to only generate one certificate for a domain at a time, upload of the certificate to shared storage if configured, checking if domain is whitelisted, communication with Let's Encrypt etc. All in all, it's fairly efficient and shouldn't add any noticeable overhead to nginx.

CHANGELOG

• 11-11-2019 - Added gzip support and dropped TLS 1.0 and 1.1 #33
• 18-04-2019 - Added WebSocket support #22
• 29-05-2017 - Fixed duplicate redirect location after container restart #2
• 19-12-2017 - Support for $SITES variable
• 2-12-2017 - Dropped HSTS by default
• 25-11-2017 - Initial release

LICENCE

MIT