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tozd/nginx-proxy

https://gitlab.com/tozd/docker/nginx-proxy

Available as:

Image inheritance

tozd/base ← tozd/dinit ← tozd/nginx ← tozd/nginx-mailer ← tozd/nginx-cron ← tozd/nginx-proxy

Tags

  • ubuntu-xenial
  • ubuntu-bionic
  • ubuntu-focal
  • ubuntu-jammy

Volumes

  • /var/log/dnsmasq: Log files for an internal lightweight DNS resolver when one is not provided by Docker and when LOG_TO_STDOUT is not set to 1.
  • /var/log/dockergen: Log files for docker-gen when LOG_TO_STDOUT is not set to 1.
  • /var/log/letsencrypt: (Debug) log files for Let's encrypt service.
  • /ssl: Volume with SSL keys for hosts, together with any optional extra configuration for them. All Let's encrypt generated keys together with Let's encrypt authentication keys are stored here as well. Persist this volume to not lose state.

Variables

  • DOCKER_HOST: Where to connect to access Docker daemon to monitor for new containers. Default is /var/run/docker.sock inside the container.
  • LETSENCRYPT_EMAIL: If set, enables automatic generation of SSL keys using Let's encrypt service. By setting it you agree to Let’s Encrypt Subscriber Agreement.
  • LETSENCRYPT_ARGS: Any additional arguments you might want to pass to Let's encrypt's certbot.
  • LOG_TO_STDOUT: If set to 1 output logs to stdout (retrievable using docker logs) instead of log volumes.

Description

Image providing a reverse-proxy using Nginx HTTP server with support for HTTPS virtual hosts.

You can use this image as it is, or you can extend it and add configuration files for your virtual hosts.

When LOG_TO_STDOUT is set to 1, Docker image logs output to stdout and stderr. All stdout output is JSON.

Automatic configuration

This image uses docker-gen to dynamically generate Nginx configuration files for containers exposing HTTP virtual hosts. This works automatically even across container restarts. You configure virtual host by configuring environment variables on containers for which you want to provide a reverse proxy:

  • VIRTUAL_HOST – a comma separated list of virtual hosts provided by the container
  • VIRTUAL_URL – a comma separated list of URL paths provided by the container; they will be mapped to the HTTP root (/) of the container
  • VIRTUAL_ALIAS – a comma separated list of URL paths provided by the container, they will be mapped to the same HTTP path of the container
  • VIRTUAL_PORT – if container exposes more than one port, or you do not want to use the default port 80, you can configure a custom port to which a reverse proxy should connect on the container
  • VIRTUAL_NETWORK – if container is connected to more than one network, this variable can be used to select which network should be used (by default, the first network is used, but the order is not guaranteed)
  • VIRTUAL_LETSENCRYPT – if set, this image will automatically generate and enable a SSL key for the virtual host using Let's encrypt service, if Let's encrypt feature is enabled

When running a Docker image with your HTTP content, you can specify environment variables.

This will make the reverse proxy resolve http://example.com/ into the example container:

docker run --name example ... --env VIRTUAL_HOST=example.com --env VIRTUAL_URL=/ ...

This will make the reverse proxy resolve http://example.com/foo into the example1 container, but This will make the reverse proxy resolve http://example.com/bar into the example2 container.

docker run --name example1 ... --env VIRTUAL_HOST=example.com --env VIRTUAL_URL=/foo ...
docker run --name example2 ... --env VIRTUAL_HOST=example.com --env VIRTUAL_URL=/bar ...

Multiple containers can provide content for the same host and URL paths – Nginx will balance load across all of them.

A difference between VIRTUAL_URL and VIRTUAL_ALIAS is that VIRTUAL_URL maps all outside paths to the internal HTTP root (/) of the container. This is useful when your container provides static content under the root and you want to expose it elsewhere to the outside. But the downside is that the internal references between resources, if a container assumes content is under /, might not work correctly. For example, a HTML tag <img src="/foobar.png" />, which would from the perspective of the container, from the outside might resolve to something completely else, or not resolve at all. This is why it is often better to serve content in containers under the same path as outside, and use VIRTUAL_ALIAS to map them 1:1. But this means that the container has to be configured accordingly as well.

HTTPS

If you want to use HTTPS for a virtual host, you should mount a /ssl volume into the container and provide SSL key for a virtual host.

For host example.com you should provide /ssl/example.com.key and /ssl/example.com.crt files. Certificate file should contain the full chain needed to validate the certificate. If those two files exist, the image will automatically configure the virtual host to use HTTPS and redirect any non-HTTPS traffic to HTTPS.

If you want any extra configuration for non-HTTPS traffic, you can provide /ssl/example.com_nonssl.conf file which will be included for the non-HTTPS configuration. Similarly, for extra configuration for the HTTPS site, provide /ssl/example.com_ssl.conf file. Of course, filenames should match the hostname of your virtual host.

Let's encrypt

If you want to enable support for automatic generation of SSL keys using Let's encrypt service, and you agree to Let’s Encrypt Subscriber Agreement, then you can set LETSENCRYPT_EMAIL environment variable to your e-mail address when running this image to enable it. From then on any container having VIRTUAL_LETSENCRYPT environment variable set will get a SSL certificate automatically generated and enabled, and periodically renewed.

All generated keys together with Let's encrypt authentication keys are stored under /ssl volume.

You should probably configure MAILTO environment variable to your e-mail address to receive reports from th daily cron job, and regularly check logs in /var/log/letsencrypt and /var/log/dockergen volumes to see if there are any issues with key generation and renewal. For e-mail sending to work you have to configure at least REMOTES environment variable as well.

You can list in /ssl/letsencrypt.manual.list file additional domains you want the container to obtain SSL keys.

Dynamic resolving of containers

If extending the image, you can put sites configuration files under /etc/nginx/sites-enabled/ to add custom sites.

Alternatively, you can mount a volume into /etc/nginx/sites-volume/ directory and provide sites there.

To support static configuration files for containers which have dynamic IP addresses, this image configures (when not provided by Docker) Nginx with an internal lightweight DNS resolver which dynamically resolves container hostnames into IPs. Here is an example of site configuration using DNS resolving:

server {
    listen 80;
    server_name example.com;

    # We want to resolve container IPs dynamically, so we use a variable to make
    # Nginx resolve it again and again and not only at the start (so that it works
    # if containers change their IPs).

    location / {
        set $example example;
        proxy_pass http://$example:3000;
    }
}

This assumes that you have a container with hostname example:

docker run --name example --hostname example ...

By default, because of caching it can take up to 5 seconds for Nginx to start resolving a virtual host to a new container IP address after a change.

GitHub mirror

There is also a read-only GitHub mirror available, if you need to fork the project there.