Docker-ReverseWebProxy

ATTENTION Raspberry Pi 3 / Buster users

This application has recently been updated to use a base image container based on Debian Bullseye. Some older, Buster based host systems may need a patch to solve an issue related to the Real Time Clock or container log errors regarding sleep. See the Troubleshooting section below.

What is it?

This application, further referred to as "Webproxy", enables to show a single website for multiple web services running on different machines and/or different ports.

The need for a solution is age-old, but what triggered the creation of this project was the deployment of Dockerized web services for a ADSB Feeder station. These web services are distributed over 1 or more Raspberry Pi's, and each of them provides a web interface on a different TCP port. As a result, the user has to remember a collection of seemingly random IP addresses and port numbers to get to these web services, which creates an awful user experience.

The Webproxy allows the user to map these web services to a single URL, differentiating them by assigning a virtual directory name for each.

The following example highlights this:

Web Service	Original address	New Address with Webproxy
readsb	http://10.0.0.191:8080	http://myip/readsb
piaware	http://10.0.0.191:8081	http://myip/piaware
tar1090	http://10.0.0.191:8082	http://myip/tar1090
planefence	http://10.0.0.191:8083	http://myip/planefence
planefinder	http://10.0.0.191:8086	http://myip/planefinder
graphs	http://10.0.0.191:8080/graphs	http://myip/graphs
radar	http://10.0.0.191:8080/radar	http://myip/radar
acarshub	http://10.0.0.188	http://myip/acarshub

How do I get it?

Prerequisite for this to work, is that you have a working Docker and Docker-compose setup. This is less than 5 minutes of work -- use this script or follow all 3 steps of the "Setting up the Host System" section at this GitBook.

Once this is done, create a working directory and download the docker-compose.yml file:

sudo mkdir -p -m 777 /opt/webproxy && cd /opt/webproxy
wget https://raw.githubusercontent.com/kx1t/docker-reversewebproxy/main/docker-compose.yml

You should EDIT the docker-compose.yml file included in this repository and configure it to your liking. See below for options. (Note - CAREFUL. YML is based on indentation levels, so make sure you keep each line at the correct indent level!)

Now, you can either run it as-is, or, if you already have another docker-compose.yml, you can copy the data of the services: section to your existing docker-compose.yml.

With that, you are ready to run the proxy!

How do I configure it?

The Webproxy can be entirely configured in the docker-compose.yml, or, optionally, you can create a more advanced setup manually. You can also start with the docker-compose.yml configuration and then add to this manually in the future. Here's how:

General parameters:

A "*" means that this is the default value

Parameter	Values	Description
AUTOGENERATE	ON*, OFF	Determines if the system will use the REVPROXY and REDIRECT settings of the docker-compose.yml file (ON), or a manually generated locations.conf file (OFF).
VERBOSELOG	ON*, OFF	Determines if the internal web service Access and Error logs will be written to the Docker log (accessible with docker logs webproxy) (ON), or that logging will be switched OFF.

You may have to adjust your port: and your volumes: mapping to your liking, especially if you are not running on the Raspberry Pi standard pi account.

Configuration of the Webproxy

If AUTOGENERATE=ON, the system will build a Webproxy based on the REVPROXY and REDIRECT parameter values.

REVPROXY defines the proxy-pairs to serve the destination target when the user browses to urltarget. The user's browser will never be redirected to an internal IP address for service, all web pages are being served from the Webproxy. As such, the process of going to the correct website/port to get the web page is completely hidden from the user.

REVPROXY has the following format: urltarget|destination For example, for REVPROXY=readsb|http://10.0.0.191:8080, a user browsing to http://mydomain/readsb will be proxied to a service located at http://10.0.0.191:8080. The user's browser will never see the internal IP address. Note - both the urltarget and the destination must be URLs or directories, and cannot be a file name. You can provide a comma separated list of urltarget|destination pairs, similar to the example in the default docker-compose.yml.

REDIRECT redirects the user's browser to a specific address. In contrast to REVPROXY, the Webproxy does NOT "front" the rendering of the website. This can be useful if there is information that you want to be available within your own subnet, but not to the outside world. The format for REDIRECT is similar to that of REVPROXY: urltarget|redirection For example, for REDIRECT=/planefinder/setup.html|http://10.0.0.191:8086/setup.html Note - for REDIRECT, both the urltarget and the redirection MAY BE a URL or a file names. Similar to REVPROXY, REDIRECT can contain comma separated entries. See example in the default docker-compose.yml.

Configuration of SSL

SSL can only be enabled if you have a domain name (a real one or a Dynamic DNS name) that currently points at your WebProxy instance. This means that your WebProxy must be accessible from the internet (forward of port 80 and port 443 required if behind a router).

The following settings will enable SSL to be part of the reverse proxy. SSL certificates are provided by Lets Encrypt.

A "*" means that this is the default value

Parameter	Values	Description
SSL	DISABLED*, ENABLED	Enable the installation of SSL certificates
SSL_EMAIL	your email address	A valid email address is needed to get a certificate
SSL_DOMAIN	A list of web domains	We will enabled SSL for these. Note - they must be reachable domains at this container for the SSL certificate to be successfully installed!
SSL_TOS	REJECT*, ACCEPT	Indicates your acceptance of the T&S's for the SSL certificateset forth at https://letsencrypt.org/repository/#let-s-encrypt-subscriber-agreement
SSL_REDIRECT	DISABLED, ENABLED*	When set to ENABLED, all incoming non-SSL traffic is redirected to use SSL

Note: your SSL certificates are valid for 90 days. The container will check daily if they need renewing, and will do so of there's less than a month before the expiration date. LetsEncrypt will start sending you emails about the pending expiration about 45 days before the deadline. Sometimes, the expiration date in this email doesn't correspond to the real expiration date of the certificates. You can safely ignore these emails as long as your container is running. If you want to check the official expiration date of your certificates, this command will show you:

docker exec -it webproxy certbot certificates

GeoIP Filtering

The Reverse Webproxy can filter incoming requests by originating IP. It uses an external GeoIP database that maps IP addresses to countries. This database is updated regularly with the latest mappings. Note - this GeoIP IP to Location mapping is not perfect, and users with a VPN can circumvent GeoIP filtering without much problems.

Parameter	Values	Description
GEOIP_DEFAULT	<empty>*, ALLOW, DISALLOW	Empty: GeoIP filtering is disabled; ALLOW: only those countries listed in the GEOIP_COUNTRIES parameter are permitted; DISALLOW: the countries listed in GEOIP_COUNTRIES are filtered.
GEOIP_COUNTRIES		Comma-separated list of 2-letter country abbreviations, for example RU,CN,BY,RS (which means Russia, China, Bielorus, Serbia).
GEOIP_RESPONSECODE	3-digit HTTP response code	Default if omitted: 403 ("Forbidden"). Other codes that may be useful: 402 (payment required), 404 (doesnt exist), 418 (I am a teapot - used to tell requestors to go away), 410 (Gone), 500 (Internal Server Error), 503 (service unavailable). See https://developer.mozilla.org/en-US/docs/Web/HTTP/Status

BlockBot

The BlockBot feature filters out HTTP requests based on a fuzzy match of the HTTP User Agent field against a list of potential matches. This can be used to somewhat effectively filter out bots that are trying to scrape your website. The BLOCKBOT parameter included docker-compose.yml file has an example of a bot filter.

Parameter	Values	Description
BLOCKBOT	string snippets of User Agent fields	Comma-separated strings, for example google,bing,yandex,msnbot. If this parameter is empty, the BlockBot functionality is disabled.
BLOCKBOT_RESPONSECODE	3-digit HTTP response code	Default if omitted: 403 ("Forbidden"). Other codes that may be useful: 402 (payment required), 404 (doesnt exist), 418 (I am a teapot - used to tell requestors to go away), 410 (Gone), 500 (Internal Server Error), 503 (service unavailable). See https://developer.mozilla.org/en-US/docs/Web/HTTP/Status

Advanced Setup

After you run the container the first time, it will create a directory named ~/.webproxy. If AUTOGENERATE=ON, there will be a locations.conf file. There will also be a locations.conf.example file that contains setup examples. If you know how to write a nginx configuration file, feel free to edit the locations.conf and add any options to your liking.

BEFORE restarting the container (important!!) edit docker-compose.yml and set AUTOGENERATE=OFF. If you don't do this, your newly created locations.conf file will be overwritten by the auto-generated one based on the REVPROXY and REDIRECT settings. (There will be a time-stamped backup file of your locations.conf file, so not everything is lost!)

Host your own web pages

You can place HTML and other web files in ~/.webproxy/html. An example index.html is already provided, and can be reached by browsing to the root URL of your system. At this time, features like php are not enabled. If you are interested in this, please file a feature request at issues. Note -- the web server inside the container does NOT run as root, so you must make sure that there are read permissions for "all" (chmod a+r) for any files you place in the html directory. Feel free to create additional subdirectories if needed for your project. Also note -- the website may not be reachable if you redirected or proxied / to some other service.

Troubleshooting

• Issue: the container log (docker logs webproxy) shows error messages like this: sleep: cannot read realtime clock: Operation not permitted

• Solution: you must upgrade libseccomp2 on your host system to version 2.4 or later. If you are using a Raspberry Pi with Buster based OS, here is a repo with a script that can automatically fix this for you.

• Issue: docker-compose up -d exits with an error

• Solution: you probably have a typo in docker-compose.yml. Make sure that all lines are at the exact indentation level, and that the last entry in the REVPROXY and REDIRECT lists do not end on a comma.

• Issue: The container complaints about port mappings during start-up

• Solution: you probably are already running another service on the same port on your host machine. The port exposed to the world is the first 80 in - PORTS: 80:80 in docker-compose.yml. You can do one of two things: scour your system for other web services on that port (another container? lighttpd? nginx?) and disable that service (or put it on another port), or change the first 80 to some other port number. For docker containers, you can check the ports that are used by each container with this command: docker ps

• Issue: Everything starts up fine, but the website doesn't render any pages

• Solution: Please take a look at the container log (docker logs webproxy) to see if there are any errors. The log will be explicit about some of the more obvious issues.

• Issue: I have troubles getting the Webproxy to work with VRS (Virtual Radar Server)

• Solution: in VRS, make sure to configure this: VRS Options -> Website -> Website Customisation -> Proxy Type = Reverse

• Issue: Planefinder doesn't work correctly

• Solution: make sure that you have added the following to the REVPROXY variable:

  planefinder|http://10.0.0.191:8086,
  ajax|http://10.0.0.191:8086/ajax,
  assets|http://10.0.0.191:8086/assets,
  

• Issue: I'm getting emails from letsencrypt.com about the pending expiration of my SSL certificates

• Solution: ignore them. As long as the container is running and SSL is enabled, the certificates are checked daily for pending expiration and will be renewed 1 month before that date. Sometimes, letsencrypt.com gets confused about the expiration dates and thinks it's earlier than is really the case. You can always check this for yourself by looking at the container logs, or by running this command: docker exec -it certbot certificates

• Issue: when adding new URLs to a system that deployment has SSL certifications, the logs show messages that requesting a certificate for the new URL failed because the user should indicate which of (multiple) accounts should be used.

• Solution: This is caused by certificates that have been added to webproxy at different points in time. To fix it, back up any web pages that are directly served by the container, and recreate the entire setup. Please note that doing this more than 5 times in a week will lock you out and prevent you from recreating existing certificates for up to a week, so USE THIS SOLUTION SPARINGLY. The solution assumes that the container name is webproxy and that its working directory is ~/.webproxy . If this is different, you may have to adapt the commands accordingly. It's preferable to feed the script line by line rather than all at once, so you can monitor the outcome.

cd ~  # go to the home directory
docker stop webproxy    # stop the webproxy container

# Back up the web pages and any custom configuration. Sudo is used to ensure also closed directories are backed up
# Only of the backup is successful, delete the working directory
sudo tar zcvf web-backup.tgz .webproxy/html .webproxy/locations.conf && sudo rm -rf .webproxy

# Recreate the webproxy. Adapt the location of your "docker-compose.yml" as needed
docker-compose -f /opt/webproxy/docker-compose.yml up -d

# Check in the logs that the issue is fixed:
sleep 30 && docker logs webproxy

# Restore the files and restart the container once more to ensure the locations.conf file is applied
sudo tar zxvf web-backup.tgz
docker restart webproxy

# You can now remove the "web-backup.tgz" file, or save it as a backup of your website.

Acknowledgements

• @Mikenye for encouraging me to look into Docker, and to suggest we need a Reverse Web Proxy to solve our web service issues. He also wrote the Github Actions scripts and taught me how to work with the s6 service layer.
• @Wiedehopf for helping me get my initial installation of nginx configured and working. Without his help, everything would have taken many weeks (!) instead of a few hours.

License

The software packages and OS layers included in this project are used with permission under license terms that are distributed with these packages.

The combination of these packages and any additional software written to combine and configure the Webproxy are Copyright 2021 by kx1t, and licensed under the GNU General Public License, version 3 or later. If you desire to use this software with a different license, please contact the author.

Summary of License Terms This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.