About Web Server Proxy

If we want to host several domains/subdomains on the same webserver we can use name-based virtual hosting. If we need to host these domains/subdomains in different webservers, each one in its own docker container, there is a problem because the ports 80/443 can be used (exposed to the host) only by one of the containers.

In such a case the Reverse Proxy module of apache2 comes to the rescue. We can have a docker container with apache2 that forwards all the http requests to the other containers (webservers), behaving like a kind of http gateway or hub. This is what wsproxy does.

Installation

• First install ds (docker scripts): https://github.com/docker-scripts/ds#installation

• Then get wsproxy from github: ds pull wsproxy

• Init a container directory for wsproxy: ds init wsproxy @wsproxy

• Initialize and fix the settings: cd /var/ds/wsproxy/; vim settings.sh

• Build image, create the container and configure it: ds make

Usage

• Create the containers of each webserver using commands like this:

  docker run -d --name=ws1 --hostname=test1.example.org webserver-1
  docker run -d --name=ws2 --hostname=test2.example.org webserver-2

  Note that no HTTP ports are exposed to the host (for example using options -p 80:80 -p 443:443).

• Add domains for test1.example.org and test2.example.org:

  ds domains-add ws1 test1.example.org
  ds domains-add ws2 test2.example.org test3.example.org

• To add a domain that is served through ssh tunnel by a remote server:

  ds sshtunnel-add test4.example.org

  This will also create the script sshtunnel-keys/test4.example.org.sh which can be used to establish the tunnel from the remote webserver.

• Get a letsencrypt.org free SSL cert for the domains:

  ds get-ssl-cert info@test1.example.org test1.example.org test2.example.org --test
  ds get-ssl-cert info@test1.example.org test1.example.org test2.example.org

Commands

domains-add <container> <domain> <domain> ...
     Add one or more domains to the configuration of the web proxy.

domains-rm <domain> <domain> ...
     Remove one or more domains from the configuration of the web proxy.

get-ssl-cert <email> <domain>... [-t,--test]
     Get free SSL certificates from letsencrypt.org

reload
    Update the configuration of apache2 and ssh.

sshtunnel-add <domain>
    Setup a domain to be served by a remote web server through a ssh tunnel.

sshtunnel-rm <domain>
    Remove the sshtunnel for a domain.

update-etc-hosts
    Update the file /etc/hosts inside the wsproxy container.

How it works

HTTP requests for a domain are redirected to HTTPS with a configuration like this:

<VirtualHost *:80>
    ServerName example.org
    ProxyPass /.well-known !
    ProxyPass / http://example.org/
    ProxyPassReverse / http://example.org/
    ProxyRequests off
</VirtualHost>

HTTPS requests are forwarded to another webserver/container with a configuration like this:

<VirtualHost _default_:443>
    ServerName example.org
    ProxyPass / https://example.org/
    ProxyPassReverse / https://example.org/

    ProxyRequests off

    SSLEngine on
    SSLCertificateFile     /etc/ssl/certs/ssl-cert-snakeoil.pem
    SSLCertificateKeyFile  /etc/ssl/private/ssl-cert-snakeoil.key
    #SSLCertificateChainFile /etc/ssl/certs/ssl-cert-snakeoil.pem

    SSLProxyEngine on
    SSLProxyVerify none
    SSLProxyCheckPeerCN off
    SSLProxyCheckPeerName off

    BrowserMatch "MSIE [2-6]" \
            nokeepalive ssl-unclean-shutdown \
            downgrade-1.0 force-response-1.0
    BrowserMatch "MSIE [17-9]" ssl-unclean-shutdown

</VirtualHost>

It is important to note that without a line like this on /etc/hosts: 172.17.0.3 example.org, apache2 would not know where to forward the request.

Also these apache2 modules have to be enabled:

a2enmod ssl proxy proxy_http proxy_connect proxy_balancer cache headers rewrite