Can't set Docker Proxy Rules to an HTTPS container on Plesk: Error 502 Bad Gateway

Symptoms

• Configuring Docker Proxy Rules for a Docker container that binds HTTPS returns this error on the website:

  502 Bad Gateway
  Bad Request
  Your browser sent a request that this server could not understand.
  Reason: You're speaking plain HTTP to an SSL-enabled server port.
  Instead use the HTTPS scheme to access this URL, please.

• After adding a Docker Proxy Rule in Domains > example.com > Docker Proxy Rules, Plesk adds proxy_pass configuration using HTTP:

  location ~ ^/.* {
  proxy_pass http://127.0.0.1:9444;
  proxy_set_header Host $host;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header X-Forwarded-Proto $scheme;
  }

Cause

This is Docker extension issue with ID EXTDOCKER-106, which will be fixed in future updates.

Resolution

While the fix is released, add the proxy rules manually, instead of using the Plesk panel feature:

1. Log into Plesk

2. Remove any rules from Domains > example.com > Docker Proxy Rules

3. Go to Domains > example.com > Apache & nginx

4. Add the following configuration to Additional nginx directives

   location ~ ^/.* {
   proxy_pass https://127.0.0.1:9444;
   proxy_set_header Host $host;
   proxy_set_header X-Real-IP $remote_addr;
   proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
   proxy_set_header X-Forwarded-Proto $scheme;
   }

5. Press OK to save the changes