nginx-contextpath

Nginx reverse proxy example with defined location directive

In this example, the reverse proxy is defined only under the /plantuml context path. All other context paths (locations) are not affected and are freely available. This allows the server to be used for more than "just" PlantUML.

References:

• Nginx documentation
• Nginx beginner's guide

Quick start

Be sure to have docker-compose.yml and nginx.conf inside your current working directory.

# start nginx and plantuml server
docker-compose up -d

# stop nginx and plantuml server
docker-compose down

Check with docker ps if both container are up and running:

$ docker ps
CONTAINER ID   IMAGE                            COMMAND                  CREATED         STATUS         PORTS                               NAMES
217e753a0dcf   plantuml/plantuml-server:jetty   "/entrypoint.sh"         4 seconds ago   Up 3 seconds   8080/tcp                            plantuml-server
9b1290c100f5   nginx:alpine                     "/docker-entrypoint.…"   4 seconds ago   Up 3 seconds   0.0.0.0:80->80/tcp, :::80->80/tcp   nginx

Open http://localhost/plantuml inside your browser. YEAH! You are now using PlantUML behind a simple Nginx reverse proxy.

Nginx configuration

...

# PlantUML
location /plantuml/ {
    proxy_set_header  HOST               $host;
    proxy_set_header  X-Forwarded-Host   $host;
    proxy_set_header  X-Forwarded-Proto  $scheme;

    proxy_pass http://plantuml-server:8080/plantuml/;
}

...

• location /plantuml/ to reverse only the context path /plantuml
• proxy_set_header HOST $host and proxy_set_header X-Forwarded-Host $host to replaces local plantuml server ip with FQDN
• proxy_set_header X-Forwarded-Proto $scheme to use reverse proxy protocol schema instead of communication schema between reverse proxy and plantuml server
• proxy_pass http://plantuml-server:8080/plantuml/ to set reverse proxy path to plantuml server. Use the docker container name plantuml-server instead of ip addresses. Also, use the same context path (BASE_URL) as PlantUML, which is configurable as an environment variable in the docker-compose file.

Nginx and PlantUML server

version: "3"

services:
  plantuml-server:
    image: plantuml/plantuml-server:jetty
    container_name: plantuml-server
    environment:
      - TZ="Europe/Berlin"
      - BASE_URL="plantuml"

  nginx:
    image: nginx:alpine
    container_name: nginx
    ports:
      - "80:80"
    environment:
      - TZ="Europe/Berlin"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro

• Set container_name to use them instead of e.g. ip addresses
• Set the environment TZ the ensure the same timezone. For example to server timezone (cat /etc/timezone)?
• plantuml-server
  • plantuml-server already exposes port 8080 to it's own local network (but not outside). Since plantuml-server and nginx are sharing a network, nginx can reach plantuml-server without further settings.
  • Set the environment BASE_URL to the preferred context path
• nginx
  • open/link port 80 to the outside
  • ./nginx.conf:/etc/nginx/nginx.conf:ro to use your own Nginx configuration (readonly)

Useful commands

# see whats going on inside your docker containers
docker logs --tail 50 --follow --timestamps nginx
docker logs --tail 50 --follow --timestamps plantuml-server