I am running a Symfony Project via drud/ddev (nginx) for local development. I did this many times before and had no issues whatsoever.

In my recent project I have to use the Mercure-Hub to push Notifications from the server to the client. I required the symfony/mercure-bundle via composer and copied the generated docker-compose content into a docker-compose.mercure.yaml (.ddev/docker-compose.mercure.yaml)
After starting the container the Mercure-Hub works seamlessly but is only reachable over http.

My problem: I only have beginner knowledge in the field of nginx and docker-compose.

I am thankful for every bit of advice! :)

Steps to reproduce

1. Setup basic Symfony Project and run it via DDEV.

2. Require symfony/mercure-bundle.

3. Copy docker-compose.yaml and docker-compose.override.yaml content to a docker-compose.mercure.yaml in the .ddev folder (change the port).

4. Configure Mercure-Hub URL in .env.

5. Start the container and visit [DDEV-URL]:[MERCURE-PORT] / subscribe a Mercure topic.

My problem

• Mercure-Hub only reachable via http.

• HTTPS call gets an 'ERR_SSL_PROTOCOL_ERROR'

My wish

• Access the Mercure-Hub URL / subscribe to Mercure topics via HTTPS.

What I've tried

• Reading the Mercure-Hub Docs and trying to adapt the Docker SSL / HTTPS instructions to my local drud/ddev environment

• Adding another server to the nginx configuration as in the Mercure-Cookbook "Using NGINX as an HTTP/2 Reverse Proxy in Front of the Hub"

• Googling a bunch

• Hours of trial and error

Files

ddev config.yaml

name: project-name
type: php
docroot: public
php_version: "8.1"
webserver_type: nginx-fpm
router_http_port: "80"
router_https_port: "443"
xdebug_enabled: true
additional_hostnames: []
additional_fqdns: []
database:
  type: mariadb
  version: "10.4"
nfs_mount_enabled: true
mutagen_enabled: false
use_dns_when_possible: true
composer_version: "2"
web_environment: []
nodejs_version: "16"

docker-compose.mercure.yaml

version: '3'

services:
  ###> symfony/mercure-bundle ###
  mercure:
    image: dunglas/mercure
    restart: unless-stopped
    environment:
      SERVER_NAME: ':3000'
      MERCURE_PUBLISHER_JWT_KEY: '!ChangeThisMercureHubJWTSecretKey!'
      MERCURE_SUBSCRIBER_JWT_KEY: '!ChangeThisMercureHubJWTSecretKey!'
      # Set the URL of your Symfony project (without trailing slash!) as value of the cors_origins directive
      MERCURE_EXTRA_DIRECTIVES: |
        cors_origins http://127.0.0.1:8000
    # Comment the following line to disable the development mode
    command: /usr/bin/caddy run -config /etc/caddy/Caddyfile.dev
    volumes:
      - mercure_data:/data
      - mercure_config:/config
    ports:
      - "3000:3000"
###< symfony/mercure-bundle ###

volumes:
  ###> symfony/mercure-bundle ###
  mercure_data:
  mercure_config:
###< symfony/mercure-bundle ###

.env

###> symfony/mercure-bundle ###
# See https://symfony.com/doc/current/mercure.html#configuration

# The URL of the Mercure hub, used by the app to publish updates (can be a local URL)
MERCURE_URL=http://ddev-pnp-master-mercure-1:3000/.well-known/mercure

# The public URL of the Mercure hub, used by the browser to connect
MERCURE_PUBLIC_URL=http://ddev-pnp-master-mercure-1:3000/.well-known/mercure

# The secret used to sign the JWTs
MERCURE_JWT_SECRET="!ChangeThisMercureHubJWTSecretKey!"

###< symfony/mercure-bundle ###

---

Edit 1

I changed my docker-compose thanks to the advice from rfay.
(only showing the relevant part below)

[...]
services:
  mercure:
    image: dunglas/mercure
    restart: unless-stopped
    expose:
      - "3000"
    environment:
      - SERVER_NAME=":3000"
      - HTTP_EXPOSE=9998:3000
      - HTTPS_EXPOSE=9999:3000
[...]

• replaced ports with expose
• added HTTP_EXPOSE & HTTPS_EXPOSE

Problem with this

Now my problem is that the container doesn't expose any ports (see docker desktop screenshot below).

docker desktop port screenshot

Solution

With the help of rfay I found the solution (which consisted of reading the ddev documentation properly lol).

What I did

• replacing ports with expose
• adding VIRTUAL_HOST, HTTP_EXPOSE and HTTPS_EXPOSE under environment
• adding container_name & labels (see code below)

My final docker-compose.mercure.yaml

version: '3'

services:
  mercure:
    image: dunglas/mercure
    restart: unless-stopped
    container_name: "ddev-${DDEV_SITENAME}-mercure-hub"
    labels:
      com.ddev.site-name: ${DDEV_SITENAME}
      com.ddev.approot: ${DDEV_APPROOT}
    expose:
      - "3000"
    environment:
      VIRTUAL_HOST: $DDEV_HOSTNAME
      SERVER_NAME: ":3000"
      HTTP_EXPOSE: "9998:3000"
      HTTPS_EXPOSE: "9999:3000"
      MERCURE_PUBLISHER_JWT_KEY: '!ChangeThisMercureHubJWTSecretKey!'
      MERCURE_SUBSCRIBER_JWT_KEY: '!ChangeThisMercureHubJWTSecretKey!'
      MERCURE_EXTRA_DIRECTIVES: |
        cors_origins https://project-name.ddev.site
    # Comment the following line to disable the development mode
    command: /usr/bin/caddy run --config /etc/caddy/Caddyfile.dev
    volumes:
      - mercure_data:/data
      - mercure_config:/config

volumes:
  mercure_data:
  mercure_config:

With this docker-compose in place my mercure container is available via HTTPS over the port 9999.

For further information see the ddev documentation: https://ddev.readthedocs.io/en/latest/users/extend/custom-compose-files/#docker-composeyaml-examples