Set up a development environment with docker (#387)

Signed-off-by: Konstantinos Sideris <sideris.konstantin@gmail.com>

docker/README.md

@@ -0,0 +1,100 @@
+Development with Docker
+---
+
+With `docker` and `docker-compose` you can easily spin up a development environment
+and start working on dendrite.
+
+### Requirements
+
+- docker
+- docker-compose (version 3+)
+
+### Configuration
+
+Copy the `dendrite-docker.yaml` file to the root of the project and rename it to
+`dendrite.yaml`. It already contains the defaults used in `docker-compose` for 
+networking so you will only have to change things like the `server_name` or to 
+toggle `naffka`.
+
+You can run the following `docker-compose` commands either from the top directory
+specifying the `docker-compose` file
+```
+docker-compose -f docker/docker-compose.yml <cmd>
+```
+or from within the `docker` directory 
+
+```
+docker-compose <cmd>
+```
+
+### Starting a monolith server
+
+For the monolith server you would need a postgres instance 
+
+```
+docker-compose up postgres
+```
+
+and the dendrite component from `bin/dendrite-monolith-server`
+
+```
+docker-compose up monolith
+```
+
+The monolith will be listening on `http://localhost:8008`.
+
+You would also have to make the following adjustments to `dendrite.yaml`.
+ - Set `use_naffka: true` 
+ - Uncomment the `database/naffka` postgres url.
+
+### Starting a multiprocess server
+
+The multiprocess server requires kafka, zookeeper and postgres
+
+```
+docker-compose up kafka zookeeper postgres
+```
+
+and the following dendrite components 
+
+```
+docker-compose up client_api media_api sync_api room_server public_rooms_api
+docker-compose up client_api_proxy
+```
+
+The `client-api-proxy` will be listening on `http://localhost:8008`.
+
+You would also have to make the following adjustments to `dendrite.yaml`.
+ - Set `use_naffka: false` 
+ - Comment out the `database/naffka` postgres url.
+
+### Starting federation
+
+```
+docker-compose up federation_api federation_sender
+docker-compose up federation_api_proxy
+```
+
+You can point other Matrix servers to `http://localhost:8448`.
+
+### Creating a new component
+
+You can create a new dendrite component by adding an entry to the `docker-compose.yml` 
+file and creating a startup script for the component in `docker/services`. 
+For more information refer to the official docker-compose [documentation](https://docs.docker.com/compose/).
+
+```yaml
+  new_component:
+    container_name: dendrite_room_server
+    hostname: new_component
+    # Start up script.
+    entrypoint: ["bash", "./docker/services/new-component.sh"]
+    # Use the common Dockerfile for all the dendrite components.
+    build: ./
+    volumes:
+      - ..:/build
+    depends_on:
+      - another_component
+    networks:
+      - internal
+```