Run Google Firestore Emulator with Docker-Compose - node.js

Question

I am trying to run my Node project as well as the Firestore Emulator with docker-compose locally in a dev environment.
I have a Dockerfile for my Node project that looks like this:
WORKDIR /app
ADD package*.json ./
RUN npm install
ADD bin ./bin
CMD [ "npm", "run", "dev" ]
Then I have a seperate Dockerfile called Dockerfile.firestorefor containerizing the Firestore Emulator. This Dockerfile looks like this:
FROM node:alpine
RUN apk add openjdk11
RUN npm install -g firebase-tools
WORKDIR /app
CMD [ "firebase", "--project=xrechnung-app", "emulators:start", "--only", "firestore" ]
The docker-compose.yml is written in the following way:
version: "3"
services:
api:
image: api
build:
context: api
dockerfile: Dockerfile.dev
depends_on:
- db
environment:
- PORT=3000
ports:
- 3000:3000
volumes:
- ./api/src:/app/src
db:
image: firestore
build:
context: api
dockerfile: Dockerfile.firestore
ports:
- 4000:4000
- 8080:8080
volumes:
- .cache/firebase/emulators/:/app/.cache/firebase/emulators/
I'm not sure about the last two lines but I found a hint in the Google Cloud docs that this could prevent multiple downloads of the emulator.
When spinning the container up with docker-compose up the Node project runs without problem and is available at localhost:3000. Also the Emulator spins up. The console logs that its running. But I can't make it available on the prescribed ports (4000 and 8080)
Did anyone try a similar thing already? I appreciate your help.

Answer 1

You probably need to set the host in the firebase.json file, like this:
{
"emulators": {
"firestore": {
"port": 8080,
"host": "0.0.0.0"
}
}
}
By default, the emulator runs only for localhost.