So I have VPS that exposes an API endpoint on localhost at port 8080.
I have a Svelte app that must need the endpoint. To build the svelte app I'm using docker-compose.yaml with
version: '3.8'
services:
frontend:
build:
context: ./frontend
target: development
volumes:
- ./frontend:/app
- /app/node_modules
ports:
- "5173:5173"
environment:
- NODE_ENV=development
and inside the frontend folder I have the Docker file
FROM node:23-alpine as development
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 5173
CMD ["npm", "run", "dev", "--", "--host"]
FROM node:23-alpine as build
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build
FROM nginx:alpine as production
COPY --from=build /app/dist /usr/share/nginx/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]
With this setup, the Svelteapp seems unable to access the local host on the host machine. The only way I was able to access it was to add the line network_mode: host to the docker-compose. yaml. In this way, I was able to access the localhost IP of the host directly with 192.168.1.17, which is the IP on my whole local network.
Is there a way to access the localhost host IP directly using localhost keyword from the container or just no hard-coding the IP which could change
There's no way, except network_mode: host, to reach the host using the localhost name. That's because when a container is on a Docker network (the default behavior), the container has it's own IP address and localhost means the container itself.
On a Docker bridge network, the main gateway is the host. You can add a name for it using extra_hosts and the special name host-gateway. It's common practice to use the hostname host.docker.internal as the name you use.
So change your docker-compose.yml file to
version: '3.8'
services:
frontend:
build:
context: ./frontend
target: development
volumes:
- ./frontend:/app
- /app/node_modules
ports:
- "5173:5173"
extra_hosts:
- host.docker.internal:host-gateway
environment:
- NODE_ENV=development
Now you can access the host from inside the container by using the hostname host.docker.internal.