Docker compose api cannot connect to host MongoDB database - docker

Question

I've moved my Mongodb from a container to a local service (it was really flaky when containerised). Problem is I cannot connect from a Node api into the locally running MongoDB service. I can get this working on my Mac, but not on Ubuntu. I've tried:
- DB_HOST=mongodb://172.17.0.1:27017/proto?authSource=admin
- DB_HOST=mongodb://localhost:27017/proto?authSource=admin
// this works locally, but not on my Ubuntu server
- DB_HOST=mongodb://host.docker.internal:27017/proto?authSource=admin
Tried adding this to my docker file:
ip -4 route list match 0/0 | awk '{print $3 "host.docker.internal"}' >> /etc/hosts && \
Also tried network bridge to no avail. Example docker compose
version: '3.3'
services:
search-api:
build: ../search-api
environment:
- PORT=3333
- DB_HOST=mongodb://host.docker.internal:27017/search?authSource=admin
- DB_USER=dbuser
- DB_PASS=password
ports:
- 3333:3333
restart: always

Answer 1

Problem can be caused by MongoDb not listening on the correct ip address and therefore blocking your access.
Either make sure you're listening to a specific ip or listening to all: 0.0.0.0
On linux the config file is per default installed here: /etc/mongod.conf
Configuration specific Ip address:
net:
bindIp: 172.17.0.1 #being your host's ip address
port: 27017
Configuration open to all connections:
net:
bindIp: 0.0.0.0
port: 27017
To get your hosts ip address (from within a container)
On docker-for-mac and docker-for-windows you can use host.docker.internal
While on linux you need to run ip route show in the container.
When running Docker natively on Linux, you can access host services using the IP address of the docker0 interface. From inside the container, this will be your default route.
For example, on my system:
$ ip addr show docker0
7: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
inet6 fe80::f4d2:49ff:fedd:28a0/64 scope link
valid_lft forever preferred_lft forever
And inside a container:
# ip route show
default via 172.17.0.1 dev eth0
172.17.0.0/16 dev eth0 src 172.17.0.4
(copied from here: How to access host port from docker container)