fix_communication_bw_conatiners.md

Communication b/w 2 different containers

We are possibly getting error

dial tcp 127.0.0.1:5432: connect: connection refused

possible cause - containers are running in 2 differnt IP' addresses

Container1	Container2

Possible Solutions

1. Using container IP:

# check n/w config of a conatiner
# IP_OF_POSTGRES_CONSTAINER can be found using below command as shown in above images
docker container inspect <<conatiner_name/id>

# To fix connection error b/w conatiners(This is not ideal as IP could chnage over time)
docker run --name simplebank -p 8080:8080 -e GIN_MODE=release -e DB_SOURCE="postgresql://root:secret@<IP_OF_POSTGRES_CONSTAINER>:5432/simple_bank?sslmode=disable" simplebank:latest

2. Using bridge network

• put both conatiners in same n/w, then they ca communicate.

# List all n/w used by docker
docker network ls

# get detail about a specific n/w
docker network inspect <networkName>

# create a new network
docker network create bank-network

# connect a conatiner to a network
docker network connect bank-network postgres12

# run both conatiner in same network
docker run --name simplebank --network bank-network -p 8080:8080 -e GIN_MODE=release  -e DB_SOURCE="postgresql://root:secret@postgres12:5432/simple_bank?sslmode=disable" simplebank:latest

• since both runnig on same n/w we can connect to postgres using conatiner name instead of IP address

• continer running on bridge n/w