I've been developing a webpage with golang using Postgres. I could run the app without a docker container and I could connect to the database, no problem occurred. However, when I dockerized my app and run it, Postgres showed an error: dial tcp 127.0.0.1:5432: connect: connection refused.
Connecting to postgres:
db, err := sql.Open("postgres", "host=localhost port=5432 user=postgres password=postgres dbname=postgres sslmode=disable")
I searched for the internet and found that inside the container localhost will direct to the container. I tried to connect specifying the IP of my server:
db, err := sql.Open("postgres", "host=XXX.XXX.XX.XXX port=5432 user=postgres password=postgres dbname=postgres sslmode=disable")
it also showed the same error: dial tcp XXX.XXX.XX.XXX:5432: connect: connection refused
when I run it without dockerizing it works fine. What to do?
Here is my dockerfile. I was just trying to upload the simplest app to the dedicated server. I logged in using ssh root@IP and installed go and postgres. I pulled my app to the server and then started it with just go build and ./app. Everything worked fine. Now I wanna run it using the dockerfile below.
FROM golang:alpine
RUN mkdir /app
ADD . /app
WORKDIR /app
COPY go.mod .
RUN go mod download
COPY . .
RUN go build -o main .
CMD ["/app/main"]
After thoroughly checking the comments by @colm.anseo, I figured out how to access the host machine in the docker container. I used the flag
--network="host" to run my docker container. So I used:
docker run -it --network="host" myapp to run the container. As I understood, this will
bind the IP of the docker container and host machine
you can read more about it in: From inside of a Docker container, how do I connect to the localhost of the machine?