[SOLVED] Mux Router doesn't work in Dockerized golang project

Mux Router doesn't work in Dockerized golang project

I tested locally and it works totally fine on my local. I can get responses from POST, GET methods.

But when I dockerize the application and try to test the same endpoints, I get nothing. I have tried all the suggestions herein Stackoverflow. So I will paste my Dockerfile and Makefile to get your opinions on it.

My Dockerfile:

FROM golang:1.16.5 AS build-env

RUN set -x \
    && apt-get update -y \
    && apt-get install -y locales \
                          make \
                          xz-utils \
                          zip \
    && rm -rf /var/lib/apt/lists/*

FROM build-env AS builder
WORKDIR /build
COPY . .
RUN set -x \
    && make

FROM debian:buster AS runner

RUN set -x \
    && apt-get update -y \
    && apt-get install -y ca-certificates \
    && rm -rf /var/lib/apt/lists/* \
    && update-ca-certificates

COPY --from=builder /build/bin/* .
CMD ["./applicaitonx"]

and my Makefile:

build:
    go build -o bin/applicaitonx -v -buildmode=exe .

to be able to build the docker, I'm using the following command;

docker build -t app .

and then I run it.

I see that the application is running and listenandserve doesn't throw an error at all. BUT mux is not routing at all. It says it listens but it doesn't. I will also copy the following part in main.go

srv := &http.Server{
    Handler: router,
    Addr: ":" + os.Getenv("PORT"),
}

if err := srv.ListenAndServe(); err != nil {
    log.Fatal("ListenAndServe: ", err)
}

I inspect all the env variables, so os.GetEnv("PORT") doesn't return null. I'm sure about it. I wrote some debug comments, and as far as I see codes doesn't go even that debug comments. So it doesn't print anything at all.

Solution

It might be possible that the port you are using inside the container is not exposed to outside world, hence you can't reach them. Try adding -p flag like below:

docker run -p P1:P2

P1 = TCP port

P2 = Container port

Please refer: this doc