What to code in Dockerfile and docker-compose.yml to pass local package in docker environment

Question

I introduced local package with go modules for server side api.
It works fine in local environment without error by commanding go run main.go .

But it does not work when commanding docker-compose up .

I want to know what to code Dockerfile and docker-compose.yml to fix.

I command go mod init at article directory.

As result, it sets module github.com/jpskgc/article in go.mod .

article
  ├ db
  ├ client
  ├ api
  │  ├ main.go
  │  ├ controller
  │  │    └ controller.go
  │  └ Dockerfile
  ├ nginx
  ├ docker-compose.yml
  ├ go.mod
  └ go.sum

main.go

package main

import (
    "database/sql"
    "os"
    "time"
    "github.com/gin-gonic/gin"
    "github.com/jpskgc/article/api/controller"
)
    api := router.Group("/api")
    {
        api.GET("/articles", func(c *gin.Context) {
            controller.GetArticleController(c, db)
        })
    }
    router.Run(":2345")
}

Dockerfile

FROM golang:latest
ENV GO111MODULE=on
WORKDIR /go/src/github.com/jpskgc/article/app
COPY . .
RUN go mod download
RUN go build
RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build
ENTRYPOINT ["/go/src/github.com/jpskgc/article/app/api"]

docker-compose.yml

version: '3'
services:
  api:
    build:
      dockerfile: Dockerfile.dev
      context: ./api
    volumes:
      - ./api:/go/src/github.com/jpskgc/article/app
    depends_on:
      - db
    tty: true
    environment:
      - AWS_ACCESS_KEY_ID
      - AWS_SECRET_ACCESS_KEY
      - MYSQL_USER
      - MYSQL_PASSWORD
      - MYSQL_HOST
      - GO111MODULE

go.mod

module github.com/jpskgc/article

go 1.12

require (
    github.com/aws/aws-sdk-go v1.23.7
    github.com/gin-contrib/cors v1.3.0
    github.com/gin-gonic/gin v1.4.0
    github.com/go-sql-driver/mysql v1.4.1
    github.com/google/uuid v1.1.1
    github.com/joho/godotenv v1.3.0
)

I expect server side api working fine without error in docker environment.
But the actual is that docker environment for server side fails to run.

Here is error message when commanding docker-compose up

build command-line-arguments: 
cannot load github.com/jpskgc/article/api/controller: 
cannot find module providing package github.com/jpskgc/article/api/controller
article_api_1 exited with code 1

Here is the entire source code on github (branch: try-golang-mod). I wish someone to give me answer code for Dockerfile and docker-compose.yml . https://github.com/jpskgc/article/tree/try-golang-mod

Answer 1

Your docker context is ./api, but the go.mod is in the parent directory, so go.mod is not included in your image.

One option could be to change your docker context to the root directory of the source tree (parent of api), and copy the files/directories into the image from there.

Answer 2

I resolve this issue in following way.

1. go mod init article/api at api directory.

article
  ├ client
  ├ api
  │  ├ main.go
  │  ├ contoroller
  │  │    └ contoroller.go
  │  ├ //
  │  ├ go.mod 
  │  ├ go.sum
  │  └ Dockerfile
  ├ nginx
  ├ go.mod
  ├ go.sum
  └ docker-compose.yml

2. fix Docekrfile

FROM golang:latest
ENV GO111MODULE=on
WORKDIR /app
COPY go.mod .
COPY go.sum .
RUN go mod download
COPY . .
RUN go build
RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build
ENTRYPOINT ["/app/api"]

3. command docker-compose down and then docker-compose up --build