go get in Dockerfile. I got cannot find package error - docker

Question

I added RUN go get to install packages during "docker-compose". However, the following cannot find package error was occurred when I run go build. I found that the packages are saved in /go/pkg/linux_amd64/.
run docker-compose and go build
$ docker-compose up -d
$ docker exec -it explorer-cli /bin/bash
# pwd
/go
# ls
bin pkg src
# echo $GOPATH
/go
# ls /go/pkg/linux_amd64/github.com/
go-sql-driver
# go build -i -o /go/bin/explorer-cli src/main.go
src/main.go:6:2: cannot find package "github.com/go-sql-driver/mysql" in any of:
/usr/local/go/src/github.com/go-sql-driver/mysql (from $GOROOT)
/go/src/github.com/go-sql-driver/mysql (from $GOPATH)
(it worked if I run "go get" manually)
# go get github.com/go-sql-driver/mysql
# ls src/
github.com main.go
# go build -i -o /go/bin/explorer-cli src/main.go
docker-compose.yml
version: '3.4'
services:
mysql:
image: mysql:latest
container_name: database
volumes:
- ./docker/:/etc/mysql/conf.d
- ./docker/:/docker-entrypoint-initdb.d
environment:
- MYSQL_RANDOM_ROOT_PASSWORD=true
- MYSQL_DATABASE=explorer
- MYSQL_USER=admin
- MYSQL_PASSWORD=12dlql*41
app:
build: .
tty: true
image: explorer-cli:latest
container_name: explorer-cli
volumes:
- ./src:/go/src
external_links:
- database
Dockerfile
FROM golang:latest
RUN apt-get update
RUN apt-get upgrade -y
ENV GOBIN /go/bin
RUN go get github.com/go-sql-driver/mysql
main.go
package main
import (
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main() {
db, err := sql.Open("mysql", "XUSER:XXXX#(database:3306)/explorer")
if err != nil {
panic(err.Error())
}
defer db.Close()
}
Update 1
I noticed big differences between the following directories.
# ls /go/pkg/linux_amd64/github.com/go-sql-driver/
mysql.a
# ls /go/src/github.com/go-sql-driver/mysql/
AUTHORS connection_go18_test.go packets.go
CHANGELOG.md connection_test.go packets_test.go
CONTRIBUTING.md const.go result.go
LICENSE driver.go rows.go
README.md driver_go18_test.go statement.go
appengine.go driver_test.go statement_test.go
benchmark_go18_test.go dsn.go transaction.go
benchmark_test.go dsn_test.go utils.go
buffer.go errors.go utils_go17.go
collations.go errors_test.go utils_go18.go
connection.go fields.go utils_go18_test.go
connection_go18.go infile.go utils_test.go
Update 2
As #aerokite said, the "volumes" was overwriting the downloaded packages. I changed like the followings and it worked.
Dockerfile
version: '3.4'
FROM golang:latest
RUN apt-get update
RUN apt-get upgrade -y
ENV GOBIN /go/bin
RUN go get github.com/go-sql-driver/mysql
RUN mkdir /go/src/explorer-cli
docker-compose
services:
mysql:
image: mysql:latest
container_name: database
volumes:
- ./docker/:/etc/mysql/conf.d
- ./docker/:/docker-entrypoint-initdb.d
environment:
- MYSQL_RANDOM_ROOT_PASSWORD=true
- MYSQL_DATABASE=explorer
- MYSQL_USER=XUSER
- MYSQL_PASSWORD=XXXX
app:
build: .
tty: true
image: explorer-cli:latest
container_name: explorer-cli
volumes:
- ./src/explorer-cli:/go/src/explorer-cli
external_links:
- database
go build
go build -i -o /go/bin/explorer-cli src/explorer-cli/main.go

Answer 1

I have tried to recreate your problem.
FROM golang:latest
RUN apt-get update
RUN apt-get upgrade -y
ENV GOBIN /go/bin
RUN go get github.com/go-sql-driver/mysql
You have provided this Dockerfile. I have build it
$ docker build -t test .
Now I exec into this image to run your go build command.
$ docker run -it test bash
Then I have created main.go, you provided, in /go/src directory.
And finally, I have built successfully without any error
$ go build -i -o /go/bin/explorer-cli src/main.go
And I think I have found your problem. I have never used docker-compose. But you will understand.
Problem is here:
app:
build: .
tty: true
image: explorer-cli:latest
container_name: explorer-cli
volumes:
- ./src:/go/src <-- problem is here
external_links:
- database
You are mounting ./src into /go/src directory in your docker. This process is overwriting directory /go/src in your docker with your local ./src. And this is removing data you got from go get github.com/go-sql-driver/mysql
Do you understand?
But when you are running go get github.com/go-sql-driver/mysql, its now getting data again.
Solution (01):
Mount your local volume into somewhere else.
volumes:
- ./src:/tmp/src
And modify your Dockerfile to move this main.go to /go/src
Solution (02):
Copy main.go into your docker. Add this line in Dockerfile
COPY ./src/main.go /go/src