CODEWITHSUNDEEP
dockergodockerfilego-gin
OrenIshShalom
OrenIshShalom

Reputation: 7102

minimal docker for golang gin REST API endpoint

I can build a simple REST API endpoint with gin + golang using this tutorial:

$ go mod init translator/golang # <--- arbitrary name, right ?
go: creating new go.mod: module translator/golang
go: to add module requirements and sums:
    go mod tidy # <--- yes boss !
$ go mod tidy                  
go: finding module for package github.com/gin-gonic/gin
go: found github.com/gin-gonic/gin in github.com/gin-gonic/gin v1.9.1
$ go run .
# ... omitted log messages ...
[GIN-debug] Listening and serving HTTP on localhost:5000

When I send an http GET request everything goes fine:

#                          |---------------| this is my route
curl http://localhost:5000/translator/golang
[
    {
        "id": "1",
        "title": "Blue Train", # <--- expected output of the tutorial, good !
        "artist": "John Coltrane",
        "price": 56.99
    },
# ... omitted ...
]

When I try to "dockerize" this process, it doesn't work:

$ cat Dockerfile
FROM golang:1.21.5
COPY main.go main.go
RUN go mod init translator/golang
# RUN go mod tidy uncommenting this gives an error
EXPOSE 5000
CMD ["go", "run"]

$ docker build --tag host --file Dockerfile .
# ... omitted for brevity ...
 => CACHED [2/4] COPY main.go main.go                                                                                                          0.0s
 => CACHED [3/4] RUN go mod init translator/golang                                                                                             0.0s
 => ERROR [4/4] RUN go mod tidy                                                                                                                0.1s
------                                                                                                                                              
 > [4/4] RUN go mod tidy:
0.129 $GOPATH/go.mod exists but should not
# ... omitted for brevity ...

$ docker run -p 8000:5000 -d -t --name scfrontgo host
$ curl http://localhost:8000/translator/golang # <--- (from another window)
curl: (7) Failed to connect to localhost port 8000 after 5 ms: Couldn't connect to server

Upvotes: 0

Views: 591

Answers (1)

OrenIshShalom
OrenIshShalom

Reputation: 7102

I think my problems originated from trying to run go mod init inside the docker. When I looked in this docker guide, I saw that the go mod init should be run on the local machine, then needs to be copied with COPY. Here is the complete Dockerfile that worked for me:

FROM golang:1.20.0
WORKDIR /app
COPY main.go ./
COPY go.mod ./
COPY go.sum ./
RUN go mod download
RUN CGO_ENABLED=0 GOOS=linux go build -o /translator
EXPOSE 5000
CMD ["/translator"]

And main.go is similar to the tutorial except for the route mentioned in the comment by David Maze:

func main() {
    router := gin.Default()
    router.GET("/translator/golang", getAlbums)
    router.Run("0.0.0.0:5000")
}

Upvotes: 0

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