How to dockerize a golang web app with maven like structure - docker

Question

I have a hard time dockerizing a web app with following structure:
├── Dockerfile
├── file1.txt
├── file2.txt
├── file3.txt
├── go.mod
└── src
├── go
│   ├── handlers
│   │   └── handlers.go
│   ├── main.go
│   └── parsetext
│   └── parsetext.go
└── resources
├── static
│   └── style.css
└── templates
├── index.html
└── result.html
I have tried multiple ways to build an image and none of them were successful so far. Here are some of them.
FROM golang:1.19
WORKDIR /app
COPY go.mod ./
COPY *.go ./
RUN go build -o /app
EXPOSE 8080
CMD [ "/app" ]
FROM golang:1.19
WORKDIR /app
COPY go.mod ./
RUN go mod download
COPY src/go/main.go app/src/go
COPY src/go/handlers/*.go app/src/go/handlers
COPY src/go/parsetext/*.go app/src/go/parsetext
COPY src/resources/static/*.css app/src/resources/static
COPY src/resources/templates/*.html app/src/resources/templates
RUN go build -o /app
EXPOSE 8080
CMD [ "/app" ]
I would truly appreciate any help with this

Answer 1

I found two issues in your Dockerfile:
COPY *.go ./:
It only copies *.go files in the current directory. I think you want to copy the whole directory like this: COPY src/go ./src/go
RUN go build -o /app:
The specified build artifact /app conflicts with the directory created by WORKDIR /app. And I think that you should specify the package to build. I believe the correct one should be: RUN go build -o theapp ./src/go (change to artifact name theapp to whatever you like).
Here is the one that may work for you. And multi-stage build is recommended.
# =============== build stage ===============
FROM golang:1.19 as build
WORKDIR /app
COPY go.mod ./
RUN go mod download
COPY src/go ./src/go
RUN go build -o theapp ./src/go
# =============== final stage ===============
FROM debian:bullseye AS final
WORKDIR /app
EXPOSE 8080
COPY --from=build /app/theapp ./
# Make sure the resources folder is copied to the correct place that your app expected.
COPY src/resources ./resources
CMD [ "/app/theapp" ]