Building Docker container that calls CGO from python

Question

My main app is python, and I have some Go code that I want to call from python inside the Docker container. Usually I have compiled the Go code using CGO with go build -buildmode=c-shared -o dllname.dll, and used that from other languages. In python I can run the dll using the ctypes module and cdll.LoadLibrary (on windows).

In my mind, this is how it would work in a Dockerfile (I am new to Docker):

1. Install Go
2. Install Go dependencies/libraries
3. Install a suitable C compiler
4. Copy the Go/Cgo source files into the container
5. Compile the Go/Cgo code into a shared binary using CGO_ENABLED=1 go build -buildmode=c-shared
6. Copy python source files into container
7. Assign python entry point with CMD

I have made many futile attempts at making such a Dockerfile. Is this doable?

Answer 1

Got it to work using the golang:1.17.2-bullseye image as suggested by jakub. This is the Dockerfile:

FROM golang:1.17.2-bullseye as builder
WORKDIR /go/src/app
COPY ./lib/cgo .
RUN go get ./...
RUN CGO_ENABLED=1 go build -buildmode=c-shared -o cgolibname.so .

FROM python:3.9
WORKDIR /app
COPY ./appname .
COPY --from=builder /go/src/app/cgolibname.so .
CMD [ "python", "main.py" ]