What methods can be used to pass source code into a Docker container?

The source code can be transferred into a Docker container in the following ways:

1. COPY or ADD in Dockerfile — the most common method. In the Dockerfile, you specify the COPY or ADD command to copy files from the build context into the image.

FROM golang:1.18
WORKDIR /app
COPY . .
RUN go build -o myapp
CMD ["./myapp"]

2. Mounting a volume — when running the container, you can mount a local directory with the source code into the container so that the code is accessible without rebuilding the image:

docker run -v $(pwd):/app myimage

3. Passing via STDIN or environment variables — less common methods, for example, you can pass a script via STDIN or an environment variable, but this is inconvenient for source code.

4. Downloading from external sources — inside the container, you can download the source code from a repository (git clone) at startup.

In practice, most often COPY in Dockerfile or mounting a volume are used for development.