Question 85277 in Docker Question posted in
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How to run "go mod download" from parent directory? – Docker

Project structure:

project_dir/
├── prj1/
│   ├── feature1/
│   ├─    |─ go.mod
│   ├─    |─ main.go
│   └─    |─ ...
│   └── ...
├── prj2/
│   ├── go.mod
│   ├── main.go
│   └── Dockerfile
│   └── ...
└── ...

The code in prj2 is referencing a function from prj1/feature1 via the go mod edit -replace command. Now, this works fine locally but I need to deploy with Docker and I am facing issues.

My docker scripts look like this:

FROM golang:1.17.5 as builder

WORKDIR /app

COPY go.* ./
ADD ./prj1 ./prj1
RUN go mod download
...

Initially, I was running docker build . from inside prj2 without the ADD command in the docker file but RUN go mod download fails with:

go mod download: github.com/name/project/[email protected] (replaced by ../prj1/feature1/): reading /prj1/feature1/go.mod: open /prj1/feature1/go.mod: no such file or directory

So, I added the ADD command to the docker file to copy prj1. Next, I cd to project_dir and ran docker build -f ./prj2/Dockerfile but RUN go mod download is now failing with

go mod download: no modules specified (see ‘go help mod download’)

So basically, my question is, how do I tell the go command that the go.mod is inside prj2?

Tags:

2

Answers


  1. 0

    Considering your replace directive references ../prj1, your ADD should be

    ADD ./prj1 ../prj1

    And your should execute your docker from prj2, not ./prj2/Dockerfile, or your COPY go.* ./ would not copy any go file.

    As commented, that would exclude prj1 from the context. So you must change your COPY to COPY ./prj2/go.* ./

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  2. 0

    I assume your docker build command is including the path to use as the build context?

    docker build -f ./prj2/Dockerfile .  # <- period

    If so, your build is running in the project_dir/ folder. There’s no go.mod file in project_dir/.

    You should cd into the prj2/ dir before trying to run go mod download

    FROM golang:1.17.5 as builder

WORKDIR /app

COPY go.* ./
ADD ./prj1 ./prj1
RUN cd prj2/ && go mod download
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