How to download all dependencies with vgo and a given go.mod?
Multi tool use
How to download all dependencies with vgo and a given go.mod?
I'm working on a go project, using vgo, with a Dockerfile, and I'd like docker to cache the dependencies of the project such that it has two properties:
go.mod
go.mod
Right now, I do:
...
RUN go get -u golang.org/x/vgo
COPY . /go/src/whatever
RUN vgo install
...
But if you change a go file, the dockerfile will have to be rebuilt from the COPY layer onwards.
COPY
What I'd like, in short, is to do:
...
RUN go get -u golang.org/x/vgo
COPY go.mod /go/src/whatever
RUN vgo install_dependencies
COPY . /go/src/whatever
RUN vgo install
...
That way, if I change go.mod, all the dependencies will be downloaded and rebuilt, but otherwise, we can proceed right to building the binary.
go.mod
I can see a couple of ways to get behavior like this, but all of them have drawbacks:
$GOPATH/src/mod
vgo mod -vendor
vgo mod -vendor
go.mod
vgo mod -vendor
Can you think of a way for me to get behavior like my imaginary vgo install_dependencies? Am I missing a vgo trick to do so?
vgo install_dependencies
vgo mod -vendor
@TimCooper for that to work I think I need the whole directory copied to the docker image, which means it’ll re-run every time I modify a go file, even if it doesn’t change any imports
– llimllib
Jul 2 at 0:14
@TimCooper verified, if you try it with only a go.mod file in a directory you get
vgo: no dependencies to vendor– llimllib
Jul 2 at 0:22
vgo: no dependencies to vendor
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Maybe I'm missing something, but why can't you run
vgo mod -vendoras a Dockerfile command?– Tim Cooper
Jul 1 at 20:57