Error with Go Get for Protobuf in Dockerfile

Question

Here's my Dockerfile:

FROM golang
RUN apt-get update
RUN go get -u github.com/golang/protobuf/{proto,protoc-gen-go}

This generates this error:

package github.com/golang/protobuf/{proto,protoc-gen-go}: invalid github.com/ import path "github.com/golang/protobuf/{proto,protoc-gen-go}"

But, if I take out that RUN directive, and just load up /bin/bash in the docker container, I can run the go get command just fine.

What's going on?

Answer 1

It's happening because the default shell is not /bin/bash , it's sh . You have two possible solutions, either you can explicitly define a shell in your RUN command like so:

RUN ["/bin/bash", "-c", "go get -u github.com/golang/protobuf/{proto,protoc-gen-go}"]

Or you can change the shell that RUN uses by default like so:

SHELL ["/bin/bash", "-c"]
RUN go get -u github.com/golang/protobuf/{proto,protoc-gen-go}

Source: https://docs.docker.com/engine/reference/builder/#/shell

Answer 2

It works if I use another shell, like bash, and put double quotes for the go command

RUN bash -c "go get github.com/golang/protobuf/{proto,protoc-gen-go}"

By the way, you can do all in only one RUN, see Dockerfiles best practices

https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/