Lightweight GCC for Alpine

Question

Is there a lightweight GCC distribution that I can install in Alpine?

I am trying to make a small Docker image. For that reason, I am using Alpine as the base image (5MB). The standard GCC install dwarfs this in comparison (>100MB).

So is there a lightweight GCC distribution that I can install on Alpine?

Note: Clang is much worse (475MB last I checked).

Answer 1

There isn't such an image available, AFAIK, but you can make GCC slimmer by deleting unneeded GCC binaries.

It very much depends on what capabilities are required from GCC.

As a starting point, I'm assuming you need C support only, which means the gcc and musl-dev packages (for standard headers) are installed, which result with a ~100MB image with Alpine 3.8.

• If you don't need Objective-C support, you could remove cc1obj, which is the Objective-C backend. On Alpine 3.8, it would be located at /usr/libexec/gcc/x86_64-alpine-linux-musl/6.4.0/cc1obj, and takes up 17.6MB.
• If you don't need link time optimization (LTO), you could remove the LTO wrapper and main executables, lto-wrapper and lto1, which take up 700kb and 16.8MB respectively. While LTO optimization may be powerful, on most applications it's likely to result with only minor speed and size improvements (few percents). Plus, you have to opt-in for LTO, which is not done by most applications, so it may be a good candidate for removal.
• You could remove the Java front end, gcj, which doesn't seem to be working anyways. It is located at /usr/bin/x86_64-alpine-linux-musl-gcj, and weights 812kb.

By removing these, and squashing the resulting image, it would shrink into 64.4MB, which is still considerably large. You may be able to shrink further by removing additional files, but then you may loose some desired functionality and with a less appealing tradeoff.

Here's an example Dockerfile:

FROM alpine:3.8

RUN set -ex && \
    apk add --no-cache gcc musl-dev

RUN set -ex && \
    rm -f /usr/libexec/gcc/x86_64-alpine-linux-musl/6.4.0/cc1obj && \
    rm -f /usr/libexec/gcc/x86_64-alpine-linux-musl/6.4.0/lto1 && \
    rm -f /usr/libexec/gcc/x86_64-alpine-linux-musl/6.4.0/lto-wrapper && \
    rm -f /usr/bin/x86_64-alpine-linux-musl-gcj

Tested using: sudo docker image build --squash -t alpine-gcc-minimal .