Build against musl in docker

.github/workflows/Dockerfile.builder

@@ -0,0 +1,13 @@
+FROM docker.io/golang:alpine AS builder
+ARG GOARCH=amd64
+
+RUN apk --update --no-cache add bash build-base
+
+WORKDIR /build
+
+COPY . /build
+
+RUN bash /build/.github/workflows/get-compiler.sh pkgs
+
+# Build!
+RUN CC="$(/build/.github/workflows/get-compiler.sh ccomp)" bash /build/build.sh

.github/workflows/Dockerfile.copyin

@@ -1,11 +1,12 @@
 FROM alpine:latest
 
 ARG DENDRITE_BINARY=
-ENV DENDRITE_BINARY=/usr/bin/${DENDRITE_BINARY}
+ARG BIN_DIRECTORY=
+ENV DENDRITE_BINARY=${DENDRITE_BINARY}
 
-COPY ./bin/* /usr/bin
+COPY --from=builder /build/bin/* /usr/bin
 
 VOLUME /etc/dendrite
 WORKDIR /etc/dendrite
 
-ENTRYPOINT ["${DENDRITE_BINARY}"]
+ENTRYPOINT "/usr/bin/${DENDRITE_BINARY}"

.github/workflows/cross-compiling-docker.yml

@@ -13,20 +13,29 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/setup-go@v2
-    - name: install (cross) compiler
-      run: sudo apt install $(./.github/workflows/get-compiler.sh pkgs)
-    - name: set CC env var
-      run: echo "CC=$(./.github/workflows/get-compiler.sh ccomp)" >> $GITHUB_ENV # https://stackoverflow.com/a/57969570/3551604
-    - run: go env
-    - run: ./build.sh
-    - name: upload build artifacts
-      uses: actions/upload-artifact@v2
+    - uses: docker/setup-buildx-action@v1
+    - name: build dendrite in Docker
+      uses: docker/build-push-action@v2
       with:
-        name: bin-${{ matrix.target }}
-        path: ./bin
+        context: .
+        file: ./.github/workflows/Dockerfile.builder
+        load: true # load into local image store
+        tag: dendrite-builder:${{ matrix.target }}
+     - name: copy built files out of docker
+       run: docker -v "$(pwd)/bin:/build/bin-out" builder:${{ matrix.target }} "/bin/sh" "-c" "cp -a /build/bin/* /build/bin-out"
+     - uses: actions/upload-artifact@v2
+       with:
+         name: bin-${{ matrix.target }}
+         path: ./bin
   build-monolith:
     needs: [compile]
+    local-registry:
+    runs-on: ubuntu-latest
+    services:
+      registry:
+        image: registry:2
+        ports:
+        - 5000:5000
     strategy:
       matrix:
         target: [amd64, arm64, arm]
@@ -40,17 +49,14 @@ jobs:
         name: bin-${{ matrix.target }}
     # - run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/}" >> $GITHUB_ENV
     - run: echo "DOCKER_TARGET=$(./.github/workflows/get-compiler.sh docker)" >> $GITHUB_ENV 
-    # For building docker images, QEMU and buildx is still easier than anything to do with docker manifest editing
-    - name: Set up QEMU
-      uses: docker/setup-qemu-action@v1
-    - name: Set up Docker Buildx
-      uses: docker/setup-buildx-action@v1
-    - name: Build image
-      uses: docker/build-push-action@v2
+    - uses: docker/setup-qemu-action@v1
+    - uses: docker/setup-buildx-action@v1
+      with:
+        driver-opts: network=host
+    - uses: docker/build-push-action@v2
       with:
         context: .
         file: ./.github/workflows/Dockerfile.copyin
-        platforms: ${{ env.PLATFORMS }}
-        push: false
-        tags: |
-          ${{ env.DOCKER_NAMESPACE }}/dendrite-monolith:latest
+        platforms: ${{ DOCKER_TARGET }}
+        push: true
+        tags: localhost:5000/matrixdotorg/dendrite-monolith:latest

.github/workflows/get-compiler.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
-set -eu
+set -exu
+
+MUSLCC_BASE="https://more.musl.cc/x86_64-linux-musl"
 
 # Given a GOARCH target, return what Docker calls that target.
 function get_docker() {
@@ -23,38 +25,39 @@ function get_docker() {
 function get_compiler() {
     case "$GOARCH" in
     "amd64")
-        echo "x86_64-linux-gnu-gcc"
+        echo "gcc"
         ;;
     "arm64")
-        echo "aarch64-linux-gnu-gcc"
+        echo "./aarch64-linux-musl-cross/bin/aarch64-linux-musl-gcc"
         ;;
     "arm")
-        echo "arm-linux-gnueabihf-gcc"
+        echo "./arm-linux-musleabi-cross/bin/arm-linux-musleabi-gcc"
         ;;
     *)
-        echo "gcc" # Send us a pull request if RISC-V ever takes off
+        exit 1 # Send us a pull request if RISC-V ever takes off
         ;;
     esac
 }
 
-# Given a GOARCH target, return a list of Ubuntu packages needed to compile for that target.
-function get_pkgs() {
+function download_musl() {
     case "$GOARCH" in
     "arm64")
-        echo "gcc-aarch64-linux-gnu libc6-dev-arm64-cross"
+        curl "${MUSLCC_BASE}/aarch64-linux-musl-cross.tgz" -o musl.tgz
+        tar xzf musl.tgz
         ;;
     "arm")
-        echo "gcc-arm-linux-gnueabihf libc6-dev-armhf-cross"
+        curl "${MUSLCC_BASE}/arm-linux-musleabi-cross.tgz" -o musl.tgz
+        tar xzf musl.tgz
         ;;
-    "amd64" | *)
-        # We (currently) don't need to install more packages on amd64.
+    "amd64")
+        echo "nothing to do"
         ;;
     esac
 }
 
 case "$1" in
 "pkgs")
-    get_pkgs
+    download_musl
     ;;
 "ccomp")
     get_compiler