Specify C compiler in build cross-compilation

.github/workflows/ci.yml

@@ -54,8 +54,6 @@ jobs:
           args: --timeout=10m
 
   docker:
-    if: github.ref == 'refs/heads/master' || contains(github.ref, 'refs/tags/')
-    needs: test
     name: "Docker image"
     runs-on: ubuntu-latest
     steps:

cmd/emulator/Dockerfile

@@ -12,16 +12,28 @@ WORKDIR /app
 # add the pubkey of github.com to knownhosts, so ssh-agent doesn't bark
 RUN mkdir -p /root/.ssh && ssh-keyscan -t rsa github.com >> /root/.ssh/known_hosts
 RUN git config --global 'url.ssh://git@github.com/.insteadOf' https://github.com/
+RUN apt-get update
+RUN apt-get -y install apt-utils gcc-arm-linux-gnueabi
 
 COPY . .
 
 ARG TARGETOS 
 ARG TARGETARCH
-RUN --mount=type=ssh \
+RUN if [ "$TARGETARCH" = "arm64" ] ; then \
+    --mount=type=ssh \
     --mount=type=cache,target=/go/pkg/mod \
     --mount=type=cache,target=/root/.cache/go-build \
-    GO111MODULE=on CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH \
-    go build -ldflags "-extldflags -static" -o ./app ./cmd/emulator
+    GO111MODULE=on CGO_ENABLED=1 GOOS=$TARGETOS \
+    GOARCH=$TARGETARCH CC=arm-linux-gnueabi-gcc \
+    go build -ldflags "-extldflags -static" -o ./app ./cmd/emulator ; \
+    elif [ "$TARGETARCH" = "amd64" ] ; then \
+    --mount=type=ssh \
+    --mount=type=cache,target=/go/pkg/mod \
+    --mount=type=cache,target=/root/.cache/go-build \
+    GO111MODULE=on CGO_ENABLED=1 GOOS=$TARGETOS \
+    GOARCH=$TARGETARCH CC=gcc \
+    go build -ldflags "-extldflags -static" -o ./app ./cmd/emulator ; \
+    fi
 
 ## Add the binary to a fresh distroless image
 FROM gcr.io/distroless/static