mimir-build-image: Explicitly set GOTOOLCHAIN=local

Signed-off-by: Arve Knudsen <[email protected]>

go.mod

@@ -2,6 +2,8 @@ module github.com/grafana/mimir
 
 go 1.21.0
 
+// Please note that this directive is ignored when building with the Mimir build image,
+// that will always use its bundled toolchain.
 toolchain go1.22.5
 
 require (

mimir-build-image/Dockerfile

@@ -9,6 +9,10 @@ FROM golang:1.22.5-bookworm
 ARG goproxyValue
 ENV GOPROXY=${goproxyValue}
 ENV SKOPEO_DEPS="libgpgme-dev libassuan-dev libbtrfs-dev libdevmapper-dev pkg-config"
+# Override toolchain directive in go.mod, to ensure the image's Go version is used.
+# Be aware that the official Go Dockerfiles already do this, but let's be explicit.
+# https://github.com/docker-library/golang/issues/472
+RUN go env -w GOTOOLCHAIN=local
 RUN apt-get update && apt-get install -y curl python3-requests python3-yaml file jq zip unzip protobuf-compiler libprotobuf-dev shellcheck libpcap-dev $SKOPEO_DEPS && \
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 RUN go install golang.org/x/tools/cmd/goimports@3fce476f0a782aeb5034d592c189e63be4ba6c9e