✨ Install Go latest + full toolchain at image build time ✨

Go is now downloaded from go.dev/dl at build time (always latest stable,
never pinned). All tools are baked into /usr/local/bin so they are on
PATH out of the box. Module cache and build cache live in the volumed
GOPATH (/usr/local/share/go) so they persist across container restarts
without re-downloading.
- Dockerfile: add /usr/local/go/bin to PATH in both build and final stage
- rootfs/root/docker/setup/05-custom.sh: full Go install + tool install
- detects arch (amd64/arm64/armv6l/386) via uname -m
- fetches latest stable version from go.dev/dl?mode=json via jq
- extracts to /usr/local/go; symlinks go+gofmt to /usr/local/bin
- installs with GOBIN=/usr/local/bin (baked into image, not in volume):
gopls, goimports, gofumpt, stringer, golangci-lint, staticcheck,
govulncheck, gotestsum, dlv, air, goreleaser, wire, mockgen (uber),
ko, protoc-gen-go, protoc-gen-go-grpc
- cleans modcache and build cache after install to keep layer lean
- rootfs/etc/profile.d/go.sh: add /usr/local/go/bin prepend so
interactive shells always find the Go distribution binaries first
Volume strategy:
/usr/local/share/go → GOPATH (module cache + build cache + user bins)
Mount a named volume or bind-mount here to avoid re-downloading modules:
docker run -v go-cache:/usr/local/share/go casjaysdevdocker/go

Dockerfile
rootfs/etc/profile.d/go.sh
rootfs/root/docker/setup/05-custom.sh

Dockerfile

@@ -58,7 +58,7 @@ ARG PACK_LIST="git make bash tini ca-certificates openssh-client curl wget tar t
 
 ENV ENV=~/.profile
 ENV SHELL="/bin/sh"
-ENV PATH="/usr/local/share/go/bin:${PATH}"
+ENV PATH="/usr/local/go/bin:/usr/local/share/go/bin:${PATH}"
 ENV TZ="${TIMEZONE}"
 ENV TIMEZONE="${TZ}"
 ENV LANG="${LANGUAGE}"
@@ -234,7 +234,7 @@ LABEL com.github.containers.toolbox="false"
 
 ENV ENV=~/.bashrc
 ENV USER="${USER}"
-ENV PATH="/usr/local/share/go/bin:${PATH}"
+ENV PATH="/usr/local/go/bin:/usr/local/share/go/bin:${PATH}"
 ENV TZ="${TIMEZONE}"
 ENV SHELL="/bin/bash"
 ENV TIMEZONE="${TZ}"