✨ 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

rootfs/etc/profile.d/go.sh

@@ -5,12 +5,20 @@
 # /data/go are symlinks to that location, so any of them can be used
 # interchangeably and the data persists across container rebuilds when
 # the volume is named.
+#
+# The Go distribution itself lives at /usr/local/go (baked into the image,
+# not volumed). Tools installed at build time land in /usr/local/bin.
 
 export GOPATH="${GOPATH:-/usr/local/share/go}"
 export GOCACHE="${GOCACHE:-${GOPATH}/cache}"
 export CGO_ENABLED="${CGO_ENABLED:-0}"
 export GOTOOLCHAIN="${GOTOOLCHAIN:-auto}"
 
+case ":${PATH}:" in
+  *":/usr/local/go/bin:"*) ;;
+  *) export PATH="/usr/local/go/bin:${PATH}" ;;
+esac
+
 case ":${PATH}:" in
   *":${GOPATH}/bin:"*) ;;
   *) export PATH="${GOPATH}/bin:${PATH}" ;;

rootfs/root/docker/setup/05-custom.sh

@@ -8,11 +8,11 @@
 # @@Copyright        :  Copyright 2026 CasjaysDev
 # @@Created          :  Fri May 29 10:20:10 PM EDT 2026
 # @@File             :  05-custom.sh
-# @@Description      :  script to run custom
-# @@Changelog        :  newScript
-# @@TODO             :  Refactor code
+# @@Description      :  Install Go latest and Go tooling
+# @@Changelog        :  Add Go install and toolchain setup
+# @@TODO             :  N/A
 # @@Other            :  N/A
-# @@Resource         :  N/A
+# @@Resource         :  https://go.dev/dl/
 # @@Terminal App     :  yes
 # @@sudo/root        :  yes
 # @@Template         :  templates/dockerfiles/init_scripts/05-custom.sh
@@ -20,18 +20,120 @@
 # shellcheck disable=SC1001,SC1003,SC2001,SC2003,SC2016,SC2031,SC2090,SC2115,SC2120,SC2155,SC2199,SC2229,SC2317,SC2329
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # Set bash options
-set -o pipefail
+set -eo pipefail
 [ "$DEBUGGER" = "on" ] && echo "Enabling debugging" && set -x$DEBUGGER_OPTIONS
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # Set env variables
 exitCode=0
 
+# Installation root for the Go distribution (not GOPATH)
+GOINSTALL_DIR="/usr/local/go"
+# GOPATH: module cache, pkg index, user-installed binaries (declared VOLUME)
+GOPATH_DIR="/usr/local/share/go"
+# Baked-in tool binaries land here so they are on the default PATH
+GOBIN_DIR="/usr/local/bin"
+# Throwaway build cache used only during this image build layer
+GOCACHE_BUILD="/tmp/go-build-cache"
+
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # Predefined actions
 
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # Main script
 
+# Map uname -m to the Go download architecture suffix
+case "$(uname -m)" in
+  x86_64)    _GOARCH="amd64"   ;;
+  aarch64)   _GOARCH="arm64"   ;;
+  armv7l)    _GOARCH="armv6l"  ;;
+  i386|i686) _GOARCH="386"     ;;
+  *)
+    echo "Unsupported architecture: $(uname -m)" >&2
+    exit 1
+    ;;
+esac
+
+# Fetch the latest stable Go version string from the official download API
+_GO_VERSION="$(curl -fsSL 'https://go.dev/dl/?mode=json' | jq -r '.[0].version')"
+echo "Installing ${_GO_VERSION} (linux/${_GOARCH})"
+
+# Remove any prior installation and extract the new tarball
+rm -rf "${GOINSTALL_DIR}"
+curl -fsSL "https://dl.google.com/go/${_GO_VERSION}.linux-${_GOARCH}.tar.gz" | tar -C /usr/local -xz
+
+# Symlink the core binaries so they are found without /usr/local/go/bin in PATH
+ln -sf "${GOINSTALL_DIR}/bin/go" "${GOBIN_DIR}/go"
+ln -sf "${GOINSTALL_DIR}/bin/gofmt" "${GOBIN_DIR}/gofmt"
+
+# Wire up the environment for the tool installation that follows
+export GOPATH="${GOPATH_DIR}"
+export GOBIN="${GOBIN_DIR}"
+export PATH="${GOINSTALL_DIR}/bin:${PATH}"
+export GOCACHE="${GOCACHE_BUILD}"
+export CGO_ENABLED="0"
+export GOTOOLCHAIN="auto"
+
+# Ensure the GOPATH directory tree exists
+mkdir -p "${GOPATH_DIR}/pkg/mod" "${GOPATH_DIR}/cache" "${GOPATH_DIR}/bin"
+
+echo "Installing Go tooling (GOBIN=${GOBIN_DIR})"
+
+# Language server - editor integration (VSCode, Neovim, etc.)
+go install golang.org/x/tools/gopls@latest
+
+# Import organiser - superset of gofmt that also manages import groups
+go install golang.org/x/tools/cmd/goimports@latest
+
+# Stricter formatter used by many golangci-lint configs
+go install mvdan.cc/gofumpt@latest
+
+# Generate String() methods for iota-based types
+go install golang.org/x/tools/cmd/stringer@latest
+
+# Meta-linter: runs golint, errcheck, ineffassign, gocyclo, and many more
+go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+
+# Standalone advanced static analyser
+go install honnef.co/go/tools/cmd/staticcheck@latest
+
+# Vulnerability scanner against the Go vulnerability database
+go install golang.org/x/vuln/cmd/govulncheck@latest
+
+# Structured test runner with better output and JUnit/JSON export
+go install gotest.tools/gotestsum@latest
+
+# Source-level debugger
+go install github.com/go-delve/delve/cmd/dlv@latest
+
+# Live-reload dev server for iterative development
+go install github.com/air-verse/air@latest
+
+# Release automation: cross-compile, sign, publish, container images
+go install github.com/goreleaser/goreleaser/v2@latest
+
+# Compile-time dependency injection code generator
+go install github.com/google/wire/cmd/wire@latest
+
+# Mock generator for interfaces (uber fork of golang/mock)
+go install go.uber.org/mock/mockgen@latest
+
+# Build Go container images without a Dockerfile
+go install github.com/google/ko@latest
+
+# protobuf Go code generator
+go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
+
+# gRPC Go code generator
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
+
+echo "Go tooling installed"
+
+# Strip the module download cache and ephemeral build cache from this layer.
+# The installed binaries in GOBIN_DIR are preserved in the image.
+go clean -modcache
+go clean -cache
+rm -rf "${GOCACHE_BUILD}"
+
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # Set the exit code
 exitCode=$?
@@ -40,4 +142,3 @@ exit $exitCode
 # - - - - - - - - - - - - - - - - - - - - - - - - -
 # ex: ts=2 sw=2 et filetype=sh
 # - - - - - - - - - - - - - - - - - - - - - - - - -
-