hack: make install-tools.sh more robust against missing deps

If a dependency of the script (go, python) is missing the script would
silently fail very early on. This change tries to avoid any failure
unless the tool in question actually depends on that dependency while
also making the missing dependency more obvious with more output.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

hack/install-tools.sh

@@ -5,15 +5,29 @@
 #   GOBIN=<dir> install-tools.sh --<tool-name>
 #
 set -e
-GO_CMD=${GO_CMD:-$(command -v go)}
-PY_CMD="${PY_CMD:-$(command -v python3)}"
-GOBIN=${GOBIN:-${GOPATH}/bin}
 
 _require_gobin() {
 	mkdir -p "${GOBIN}"
 }
 
+_require_go() {
+	if [ -z "$GO_CMD" ]; then
+		echo "error: go command required, but not found" >&2
+		echo "(set GO_CMD to specify go command)" >&2
+		exit 5
+	fi
+}
+
+_require_py() {
+	if [ -z "$PY_CMD" ]; then
+		echo "error: python3 command required, but not found" >&2
+		echo "(set PY_CMD to specify python command)" >&2
+		exit 5
+	fi
+}
+
 _install_tool() {
+	_require_go
 	GOBIN="${GOBIN}" ${GO_CMD} install "$1"
 }
 
@@ -43,11 +57,25 @@ _install_gosec() {
 
 _install_gitlint() {
 	_require_gobin
+	_require_py
 	"${PY_CMD}" -m venv "${GOBIN}/.py"
 	"${GOBIN}/.py/bin/pip" install "gitlint==0.19.1"
 	ln -s "${GOBIN}/.py/bin/gitlint"  "${GOBIN}/gitlint"
 }
 
+GOBIN="${GOBIN:-${GOPATH}/bin}"
+
+if [ -z "$GO_CMD" ]; then
+    if ! GO_CMD="$(command -v go)"; then
+        echo "warning: failed to find go command" >&2
+    fi
+fi
+if [ -z "$PY_CMD" ]; then
+    if ! PY_CMD="$(command -v python3)"; then
+        echo "warning: failed to find python3 command" >&2
+    fi
+fi
+
 case "$1" in
 	--kustomize)
 		_require_gobin