hack: use long SHA for DOCKER_GITCOMMIT

This better aligns to GHA/CI settings, and is in general a better
practice in the year 2023.

We also drop the 'unsupported' fallback for `git rev-parse` in the
Makefile; we have a better fallback behavior for an empty
DOCKER_GITCOMMIT in `hack/make.sh`.

Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>

Makefile

@@ -7,7 +7,7 @@ BUILDX ?= $(DOCKER) buildx
 DOCKER_GRAPHDRIVER := $(if $(DOCKER_GRAPHDRIVER),$(DOCKER_GRAPHDRIVER),$(shell docker info 2>&1 | grep "Storage Driver" | sed 's/.*: //'))
 export DOCKER_GRAPHDRIVER
 
-DOCKER_GITCOMMIT := $(shell git rev-parse --short HEAD || echo unsupported)
+DOCKER_GITCOMMIT := $(shell git rev-parse HEAD)
 export DOCKER_GITCOMMIT
 
 # allow overriding the repository and branch that validation scripts are running

hack/make.sh

@@ -51,7 +51,7 @@ fi
 if [ "$DOCKER_GITCOMMIT" ]; then
 	GITCOMMIT="$DOCKER_GITCOMMIT"
 elif command -v git &> /dev/null && [ -e .git ] && git rev-parse &> /dev/null; then
-	GITCOMMIT=$(git rev-parse --short HEAD)
+	GITCOMMIT=$(git rev-parse HEAD)
 	if [ -n "$(git status --porcelain --untracked-files=no)" ]; then
 		GITCOMMIT="$GITCOMMIT-unsupported"
 		echo "#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
@@ -66,8 +66,8 @@ elif command -v git &> /dev/null && [ -e .git ] && git rev-parse &> /dev/null; t
 else
 	echo >&2 'error: .git directory missing and DOCKER_GITCOMMIT not specified'
 	echo >&2 '  Please either build with the .git directory accessible, or specify the'
-	echo >&2 '  exact (--short) commit hash you are building using DOCKER_GITCOMMIT for'
-	echo >&2 '  future accountability in diagnosing build issues.  Thanks!'
+	echo >&2 '  exact commit hash you are building using DOCKER_GITCOMMIT for future'
+	echo >&2 '  accountability in diagnosing build issues.  Thanks!'
 	exit 1
 fi