go mod replace version-timestamp-hash extractor

go_mod_replace_version.sh

#!/bin/bash
#
# This script is used to generate a version string for the go.mod replace directive.
# This is of the format version-timestamp-hash, where version is the current version of the module,
# timestamp is the current time in UTC, and hash is the short git hash of the current commit.
#
# This script emits the "version-timestamp-hash" based on the current git HEAD.
#
# If passed with an argument, that string is used as the version,
# otherwise "v0.0.0" is used as the default version.
#
#

VERSION=${1:-"v0.0.0"}

DT=$(TZ=UTC git show -s --format=%cd --date='format-local:%Y%m%d%H%M%S' HEAD)

HASHISH=$(git rev-parse --short=12 HEAD)

echo "$VERSION-$DT-$HASHISH"