hack/release.sh: Add a release script

Matthew had expressed interest in a lovely release script on IRC.
Here's my attempt to encode the changes from the v0.5.4 release
branch.  I've also added tag signing, so you may be prompted for your
passphrase during that step.

The version scheme for 0.x.y is 0.${month}.${count_that_month} [1].
We could automatically calculate those with a dozen or so lines of
shell script, but we don't think that's worth the maintenance burden
when it's easy enough for the caller to think them up on their own
[2].

The spec sed also bumps the Python package version to match, which
seems like the intended behavior until 1.0 when the Python code will
move into its own repository [3].

[1]: https://github.com/projectatomic/libpod/pull/867#issuecomment-393731907
[2]: https://github.com/projectatomic/libpod/pull/867#issuecomment-393743295
[3]: https://github.com/projectatomic/libpod/issues/786#issuecomment-390682012

Signed-off-by: W. Trevor King <wking@tremily.us>

hack/release.sh

@@ -0,0 +1,80 @@
+#!/bin/sh
+#
+# Cut a libpod release.  Usage:
+#
+#   $ hack/release.sh <version> <next-version>
+#
+# For example:
+#
+#   $ hack/release.sh 1.2.3 1.3.0
+#
+# for "I'm cutting 1.2.3, and want to use 1.3.0-dev for future work".
+
+VERSION="$1"
+NEXT_VERSION="$2"
+DATE=$(date '+%Y-%m-%d')
+LAST_TAG=$(git describe --tags --abbrev=0)
+
+write_go_version()
+{
+	LOCAL_VERSION="$1"
+	sed -i "s/^\(const Version = \"\).*/\1${LOCAL_VERSION}\"/" version/version.go
+}
+
+write_python_version()
+{
+	LOCAL_VERSION="$1"
+	sed -i "s/^\( *version='*\).*/\1${LOCAL_VERSION}'/" contrib/python/setup.py
+}
+
+write_spec_version()
+{
+	LOCAL_VERSION="$1"
+	sed -i "s/^\(Version: *\).*/\1${LOCAL_VERSION}/" contrib/spec/podman.spec.in
+}
+
+write_makefile_epoch()
+{
+	LOCAL_EPOCH="$1"
+	sed -i "s/^\(EPOCH_TEST_COMMIT ?= \).*/\1${LOCAL_EPOCH}/" Makefile
+}
+
+write_changelog()
+{
+	echo "- Changelog for v${VERSION} (${DATE})" >.changelog.txt &&
+	git log --no-merges --format='  * %s' "${LAST_TAG}..HEAD" >>.changelog.txt &&
+	echo >>.changelog.txt &&
+	cat changelog.txt >>.changelog.txt &&
+	mv -f .changelog.txt changelog.txt
+}
+
+release_commit()
+{
+	write_go_version "${VERSION}" &&
+	write_python_version "${VERSION}" &&
+	write_changelog &&
+	git commit -asm "Bump to v${VERSION}"
+}
+
+dev_version_commit()
+{
+	write_go_version "${NEXT_VERSION}-dev" &&
+	write_python_version "${NEXT_VERSION}" &&
+	write_spec_version "${VERSION}" &&
+	git commit -asm "Bump to v${NEXT_VERSION}-dev"
+}
+
+epoch_commit()
+{
+	LOCAL_EPOCH="$1"
+	write_makefile_epoch "${LOCAL_EPOCH}" &&
+	git commit -asm 'Bump gitvalidation epoch'
+}
+
+git fetch origin &&
+git checkout -b "bump-${VERSION}" origin/master &&
+EPOCH=$(git rev-parse HEAD) &&
+release_commit &&
+git tag -s -m "version ${VERSION}" "v${VERSION}" &&
+dev_version_commit &&
+epoch_commit "${EPOCH}"