Add release tagging script

Makefile

@@ -75,3 +75,6 @@ image images:
 
 render:
 	scripts/ops.sh render
+
+release:
+	scripts/ops.sh release

scripts/ops.sh

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+function usage() {
+  echo "Usage: $0 <check|release>"
+  exit 1
+}
+
+function check() {
+  output=${1:-verbose}
+  for cmd in git semver; do
+    command -v ${cmd} 2>/dev/null 1>&2 || (echo "Error: ${cmd} not found in path" && exit 1)
+    [[ "$output" = "silent" ]] || echo "Found ${cmd}"
+  done
+  [[ "$output" = "silent" ]] || echo "OK"
+}
+
+function release {
+  git fetch --all
+
+  src_branch=$(git rev-parse --abbrev-ref ${1:-HEAD})
+  src_branch_base=${src_branch#origin/*}
+  src_branch_topic=${src_branch_base%%/*}
+  src_branch_version=${src_branch_base#*/}
+
+  if [[ "$src_branch_topic" != "release" ]]; then
+    echo "Unsupported branch type: ${src_branch_topic}"
+    exit 1
+  fi
+
+  last_tag=$(git describe --abbrev=0 ${src_branch})
+  tag=$(semver --range $src_branch_version $last_tag || true)
+  if [[ -z "$tag" ]]; then
+    tag="$src_branch_version.0"
+  else
+    tag=$(semver --increment $tag)
+  fi
+
+  message=$(
+    echo -e "Release $tag\n"
+    git log --oneline $last_tag..$src_branch | sed -re 's/^[^ ]+/-/' | (grep -vE "^- (Merge (branch|tag) |Bump)" || [ $? -eq 1 ])
+  )
+
+  git tag -a "$tag" -m "$message"
+  git push --tags
+}
+
+action=${1:-}
+
+case "${action}" in
+release)
+  check silent
+  release
+  ;;
+check)
+  check verbose
+  ;;
+*)
+  echo "Error: invalid action: ${action}"
+  usage
+  ;;
+esac