Add generate-changelog script

scripts/generate-changelog.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+set -o errexit
+set -o nounset
+
+__dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+__parent="$(dirname "$__dir")"
+
+CHANGELOG_FILE_NAME="CHANGELOG.md"
+CHANGELOG_TMP_FILE_NAME="CHANGELOG.tmp"
+TARGET_SHA=$(git rev-parse HEAD)
+PREVIOUS_RELEASE_SHA=$(git rev-list -n 1 $(git describe --abbrev=0 --match='v*.*.*' --tags))
+
+if [ $TARGET_SHA == $PREVIOUS_RELEASE_SHA ]; then
+  echo "Nothing to do"
+  exit 0
+fi
+
+PREVIOUS_CHANGELOG=$(sed -n -e "/## $(git describe --abbrev=0 --match='v*.*.*' --tags | tr -d v)/,\$p" $__parent/$CHANGELOG_FILE_NAME)
+
+if [ -z "$PREVIOUS_CHANGELOG" ]
+then
+    echo "Unable to locate previous changelog contents."
+    exit 1
+fi
+
+CHANGELOG=$($(go env GOPATH)/bin/changelog-build -this-release $TARGET_SHA \
+                      -last-release $PREVIOUS_RELEASE_SHA \
+                      -git-dir $__parent \
+                      -entries-dir .changelog \
+                      -changelog-template $__dir/changelog.tmpl \
+                      -note-template $__dir/release-note.tmpl)
+
+if [ -z "$CHANGELOG" ]
+then
+    echo "No changelog generated."
+    exit 0
+fi
+
+rm -f $CHANGELOG_TMP_FILE_NAME
+
+sed -n -e "1{/## /p;}" $__parent/$CHANGELOG_FILE_NAME > $CHANGELOG_TMP_FILE_NAME
+echo "$CHANGELOG" >> $CHANGELOG_TMP_FILE_NAME
+echo >> $CHANGELOG_TMP_FILE_NAME
+echo "$PREVIOUS_CHANGELOG" >> $CHANGELOG_TMP_FILE_NAME
+
+cp $CHANGELOG_TMP_FILE_NAME $CHANGELOG_FILE_NAME
+
+rm $CHANGELOG_TMP_FILE_NAME
+
+echo "Successfully generated changelog."
+
+exit 0