chore: add changelog scripts

.github/changelog/changelog.tmpl

@@ -0,0 +1,56 @@
+{{- if .NotesByType.deprecation -}}
+### :warning: **Deprecations**
+
+{{range .NotesByType.deprecation -}}
+* {{ template "note" .}}
+{{ end -}}
+{{- end -}}
+
+{{- if index .NotesByType "breaking-change" -}}
+### :rotating_light: **Breaking Changes**
+
+{{range index .NotesByType "breaking-change" -}}
+* {{ template "note" .}}
+{{ end -}}
+{{- end -}}
+
+{{- if index .NotesByType "feature" -}}
+### :rocket: **New Features**
+
+{{range index .NotesByType "feature" -}}
+* {{ template "note" .}}
+{{ end -}}
+{{- end -}}
+
+{{- $improvements := combineTypes .NotesByType.improvement .NotesByType.enhancement -}}
+{{- if $improvements }}
+### :tada: **Improvements**
+
+{{range $improvements | sort -}}
+* {{ template "note" . }}
+{{ end -}}
+{{- end -}}
+
+{{- if .NotesByType.bug }}
+### :bug: **Bug Fixes**
+
+{{range .NotesByType.bug -}}
+* {{ template "note" . }}
+{{ end -}}
+{{- end -}}
+
+{{- if .NotesByType.note -}}
+### :information_source: **Notes**
+
+{{range .NotesByType.note -}}
+* {{ template "note" .}}
+{{ end -}}
+{{- end -}}
+
+{{- if .NotesByType.dependency }}
+### :dependabot: **Dependencies**
+
+{{range .NotesByType.dependency | sort -}}
+* {{ template "note" . }}
+{{ end -}}
+{{- end -}}

.github/changelog/generate-changelog.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+
+set -o errexit
+set -o nounset
+
+__dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+__parent="$(dirname "$__dir")"
+__root="$(dirname "$__parent")"
+
+CHANGELOG_FILE_NAME="CHANGELOG.md"
+CHANGELOG_TMP_FILE_NAME="CHANGELOG.tmp"
+TARGET_SHA=$(git rev-parse HEAD)
+PREVIOUS_RELEASE_TAG=$(git describe --abbrev=0 --match='v*.*.*' --tags)
+PREVIOUS_RELEASE_SHA=$(git rev-list -n 1 $PREVIOUS_RELEASE_TAG)
+
+if [ $TARGET_SHA == $PREVIOUS_RELEASE_SHA ]; then
+  echo "Nothing to do"
+  exit 0
+fi
+
+PREVIOUS_CHANGELOG=$(sed -n -e "/# ${PREVIOUS_RELEASE_TAG#v}/,\$p" $__root/$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 $__root \
+                      -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;}" $__root/$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

.github/changelog/release-note.tmpl

@@ -0,0 +1,3 @@
+{{- define "note" -}}
+{{.Body}} (GH-{{- .Issue -}})
+{{- end -}}