build: add tool to auto-generate changelog (#5)

Add the `git-chglog` tool to handle auto-generating the project changelog
based on the commit history. Add a custom configuration and file template.
Update the Makefile to include a command to generate the changelog.

Makefile

@@ -14,6 +14,9 @@ format:
 	go fmt $(go list ./... | grep -v /vendor/)
 	go vet $(go list ./... | grep -v /vendor/)
 
+generateChangelog:
+	./tools/git-chglog_linux_amd64 --config tools/chglog/config.yml 0.0.0.. > CHANGELOG.md
+
 build/snapshot:
 	./tools/goreleaser_linux_amd64 --snapshot --rm-dist --skip-publish
 

tools/chglog/CHANGELOG.tpl.md

@@ -0,0 +1,60 @@
+# CHANGELOG
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog], and this project adheres to [Semantic Versioning].
+
+{{ if .Versions -}}
+## [Unreleased]
+{{- if .Unreleased.CommitGroups }}
+{{ template "commits" .Unreleased.CommitGroups }}
+{{- end -}}
+
+{{- if .Unreleased.NoteGroups -}}
+{{ template "notes" .Unreleased.NoteGroups }}
+{{- end -}}
+{{- end -}}
+
+{{ range .Versions -}}
+## {{ if .Tag.Previous }}[{{ .Tag.Name }}]{{ else }}{{ .Tag.Name }}{{ end }} - {{ datetime "2006-01-02" .Tag.Date }}
+{{ template "commits" .CommitGroups }}
+{{- if .NoteGroups -}}
+{{ template "notes" .NoteGroups }}
+{{- end -}}
+{{ end }}
+---
+
+*This changelog is automatically generated by [git-chglog]*
+
+[Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
+[Semantic Versioning]: https://semver.org/spec/v2.0.0.html
+[git-chglog]: https://github.com/git-chglog/git-chglog
+
+{{- if .Versions }}
+[Unreleased]: {{ .Info.RepositoryURL }}/compare/{{ $latest := index .Versions 0 }}{{ $latest.Tag.Name }}...develop
+{{ range .Versions -}}
+{{ if .Tag.Previous -}}
+[{{ .Tag.Name }}]: {{ $.Info.RepositoryURL }}/compare/{{ .Tag.Previous.Name }}...{{ .Tag.Name }}
+{{ end -}}
+{{ end -}}
+{{ end -}}
+
+{{- define "notes" }}
+{{- range . -}}
+### {{ .Title }}
+{{ range .Notes -}}
+- {{ .Body }}
+{{ end }}
+{{ end }}
+{{ end -}}
+
+{{- define "commits" }}
+{{- range . -}}
+{{ if or (eq .RawTitle "feat") (eq .RawTitle "fix") }}
+### {{ .Title }}
+{{ range .Commits -}}
+- ({{ .Hash.Short }}) {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Header }}
+{{ end }}
+{{ end -}}
+{{ end -}}
+{{ end -}}

tools/chglog/config.yml

@@ -0,0 +1,23 @@
+style: gitlab
+template: CHANGELOG.tpl.md
+info:
+  title: CHANGELOG
+  repository_url: https://gitlab.com/hectorjsmith/fail2ban-prometheus-exporter
+options:
+  commit_groups:
+    title_maps:
+      feat: Added
+      fix: Fixed
+      revert: Reverted
+  header:
+    pattern: "^(\\w*)\\:\\s(.*)$"
+    pattern_maps:
+      - Type
+      - Subject
+  notes:
+    keywords:
+      - BREAKING CHANGE
+      - Changed
+      - Deprecated
+      - Removed
+      - Security