Add grafana gitea-mixin (go-gitea#17758)

This PR adds gitea-mixin, configurable Grafana dashboards (and potentially prometheus alerts+recording rules) based on Gitea [metrics](https://docs.gitea.io/en-us/config-cheat-sheet/#metrics-metrics).

The overview dashboard is described using jsonnet and grafonnet library: https://grafana.github.io/grafonnet-lib/

Mixins help to define dashboard and alerts as code so they can be collaboratively improved by the users.

![image](https://user-images.githubusercontent.com/14870891/142862822-fe57b384-c74a-4103-8548-033e92f90751.png)

__
## Generate config files

You can manually generate dashboards, but first you should install some tools:

```bash
go get github.com/jsonnet-bundler/jsonnet-bundler/cmd/jb
go get github.com/google/go-jsonnet/cmd/jsonnet
# or in brew: brew install go-jsonnet
```

For linting and formatting, you would also need `mixtool` and `jsonnetfmt` installed. If you
have a working Go development environment, it's easiest to run the following:

```bash
go get github.com/monitoring-mixins/mixtool/cmd/mixtool
go get github.com/google/go-jsonnet/cmd/jsonnetfmt
```

The files in `dashboards_out` need to be imported
into your Grafana server.  The exact details will be depending on your environment.

Edit `config.libsonnet` (for example, list of Gitea metrics to be shown under stats can be adjusted). if required and then build JSON dashboard files for Grafana:

```bash
make
```


For more about mixins, please see:
https://github.com/monitoring-mixins/docs
https://www.youtube.com/watch?v=GDdnL5R_l-Y* add gitea mixin

* remove alerts/rules

* gitea-mixin: add interval factor of 1/2 to remove duplicated change events

* gitea-mixin: fix changes panel, add aggregation interval for changes panel

* gitea-mixin: add totals singlestat

* gitea mixin: switch change graph to timeseries type

* add color overrides for issue labels

* bump grafonnet version

* gitea-mixin: convert graphs to timeseries

* gitea-mixin:  make fmt

* gitea-mixin: add .PHONE in Makefile

* gitea-mixin: add time configration

* gitea-mixin: make fmt and collapse addPanel grid

* gitea-mixin: add static ids for shared panels

* gitea-mixin: add flags showIssuesByRepository, showIssuesByLabel to show/hide corresponding panels

* gitea-mixin: update aggregation interval

* gitea-mixin: update defaults

* gitea-mixin: update panel names

* rename dir to gitea-monitoring-mixin

* gitea-mixin: add gitea_issues_open, gitea_issues_closed metrics

* gitea-mixin: update visible name for datasource

* gitea-mixin: update README

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>

contrib/gitea-monitoring-mixin/.gitignore

@@ -0,0 +1,2 @@
+dashboards_out
+vendor

contrib/gitea-monitoring-mixin/Makefile

@@ -0,0 +1,31 @@
+JSONNET_FMT := jsonnetfmt -n 2 --max-blank-lines 1 --string-style s --comment-style s
+
+.PHONY: all
+all: build dashboards_out
+
+vendor: jsonnetfile.json
+	jb install
+
+.PHONY: build
+build: vendor
+
+.PHONY: fmt
+fmt:
+	find . -name 'vendor' -prune -o -name '*.libsonnet' -print -o -name '*.jsonnet' -print | \
+		xargs -n 1 -- $(JSONNET_FMT) -i
+
+.PHONY: lint
+lint: build
+	find . -name 'vendor' -prune -o -name '*.libsonnet' -print -o -name '*.jsonnet' -print | \
+		while read f; do \
+			$(JSONNET_FMT) "$$f" | diff -u "$$f" -; \
+		done
+	mixtool lint mixin.libsonnet
+
+dashboards_out: mixin.libsonnet config.libsonnet $(wildcard dashboards/*)
+	@mkdir -p dashboards_out
+	jsonnet -J vendor -m dashboards_out lib/dashboards.jsonnet
+
+.PHONY: clean
+clean:
+	rm -rf dashboards_out

contrib/gitea-monitoring-mixin/README.md

@@ -0,0 +1,33 @@
+# Gitea Mixin
+
+Gitea Mixin is a set of configurable Grafana dashboards based on the metrics exported by the Gitea built-in metrics endpoint.
+
+## Generate config files
+
+You can manually generate dashboards, but first you should install some tools:
+
+```bash
+go install github.com/jsonnet-bundler/jsonnet-bundler/cmd/jb@latest
+go install github.com/google/go-jsonnet/cmd/jsonnet@latest
+# or in brew: brew install go-jsonnet
+```
+
+For linting and formatting, you would also need `mixtool` and `jsonnetfmt` installed. If you
+have a working Go development environment, it's easiest to run the following:
+
+```bash
+go install github.com/monitoring-mixins/mixtool/cmd/mixtool@latest
+go install github.com/google/go-jsonnet/cmd/jsonnetfmt@latest
+```
+
+The files in `dashboards_out` need to be imported
+into your Grafana server.  The exact details will be depending on your environment.
+
+Edit `config.libsonnet` if required and then build JSON dashboard files for Grafana:
+
+```bash
+make
+```
+
+For more advanced uses of mixins, see
+https://github.com/monitoring-mixins/docs.

contrib/gitea-monitoring-mixin/config.libsonnet

@@ -0,0 +1,99 @@
+{
+  _config+:: {
+    local c = self,
+    dashboardNamePrefix: 'Gitea',
+    dashboardTags: ['gitea'],
+    dashboardPeriod: 'now-1h',
+    dashboardTimezone: 'default',
+    dashboardRefresh: '1m',
+
+    // please see https://docs.gitea.io/en-us/config-cheat-sheet/#metrics-metrics
+    // Show issue by repository metrics with format gitea_issues_by_repository{repository="org/repo"} 5.
+    // Requires Gitea 1.16.0 with ENABLED_ISSUE_BY_REPOSITORY set to true.
+    showIssuesByRepository: true,
+    // Show graphs for issue by label metrics with format gitea_issues_by_label{label="bug"} 2.
+    // Requires Gitea 1.16.0 with ENABLED_ISSUE_BY_LABEL set to true.
+    showIssuesByLabel: true,
+
+    // Requires Gitea 1.16.0.
+    showIssuesOpenClose: true,
+
+    // add or remove metrics from dashboard
+    giteaStatMetrics:
+      [
+        {
+          name: 'gitea_organizations',
+          description: 'Organizations',
+        },
+        {
+          name: 'gitea_teams',
+          description: 'Teams',
+        },
+        {
+          name: 'gitea_users',
+          description: 'Users',
+        },
+        {
+          name: 'gitea_repositories',
+          description: 'Repositories',
+        },
+        {
+          name: 'gitea_milestones',
+          description: 'Milestones',
+        },
+        {
+          name: 'gitea_stars',
+          description: 'Stars',
+        },
+        {
+          name: 'gitea_releases',
+          description: 'Releases',
+        },
+      ]
+      +
+      if c.showIssuesOpenClose then
+        [
+          {
+            name: 'gitea_issues_open',
+            description: 'Issues opened',
+          },
+          {
+            name: 'gitea_issues_closed',
+            description: 'Issues closed',
+          },
+        ] else
+        [
+          {
+            name: 'gitea_issues',
+            description: 'Issues',
+          },
+        ],
+    //set this for using label colors on graphs
+    issueLabels: [
+      {
+        label: 'bug',
+        color: '#ee0701',
+      },
+      {
+        label: 'duplicate',
+        color: '#cccccc',
+      },
+      {
+        label: 'invalid',
+        color: '#e6e6e6',
+      },
+      {
+        label: 'enhancement',
+        color: '#84b6eb',
+      },
+      {
+        label: 'help wanted',
+        color: '#128a0c',
+      },
+      {
+        label: 'question',
+        color: '#cc317c',
+      },
+    ],
+  },
+}

contrib/gitea-monitoring-mixin/dashboards/dashboards.libsonnet

@@ -0,0 +1 @@
+(import 'overview.libsonnet')