Gitpod config (#7749)

Signed-off-by: Sven Efftinge <sven.efftinge@typefox.io>

.gitpod.yml

@@ -0,0 +1,18 @@
+tasks:
+  - init: 
+      make build
+    command: |
+      gp sync-done build
+      ./prometheus --config.file=documentation/examples/prometheus.yml
+  - command: |
+      cd web/ui/react-app
+      gp sync-await build
+      unset BROWSER
+      export DANGEROUSLY_DISABLE_HOST_CHECK=true
+      yarn start
+    openMode: split-right
+ports:
+  - port: 3000
+    onOpen: open-preview
+  - port: 9090
+    onOpen: ignore

CONTRIBUTING.md

@@ -28,6 +28,8 @@ Should you wish to work on an issue, please claim it first by commenting on the
 
 Please check the [`low-hanging-fruit`](https://github.com/prometheus/prometheus/issues?q=is%3Aissue+is%3Aopen+label%3A%22low+hanging+fruit%22) label to find issues that are good for getting started. If you have questions about one of the issues, with or without the tag, please comment on them and one of the maintainers will clarify it. For a quicker response, contact us over [IRC](https://prometheus.io/community).
 
+You can [spin up a prebuilt dev environment](https://gitpod.io/#https://github.com/prometheus/prometheus) using Gitpod.io.
+
 For complete instructions on how to compile see: [Building From Source](https://github.com/prometheus/prometheus#building-from-source)
 
 For quickly compiling and testing your changes do:

README.md

@@ -6,6 +6,7 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/prometheus/prometheus)](https://goreportcard.com/report/github.com/prometheus/prometheus)
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/486/badge)](https://bestpractices.coreinfrastructure.org/projects/486)
 [![fuzzit](https://app.fuzzit.dev/badge?org_id=prometheus&branch=master)](https://fuzzit.dev)
+[![Gitpod ready-to-code](https://img.shields.io/badge/Gitpod-ready--to--code-blue?logo=gitpod)](https://gitpod.io/#https://github.com/prometheus/prometheus)
 
 Visit [prometheus.io](https://prometheus.io) for the full documentation,
 examples and guides.