docs(contributing): expand contribution guidelines with new sections

docs/content/en/docs-dev/contribution-guidelines/contributing.md

@@ -1,9 +1,253 @@
 ---
-title: "Contributing"
-linkTitle: "Contributing"
+title: "Contribute to PipeCD"
+linkTitle: "Contribute to PipeCD"
 weight: 1
 description: >
   This page describes how to contribute to PipeCD.
 ---
 
-PipeCD is an open source project that anyone in the community can use, improve, and enjoy. We'd love you to join us! [Contributing to PipeCD](https://github.com/pipe-cd/pipecd/tree/master/CONTRIBUTING.md) is the best place to start with.
+PipeCD is an open source project that anyone in the community can use, improve, and enjoy. We'd love you to join us!
+
+## Code of Conduct
+
+PipeCD follows the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md). Please read it to understand which actions are acceptable and which are not.
+
+## Ways to Contribute
+
+There are many ways to contribute, and many don't involve writing code:
+
+- **Use PipeCD** — Follow the [Quickstart](/docs/quickstart/) and report issues you encounter
+- **Triage issues** — Browse [open issues](https://github.com/pipe-cd/pipecd/issues), provide workarounds, ask for clarification, or suggest labels
+- **Fix bugs** — Issues labeled [good first issue](https://github.com/pipe-cd/pipecd/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) are great starting points
+- **Improve docs** — See [Contribute to PipeCD Documentation](../contributing-documentation/)
+- **Participate in discussions** — Share ideas in [GitHub Discussions](https://github.com/pipe-cd/pipecd/discussions)
+
+## Development Setup
+
+### Project Structure
+
+PipeCD consists of several components:
+
+| Component | Description |
+|-----------|-------------|
+| [cmd/pipecd](https://github.com/pipe-cd/pipecd/tree/master/cmd/pipecd) | Control Plane — manages deployment data and provides gRPC API |
+| [cmd/piped](https://github.com/pipe-cd/pipecd/tree/master/cmd/piped) | Piped agent — runs in your cluster |
+| [cmd/pipectl](https://github.com/pipe-cd/pipecd/tree/master/cmd/pipectl) | Command-line tool |
+| [cmd/launcher](https://github.com/pipe-cd/pipecd/tree/master/cmd/launcher) | Command executor for remote upgrade |
+| [web](https://github.com/pipe-cd/pipecd/tree/master/web) | Web UI |
+| [docs](https://github.com/pipe-cd/pipecd/tree/master/docs) | Documentation |
+
+### Prerequisites
+
+- Go (check `go.mod` for version)
+- Node.js and Yarn (for web development)
+- Docker
+- kubectl
+- kind (Kubernetes in Docker)
+
+### Starting a Local Environment
+
+#### 1. Update Dependencies
+
+```bash
+make update/go-deps
+make update/web-deps
+```
+
+> Starting a local environment may fail if dependencies are not up to date.
+
+#### 2. Start Local Cluster and Registry
+
+```bash
+make up/local-cluster
+```
+
+This creates the `pipecd` Kubernetes namespace and starts a local registry.
+
+To clean up later:
+
+```bash
+make down/local-cluster
+```
+
+#### 3. Run Control Plane
+
+```bash
+make run/pipecd
+```
+
+To stop:
+
+```bash
+make stop/pipecd
+```
+
+#### 4. Port Forward
+
+In a separate terminal:
+
+```bash
+kubectl port-forward -n pipecd svc/pipecd 8080
+```
+
+#### 5. Access the UI
+
+Open [http://localhost:8080?project=quickstart](http://localhost:8080?project=quickstart)
+
+Login credentials:
+- **Username:** `hello-pipecd`
+- **Password:** `hello-pipecd`
+
+### Running Piped Agent
+
+1. Ensure Control Plane is running and accessible.
+
+2. Register a new Piped:
+   - Go to Settings → Piped (or [http://localhost:8080/settings/piped?project=quickstart](http://localhost:8080/settings/piped?project=quickstart))
+   - Add a new piped and copy the generated Piped ID and base64 key
+
+3. Create `piped-config.yaml` in the repository root:
+
+   > **Tip:** Create a `.dev` folder (gitignored) for multiple config files.
+
+   ```yaml
+   apiVersion: pipecd.dev/v1beta1
+   kind: Piped
+   spec:
+     projectID: quickstart
+     pipedID: <YOUR_PIPED_ID>
+     pipedKeyData: <YOUR_PIPED_BASE64_KEY>
+     apiAddress: localhost:8080
+     repositories:
+       - repoId: example
+         remote: git@github.com:pipe-cd/examples.git
+         branch: master
+     syncInterval: 1m
+     platformProviders:
+       - name: example-kubernetes
+         type: KUBERNETES
+         config:
+           kubeConfigPath: /path/to/.kube/config
+   ```
+
+4. Start the Piped agent:
+
+   ```bash
+   make run/piped CONFIG_FILE=path/to/piped-config.yaml INSECURE=true
+   ```
+
+### Useful Commands
+
+Check the [Makefile](https://github.com/pipe-cd/pipecd/blob/master/Makefile) for available commands. Common ones:
+
+```bash
+make check          # Run all checks (lint, test, etc.)
+make test/go        # Run Go tests
+make test/web       # Run web tests
+make build/go       # Build Go binaries
+```
+
+## Pull Request Process
+
+### Before You Start
+
+1. **Find or create an issue** — Check if an issue exists, or open one for new features/bugs
+2. **Claim the issue** — Comment "I'd like to work on this" to get assigned (expected to submit PR within 7 days)
+3. **Investigate first** — Discuss your approach in the issue before coding to reduce back-and-forth on the PR
+4. **Focus on one issue** — Especially for newcomers, work on one issue at a time
+
+### Submitting a Pull Request
+
+1. **Keep PRs small** — Aim for ~300 lines of diff. Split larger changes into multiple PRs.
+
+2. **Use descriptive titles** — Follow commit message style: present tense, capitalize first letter
+
+   ```
+   Add imports to Terraform plan result
+   ```
+
+3. **Sign off commits** — Required for DCO compliance:
+
+   ```bash
+   git commit -s -m "Your commit message"
+   ```
+
+4. **Run checks before submitting:**
+
+   ```bash
+   make check
+   ```
+
+5. **Target the `master` branch** — All PRs should be opened against `master`
+
+### User-Facing Changes
+
+If your change affects users, update the PR description:
+
+```md
+**Does this PR introduce a user-facing change?**:
+- **How are users affected by this change**:
+- **Is this breaking change**:
+- **How to migrate (if breaking change)**:
+```
+
+### Licensing
+
+By contributing, you agree to license your contributions under the Apache License Version 2.0. Add this header to new files:
+
+```go
+// Copyright 2025 The PipeCD Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+```
+
+## Reporting Issues
+
+### Bugs
+
+File bugs at [GitHub Issues](https://github.com/pipe-cd/pipecd/issues/new?assignees=&labels=kind%2Fbug&projects=&template=bug-report.md):
+
+- **One issue, one bug**
+- **Provide reproduction steps** — List all steps to reproduce the issue
+
+### Security Issues
+
+Report security vulnerabilities privately via Slack or Twitter DM to maintainers listed in [MAINTAINERS.md](https://github.com/pipe-cd/pipecd/blob/master/MAINTAINERS.md).
+
+### Feature Requests
+
+- [Enhancement request](https://github.com/pipe-cd/pipecd/issues/new?assignees=&labels=kind%2Fenhancement&projects=&template=enhancement.md) — Improvements to existing features
+- [Feature request](https://github.com/pipe-cd/pipecd/issues/new?assignees=&labels=kind%2Ffeature&projects=&template=new-feature.md) — Entirely new features
+
+## Join the Community
+
+### Slack
+
+We have a `#pipecd` channel on [CNCF Slack](https://cloud-native.slack.com/) for discussions and help. You can also assist other users in the channel.
+
+### Community Meetings
+
+We host [PipeCD Development and Community Meetings](https://zoom-lfx.platform.linuxfoundation.org/meeting/96831504919?password=2f60b8ec-5896-40c8-aa1d-d551ab339d00) every 2 weeks where we share project news, demos, answer questions, and triage issues. View the [Meeting Notes and Agenda](https://bit.ly/pipecd-mtg-notes).
+
+### Become a Member
+
+If you'd like to join the pipe-cd GitHub organization:
+
+- Have at least 5 PRs merged to repositories in the pipe-cd organization
+- Attend a PipeCD public community meeting
+
+Membership isn't required to contribute—it's for those who want to contribute long-term or take ownership of features.
+
+## What Happens Next?
+
+The maintainers will review your PR. We'll help with obvious issues and work with you to get it merged. Thank you for contributing!