Add RELEASING.md how-to document (#37)

Signed-off-by: Antonio Paolillo <[email protected]>

Author: apaolillo

CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes to pythainer will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
 ## [0.0.5] - 2025-09-15
 
 ### Added

RELEASING.md

@@ -0,0 +1,111 @@
+# Releasing pythainer
+
+This document records the exact steps to publish a new release of pythainer.
+
+Prereqs:
+- You have push access to the repo and the PyPI project.
+- `CHANGELOG.md` follows Keep a Changelog and Semantic Versioning.
+- Version in `pyproject.toml` is maintained manually (PEP 440).
+- CI is green on `main`.
+
+Versioning Tag format: `v0.X.Y`
+
+Date format: `YYYY-MM-DD`.
+
+---
+
+## 1) Prepare the release
+
+1. Pick the version number `0.X.Y`.
+
+2. Update `CHANGELOG.md`:
+   - Add a new section `## [0.X.Y] - YYYY-MM-DD` under `[Unreleased]`.
+   - Move curated changes from `[Unreleased]` into `0.X.Y`.
+
+3. Bump the version in `pyproject.toml`:
+   ```toml
+   [project]
+   version = "0.X.Y"
+    ```
+
+4. Sanity checks locally:
+
+   ```bash
+   ./scripts/all_checks.sh
+   pytest -q
+   git clean -ndx
+   git status
+   ```
+
+5. Create a short-lived release branch and commit:
+    ```bash
+    git checkout -b release
+    git add -u
+    git commit -s -m "Release 0.X.Y"
+    git push -u origin release
+    ```
+
+6. Open the corresponding PR on GitHub. When CI is green, merge.
+
+---
+
+## 2) Tag the release
+
+After the PR is merged:
+
+```bash
+git checkout main
+git pull --prune
+git tag -a "v0.X.Y" -m "Release v0.X.Y"
+git push origin v0.X.Y
+```
+
+---
+
+## 3) Build artifacts locally
+
+Use a fresh clone and venv to avoid leaking deps:
+
+```bash
+git clone https://github.com/apaolillo/pythainer.git
+cd pythainer/
+python3 -m venv .venv-release
+. .venv-release/bin/activate
+python3 -m pip install --upgrade pip
+python3 -m pip install --upgrade build twine
+python3 -m build          # creates dist/*.whl and dist/*.tar.gz
+python3 -m twine check dist/*
+```
+
+Quick inspection:
+
+* Confirm wheel exists (preferably `py3-none-any.whl` for pure Python).
+* Confirm tarball contains only expected files.
+
+---
+
+## 4) Publish to PyPI
+
+```bash
+# still in the .venv-release
+python3 -m twine upload dist/*
+```
+
+You will need a `~/.pypirc` or to paste your `__token__` API token when prompted.
+
+---
+
+## 5) Verify the release
+
+* PyPI page: [https://pypi.org/project/pythainer/](https://pypi.org/project/pythainer/)
+* Clean venv install:
+
+  ```bash
+  python3 -m venv /tmp/venv-verify && . /tmp/venv-verify/bin/activate
+  pip install -U pip
+  pip install pythainer==0.X.Y
+  pythainer --help
+  deactivate
+  ```
+* Check that README renders correctly on PyPI.
+* Profit.