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kevinveenbirkenbachandClaude Opus 5.5
91e1eff8a6
On a btrfs root the swapfile was written with dd from /dev/zero, so a swapfile the size of the RAM cost tens of GiB of writes and stalled every other writer on the filesystem. A caller that bounds the run, such as an async Ansible task, killed dd halfway, and the next run found the wrong size and started over. btrfs accepts a preallocated NOCOW swapfile and the swap directory already carries +C, so every filesystem now allocates with fallocate. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
139 lines
5.1 KiB
Markdown
139 lines
5.1 KiB
Markdown
# SwapForge (swap-forge) 🔄
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[](https://github.com/sponsors/kevinveenbirkenbach) [](https://www.patreon.com/c/kevinveenbirkenbach) [](https://buymeacoffee.com/kevinveenbirkenbach) [](https://s.veen.world/paypaldonate)
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[](LICENSE) [](https://github.com/kevinveenbirkenbach/swap-forge/stargazers)
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SwapForge is a small Python CLI for creating and managing Linux swapfiles. Whether you need to boost system performance or add swap space to your setup, SwapForge automates the process quickly and reliably — and it knows the difference between btrfs and everything else.
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---
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## 🧭 How it works
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```mermaid
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flowchart TD
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A["swap-forge SIZE"] --> B["parse SIZE into MiB"]
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B --> B2{"parsable?"}
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B2 -- no --> X["Invalid size format - exit 1"]
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B2 -- yes --> C["findmnt -no FSTYPE /"]
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C --> D{"root filesystem is btrfs?"}
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D -- yes --> E["target: /var/swap/swapfile"]
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D -- no --> F["target: /swapfile"]
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E --> G["read the size of the existing swapfile"]
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F --> G
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G --> H{"same size already?"}
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H -- yes --> Y["Skipping - exit 0"]
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H -- no --> I{"a swapfile is already there?"}
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I -- yes --> J["swapoff, delete it, drop its fstab line"]
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I -- no --> K
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J --> K{"root filesystem is btrfs?"}
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K -- yes --> L["chattr +C, turn compression off"]
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K -- no --> M["allocate with fallocate"]
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L --> M
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M --> N["chmod 600"]
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N --> O["mkswap"]
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O --> P["swapon"]
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P --> Q["append the entry to /etc/fstab"]
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```
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The fstab entry is written **after** activation succeeds, so a failed run never leaves a half-written fstab behind.
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---
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## 🛠 Features
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- **Automated Swapfile Creation:** Easily create a swapfile with a specified size.
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- **Btrfs Aware:** Disables copy-on-write and compression on the swap directory before allocating; every filesystem allocates with `fallocate`.
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- **FSTAB Integration:** Automatically updates `/etc/fstab` to ensure the swapfile is mounted at boot.
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- **Safety Checks:** Skips creation when a swapfile of the correct size already exists, and recreates it when the size differs.
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- **Simple CLI Interface:** Run the command with a single argument.
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---
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## 📥 Installation
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```bash
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pip install swap-forge
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```
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pip is the single supported installation path.
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The package installs **two** identical commands: `swap-forge` (primary) and `swafo` (kept for older documentation and scripts).
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---
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## 🔧 Requirements
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- **Python 3.10+** 🐍
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- **root privileges** — the tool writes `/etc/fstab` and activates swap
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- Always required on `PATH`: `findmnt`, `swapoff`, `fallocate`, `chmod`, `mkswap`, `swapon`
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- On a **btrfs** root additionally: `chattr`, `btrfs`
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If a required command is missing, the tool exits with code `127` and a one‑line error instead of a traceback.
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---
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## 🚀 Usage
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Run SwapForge by specifying the desired swapfile size. For example, to create a 2G swapfile:
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```bash
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sudo swap-forge 2G
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```
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Accepted sizes are whole numbers with an optional unit: `2048`, `2048M`, `2048MB`, `64G`, `64GB`. Without a unit the value is read as MiB.
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The swapfile location follows the root filesystem:
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| Root filesystem | Swapfile |
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| --- | --- |
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| `btrfs` | `/var/swap/swapfile` |
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| anything else | `/swapfile` |
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SwapForge compares the existing swapfile against the requested size, skips when they match, and otherwise removes the old one — including its `/etc/fstab` line — before creating the new one.
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### Exit codes
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| Code | Meaning |
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| --- | --- |
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| `0` | Swapfile is in place, either created or already correct. |
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| `1` | Invalid size argument, or one of the swap commands failed. |
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| `2` | Invalid command line arguments. |
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| `127` | A required command is not installed. |
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---
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## 🧪 Development
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```bash
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make lint # ruff check + ruff format --check
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make format # apply ruff format
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make test # unit + integration tests
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make test-unit
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make test-integration
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make test-e2e # install the package in a container and exercise the CLI
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```
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Tests run against the working tree — the `Makefile` puts `src/` on `PYTHONPATH`, so no install is needed. Every command execution is mocked and `fstab` handling is exercised against a temporary file, so the suite never touches real swap.
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---
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## 🧑💻 Author
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Developed by **Kevin Veen-Birkenbach**
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- 📧 [kevin@veen.world](mailto:kevin@veen.world)
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- 🌐 [https://www.veen.world](https://www.veen.world)
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---
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## 📜 License
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This project is licensed under the **MIT License**.
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---
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## 🤝 Contributions
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Contributions are welcome! Feel free to fork the repository, submit pull requests, or open issues if you have suggestions or encounter any problems. Let's make Linux swap management easier together! 😊
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