82 lines
3.2 KiB
Markdown
82 lines
3.2 KiB
Markdown
# doos
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Version: see `VERSION` (currently 0.1.3). Release history: `CHANGELOG.md`.
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User-level containers in C++20: overlayfs over the host's `/usr`, `/etc`, `/opt`, user/mount/pid namespaces, networking through slirp4netns. No root at runtime.
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```
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doos list
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doos get_or_create [--net slirp|host|none] NAME
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doos attach [--net slirp|host|none] NAME [-- CMD...]
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doos delete [--yes] NAME
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```
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Build: `cmake -S . -B build && cmake --build build`. Test: `tests/run.sh`.
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Requirements: Linux >= 5.11, `slirp4netns` for the default network mode. On Ubuntu 24.04+ install the AppArmor profile once:
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```
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sudo cp apparmor/doos /etc/apparmor.d/doos && sudo apparmor_parser -r /etc/apparmor.d/doos
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```
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See `SPEC.md` (behavior, limits) and `docs/RESEARCH.md` (what works, measurements, known gaps).
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## Usage examples
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```
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doos get_or_create dev # created dev
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doos attach dev # interactive shell as root inside
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doos attach dev -- apt --version # run one command
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doos attach --net none sandbox -- sh # no network at all
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doos list
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doos delete dev # dry run: shows what would go
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doos delete --yes dev # really deletes
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```
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Container writes to `/usr`, `/etc`, `/opt` stay in the container (copy-on-write);
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`/root` and `/var` are private and persistent. `/tmp` is memory-backed and lost on exit.
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A container is `running` while its first `attach` command is alive; more `attach` calls
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join it. Data persists until `delete --yes`.
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## Current limits you will hit
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Tools run fine (curl, git, gcc, python3, pip, ping all verified). Package management does
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not: `apt-get update` needs a seeded `/var` and `-o APT::Sandbox::User=root`, and
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`apt-get install` cannot finish configuring packages because host-root-owned files are
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unwritable and unchownable inside. Details, measurements and the fix are in
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`docs/RESEARCH.md` (G7, "Field trial").
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## Configuration
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| Variable | Meaning |
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| `DOOS_HOME` | State directory (default `~/.local/share/doos`). No `,` or `:` allowed. |
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| `XDG_DATA_HOME` | Used as `$XDG_DATA_HOME/doos` when `DOOS_HOME` is unset. |
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## Troubleshooting
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| Message | Cause and fix |
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| `write /proc/<pid>/uid_map ... blocked` or `mount ...: Permission denied` | AppArmor restricts user namespaces. Install `apparmor/doos` (command above). |
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| `slirp4netns failed to start` | Install `slirp4netns`, or use `--net none` / `--net host`. |
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| `state path must not contain ',' or ':'` | Set `DOOS_HOME` to a plain path. |
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| `container 'x' is running` on delete | Exit the attached command first. |
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| `container limit reached (64)` | Delete one first. |
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## Safety summary
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Host files are never written: system dirs are reached only through overlayfs. Host
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`/home`, `/sys` and host loopback are not reachable in the default mode. `--net host`
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removes network isolation and is opt-in. Known gaps (no cgroups, readable host `/etc`)
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are listed with researched solutions (G1 to G6, not implemented) in `docs/RESEARCH.md`.
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## Project docs
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| File | Content |
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|---|---|
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| `SPEC.md` | Behavior contract and limits |
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| `docs/ARCHITECTURE.md` | Code map and flows |
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| `docs/RESEARCH.md` | What works unprivileged, measurements, gaps |
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| `AGENTS.md` | Rules for AI agents, release workflow |
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| `CHANGELOG.md` | Release history |
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