# OxygenFlow

Hermetic pipelines for Oxygen repositories:

- a typed pipeline in `.flow/pipeline.kdl`

- jobs run in isolation tiers, Firecracker microVMs by default

- the host writes the receipts

- results go to OxygenHub as checks and appear on its Flow tab

The specification is [docs/spec.md](docs/spec.md). What works today is

[docs/m0.md](docs/m0.md).

## A pipeline

```kdl

schema-version 1

sandbox "alpine" {

    runtime "microvm"

    rootfs "cas://blob/…"      // printed by `flow rootfs import`

    memory-limit "256MiB"

    network "isolated"

}

job "build" {

    sandbox "alpine"

    exec "make"

}

job "test" {

    sandbox "alpine"

    depends-on "build"

    exec "sh" "-eu" "test.sh"   // argv, run as written: no shell unless you name one

}

```

Each job boots its own microVM:

- it has no network device

- the rootfs is read-only

- the workspace is the state being built, read-write at `/src`

- the job runs as a user that is not root

This repository's own pipeline is [.flow/pipeline.kdl](.flow/pipeline.kdl).

## Deploying the runner on Earth

`make deploy-runner` builds `flow` and the static `flow-init`, installs them

under `/home/claude/flow` (keeping the previous files as `.prev`), re-pins

`flow-init` in `flow.toml` and restarts the `flow-runner` service.

## A Windows runner

A Windows machine runs WASM jobs (the other tiers are Linux's). Each

release carries `flow-windows-x86_64.exe` (from the `dist` job):

    flow.exe --home C:\flow runner register https://oxygenhub.io --token flowreg_… --name win-1 --label windows

    flow.exe --home C:\flow runner

The token comes from the hub (Admin › Runners, or `POST /api/v1/user/runner-token`

for a runner of your own repositories). A pipeline sends it work with a

`runtime "wasm"` sandbox and `runs-on "windows"`. To keep it running, a

Task Scheduler task at start-up with that command (restarting on failure)

does; set it to restart on failure, as a runner that leaves for a new build

exits 75 (`flow runner update`, spec §11.5.3). What a Windows runner does

not do yet: report load and kernel, or drain when Windows stops it

(oxygenflow#83).

## Commands

    flow check                 # validate .flow/pipeline.kdl, print jobs and the pipeline hash

    flow run [JOB…]            # run the pipeline on this directory, locally, in microVMs

    flow rootfs import T.tgz --sha256 HEX   # make a rootfs image; prints the `rootfs` line to pin

                  [--env NAME=value …]      #   with the image's own environment (a Dockerfile's ENV)

    flow rootfs list

    flow hash FILE             # BLAKE3, for pinning in flow.toml

    flow runner                # claim and run jobs for the hub in flow.toml

    flow runner update --from FILE [--dry-run]   # install a new flow build in place of this one (spec §11.5.3)

## A Flow home

`$FLOW_HOME` (default `~/.local/share/flow`) holds:

- `flow.toml`

- the pinned Firecracker binary, guest kernel and `flow-init`

- rootfs images under `cas/`

- scratch space

Every pinned file is checked against its BLAKE3 before use.

```toml

[microvm]

firecracker = { path = "bin/firecracker", blake3 = "…" }

kernel = { path = "kernel/vmlinux", blake3 = "…" }

init = { path = "bin/flow-init", blake3 = "…" }

[runner]                     # only for `flow runner`

hub = "https://hub.example:7343"

token = "…"                  # listed in the hub's [flow] runner_tokens

ca = "/path/to/hub-ca.pem"   # when the hub's certificate is self-signed

name = "runner-1"

max_jobs = 3                 # jobs at once (default 1)

memory_mib = 24576           # what they may use together; a lone job may use it all

cpus = 8

```

Setting one up needs Linux x86-64 with KVM and e2fsprogs 1.43 or later:

1. Build `flow` with `cargo build --release -p flow`. Build the guest init

   as a static binary:

   `RUSTFLAGS="-C target-feature=+crt-static" cargo build --release -p flow-init --target x86_64-unknown-linux-gnu`.

2. Download Firecracker v1.17.0 from its GitHub release, and check the

   published SHA-256. Download the guest kernel

   `firecracker-ci/v1.15/x86_64/vmlinux-6.1.155` from Firecracker's CI

   bucket.

3. Run `flow rootfs import alpine-minirootfs-3.24.2-x86_64.tar.gz --sha256 …`.

4. Write `flow.toml`, pinning each file by its `flow hash`.

On OxygenHub, `hub.toml` lists the runner token and the repositories whose

pushes run pipelines:

```toml

[flow]

runner_tokens = ["…"]

repos = ["owner/*"]

```

## Tests

**Changelog:** a commit that changes code adds a line under `## Unreleased` in CHANGELOG.md (Added, Changed, Fixed or Security, with the issue number); versions change only at release. `scripts/changelog-check.sh [PATH...]` checks it for the paths a commit takes (the working copy's changes without any) and runs in the gate; `NO_CHANGELOG=1` for code changes users won't notice.

`cargo test --workspace` runs every test that needs no VM. The microVM

conformance test also runs when `FLOW_TEST_HOME` names a Flow home and

`FLOW_TEST_ROOTFS` is the hash of an Alpine rootfs in it. The test checks

literal argv, network isolation, the read-only rootfs, and that dependents

are skipped after a failure.

## oxygen as a pinned subrepo

`flow` builds against `deps/oxygen`, a subrepo (`oxy submodule`) pinned to an exact state, so builds are reproducible and OxygenFlow can build this repository without network. `make pins` moves it to oxygen's `main` on Earth (push oxygen first); the next commit records the new pin. Format only this workspace, `cargo fmt -p flow -p flow-core -p flow-init`: `--all` also reaches `deps/`. After a fresh clone, `oxy submodule update --init` fetches it.