setup-ci-host

# Setup CI Host Prepares a new physical host to run miles GitHub Actions CI runners by making `/data/miles_ci` canonical on the host. The miles CI workflow (`.github/workflows/_run-ci.yml`) bind-mounts `/data/miles_ci` and its subdirectories (`models`, `datasets`, `hf_cache`) from the host into every CI job container, using literal paths everywhere. For that to work, every CI host must provide `/data/miles_ci` either as a real directory on its biggest disk OR as a symlink to wherever the real big disk is. This script automates that. Run this once on each new CI host, before the runner-setup steps in [`tests/ci/README.md`](../../../tests/ci/README.md) or the externally-managed flow in [`manage-gh-runners`](../manage-gh-runners/). ## Usage ```shell cd /root/miles/.claude/skills/setup-ci-host ./setup-host.sh ``` Re-runs are safe: the script is idempotent and a no-op on hosts that already have `/data/miles_ci` correctly set up. ## What it does 1. Probes mounted filesystems with `df` and picks the mount point with the most total bytes, excluding `tmpfs`/`devtmpfs`/`overlay`/`squashfs` and system mounts (`/`, `/boot`, `/dev`, `/proc`, `/run`, `/sys`). 2. **If the biggest mount is `/data`** (the canonical case): ensures `/data/miles_ci` exists as a real directory. Done. 3. **If the biggest mount is something else** (e.g. `/mnt/nvme0n1`): ensures `<big_disk>/miles_ci` exists as a real directory, then atomically replaces `/data/miles_ci` with a symlink pointing to `<big_disk>/miles_ci` (creates `/data` first if missing). 4. Creates `/data/miles_ci/models`, `/data/miles_ci/datasets`, `/data/miles_ci/hf_cache` if they do not exist. 5. Prints a summary: chosen mount, whether `/data/miles_ci` is a real dir or a symlink, free space on the backing disk. ## Verification After running, the operator can confirm the result with: ```shell ls -la /data/miles_ci df -h /data/miles_ci readlink /data/miles_ci || echo "(real directory, not a symlink)" ``` The first command should list the four subdirs (`models`, `datasets`, `hf_cache`, plus any existing `runner_<hostname>` work dirs). `df -h` should report on the host's big disk regardless of whether `/data/miles_ci` is real or a symlink. `readlink` succeeds only when `/data/miles_ci` is a symlink. ## When to re-run - After adding a larger disk to the host (the script will re-detect; if `/data/miles_ci` already exists pointing at a smaller disk, the script prompts before moving anything — see [Safety](#safety)). - After noticing CI mount errors that suggest `/data/miles_ci` is wrong. ## Safety The script never silently overwrites a `/data/miles_ci` that already exists and points somewhere unexpected. When run from a terminal, it prompts the operator interactively; in non-interactive contexts (cron, CI, scripts) it refuses and exits non-zero so a human always makes the destructive call. Two prompts can appear: 1. **Existing real directory on the wrong disk** — `/data/miles_ci` has data but the biggest disk is elsewhere. Options: - `[m] migrate`: `rsync` the data to the big disk, then `rm -rf` the original and symlink. Preserves data. - `[w] wipe`: `rm -rf` the original (data lost), then symlink. Requires typing `yes` to confirm. - `[a] abort` (default): leave everything as-is, exit non-zero. 2. **Existing symlink pointing at the wrong target** — `/data/miles_ci` already symlinks somewhere, but not to the current biggest disk. The prompt asks `[y/N]` to re-point. Re-pointing does NOT migrate data from the old target; only the symlink changes. The script requires root (or write access to `/data`). It will detect a non-root invocation and suggest `sudo ./setup-host.sh`. ## Inside the container Once the host side is prepared, the runner container's compose mount `/data/miles_ci:/data/miles_ci` works as an identity bind (per the docker-out- of-docker requirement explained in `docker-compose.yml`). The inner job container sees `/data/miles_ci` as a real bind from the host's canonical path, whether or not the host side is itself a symlink — Docker resolves the host symlink at bind time, so the container always sees the underlying directory. This is the desired behavior.