41 lines
1.9 KiB
Nix
41 lines
1.9 KiB
Nix
# The pre-start check of a container's root, for one of hyperhive's own
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# declarative containers.
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#
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# nixpkgs' start script runs as host root against the container's own root,
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# which is persistent and writable by the container, and its `mkdir`, `chmod`,
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# `touch` and `cp` follow links the container planted there. `hive-priv
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# check-rootfs` looks at the paths the script touches (rules in
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# `hive-priv/src/prestart.rs`). With `--warn-only` it logs each violation at
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# warning level and lets the start go on. The line carries systemd's `-`
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# prefix, so a crash or a failed exec of the check cannot fail the start either.
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# The agent containers run it strict
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# from their per-agent drop-in (hive-priv's `WriteResourceLimits`).
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#
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# Pure function, not a NixOS module. A container's module calls it with its
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# own name and folds the result into its unit:
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#
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# rootfsCheck = import ./lib/container-rootfs-check.nix { inherit config; };
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# # systemd.services."container@${machine}" = lib.mkMerge [ (rootfsCheck.warnOnly machine) … ];
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#
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# The name list is the callers', never `config.containers`: that also holds
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# containers the operator runs that hyperhive doesn't own, and those get
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# nothing. nixpkgs renders each declarative container as its own
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# `container@<name>` unit (`nixos-containers.nix`, the `mapAttrsToList` that
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# builds `container@${name}`), so a setting on that unit reaches that
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# container only.
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#
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# The binary is run through `hivePriv`, a path that does not change with the hyperhive
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# build. `hive-priv.nix` points the symlink at the current package, so the
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# unit text is the same across builds and a switch does not restart the
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# container for it.
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{ ... }:
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rec {
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hivePriv = "/run/hive-rootfs-check";
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# Attributes for `systemd.services."container@<name>"`.
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warnOnly = name: {
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serviceConfig.ExecStartPre = [
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"-${hivePriv} check-rootfs --warn-only ${name}"
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];
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};
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}
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