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hyperhive/nix/host-modules/hive-priv-cache.nix

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Nix

# The binary-cache facts the host's nix daemon, hive-priv (root) and hive-c0re
# use, kept where only root can change them.
#
# hive-c0re pulls an agent's closure with `nix-store --realise` through the
# host's nix daemon, which substitutes each path from the swarm cache or from
# its other substituters (cache.nixos.org) and stores it only if a key in its
# `trusted-public-keys` signed it. hive-priv applies a closure only if the
# swarm's key signed it. Neither decision may come from a file hive-c0re writes:
#
# - the cache's address is the host's
# {option}`services.hyperhive.swarm.attic.domain` and `cache`;
# - the cache's public key and the pull token are read from the store by a root
# oneshot, `hive-priv-cache-facts`, under this hive's own store identity. The
# key lands in `/run/hyperhive-priv/attic/public-key` (directory `0700`, file
# `0600`).
# The cache's address, the key and a netrc also land in a nix.conf fragment,
# `/run/hyperhive-nix/cache.conf`, as `extra-substituters`,
# `extra-trusted-public-keys` and `netrc-file`, which the host's nix.conf
# includes (`!include`, so a host whose unit has not run yet still starts).
# Every client of the daemon (hive-c0re, agent containers on `nixBuilds =
# host`) can have a swarm closure substituted; closures hold no secret;
# - that netrc, `/run/hyperhive-nix/netrc` (`root:root 0600`), is the pull
# token's entry plus the entries of the host's own netrc, which
# `netrc-file` would otherwise replace. The host's netrc is
# `nix.settings.netrc-file` when the host sets it, else nix's default
# `/etc/nix/netrc`. The unit merges again on every run, so an edit reaches the
# daemon within the timer's ten minutes. A netrc named only in
# `nix.extraOptions` is not seen.
#
# hive-c0re keeps its own copies under `/run/hyperhive/attic/` for the probe.
{
pkgs,
lib,
config,
...
}:
let
hyperhiveCfg = config.services.hyperhive;
hiveController = hyperhiveCfg.deploy.hive-controller;
tls = hiveController.tls;
baoCfg = hyperhiveCfg.swarm.bao;
baoDeploy = hyperhiveCfg.deploy.bao;
atticCfg = hyperhiveCfg.swarm.attic;
# Without a cache to name, a hive name to read under or an identity to log
# in with there is nothing to fetch, and hive-priv has no cache to download
# from.
enabled =
hiveController.enable
&& atticCfg.domain != null
&& atticCfg.cache != null
&& hiveController.hiveName != null
&& tls.baoHiveIdentityCertFile != null
&& tls.baoHiveIdentityKeyFile != null;
dir = "/run/hyperhive-priv/attic";
confDir = "/run/hyperhive-nix";
confFile = "${confDir}/cache.conf";
cacheUrl = "https://${atticCfg.domain}/${atticCfg.cache}";
netrcFile = "${confDir}/netrc";
# `netrc-file` is not additive: the fragment's setting replaces the host's.
hostNetrc = toString (config.nix.settings.netrc-file or "/etc/nix/netrc");
# Where the store runs on this host, the first login waits for its container.
# No `wants`: a pull would start the container mid-switch on the old closure.
storeContainer = lib.optional baoDeploy.enable "container@${baoCfg.machine}.service";
storeRetry = import ./lib/store-retry.nix { };
storeRefreshTimer = import ./lib/store-refresh-timer.nix { };
in
{
config = lib.mkIf enabled {
systemd.tmpfiles.rules = [
"d /run/hyperhive-priv 0700 root root - -"
"d ${confDir} 0755 root root - -"
];
# `!include` tolerates a fragment that does not exist yet.
nix.extraOptions = "!include ${confFile}";
systemd.services.hive-priv-cache-facts = {
description = "Read the swarm cache's public key and pull token for the host's nix daemon and hive-priv";
wantedBy = [ "multi-user.target" ];
wants = [ "network-online.target" ];
after = [
"network-online.target"
"systemd-tmpfiles-setup.service"
]
++ storeContainer;
path = [
baoDeploy.package
pkgs.coreutils
pkgs.gnugrep
pkgs.systemd
];
environment = {
BAO_ADDR = "https://${baoCfg.domain}:${toString baoCfg.port}";
BAO_CLIENT_CERT = tls.baoHiveIdentityCertFile;
BAO_CLIENT_KEY = tls.baoHiveIdentityKeyFile;
}
// lib.optionalAttrs (baoDeploy.serverCaFile != null) {
BAO_CACERT = baoDeploy.serverCaFile;
};
# ./lib/store-retry.nix: the login fails for as long as the store is
# sealed or down.
inherit (storeRetry) startLimitBurst startLimitIntervalSec;
serviceConfig = storeRetry.serviceConfig // {
Type = "oneshot";
UMask = "0077";
SyslogIdentifier = "hive-priv-cache-facts";
TimeoutStartSec = "5min";
};
script = import ./lib/attic-root-facts.nix { inherit lib; } {
hive = hiveController.hiveName;
host = atticCfg.domain;
inherit
dir
confFile
netrcFile
hostNetrc
;
url = cacheUrl;
};
};
systemd.timers.hive-priv-cache-facts = storeRefreshTimer "re-read the swarm cache's facts for hive-priv";
};
}