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record whether an agent's config sets privateUsers in its closure record

This commit is contained in:
atlas 2026-11-01 16:05:36 +01:00 • committed by mara
commit 3ca660e558
9 changed files with 178 additions and 6 deletions

View file

@ -317,6 +317,7 @@ mod tests {
system: "x86_64-linux".to_owned(),
built_unix: 1,
cached: true,
private_users: false,
}
}

View file

@ -285,6 +285,7 @@ fn closure(meta_rev: &str, cached: bool) -> AgentClosure {
system: "x86_64-linux".to_owned(),
built_unix: 1,
cached,
private_users: false,
}
}

View file

@ -422,12 +422,14 @@ async fn handle_meta(
out_path,
system,
cached,
private_users,
} => tracing::info!(
agent = %job.agent,
meta_rev = %job.meta_rev,
%out_path,
%system,
cached,
private_users,
"agent meta build built"
),
FromMetaReply::Failed { error_tail } => tracing::warn!(
@ -641,6 +643,7 @@ mod tests {
out_path: "/nix/store/x".to_owned(),
system: "s".to_owned(),
cached: false,
private_users: false,
}
})
.await;
@ -656,6 +659,7 @@ mod tests {
out_path: "/nix/store/x".to_owned(),
system: "s".to_owned(),
cached: false,
private_users: false,
}
})
.await;

View file

@ -92,6 +92,7 @@ impl Builder {
out_path,
system: self.system.clone(),
cached: false,
private_users: self.private_users(job, token).await,
},
Reply::Failed { error_tail } => FromMetaReply::Failed { error_tail },
},
@ -170,12 +171,39 @@ impl Builder {
/// the hives build. No input is overridden: the committed `flake.lock`
/// decides all of them.
fn meta_attr(&self, job: &BuildFromMeta) -> String {
format!("{}.system.build.toplevel", self.meta_config(job))
}
/// The agent's evaluated NixOS config in `internal/meta` at the commit.
fn meta_config(&self, job: &BuildFromMeta) -> String {
format!(
"git+{}/{META_REPO_PATH}.git?rev={}#nixosConfigurations.{}.config.system.build.toplevel",
"git+{}/{META_REPO_PATH}.git?rev={}#nixosConfigurations.{}.config",
self.forge_url, job.meta_rev, job.agent
)
}
/// Whether the agent's config sets `services.hyperhive.agent.user.privateUsers`,
/// read by `nix eval` of the flake the build just evaluated, in this
/// sandbox. Anything but a clean `true` is false: an agent whose module
/// predates the option, a failed eval and a timeout all keep the agent out
/// of a user namespace.
async fn private_users(&self, job: &BuildFromMeta, token: &str) -> bool {
let mut cmd = self.nix_command(token);
cmd.args(EVAL_FLAGS)
.arg(format!("{}.{PRIVATE_USERS_OPTION}", self.meta_config(job)));
match run_raw(cmd, self.deadline).await {
Ok((status, out, _)) if status.success() => parse_flag(&out),
Ok((status, _, err)) => {
tracing::info!(agent = %job.agent, %status, error = %tail(&String::from_utf8_lossy(&err), status), "privateUsers not read; the agent stays out of a user namespace");
false
}
Err(why) => {
tracing::warn!(agent = %job.agent, %why, "privateUsers not read; the agent stays out of a user namespace");
false
}
}
}
/// The config commit as a flake reference, fetched through the PR's head
/// ref.
fn agent_url(&self, job: &BuildAgent) -> String {
@ -199,6 +227,26 @@ const BUILD_FLAGS: [&str; 8] = [
"--print-build-logs",
];
/// What every `nix eval` of an option starts with: JSON out, nothing written to
/// the flake's lock, the flake's own `nix.conf` settings refused.
const EVAL_FLAGS: [&str; 7] = [
"eval",
"--json",
"--no-write-lock-file",
"--option",
"accept-flake-config",
"false",
"--quiet",
];
/// The agent option the controller records, relative to the evaluated config.
const PRIVATE_USERS_OPTION: &str = "services.hyperhive.agent.user.privateUsers";
/// `nix eval --json` of a bool: true only for exactly `true`.
fn parse_flag(out: &[u8]) -> bool {
out.trim_ascii() == b"true"
}
/// `nix flake lock` of the flake in the working directory. The flake's config
/// is not trusted, and nothing is built.
const LOCK_ARGS: &[&str] = &["flake", "lock", "--option", "accept-flake-config", "false"];
@ -484,6 +532,47 @@ mod tests {
);
}
/// The reply carries what the evaluated config says about the option, and
/// anything but a clean `true` reads as false. The `true` arm is the
/// control for the others.
#[tokio::test]
async fn a_meta_build_reports_the_agents_private_users_option() {
for (i, (answer, want)) in [
("echo true", true),
("echo false", false),
("echo null", false),
("echo true; exit 1", false),
("echo error: attribute missing >&2; exit 1", false),
]
.into_iter()
.enumerate()
{
let nix = fake_nix(
&format!("private-users-{i}"),
&format!("if [ \"$1\" = eval ]; then {answer}; else echo /nix/store/x; fi\n"),
);
let b = Builder { nix, ..builder() };
let reply = b.build_from_meta(&meta_job(), "t").await;
assert!(
matches!(&reply, FromMetaReply::Built { private_users, .. } if *private_users == want),
"{answer}: {reply:?}"
);
}
}
#[test]
fn the_option_is_read_from_the_evaluated_config_not_the_toplevel() {
assert_eq!(
format!(
"{}.{PRIVATE_USERS_OPTION}",
builder().meta_config(&meta_job())
),
"git+https://forge.example/internal/meta.git\
?rev=0123456789abcdef0123456789abcdef01234567\
#nixosConfigurations.atlas.config.services.hyperhive.agent.user.privateUsers"
);
assert!(parse_flag(b"true\n") && !parse_flag(b"false\n") && !parse_flag(b""));
}
#[test]
fn a_meta_job_that_would_bend_the_reference_is_refused() {
for bad in [
@ -520,6 +609,7 @@ mod tests {
out_path: format!("{} {}", BUILD_FLAGS.join(" "), b.meta_attr(&meta_job())),
system: "x86_64-linux".to_owned(),
cached: false,
private_users: false,
}
);
}

View file

@ -208,7 +208,10 @@ pub async fn cache_built(
let (
Some(cache),
FromMetaReply::Built {
out_path, system, ..
out_path,
system,
private_users,
..
},
) = (cache, &reply)
else {
@ -234,6 +237,7 @@ pub async fn cache_built(
out_path: out_path.clone(),
system: system.clone(),
cached: true,
private_users: *private_users,
}
}
Err(reason) => {
@ -258,6 +262,7 @@ mod tests {
out_path: OUT.to_owned(),
system: "x86_64-linux".to_owned(),
cached: false,
private_users: false,
}
}

View file

@ -288,12 +288,13 @@ async fn rebuild(world: &impl World, agent: &str, stored: Stored) -> Outcome {
return Outcome::Unavailable;
}
};
let (out_path, system, cached) = match reply {
let (out_path, system, cached, private_users) = match reply {
FromMetaReply::Built {
out_path,
system,
cached,
} => (out_path, system, cached),
private_users,
} => (out_path, system, cached, private_users),
FromMetaReply::Failed { error_tail } => {
tracing::warn!(%agent, %meta_rev, %error_tail, "cache miss: the rebuild failed");
return Outcome::Failed;
@ -321,6 +322,7 @@ async fn rebuild(world: &impl World, agent: &str, stored: Stored) -> Outcome {
system,
built_unix: unix_now(),
cached: true,
private_users,
};
match replace_if_current(world, agent, &now).await {
Ok(true) => Outcome::PathChanged,
@ -558,6 +560,7 @@ mod tests {
system: "x86_64-linux".to_owned(),
built_unix: 7,
cached,
private_users: false,
}
}
@ -644,6 +647,7 @@ mod tests {
out_path: out_path.to_owned(),
system: "x86_64-linux".to_owned(),
cached,
private_users: false,
}
}
@ -888,6 +892,32 @@ mod tests {
);
}
/// The record a rebuild at another path writes carries what the builder
/// answered about the user namespace, not what the old record held.
#[tokio::test]
async fn the_replacement_record_carries_the_rebuilds_private_users_answer() {
let other = path("iris-other");
let FromMetaReply::Built {
out_path,
system,
cached,
..
} = built(&other, true)
else {
unreachable!()
};
let answer = FromMetaReply::Built {
out_path,
system,
cached,
private_users: true,
};
let world = Fake::missing(&["iris"]).answering("iris", answer);
pass_at(&world, &mut Backoff::default(), Instant::now()).await;
let writes = world.writes();
assert_eq!(writes.len(), 1);
assert!(writes[0].1.private_users);
}
#[tokio::test]
async fn another_path_leaves_a_record_that_moved_on() {
let world = Fake::missing(&["iris"]).answering("iris", built(&path("iris-other"), true));

View file

@ -370,6 +370,7 @@ pub(crate) async fn run(
out_path,
system,
cached,
private_users,
}) => {
let built_rev = meta_rev.clone();
let closure = AgentClosure {
@ -378,6 +379,7 @@ pub(crate) async fn run(
system,
built_unix: unix_now(),
cached,
private_users,
};
match queue.record(&agent, &closure).await {
Ok(()) => {
@ -486,10 +488,15 @@ mod tests {
}
fn built_cached(cached: bool) -> Self {
Self::built_with(cached, false)
}
fn built_with(cached: bool, private_users: bool) -> Self {
Self::answering(Ok(FromMetaReply::Built {
out_path: "/nix/store/x-toplevel".to_owned(),
system: "x86_64-linux".to_owned(),
cached,
private_users,
}))
}
}
@ -617,6 +624,22 @@ mod tests {
}
}
/// The record says what the builder said about the agent's user namespace,
/// both ways; a builder that said nothing leaves it off.
#[tokio::test]
async fn the_record_carries_the_builders_private_users_answer() {
for private_users in [true, false] {
let queue = FakeQueue::built_with(true, private_users);
let outcome = run_with(&FakeHead::reading(Ok(Some(REV))), &queue).await;
assert_eq!(outcome, Outcome::Done);
let recorded = queue.recorded.lock().unwrap();
let [(_, closure)] = recorded.as_slice() else {
panic!("one record: {recorded:?}")
};
assert_eq!(closure.private_users, private_users);
}
}
/// Any `nix` failure, a timeout included, fails the node at once with what
/// the builder said: not a no-verdict failure, and nothing is recorded. The
/// green test above is the control that a record is written when the build
@ -898,6 +921,7 @@ mod tests {
system: "x86_64-linux".to_owned(),
built_unix: 1,
cached: false,
private_users: true,
};
client.record("atlas", &closure).await.expect("written");
closure.store_path = "/nix/store/b".to_owned();

View file

@ -36,6 +36,12 @@ pub struct AgentClosure {
/// written before the field existed reads as false.
#[serde(default)]
pub cached: bool,
/// Whether the agent's evaluated config sets
/// `services.hyperhive.agent.user.privateUsers`: the agent runs in its own
/// user namespace. A record written before the field existed reads as
/// false, which keeps the agent out of one.
#[serde(default)]
pub private_users: bool,
}
#[cfg(test)]
@ -56,6 +62,7 @@ mod tests {
system: "x86_64-linux".to_owned(),
built_unix: 7,
cached: true,
private_users: true,
};
let wire = serde_json::json!({
"meta_rev": "abc",
@ -63,6 +70,7 @@ mod tests {
"system": "x86_64-linux",
"built_unix": 7,
"cached": true,
"private_users": true,
});
assert_eq!(serde_json::to_value(&value).expect("encodes"), wire);
assert_eq!(
@ -72,7 +80,7 @@ mod tests {
}
#[test]
fn a_record_without_the_field_reads_as_not_cached() {
fn a_record_without_the_fields_reads_as_not_cached_and_not_namespaced() {
let old = serde_json::json!({
"meta_rev": "abc",
"store_path": "/nix/store/x",
@ -81,5 +89,6 @@ mod tests {
});
let record = serde_json::from_value::<AgentClosure>(old).expect("decodes");
assert!(!record.cached);
assert!(!record.private_users);
}
}

View file

@ -149,6 +149,11 @@ pub enum FromMetaReply {
system: String,
#[serde(default)]
cached: bool,
/// Whether the agent's evaluated config sets
/// `services.hyperhive.agent.user.privateUsers`. A builder that
/// predates the field answers without it, which reads as false.
#[serde(default)]
private_users: bool,
},
/// The build did not succeed: the last lines `nix` printed, or why it
/// stopped (it timed out, or could not start). The controller holds the
@ -262,12 +267,14 @@ mod tests {
out_path: "/nix/store/x".to_owned(),
system: "x86_64-linux".to_owned(),
cached: true,
private_users: true,
},
json!({
"state": "built",
"out_path": "/nix/store/x",
"system": "x86_64-linux",
"cached": true,
"private_users": true,
}),
),
(
@ -292,7 +299,7 @@ mod tests {
}
#[test]
fn a_built_reply_from_a_builder_without_the_field_reads_as_not_cached() {
fn a_built_reply_from_a_builder_without_the_fields_reads_as_not_cached_and_not_namespaced() {
let old = json!({"state": "built", "out_path": "/nix/store/x", "system": "s"});
assert_eq!(
serde_json::from_value::<FromMetaReply>(old).expect("decodes"),
@ -300,6 +307,7 @@ mod tests {
out_path: "/nix/store/x".to_owned(),
system: "s".to_owned(),
cached: false,
private_users: false,
}
);
}