max / makenotwork

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1	//! Atomic symlink-swap deploys.
2	//!
3	//! Layout on every target (MM, A nodes, B nodes, ...):
4	//!
5	//! <release_root>/
6	//! releases/
7	//! 0.8.1/
8	//! server <- the binary
9	//! 0.8.2/
10	//! server
11	//! current -> releases/0.8.2
12	//!
13	//! `ln -sfn` makes the swap atomic on Linux. systemd units should point at
14	//! `<release_root>/current/server` so a swap + reload picks up the new binary
15	//! without a window where the unit references a missing path.
16	//!
17	//! v0 only implements local deploys (used for MM and for localhost-dev
18	//! "remote" nodes whose ssh_target is `local`). Real SSH/rsync deploys are
19	//! follow-up work — see the `remote_deploy_stub` branch.
20
21	use crate::topology::Node;
22	use anyhow::{Context, Result};
23	use std::path::{Path, PathBuf};
24	use tokio::process::Command;
25
26	pub async fn deploy_local(release_root: &Path, version: &str, binary: &Path) -> Result<PathBuf> {
27	let release_dir = release_root.join("releases").join(version);
28	tokio::fs::create_dir_all(&release_dir).await?;
29	let dest = release_dir.join("server");
30	tokio::fs::copy(binary, &dest)
31	.await
32	.with_context(\|\| format!("copy {} -> {}", binary.display(), dest.display()))?;
33
34	let current = release_root.join("current");
35	// ln -sfn is atomic on Linux; on macOS the dev path is non-prod so the
36	// race is irrelevant. We shell out rather than using std::os::unix::fs
37	// symlink + rename because the rename-over-symlink pattern is platform-fussy.
38	let target = format!("releases/{version}");
39	let out = Command::new("ln")
40	.args(["-sfn", &target])
41	.arg(&current)
42	.output()
43	.await?;
44	anyhow::ensure!(
45	out.status.success(),
46	"symlink swap failed: {}",
47	String::from_utf8_lossy(&out.stderr),
48	);
49	Ok(release_dir)
50	}
51
52	pub async fn deploy_node(node: &Node, version: &str, binary: &Path) -> Result<PathBuf> {
53	if node.ssh_target == "local" \|\| node.ssh_target.is_empty() {
54	return deploy_local(Path::new(&node.release_root), version, binary).await;
55	}
56	remote_deploy_stub(node, version, binary).await
57	}
58
59	async fn remote_deploy_stub(node: &Node, version: &str, _binary: &Path) -> Result<PathBuf> {
60	// Real implementation: rsync the binary to <ssh_target>:<release_root>/releases/<version>/server,
61	// then ssh <ssh_target> "ln -sfn releases/<version> current && systemctl reload-or-restart <unit>".
62	// Wiring this up needs a story for systemd unit naming and ssh key/auth conventions; deferring
63	// until the localhost smoke loop is settled and we know which knobs matter.
64	anyhow::bail!(
65	"remote deploy not yet implemented (node {} -> {}); use ssh_target=local for dev",
66	node.name,
67	node.ssh_target,
68	);
69	#[allow(unreachable_code)]
70	Ok(PathBuf::from(&node.release_root).join("releases").join(version))
71	}
72