systemd prototyping (meta-pytorch#1960)

Summary: Pull Request resolved: meta-pytorch#1960

Differential Revision: D87582955

Author: shayne-fletcher

hyperactor_mesh/Cargo.toml

@@ -74,6 +74,7 @@ serde_bytes = "0.11"
 serde_json = { version = "1.0.140", features = ["alloc", "float_roundtrip", "raw_value", "unbounded_depth"] }
 serde_multipart = { version = "0.0.0", path = "../serde_multipart" }
 strum = { version = "0.27.1", features = ["derive"] }
+systemd = { version = "0.10.1", optional = true }
 tempfile = "3.22"
 thiserror = "2.0.12"
 tokio = { version = "1.47.1", features = ["full", "test-util", "tracing"] }
@@ -92,5 +93,9 @@ proptest = "1.5"
 timed_test = { version = "0.0.0", path = "../timed_test" }
 tracing-test = { version = "0.2.3", features = ["no-env-filter"] }
 
+[features]
+default = []
+systemd = ["dep:systemd"]
+
 [lints]
 rust = { unexpected_cfgs = { check-cfg = ["cfg(fbcode_build)"], level = "warn" } }