Autoconfigure network without DHCP

Passt includes a DHCP server to allow guests to easily configure the network without being aware passt is on the other side. But we _are_ aware of that, so we can take advantage of it. Instead of using DHCP, read the configuration output from passt, marshall it into some environment variables, pass it to the guest, and have krun-guest read it and apply it using rtnetlink. By doing that, we reduce the startup time in half, from... $ time krun /bin/false (...) real 0m4,301s ... to ... $ time krun /bin/false (...) real 0m1,966s In addition of reducing the boot time, this potentially will prevent some of the dhcp issues we've seen in the past. Signed-off-by: Sergio Lopez <[email protected]>
AsahiLinux · Oct 18, 2024 · 61baffe · 61baffe
1 parent c11ac74
commit 61baffe
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Showing 7 changed files with 383 additions and 89 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/crates/muvm/Cargo.toml b/crates/muvm/Cargo.toml
@@ -13,10 +13,13 @@ anyhow = { version = "1.0.82", default-features = false, features = ["std"] }
 bpaf = { version = "0.9.11", default-features = false, features = [] }
 byteorder = { version = "1.5.0", default-features = false, features = ["std"] }
 env_logger = { version = "0.11.3", default-features = false, features = ["auto-color", "humantime", "unstable-kv"] }
+futures-util = { version = "0.3.30", default-features = false, features = [] }
 krun-sys = { path = "../krun-sys", version = "1.9.1", default-features = false, features = [] }
 log = { version = "0.4.21", default-features = false, features = ["kv"] }
 nix = { version = "0.28.0", default-features = false, features = ["user"] }
+regex = { version = "1.10.6" }
 rustix = { version = "0.38.34", default-features = false, features = ["fs", "mount", "process", "std", "system", "use-libc-auxv"] }
+rtnetlink = { version = "0.14.1" }
 serde = { version = "1.0.203", default-features = false, features = ["derive"] }
 serde_json = { version = "1.0.117", default-features = false, features = ["std"] }
 tempfile = { version = "3.10.1", default-features = false, features = [] }

diff --git a/crates/muvm/src/bin/muvm.rs b/crates/muvm/src/bin/muvm.rs
@@ -233,13 +233,19 @@ fn main() -> Result<()> {
         }
     }
 
+    let mut env = prepare_env_vars(env).context("Failed to prepare environment variables")?;
+    env.insert(
+        "MUVM_SERVER_PORT".to_owned(),
+        options.server_port.to_string(),
+    );
+
     {
         let passt_fd: OwnedFd = if let Some(passt_socket) = options.passt_socket {
             connect_to_passt(passt_socket)
                 .context("Failed to connect to `passt`")?
                 .into()
         } else {
-            start_passt(options.server_port)
+            start_passt(options.server_port, &mut env)
                 .context("Failed to start `passt`")?
                 .into()
         };
@@ -355,12 +361,6 @@ fn main() -> Result<()> {
         muvm_guest_args.push(arg);
     }
 
-    let mut env = prepare_env_vars(env).context("Failed to prepare environment variables")?;
-    env.insert(
-        "MUVM_SERVER_PORT".to_owned(),
-        options.server_port.to_string(),
-    );
-
     let mut krun_config = KrunConfig {
         args: Vec::new(),
         envs: Vec::new(),