guest: set hostname from launch config

crates/guest/src/init.rs

@@ -5,7 +5,7 @@ use ipnetwork::IpNetwork;
 use krata::ethtool::EthtoolHandle;
 use krata::idm::client::IdmClient;
 use krata::launchcfg::{LaunchInfo, LaunchNetwork};
-use libc::{setsid, TIOCSCTTY};
+use libc::{sethostname, setsid, TIOCSCTTY};
 use log::{trace, warn};
 use nix::ioctl_write_int_bad;
 use nix::unistd::{dup2, execve, fork, ForkResult, Pid};
@@ -91,6 +91,18 @@ impl GuestInit {
         self.nuke_initrd().await?;
         self.bind_new_root().await?;
 
+        if let Some(hostname) = launch.hostname.clone() {
+            let result = unsafe {
+                sethostname(
+                    hostname.as_bytes().as_ptr() as *mut libc::c_char,
+                    hostname.len(),
+                )
+            };
+            if result != 0 {
+                warn!("failed to set hostname: {}", result);
+            }
+        }
+
         if let Some(network) = &launch.network {
             trace!("initializing network");
             if let Err(error) = self.network_setup(network).await {

crates/krata/src/launchcfg.rs

@@ -29,6 +29,7 @@ pub struct LaunchNetwork {
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct LaunchInfo {
+    pub hostname: Option<String>,
     pub network: Option<LaunchNetwork>,
     pub env: HashMap<String, String>,
     pub run: Option<Vec<String>>,

crates/runtime/src/launch.rs

@@ -64,6 +64,12 @@ impl GuestLauncher {
         let ipv6_network_mask: u32 = 10;
 
         let launch_config = LaunchInfo {
+            hostname: Some(
+                request
+                    .name
+                    .map(|x| x.to_string())
+                    .unwrap_or_else(|| format!("krata-{}", uuid)),
+            ),
             network: Some(LaunchNetwork {
                 link: "eth0".to_string(),
                 ipv4: LaunchNetworkIpv4 {