providers/vmware: support injecting custom network kargs

src/initrd/mod.rs

@@ -1,10 +1,12 @@
-/// Agent logic running at early boot.
-///
-/// This is run early-on in initrd, possibly before networking and other
-/// services are configured, so it may not be able to use all usual metadata
-/// fetcher.
-use crate::errors::*;
+//! Agent logic running at early boot.
+//!
+//! This is run early-on in initrd, possibly before networking and other
+//! services are configured, so it may not be able to use all usual metadata
+//! fetcher.
 
+use crate::errors::*;
+use crate::providers::vmware::VmwareProvider;
+use crate::providers::MetadataProvider;
 use std::fs::File;
 use std::io::Write;
 
@@ -14,8 +16,7 @@ static KARGS_PATH: &str = "/etc/cmdline.d/50-afterburn-network-kargs.conf";
 /// Fetch network kargs for the given provider.
 pub(crate) fn fetch_network_kargs(provider: &str) -> Result<Option<String>> {
     match provider {
-        // TODO(lucab): wire-in vmware guestinfo logic.
-        "vmware" => Ok(None),
+        "vmware" => VmwareProvider::try_new()?.rd_network_kargs(),
         _ => Ok(None),
     }
 }

src/providers/vmware/amd64.rs

@@ -2,29 +2,38 @@
 //!
 //! This uses the guest->host backdoor protocol for introspection.
 
-use error_chain::bail;
-
 use super::VmwareProvider;
 use crate::errors::*;
+use error_chain::bail;
+
+/// Guestinfo key for network kargs.
+static INITRD_NET_KARGS: &str = "guestinfo.afterburn.initrd.network-kargs";
 
 impl VmwareProvider {
+    /// Build the VMware provider, fetching and caching guestinfo entries.
     pub fn try_new() -> Result<Self> {
         if !vmw_backdoor::is_vmware_cpu() {
             bail!("not running on VMWare CPU");
         }
 
         let mut backdoor = vmw_backdoor::probe_backdoor()?;
         let mut erpc = backdoor.open_enhanced_chan()?;
-        let guestinfo_net_kargs = Self::get_net_kargs(&mut erpc)?;
+        let guestinfo_net_kargs = Self::fetch_guestinfo(&mut erpc, INITRD_NET_KARGS)?;
 
         let provider = Self {
             guestinfo_net_kargs,
         };
+
+        slog_scope::trace!("cached vmware provider: {:?}", provider);
         Ok(provider)
     }
 
-    fn get_net_kargs(_erpc: &mut vmw_backdoor::EnhancedChan) -> Result<Option<String>> {
-        // TODO(lucab): pick a stable key name and implement this logic.
-        Ok(None)
+    /// Retrieve the value of a guestinfo string property, by key.
+    fn fetch_guestinfo(erpc: &mut vmw_backdoor::EnhancedChan, key: &str) -> Result<Option<String>> {
+        let guestinfo = erpc
+            .get_guestinfo(key.as_bytes())
+            .chain_err(|| "failed to retrieve network kargs")?
+            .map(|bytes| String::from_utf8_lossy(&bytes).into_owned());
+        Ok(guestinfo)
     }
 }