providers: add experimental initrd network bootstrap

This adds initial/experimental support for bootstrapping the network
in the initrd. It is meant to support weird cloud providers where
DHCP is not available or not usable.
This feature is currently reachable as a dedicated `exp rd-net-bootstrap`
subcommand.
The first provider where this logic is required is `ibmcloud-classic`.

dracut/30afterburn/afterburn-net-bootstrap.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Afterburn network bootstrapping
+# IBM Cloud (Classic) has no DHCP.
+ConditionKernelCommandLine=|ignition.platform.id=ibmcloud-classic
+
+Before=ignition-fetch.service
+
+OnFailure=emergency.target
+OnFailureJobMode=isolate
+
+[Service]
+ExecStart=/usr/bin/afterburn exp rd-net-bootstrap --cmdline
+Type=oneshot

dracut/30afterburn/module-setup.sh

@@ -16,9 +16,14 @@ install() {
     inst_simple "$moddir/afterburn-hostname.service" \
         "$systemdutildir/system/afterburn-hostname.service"
 
+    inst_simple "$moddir/afterburn-net-bootstrap.service" \
+        "$systemdutildir/system/afterburn-net-bootstrap.service"
+
     # We want the afterburn-hostname to be firstboot only, so Ignition-provided
     # hostname changes do not get overwritten on subsequent boots
-
     mkdir -p "$initdir/$systemdsystemunitdir/ignition-complete.target.requires"
     ln -s "../afterburn-hostname.service" "$initdir/$systemdsystemunitdir/ignition-complete.target.requires/afterburn-hostname.service"
+
+    mkdir -p "$initdir/$systemdsystemunitdir/ignition-fetch.service.requires"
+    ln -s "../afterburn-net-boostrap.service" "$initdir/$systemdsystemunitdir/ignition-fetch.service.requires/afterburn-net-bootstrap.service"
 }

src/cli/exp.rs

@@ -0,0 +1,58 @@
+//! `exp` CLI sub-command.
+
+use crate::errors::*;
+use crate::metadata;
+use clap::ArgMatches;
+use error_chain::bail;
+
+#[derive(Debug)]
+pub enum CliExp {
+    NetBootstrap(CliNetBootstrap),
+}
+
+impl CliExp {
+    /// Parse sub-command into configuration.
+    pub(crate) fn parse(app_matches: &ArgMatches) -> Result<super::CliConfig> {
+        if app_matches.subcommand_name().is_none() {
+            bail!("missing exp subcommand");
+        }
+
+        let cfg = match app_matches.subcommand() {
+            ("rd-net-bootstrap", Some(matches)) => CliNetBootstrap::parse(matches)?,
+            (x, _) => unreachable!("unrecognized exp subcommand '{}'", x),
+        };
+
+        Ok(super::CliConfig::Exp(cfg))
+    }
+
+    // Run sub-command.
+    pub(crate) fn run(&self) -> Result<()> {
+        match self {
+            CliExp::NetBootstrap(cmd) => cmd.run()?,
+        };
+        Ok(())
+    }
+}
+
+/// Sub-command for network bootstrap.
+#[derive(Debug)]
+pub struct CliNetBootstrap {
+    platform: String,
+}
+
+impl CliNetBootstrap {
+    /// Parse sub-command into configuration.
+    pub(crate) fn parse(matches: &ArgMatches) -> Result<CliExp> {
+        let platform = super::parse_provider(matches)?;
+
+        let cfg = Self { platform };
+        Ok(CliExp::NetBootstrap(cfg))
+    }
+
+    /// Run the sub-command.
+    pub(crate) fn run(&self) -> Result<()> {
+        let provider = metadata::fetch_metadata(&self.platform)?;
+        provider.rd_net_bootstrap()?;
+        Ok(())
+    }
+}

src/cli/mod.rs

@@ -2,8 +2,10 @@
 
 use crate::errors::*;
 use clap::{crate_version, App, Arg, ArgMatches, SubCommand};
+use error_chain::bail;
 use slog_scope::trace;
 
+mod exp;
 mod multi;
 
 /// Path to kernel command-line (requires procfs mount).
@@ -13,13 +15,15 @@ const CMDLINE_PATH: &str = "/proc/cmdline";
 #[derive(Debug)]
 pub(crate) enum CliConfig {
     Multi(multi::CliMulti),
+    Exp(exp::CliExp),
 }
 
 impl CliConfig {
     /// Parse CLI sub-commands into configuration.
     pub fn parse_subcommands(app_matches: ArgMatches) -> Result<Self> {
         let cfg = match app_matches.subcommand() {
             ("multi", Some(matches)) => multi::CliMulti::parse(matches)?,
+            ("exp", Some(matches)) => exp::CliExp::parse(matches)?,
             (x, _) => unreachable!("unrecognized subcommand '{}'", x),
         };
 
@@ -30,6 +34,7 @@ impl CliConfig {
     pub fn run(self) -> Result<()> {
         match self {
             CliConfig::Multi(cmd) => cmd.run(),
+            CliConfig::Exp(cmd) => cmd.run(),
         }
     }
 }
@@ -44,62 +49,97 @@ pub(crate) fn parse_args(argv: impl IntoIterator<Item = String>) -> Result<CliCo
     Ok(cfg)
 }
 
+/// Parse provider ID from flag or kargs.
+fn parse_provider(matches: &clap::ArgMatches) -> Result<String> {
+    let provider = match (matches.value_of("provider"), matches.is_present("cmdline")) {
+        (Some(provider), false) => String::from(provider),
+        (None, true) => crate::util::get_platform(CMDLINE_PATH)?,
+        (None, false) => bail!("must set either --provider or --cmdline"),
+        (Some(_), true) => bail!("cannot process both --provider and --cmdline"),
+    };
+
+    Ok(provider)
+}
+
 /// CLI setup, covering all sub-commands and arguments.
 fn cli_setup<'a, 'b>() -> App<'a, 'b> {
     // NOTE(lucab): due to legacy translation there can't be global arguments
     //  here, i.e. a sub-command is always expected first.
-    App::new("Afterburn").version(crate_version!()).subcommand(
-        SubCommand::with_name("multi")
-            .about("Perform multiple tasks in a single call")
-            .arg(
-                Arg::with_name("legacy-cli")
-                    .long("legacy-cli")
-                    .help("Whether this command was translated from legacy CLI args")
-                    .hidden(true),
-            )
-            .arg(
-                Arg::with_name("provider")
-                    .long("provider")
-                    .help("The name of the cloud provider")
-                    .global(true)
-                    .takes_value(true),
-            )
-            .arg(
-                Arg::with_name("cmdline")
-                    .long("cmdline")
-                    .global(true)
-                    .help("Read the cloud provider from the kernel cmdline"),
-            )
-            .arg(
-                Arg::with_name("attributes")
-                    .long("attributes")
-                    .help("The file into which the metadata attributes are written")
-                    .takes_value(true),
-            )
-            .arg(
-                Arg::with_name("check-in")
-                    .long("check-in")
-                    .help("Check-in this instance boot with the cloud provider"),
-            )
-            .arg(
-                Arg::with_name("hostname")
-                    .long("hostname")
-                    .help("The file into which the hostname should be written")
-                    .takes_value(true),
-            )
-            .arg(
-                Arg::with_name("network-units")
-                    .long("network-units")
-                    .help("The directory into which network units are written")
-                    .takes_value(true),
-            )
-            .arg(
-                Arg::with_name("ssh-keys")
-                    .long("ssh-keys")
-                    .help("Update SSH keys for the given user")
-                    .takes_value(true),
-            ),
-    )
+    App::new("Afterburn")
+        .version(crate_version!())
+        .subcommand(
+            SubCommand::with_name("multi")
+                .about("Perform multiple tasks in a single call")
+                .arg(
+                    Arg::with_name("legacy-cli")
+                        .long("legacy-cli")
+                        .help("Whether this command was translated from legacy CLI args")
+                        .hidden(true),
+                )
+                .arg(
+                    Arg::with_name("provider")
+                        .long("provider")
+                        .help("The name of the cloud provider")
+                        .global(true)
+                        .takes_value(true),
+                )
+                .arg(
+                    Arg::with_name("cmdline")
+                        .long("cmdline")
+                        .global(true)
+                        .help("Read the cloud provider from the kernel cmdline"),
+                )
+                .arg(
+                    Arg::with_name("attributes")
+                        .long("attributes")
+                        .help("The file into which the metadata attributes are written")
+                        .takes_value(true),
+                )
+                .arg(
+                    Arg::with_name("check-in")
+                        .long("check-in")
+                        .help("Check-in this instance boot with the cloud provider"),
+                )
+                .arg(
+                    Arg::with_name("hostname")
+                        .long("hostname")
+                        .help("The file into which the hostname should be written")
+                        .takes_value(true),
+                )
+                .arg(
+                    Arg::with_name("network-units")
+                        .long("network-units")
+                        .help("The directory into which network units are written")
+                        .takes_value(true),
+                )
+                .arg(
+                    Arg::with_name("ssh-keys")
+                        .long("ssh-keys")
+                        .help("Update SSH keys for the given user")
+                        .takes_value(true),
+                ),
+        )
+        .subcommand(
+            SubCommand::with_name("exp")
+                .about("experimental commands")
+                .subcommand(
+                    SubCommand::with_name("rd-net-bootstrap")
+                        .about("Bootstrap network in initrd")
+                        .arg(
+                            Arg::with_name("provider")
+                                .long("provider")
+                                .help("The name of the cloud provider")
+                                .global(true)
+                                .takes_value(true),
+                        )
+                        .arg(
+                            Arg::with_name("cmdline")
+                                .long("cmdline")
+                                .global(true)
+                                .help("Read the cloud provider from the kernel cmdline"),
+                        ),
+                ),
+        )
 }
 
 /// Translate command-line arguments from legacy mode.
@@ -139,8 +179,6 @@ fn translate_legacy_args(cli: impl IntoIterator<Item = String>) -> impl Iterator
     })
 }
 
-impl CliConfig {}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/cli/multi.rs

@@ -1,9 +1,7 @@
 //! `multi` CLI sub-command.
 
-use super::CMDLINE_PATH;
 use crate::errors::*;
 use crate::metadata;
-use error_chain::bail;
 
 #[derive(Debug)]
 pub struct CliMulti {
@@ -18,7 +16,7 @@ pub struct CliMulti {
 impl CliMulti {
     /// Parse flags for the `multi` sub-command.
     pub(crate) fn parse(matches: &clap::ArgMatches) -> Result<super::CliConfig> {
-        let provider = Self::parse_provider(matches)?;
+        let provider = super::parse_provider(matches)?;
 
         let multi = Self {
             attributes_file: matches.value_of("attributes").map(String::from),
@@ -42,18 +40,6 @@ impl CliMulti {
         Ok(super::CliConfig::Multi(multi))
     }
 
-    /// Parse provider ID from flag or kargs.
-    fn parse_provider(matches: &clap::ArgMatches) -> Result<String> {
-        let provider = match (matches.value_of("provider"), matches.is_present("cmdline")) {
-            (Some(provider), false) => String::from(provider),
-            (None, true) => crate::util::get_platform(CMDLINE_PATH)?,
-            (None, false) => bail!("must set either --provider or --cmdline"),
-            (Some(_), true) => bail!("cannot process both --provider and --cmdline"),
-        };
-
-        Ok(provider)
-    }
-
     /// Run the `multi` sub-command.
     pub(crate) fn run(self) -> Result<()> {
         // fetch the metadata from the configured provider

src/providers/ibmcloud_classic/mod.rs

@@ -293,6 +293,29 @@ impl MetadataProvider for IBMClassicProvider {
         warn!("boot check-in requested, but not supported on this platform");
         Ok(())
     }
+
+    fn rd_net_bootstrap(&self) -> Result<()> {
+        let net_ifaces = self.networks()?;
+        let mut nameservers = vec![];
+
+        // Configure network.
+        for iface in net_ifaces {
+            iface.ip_apply()?;
+
+            // Collect nameservers for later.
+            for ns in iface.nameservers {
+                if !nameservers.contains(&ns) {
+                    nameservers.push(ns);
+                }
+            }
+        }
+
+        // Configure DNS resolvers.
+        let mut resolvconf = File::create("/etc/resolv.conf")?;
+        crate::network::utils::write_resolvconf(&mut resolvconf, &nameservers)?;
+
+        Ok(())
+    }
 }
 
 impl Drop for IBMClassicProvider {

src/providers/mod.rs

@@ -35,17 +35,16 @@ pub mod openstack;
 pub mod packet;
 pub mod vagrant_virtualbox;
 
+use crate::errors::*;
+use crate::network;
+use openssh_keys::PublicKey;
+use slog_scope::warn;
 use std::collections::HashMap;
 use std::fs::{self, File};
 use std::io::prelude::*;
 use std::path::Path;
-
-use openssh_keys::PublicKey;
 use users::{self, User};
 
-use crate::errors::*;
-use crate::network;
-
 #[cfg(not(feature = "cl-legacy"))]
 const ENV_PREFIX: &str = "AFTERBURN_";
 #[cfg(feature = "cl-legacy")]
@@ -183,6 +182,12 @@ pub trait MetadataProvider {
     /// netdev: https://www.freedesktop.org/software/systemd/man/systemd.netdev.html
     fn virtual_network_devices(&self) -> Result<Vec<network::VirtualNetDev>>;
 
+    /// Bootstrap initramfs networking.
+    fn rd_net_bootstrap(&self) -> Result<()> {
+        warn!("initramfs network bootstrap requested, but not supported on this platform");
+        Ok(())
+    }
+
     fn write_attributes(&self, attributes_file_path: String) -> Result<()> {
         let mut attributes_file = create_file(&attributes_file_path)?;
         for (k, v) in self.attributes()? {