Factor out the ignite container command into a separate ignite-spawn …

…binary

cmd/ignite-spawn/ignite-spawn.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/weaveworks/ignite/pkg/container"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
+	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
+)
+
+func main() {
+	if err := Run(); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+// Run runs the main cobra command of this application
+func Run() error {
+	if len(os.Args) != 1 {
+		fmt.Printf("Usage: ignite-spawn [VM ID]")
+		os.Exit(0)
+	}
+
+	vmID := os.Args[0]
+	opts, err := NewOptions(loader.NewResLoader(), vmID)
+	if err != nil {
+		return err
+	}
+
+	return StartVM(opts)
+}
+
+func StartVM(co *options) error {
+	// Setup networking inside of the container, return the available interfaces
+	dhcpIfaces, err := container.SetupContainerNetworking()
+	if err != nil {
+		return fmt.Errorf("network setup failed: %v", err)
+	}
+	// Serve DHCP requests for those interfaces
+	if err := container.StartDHCPServers(co.vm, dhcpIfaces); err != nil {
+		return err
+	}
+
+	// VM state handling
+	if err := co.vm.SetState(vmmd.Running); err != nil {
+		return fmt.Errorf("failed to update VM state: %v", err)
+	}
+	defer co.vm.SetState(vmmd.Stopped) // Performs a save, all other metadata-modifying defers need to be after this
+
+	// Remove the snapshot overlay post-run, which also removes the detached backing loop devices
+	defer co.vm.RemoveSnapshot()
+
+	// Remove the IP addresses post-run
+	defer co.vm.ClearIPAddresses()
+
+	// Remove the port mappings post-run
+	defer co.vm.ClearPortMappings()
+
+	// Execute Firecracker
+	if err := container.ExecuteFirecracker(co.vm, dhcpIfaces); err != nil {
+		return fmt.Errorf("runtime error for VM %q: %v", co.vm.ID, err)
+	}
+
+	return nil
+}

cmd/ignite-spawn/options.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
+	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
+)
+
+type options struct {
+	vm *vmmd.VMMetadata
+}
+
+func NewOptions(l *loader.ResLoader, vmMatch string) (*options, error) {
+	co := &options{}
+
+	if allVMS, err := l.VMs(); err == nil {
+		if co.vm, err = allVMS.MatchSingle(vmMatch); err != nil {
+			return nil, err
+		}
+	} else {
+		return nil, err
+	}
+
+	return co, nil
+}

cmd/ignite/cmd/root.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/lithammer/dedent"
 	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
 )
 
 // NewIgniteCommand returns the root command for ignite
@@ -70,7 +71,7 @@ func NewIgniteCommand(in io.Reader, out, err io.Writer) *cobra.Command {
 		`, imageCmd.Short, kernelCmd.Short, vmCmd.Short)),
 	}
 
-	logs.AddQuietFlag(root.PersistentFlags())
+	AddQuietFlag(root.PersistentFlags())
 
 	root.AddCommand(imageCmd)
 	root.AddCommand(kernelCmd)
@@ -92,3 +93,8 @@ func NewIgniteCommand(in io.Reader, out, err io.Writer) *cobra.Command {
 	root.AddCommand(NewCmdVersion(os.Stdout))
 	return root
 }
+
+// AddQuietFlag adds the quiet flag to a flagset
+func AddQuietFlag(fs *pflag.FlagSet) {
+	fs.BoolVarP(&logs.Quiet, "quiet", "q", logs.Quiet, "The quiet mode allows for machine-parsable output, by printing only IDs")
+}

cmd/ignite/cmd/vmcmd/vm.go

@@ -4,8 +4,8 @@ import (
 	"io"
 
 	"github.com/weaveworks/ignite/cmd/ignite/run"
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/errutils"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 
 	"github.com/lithammer/dedent"
 	"github.com/spf13/cobra"

cmd/ignite/run/images.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 
 	"github.com/c2h5oh/datasize"
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/imgmd"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/util"
 )
 

cmd/ignite/run/kernels.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 
 	"github.com/c2h5oh/datasize"
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/kernmd"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/util"
 )
 

cmd/ignite/run/ps.go

@@ -4,9 +4,9 @@ import (
 	"fmt"
 
 	"github.com/c2h5oh/datasize"
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/imgmd"
 	"github.com/weaveworks/ignite/pkg/metadata/kernmd"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
 	"github.com/weaveworks/ignite/pkg/util"
 )

cmd/ignite/run/rm.go

@@ -3,8 +3,8 @@ package run
 import (
 	"fmt"
 
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/logs"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
 )
 

cmd/ignite/run/run.go

@@ -1,8 +1,8 @@
 package run
 
 import (
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 )
 
 type RunFlags struct {

cmd/ignite/run/stop.go

@@ -3,8 +3,8 @@ package run
 import (
 	"fmt"
 
-	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/constants"
+	"github.com/weaveworks/ignite/pkg/metadata/loader"
 	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
 	"github.com/weaveworks/ignite/pkg/util"
 )

pkg/container/dhcp.go

@@ -1,17 +1,58 @@
 package container
 
 import (
+	"fmt"
 	"net"
+	"os"
 	"time"
 
-	"github.com/weaveworks/ignite/pkg/constants"
-
 	dhcp "github.com/krolaw/dhcp4"
 	"github.com/krolaw/dhcp4/conn"
+	"github.com/miekg/dns"
+	"github.com/weaveworks/ignite/pkg/constants"
+	"github.com/weaveworks/ignite/pkg/metadata/vmmd"
+	"github.com/weaveworks/ignite/pkg/util"
 )
 
 var leaseDuration, _ = time.ParseDuration(constants.DHCP_INFINITE_LEASE) // Infinite lease time
 
+// StartDHCPServers starts multiple DHCP servers for the VM, one per interface
+func StartDHCPServers(vm *vmmd.VMMetadata, dhcpIfaces []DHCPInterface) error {
+	// Generate the MAC addresses for the VM's adapters
+	macAddresses := make([]string, 0, len(dhcpIfaces))
+	if err := util.NewMAC(&macAddresses); err != nil {
+		return fmt.Errorf("failed to generate MAC addresses: %v", err)
+	}
+
+	// Fetch the DNS servers given to the container
+	clientConfig, err := dns.ClientConfigFromFile("/etc/resolv.conf")
+	if err != nil {
+		return fmt.Errorf("failed to get DNS configuration: %v", err)
+	}
+
+	for i := range dhcpIfaces {
+		dhcpIface := &dhcpIfaces[i]
+		// Set the VM hostname to the VM ID
+		dhcpIface.Hostname = vm.ID.String()
+
+		// Set the MAC address filter for the DHCP server
+		dhcpIface.MACFilter = macAddresses[i]
+
+		// Add the DNS servers from the container
+		dhcpIface.SetDNSServers(clientConfig.Servers)
+
+		vm.AddIPAddress(dhcpIface.VMIPNet.IP)
+
+		go func() {
+			fmt.Printf("Starting DHCP server for interface %s (%s)\n", dhcpIface.Bridge, dhcpIface.VMIPNet.IP)
+			if err := dhcpIface.StartBlockingServer(); err != nil {
+				fmt.Fprintf(os.Stderr, "%s DHCP server error: %v\n", dhcpIface.Bridge, err)
+			}
+		}()
+	}
+	return nil
+}
+
 type DHCPInterface struct {
 	VMIPNet    *net.IPNet
 	GatewayIP  *net.IP
@@ -22,14 +63,16 @@ type DHCPInterface struct {
 	dnsServers []byte
 }
 
-func RunDHCP(dhcpIface *DHCPInterface) error {
-	packetConn, err := conn.NewUDP4BoundListener(dhcpIface.Bridge, ":67")
+// StartBlockingServer starts a blocking DHCP server on port 67
+func (i *DHCPInterface) StartBlockingServer() error {
+	packetConn, err := conn.NewUDP4BoundListener(i.Bridge, ":67")
 	if err != nil {
 		return err
 	}
-	return dhcp.Serve(packetConn, dhcpIface)
+	return dhcp.Serve(packetConn, i)
 }
 
+// ServeDHCP responds to a DHCP request
 func (i *DHCPInterface) ServeDHCP(p dhcp.Packet, msgType dhcp.MessageType, options dhcp.Options) dhcp.Packet {
 	var respMsg dhcp.MessageType
 	switch msgType {