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Merge pull request #2401 from xzkutor/main

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incusf/dhcp: run DHCP client on all container interfaces and aggregate DNS from all leases
This commit is contained in:
Stéphane Graber
2025-08-18 23:36:57 -04:00
committed by GitHub
parent f89169eb86 01f9a79432
commit 8a2598a524
1 changed files with 142 additions and 79 deletions
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221
cmd/incusd/main_forknet.go
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@@ -243,8 +243,8 @@ type cmdForknet struct {
global *cmdGlobal
applyDNSMu sync.Mutex
dhcpv4Lease *nclient4.Lease
dhcpv6Lease *dhcpv6.Message
dhcpv4Leases map[string]*nclient4.Lease
dhcpv6Leases map[string]*dhcpv6.Message
instNetworkPath string
}
@@ -318,21 +318,6 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
logger.SetOutput(io.Discard)
}
iface := "eth0"
logger.WithField("interface", iface).Info("running dhcp")
// Bring the interface up.
link := &ip.Link{
Name: iface,
}
err := link.SetUp()
if err != nil {
logger.WithField("interface", iface).Error("Giving up on DHCP, couldn't bring up interface")
return nil
}
// Read the hostname.
bb, err := os.ReadFile(filepath.Join(c.instNetworkPath, "hostname"))
if err != nil {
@@ -348,25 +333,68 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
return err
}
errorChannel := make(chan error, 2)
go c.dhcpRunV4(errorChannel, iface, hostname, logger)
go c.dhcpRunV6(errorChannel, iface, hostname, logger)
err1 := <-errorChannel
if err1 != nil {
logger.WithError(err1).Error("DHCP client failed")
// Enumerate network interfaces and skip loopback.
ifaces, err := net.Interfaces()
if err != nil {
logger.WithError(err).Error("Giving up on DHCP, couldn't list interfaces")
return err
}
err2 := <-errorChannel
if err2 != nil {
logger.WithError(err2).Error("DHCP client failed")
var names []string
for _, ifi := range ifaces {
if ifi.Flags&net.FlagLoopback != 0 {
continue
}
names = append(names, ifi.Name)
}
if err1 == nil && err2 == nil {
if len(names) == 0 {
logger.Info("No non-loopback interfaces found; nothing to do for DHCP")
return nil
}
return fmt.Errorf("DHCP failure, client1=%v client2=%v", err1, err2)
// Initialize per-interface lease maps.
c.applyDNSMu.Lock()
c.dhcpv4Leases = map[string]*nclient4.Lease{}
c.dhcpv6Leases = map[string]*dhcpv6.Message{}
c.applyDNSMu.Unlock()
// Buffer size is 2 goroutines per iface.
errorChannel := make(chan error, len(names)*2)
// Launch DHCP clients for each iface.
for _, iface := range names {
logger := logger.WithField("interface", iface).Logger
logger.Info("running dhcp on interface")
link := &ip.Link{
Name: iface,
}
err := link.SetUp()
if err != nil {
logger.WithField("interface", iface).WithError(err).Error("Giving up on DHCP for this interface, couldn't bring up interface")
// continue to try other interfaces
continue
}
go c.dhcpRunV4(errorChannel, iface, hostname, logger)
go c.dhcpRunV6(errorChannel, iface, hostname, logger)
}
// Wait for all goroutines to return (2 per interface).
var finalErr error
for i := 0; i < len(names)*2; i++ {
err := <-errorChannel
if err != nil {
logger.WithError(err).Error("DHCP client failed")
finalErr = fmt.Errorf("some DHCP clients failed (one or more)")
}
}
return finalErr
}
func (c *cmdForknet) dhcpRunV4(errorChannel chan error, iface string, hostname string, logger *logrus.Logger) {
@@ -415,7 +443,7 @@ func (c *cmdForknet) dhcpRunV4(errorChannel chan error, iface string, hostname s
}
c.applyDNSMu.Lock()
c.dhcpv4Lease = lease
c.dhcpv4Leases[iface] = lease
c.applyDNSMu.Unlock()
err = c.dhcpApplyDNS(logger)
@@ -480,7 +508,7 @@ func (c *cmdForknet) dhcpRunV4(errorChannel chan error, iface string, hostname s
// Handle DHCP renewal.
for {
// Caslculate the renewal time.
// Calculate the renewal time.
var t1 time.Duration
if lease.ACK != nil {
@@ -579,7 +607,7 @@ func (c *cmdForknet) dhcpRunV6(errorChannel chan error, iface string, hostname s
// Update DNS.
c.applyDNSMu.Lock()
c.dhcpv6Lease = reply
c.dhcpv6Leases[iface] = reply
c.applyDNSMu.Unlock()
err = c.dhcpApplyDNS(logger)
@@ -602,7 +630,7 @@ func (c *cmdForknet) dhcpRunV6(errorChannel chan error, iface string, hostname s
}
c.applyDNSMu.Lock()
c.dhcpv6Lease = reply
c.dhcpv6Leases[iface] = reply
c.applyDNSMu.Unlock()
err = c.dhcpApplyDNS(logger)
@@ -678,14 +706,56 @@ func (c *cmdForknet) dhcpRunV6(errorChannel chan error, iface string, hostname s
}
func (c *cmdForknet) dhcpApplyDNS(logger *logrus.Logger) error {
c.applyDNSMu.Lock()
defer c.applyDNSMu.Unlock()
nameservers := map[string]struct{}{}
searchLabels := []string{}
domainNames := []string{}
// Skip touching resolv.conf if no leases.
if c.dhcpv4Lease == nil && c.dhcpv6Lease == nil {
return nil
c.applyDNSMu.Lock()
// IPv4 leases.
for _, lease := range c.dhcpv4Leases {
if lease == nil || lease.Offer == nil {
continue
}
// Nameservers from DHCPv4.
for _, ns := range lease.Offer.DNS() {
nameservers[ns.String()] = struct{}{}
}
// Domain name (option 15).
dn := lease.Offer.DomainName()
if dn != "" {
domainNames = append(domainNames, dn)
}
// Domain search list (option 119).
ds := lease.Offer.DomainSearch()
if ds != nil && len(ds.Labels) > 0 {
searchLabels = append(searchLabels, ds.Labels...)
}
}
// IPv6 leases.
for _, reply := range c.dhcpv6Leases {
if reply == nil {
continue
}
// Nameservers from DHCPv6.
for _, ns := range reply.Options.DNS() {
nameservers[ns.String()] = struct{}{}
}
// Domain search list.
dsl := reply.Options.DomainSearchList()
if dsl != nil && len(dsl.Labels) > 0 {
searchLabels = append(searchLabels, dsl.Labels...)
}
}
c.applyDNSMu.Unlock()
// Create resolv.conf.
f, err := os.Create(filepath.Join(c.instNetworkPath, "resolv.conf"))
if err != nil {
@@ -695,53 +765,46 @@ func (c *cmdForknet) dhcpApplyDNS(logger *logrus.Logger) error {
defer f.Close()
// IPv4 addresses.
if c.dhcpv4Lease != nil {
if len(c.dhcpv4Lease.Offer.DNS()) > 0 {
for _, nameserver := range c.dhcpv4Lease.Offer.DNS() {
_, err = fmt.Fprintf(f, "nameserver %s\n", nameserver)
if err != nil {
logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
return err
}
}
if c.dhcpv4Lease.Offer.DomainName() != "" {
_, err = fmt.Fprintf(f, "domain %s\n", c.dhcpv4Lease.Offer.DomainName())
if err != nil {
logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
return err
}
}
if c.dhcpv4Lease.Offer.DomainSearch() != nil && len(c.dhcpv4Lease.Offer.DomainSearch().Labels) > 0 {
_, err = fmt.Fprintf(f, "search %s\n", strings.Join(c.dhcpv4Lease.Offer.DomainSearch().Labels, ", "))
if err != nil {
logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
return err
}
}
// Write unique nameservers.
for ns := range nameservers {
_, err = fmt.Fprintf(f, "nameserver %s\n", ns)
if err != nil {
logger.WithError(err).Error("Giving up on DHCP, couldn't write resolv.conf")
return err
}
}
// IPv6 addresses.
if c.dhcpv6Lease != nil {
if len(c.dhcpv6Lease.Options.DNS()) > 0 {
for _, nameserver := range c.dhcpv6Lease.Options.DNS() {
_, err = fmt.Fprintf(f, "nameserver %s\n", nameserver)
if err != nil {
logger.WithError(err).Error("Giving up on DHCPv6, couldn't prepare resolv.conf")
return err
}
// Prefer a search list if present; otherwise write a single domain if available.
if len(searchLabels) > 0 {
seen := map[string]struct{}{}
out := []string{}
for _, s := range searchLabels {
if s == "" {
continue
}
if c.dhcpv6Lease.Options.DomainSearchList() != nil && len(c.dhcpv6Lease.Options.DomainSearchList().Labels) > 0 {
_, err = fmt.Fprintf(f, "search %s\n", strings.Join(c.dhcpv6Lease.Options.DomainSearchList().Labels, ", "))
if err != nil {
logger.WithError(err).Error("Giving up on DHCPv6, couldn't prepare resolv.conf")
return err
}
_, ok := seen[s]
if ok {
continue
}
seen[s] = struct{}{}
out = append(out, s)
}
if len(out) > 0 {
_, err = fmt.Fprintf(f, "search %s\n", strings.Join(out, ", "))
if err != nil {
logger.WithError(err).Error("Giving up on DHCP, couldn't write resolv.conf")
return err
}
}
} else if len(domainNames) > 0 {
_, err = fmt.Fprintf(f, "domain %s\n", domainNames[0])
if err != nil {
logger.WithError(err).Error("Giving up on DHCP, couldn't write resolv.conf")
return err
}
}