feat: support IPv6-only clusters via configurable bind address#333
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The storage apiserver never set a bind address, leaving it at the apiserver default 0.0.0.0, which cannot accept connections on IPv6-only clusters. The binary takes no apiserver flags (main.go runs flag.Parse with only -kubeconfig registered), so --bind-address cannot be passed at runtime; configuration is the only lever. Add a serverBindAddress config field wired into SecureServing.BindAddress (mirroring the existing serverBindPort), defaulting to "::" so IPv6-only clusters serve out of the box. With bindv6only=0 (Linux default) "::" also accepts IPv4/dual-stack traffic; operators can force IPv4-only with serverBindAddress: "0.0.0.0". Also add ::1 to the self-signed cert loopback SANs so IPv6 loopback TLS works on the self-signed path. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Matthias Bertschy <matthias.bertschy@gmail.com>
📝 WalkthroughWalkthroughThis PR adds IPv6 dual-stack support to the storage server by introducing a configurable ChangesIPv6 Dual-Stack Server Bind Address
Estimated code review effort🎯 2 (Simple) | ⏱️ ~8 minutes Poem
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@pkg/cmd/server/start.go`:
- Around line 127-129: The code currently ignores an unparsable
o.StorageConfig.ServerBindAddress in the ParseIPSloppy block; change the
behavior to fail fast by adding validation in the Validate() method: call
netutils.ParseIPSloppy(o.StorageConfig.ServerBindAddress) there and if the
provided ServerBindAddress is non-empty and ParseIPSloppy returns nil, return a
descriptive error; keep the current assignment to
o.RecommendedOptions.SecureServing.BindAddress only when ParseIPSloppy succeeds.
Ensure you reference ParseIPSloppy, o.StorageConfig.ServerBindAddress,
o.RecommendedOptions.SecureServing.BindAddress and the Validate() method when
implementing this check.
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Fix all unresolved CodeRabbit comments on this PR:
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📒 Files selected for processing (3)
pkg/cmd/server/start.gopkg/config/config.gopkg/config/config_test.go
Comment on lines
+127
to
+129
| if bindIP := netutils.ParseIPSloppy(o.StorageConfig.ServerBindAddress); bindIP != nil { | ||
| o.RecommendedOptions.SecureServing.BindAddress = bindIP | ||
| } |
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Fail fast on invalid serverBindAddress instead of silently falling back.
At Line 127, an unparsable value is ignored and the server continues with the default bind address. A typo in config can unintentionally expose/listen on an unintended interface and break IPv6-only intent. Validate this in Validate() and return an error.
Suggested fix
func (o WardleServerOptions) Validate(_ []string) error {
var errors []error
errors = append(errors, o.RecommendedOptions.Validate()...)
errors = append(errors, o.ComponentGlobalsRegistry.Validate()...)
+ if ip := netutils.ParseIPSloppy(o.StorageConfig.ServerBindAddress); ip == nil {
+ errors = append(errors, fmt.Errorf("invalid serverBindAddress %q: expected an IP literal", o.StorageConfig.ServerBindAddress))
+ }
return utilerrors.NewAggregate(errors)
}🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@pkg/cmd/server/start.go` around lines 127 - 129, The code currently ignores
an unparsable o.StorageConfig.ServerBindAddress in the ParseIPSloppy block;
change the behavior to fail fast by adding validation in the Validate() method:
call netutils.ParseIPSloppy(o.StorageConfig.ServerBindAddress) there and if the
provided ServerBindAddress is non-empty and ParseIPSloppy returns nil, return a
descriptive error; keep the current assignment to
o.RecommendedOptions.SecureServing.BindAddress only when ParseIPSloppy succeeds.
Ensure you reference ParseIPSloppy, o.StorageConfig.ServerBindAddress,
o.RecommendedOptions.SecureServing.BindAddress and the Validate() method when
implementing this check.
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Summary:
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Problem
The storage apiserver does not come up on IPv6-only clusters. Confirmed from a live pod: it listens on
0.0.0.0:8443(the apiserver default), which cannot accept IPv6 connections.Root cause:
SecureServing.BindAddressis never set. The binary is config-driven, not flag-driven —main.goruns stdlibflag.Parse()with only-kubeconfigregistered, so passing--bind-addressto the process is rejected (flag provided but not defined: -bind-address). Configuration is the only available lever.Change
serverBindAddressconfig field (pkg/config/config.go) and wire it intoSecureServing.BindAddressinpkg/cmd/server/start.go, mirroring howserverBindPortis already handled."::"so IPv6-only clusters serve with no Helm changes. Withbindv6only=0(the Linux default)"::"also accepts IPv4/dual-stack traffic, so existing clusters keep working.serverBindAddress: "0.0.0.0"to force IPv4-only binding.::1to the self-signed cert loopback SANs (start.go) for IPv6 loopback TLS on the self-signed path.Testing
go build ./...passes.go test ./pkg/config/...passes (updatedTestLoadConfigexpectation for the new default).Notes
serverBindAddressvalue flows through the existing config mount (/etc/config/config.json); the Helm chart can expose it but no chart change is required for the default to take effect./128) and IPv6-safe HTTPEndpoint URL parsing — data-correctness fixes tracked separately.🤖 Generated with Claude Code
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