core: preserve metrics registry in Context.WithValue (#7861)

* core: preserve metrics registry in Context.WithValue Context.WithValue rebuilt the Context without copying the unexported metricsRegistry field, so any module provisioned under a context derived via WithValue saw a nil registry from GetMetricsRegistry(). * Potential fix for pull request finding Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> Signed-off-by: Kévin Dunglas <kevin@dunglas.fr> --------- Signed-off-by: Kévin Dunglas <kevin@dunglas.fr> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Kévin Dunglas committed Jul 7, 2026 at 20:52 UTC 4e62095245005b17f290dd1e4d9afe983df180ee

2 files changed +19

context.go

@@ -676,6 +676,7 @@ func (ctx *Context) WithValue(key, value any) Context {

676 ancestry: ctx.ancestry,

677 cleanupFuncs: ctx.cleanupFuncs,

678 exitFuncs: ctx.exitFuncs,

679 + metricsRegistry: ctx.metricsRegistry,

680 }

681 }

682

context_test.go

+18

@@ -15,10 +15,28 @@

15 package caddy

17 import (

18 + "context"

19 "encoding/json"

20 "io"

21 + "testing"

22 )

24 +func TestContextWithValuePreservesMetricsRegistry(t *testing.T) {

25 + ctx, cancel := NewContext(Context{Context: context.Background()})

26 + t.Cleanup(cancel)

27 +

28 + reg := ctx.GetMetricsRegistry()

29 + if reg == nil {

30 + t.Fatal("expected a metrics registry on the base context")

31 + }

32 +

33 + type testKey struct{}

34 + derived := ctx.WithValue(testKey{}, "value")

35 + if got := derived.GetMetricsRegistry(); got != reg {

36 + t.Fatalf("WithValue must preserve the metrics registry: got %p, want %p", got, reg)

37 + }

38 +}

39 +

40 func ExampleContext_LoadModule() {

41 // this whole first part is just setting up for the example;

42 // note the struct tags - very important; we specify inline_key