Write the registry's trust into the runtime's file and reload the runtime instead of restarting it; prefix reload-on like restart-on (hq ADR 0102)

internal/catalogue/computed_test.go

@@ -1,6 +1,7 @@
 package catalogue
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 )
@@ -157,3 +158,47 @@ func TestTwoWaysToBeOnAPrivateNetworkRefuseAndNameBoth(t *testing.T) {
 		}
 	}
 }
+
+// reloading answers the runtime's trust as the networking module does (novox/hq ADR 0102): a file
+// written into, and the runtime reloaded on it.
+type reloading struct{}
+
+func (reloading) Resources(node string) ([]map[string]any, bool, error) {
+	return []map[string]any{
+		{"id": "registry-trust", "type": "file", "path": "/etc/docker/daemon.json",
+			"merge": MergeJSON, "into": "json", "content": `{"insecure-registries":["r:5000"]}`},
+		{"id": "registry-trust-reload", "type": "service", "unit": "docker.service",
+			"state": "running", "reload-on": []string{"registry-trust"}},
+	}, true, nil
+}
+
+func TestWhatAServiceIsReloadedOnIsNamedAsTheHostWillSeeIt(t *testing.T) {
+	// Ids are prefixed with their module on the way out. An unprefixed reload-on would name a
+	// resource the host never sees, and the runtime would never be reloaded for its trust.
+	got, err := Resolve(computedShelf(), []string{"mesh-network"}, workstation(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := got.Declaration(Rendering{Generators: map[string]Generator{"mesh-network": reloading{}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var file, service map[string]any
+	for _, r := range out {
+		switch r["type"] {
+		case "file":
+			file = r
+		case "service":
+			service = r
+		}
+	}
+	if file == nil || service == nil {
+		t.Fatalf("got %v", out)
+	}
+	if file["into"] != "json" {
+		t.Errorf("into did not reach the host: %v", file)
+	}
+	if want := "[" + file["id"].(string) + "]"; fmt.Sprint(service["reload-on"]) != want {
+		t.Errorf("reload-on names %v, the file is %v", service["reload-on"], file["id"])
+	}
+}

internal/catalogue/declaration.go

@@ -559,6 +559,11 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 			if renamed := reflectsRenamed(m.Module, resource["restart-on"]); renamed != nil {
 				copied["restart-on"] = renamed
 			}
+			// And what it is reloaded on, by the same rule (novox/hq ADR 0102): an id left
+			// unprefixed matches nothing, and the service is never reloaded.
+			if renamed := reflectsRenamed(m.Module, resource["reload-on"]); renamed != nil {
+				copied["reload-on"] = renamed
+			}
 			owner[fmt.Sprint(copied["id"])] = m.Module
 			out = append(out, copied)
 		}