chore: add Caddy config to ServiceSpec, load x-caddy to it

pkg/api/caddy.go

@@ -0,0 +1,8 @@
+package api
+
+// CaddySpec is the Caddy reverse proxy configuration for a service.
+type CaddySpec struct {
+	// Config contains the Caddy config (Caddyfile) content. It must not conflict with the Caddy configs
+	// of other services.
+	Config string
+}

pkg/api/service.go

@@ -6,6 +6,7 @@ import (
 	"maps"
 	"regexp"
 	"slices"
+	"strings"
 
 	"github.com/distribution/reference"
 	"github.com/google/go-cmp/cmp"
@@ -42,6 +43,10 @@ func ValidateServiceID(id string) bool {
 // ServiceSpec defines the desired state of a service.
 // ATTENTION: after changing this struct, verify if deploy.EvalContainerSpecChange needs to be updated.
 type ServiceSpec struct {
+	// Caddy is the optional Caddy reverse proxy configuration for the service.
+	// Caddy and Ports cannot be specified simultaneously.
+	Caddy *CaddySpec `json:",omitempty"`
+	// Container defines the desired state of each container in the service.
 	Container ContainerSpec
 	// Mode is the replication mode of the service. Default is ServiceModeReplicated if empty.
 	Mode string
@@ -49,6 +54,7 @@ type ServiceSpec struct {
 	// Placement defines the placement constraints for the service.
 	Placement Placement
 	// Ports defines what service ports to publish to make the service accessible outside the cluster.
+	// Caddy and Ports cannot be specified simultaneously.
 	Ports []PortSpec
 	// Replicas is the number of containers to run for the service. Only valid for a replicated service.
 	Replicas uint `json:",omitempty"`
@@ -112,10 +118,17 @@ func (s *ServiceSpec) Validate() error {
 			return fmt.Errorf("service name too long (max 63 characters): %q", s.Name)
 		}
 		if !dnsLabelRegexp.MatchString(s.Name) {
-			return fmt.Errorf("invalid service name: %q. must be 1-63 characters, lowercase letters, numbers, and dashes only; must start and end with a letter or number", s.Name)
+			return fmt.Errorf("invalid service name: %q. must be 1-63 characters, lowercase letters, numbers, "+
+				"and dashes only; must start and end with a letter or number", s.Name)
 		}
 	}
 
+	// Validate that Caddy and Ports are not used together.
+	if s.Caddy != nil && strings.TrimSpace(s.Caddy.Config) != "" && len(s.Ports) > 0 {
+		return fmt.Errorf("ports and Caddy configuration cannot be specified simultaneously: " +
+			"Caddy config is auto-generated from ports, use only one of them")
+	}
+
 	for _, p := range s.Ports {
 		if (p.Mode == "" || p.Mode == PortModeIngress) &&
 			p.Protocol != ProtocolHTTP && p.Protocol != ProtocolHTTPS {
@@ -151,11 +164,16 @@ func (s *ServiceSpec) Validate() error {
 func (s *ServiceSpec) Clone() ServiceSpec {
 	spec := *s
 
+	if s.Caddy != nil {
+		caddyCopy := *s.Caddy
+		spec.Caddy = &caddyCopy
+	}
+	spec.Container = s.Container.Clone()
+
 	if s.Ports != nil {
 		spec.Ports = make([]PortSpec, len(s.Ports))
 		copy(spec.Ports, s.Ports)
 	}
-	spec.Container = s.Container.Clone()
 
 	if s.Volumes != nil {
 		spec.Volumes = make([]VolumeSpec, len(s.Volumes))

pkg/api/service_test.go

@@ -0,0 +1,104 @@
+package api
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestServiceSpec_Validate_CaddyAndPorts(t *testing.T) {
+	tests := []struct {
+		name    string
+		spec    ServiceSpec
+		wantErr string
+	}{
+		{
+			name: "valid with neither Caddy nor Ports",
+			spec: ServiceSpec{
+				Name: "test",
+				Container: ContainerSpec{
+					Image: "nginx:latest",
+				},
+			},
+			wantErr: "",
+		},
+		{
+			name: "valid with Caddy only",
+			spec: ServiceSpec{
+				Name: "test",
+				Container: ContainerSpec{
+					Image: "nginx:latest",
+				},
+				Caddy: &CaddySpec{
+					Config: "example.com {\n  reverse_proxy :8080\n}",
+				},
+			},
+			wantErr: "",
+		},
+		{
+			name: "valid with Ports only",
+			spec: ServiceSpec{
+				Name: "test",
+				Container: ContainerSpec{
+					Image: "nginx:latest",
+				},
+				Ports: []PortSpec{
+					{
+						ContainerPort: 80,
+						Protocol:      ProtocolHTTP,
+					},
+				},
+			},
+			wantErr: "",
+		},
+		{
+			name: "valid with empty Caddy config and Ports",
+			spec: ServiceSpec{
+				Name: "test",
+				Container: ContainerSpec{
+					Image: "nginx:latest",
+				},
+				Caddy: &CaddySpec{
+					Config: "",
+				},
+				Ports: []PortSpec{
+					{
+						ContainerPort: 80,
+						Protocol:      ProtocolHTTP,
+					},
+				},
+			},
+			wantErr: "",
+		},
+		{
+			name: "invalid with both Caddy and Ports",
+			spec: ServiceSpec{
+				Name: "test",
+				Container: ContainerSpec{
+					Image: "nginx:latest",
+				},
+				Caddy: &CaddySpec{
+					Config: "example.com {\n  reverse_proxy :8080\n}",
+				},
+				Ports: []PortSpec{
+					{
+						ContainerPort: 80,
+						Protocol:      ProtocolHTTP,
+					},
+				},
+			},
+			wantErr: "ports and Caddy configuration cannot be specified simultaneously",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.spec.Validate()
+			if tt.wantErr == "" {
+				require.NoError(t, err)
+			} else {
+				require.ErrorContains(t, err, tt.wantErr)
+			}
+		})
+	}
+}