refactor: move api, client, compose packages to pkg

pkg/client/resolver.go

@@ -0,0 +1,133 @@
+package client
+
+import (
+	"fmt"
+	"github.com/distribution/reference"
+	"github.com/psviderski/uncloud/internal/secret"
+	"github.com/psviderski/uncloud/pkg/api"
+	"strings"
+)
+
+type ImageDigestResolver interface {
+	Resolve(image string) (string, error)
+}
+
+// ServiceSpecResolver transforms user-provided service specs into deployment-ready form.
+type ServiceSpecResolver struct {
+	ClusterDomain string
+	ImageResolver ImageDigestResolver
+}
+
+// Resolve transforms a service spec into its fully resolved form ready for deployment.
+func (r *ServiceSpecResolver) Resolve(spec *api.ServiceSpec) error {
+	if err := spec.Validate(); err != nil {
+		return fmt.Errorf("invalid service spec: %w", err)
+	}
+
+	steps := []func(*api.ServiceSpec) error{
+		r.applyDefaults,
+		r.resolveServiceName,
+		r.resolveImageDigest,
+		r.expandIngressPorts,
+	}
+
+	for _, step := range steps {
+		if err := step(spec); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (r *ServiceSpecResolver) applyDefaults(spec *api.ServiceSpec) error {
+	if spec.Mode == "" {
+		spec.Mode = api.ServiceModeReplicated
+	}
+	// Ensure the replicated service has at least one replica.
+	if spec.Mode == api.ServiceModeReplicated && spec.Replicas == 0 {
+		spec.Replicas = 1
+	}
+
+	return nil
+}
+
+func (r *ServiceSpecResolver) resolveServiceName(spec *api.ServiceSpec) error {
+	if spec.Name != "" {
+		return nil
+	}
+
+	// Generate a random service name from the image when not provided.
+	img, err := reference.ParseDockerRef(spec.Container.Image)
+	if err != nil {
+		return fmt.Errorf("invalid image: %w", err)
+	}
+	// Get the image name without the repository and tag/digest parts.
+	imageName := reference.FamiliarName(img)
+	// Get the last part of the image name (path), e.g. "nginx" from "bitnami/nginx".
+	if i := strings.LastIndex(imageName, "/"); i != -1 {
+		imageName = imageName[i+1:]
+	}
+	// Append a random suffix to the image name to generate an optimistically unique service name.
+	suffix, err := secret.RandomAlphaNumeric(4)
+	if err != nil {
+		return fmt.Errorf("generate random suffix: %w", err)
+	}
+	spec.Name = fmt.Sprintf("%s-%s", imageName, suffix)
+
+	return nil
+}
+
+func (r *ServiceSpecResolver) resolveImageDigest(spec *api.ServiceSpec) error {
+	if r.ImageResolver == nil {
+		// Skip digest resolution when no resolver is provided.
+		return nil
+	}
+
+	imageDigest, err := r.ImageResolver.Resolve(spec.Container.Image)
+	if err != nil {
+		return fmt.Errorf("resolve image digest: %w", err)
+	}
+	spec.Container.Image = imageDigest
+
+	return nil
+}
+
+// expandIngressPorts processes HTTP(S) ingress ports in a service spec by:
+// 1. Setting a default hostname (service-name.cluster-domain) for ports without a hostname.
+// 2. Duplicating a port with a cluster domain hostname for ports with external domains.
+// This ensures every ingress port is accessible via the cluster domain, while preserving any custom domains specified
+// by the user.
+func (r *ServiceSpecResolver) expandIngressPorts(spec *api.ServiceSpec) error {
+	for i, port := range spec.Ports {
+		if port.Protocol != api.ProtocolHTTP && port.Protocol != api.ProtocolHTTPS {
+			continue
+		}
+
+		if port.Hostname == "" {
+			if r.ClusterDomain == "" {
+				return fmt.Errorf("cluster domain must be reserved to generate hostname for ingress port: %d/%s",
+					port.ContainerPort, port.Protocol)
+			}
+			// Assign the default hostname (service-name.cluster-domain).
+			spec.Ports[i].Hostname = fmt.Sprintf("%s.%s", spec.Name, r.ClusterDomain)
+		} else {
+			if r.ClusterDomain == "" {
+				// When no cluster domain is reserved, use only the provided hostname.
+				continue
+			}
+
+			if strings.HasSuffix(port.Hostname, "."+r.ClusterDomain) {
+				// If the hostname is already a cluster subdomain, use as is.
+				continue
+			}
+			// For external domains, duplicate the port with a service-name.cluster-domain hostname so the service
+			// can be accessed via both hostnames.
+			newPort := port
+			newPort.Hostname = fmt.Sprintf("%s.%s", spec.Name, r.ClusterDomain)
+			spec.Ports = append(spec.Ports, newPort)
+		}
+	}
+
+	return nil
+}