cli: use Bazel container images

internal/containerimage/containerimage.go

@@ -0,0 +1,112 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+/*
+This package provides container image names, registry info and digests.
+
+It should only be used by the CLI and never be imported by any package that
+ends up in a container image to avoid circular dependencies.
+*/
+package containerimage
+
+import (
+	"errors"
+	"path"
+	"regexp"
+)
+
+// Image is a container image reference.
+// It has the following format:
+// <registry>/<prefix>/<name>:<tag>@<digest>
+// where <registry> is the registry where the image is located,
+// <prefix> is the (optional) prefix of the image name,
+// <name> is the name of the image,
+// <tag> is the (optional) tag of the image,
+// <digest> is the digest of the image.
+type Image struct {
+	// Registry is the registry where the image is located.
+	Registry string
+	// Prefix is the prefix of the image name.
+	Prefix string
+	// Name is the name of the image.
+	Name string
+	// Tag is the tag of the image.
+	Tag string
+	// Digest is the digest of the image.
+	Digest string
+}
+
+// Validate validates the image.
+func (i Image) Validate() error {
+	if i.Registry == "" {
+		return errors.New("image registry is empty")
+	}
+	if i.Name == "" {
+		return errors.New("image name is empty")
+	}
+	if i.Digest == "" {
+		return errors.New("image digest is empty")
+	}
+	if matched := digestRegexp.MatchString(i.Digest); !matched {
+		return errors.New("image digest is not valid")
+	}
+
+	return nil
+}
+
+// String returns the image as a string.
+// The format is <registry>/<prefix>/<name>:<tag>@<digest>
+// or a shorter version if prefix or tag are empty.
+func (i Image) String() string {
+	var base string
+	if i.Prefix == "" {
+		base = path.Join(i.Registry, i.Name)
+	} else {
+		base = path.Join(i.Registry, i.Prefix, i.Name)
+	}
+	var tag string
+	if i.Tag != "" {
+		tag = ":" + i.Tag
+	}
+	return base + tag + "@" + i.Digest
+}
+
+// Builder is a builder for container images.
+type Builder struct {
+	Default  Image
+	Registry string
+	Prefix   string
+}
+
+// NewBuilder creates a new builder for container images.
+func NewBuilder(def Image, registry, prefix string) *Builder {
+	return &Builder{
+		Default:  def,
+		Registry: registry,
+		Prefix:   prefix,
+	}
+}
+
+// Build builds a container image.
+func (b *Builder) Build() Image {
+	img := Image{}
+	if b.Registry == "" {
+		img.Registry = b.Default.Registry
+	} else {
+		img.Registry = b.Registry
+	}
+	if b.Prefix == "" {
+		img.Prefix = b.Default.Prefix
+	} else {
+		img.Prefix = b.Prefix
+	}
+	img.Name = b.Default.Name
+	img.Tag = b.Default.Tag
+	img.Digest = b.Default.Digest
+	return img
+}
+
+var digestRegexp = regexp.MustCompile(`^sha256:[a-f0-9]{64}$`)