blueprint: add support for containers

Add a new `containers` section that can be used to request the
embedding of containers into images. The only requirement is
the source property to specify where to fetch the container from.
This suppports specifying the digest of the container or the tag.
In case none is given it defaults to the `latest` tag. The `Name`
field can be used to optionally specify a name to use inside the
image.
NB: currently no tools or apis support container resolution yet.
This follows in the next commits.

cmd/gen-manifests/main.go

@@ -49,6 +49,7 @@ type crBlueprint struct {
 	Packages       []blueprint.Package       `json:"packages,omitempty"`
 	Modules        []blueprint.Package       `json:"modules,omitempty"`
 	Groups         []blueprint.Group         `json:"groups,omitempty"`
+	Containers     []blueprint.Container     `json:"containers,omitempty"`
 	Customizations *blueprint.Customizations `json:"customizations,omitempty"`
 	Distro         string                    `json:"distro,omitempty"`
 }

internal/blueprint/blueprint.go

@@ -18,6 +18,7 @@ type Blueprint struct {
 	Packages       []Package       `json:"packages" toml:"packages"`
 	Modules        []Package       `json:"modules" toml:"modules"`
 	Groups         []Group         `json:"groups" toml:"groups"`
+	Containers     []Container     `json:"containers,omitempty" toml:"containers,omitempty"`
 	Customizations *Customizations `json:"customizations,omitempty" toml:"customizations,omitempty"`
 	Distro         string          `json:"distro" toml:"distro"`
 }
@@ -41,6 +42,13 @@ type Group struct {
 	Name string `json:"name" toml:"name"`
 }
 
+type Container struct {
+	Source string `json:"source" toml:"source"`
+	Name   string `json:"name,omitempty" toml:"name,omitempty"`
+
+	TLSVerify *bool `json:"tls-verify,omitempty" toml:"tls-verify,omitempty"`
+}
+
 // DeepCopy returns a deep copy of the blueprint
 // This uses json.Marshal and Unmarshal which are not very efficient
 func (b *Blueprint) DeepCopy() Blueprint {