dependencies

1 files changed, 25 insertions, 2 deletions

diff --git a/internal/resource/resource.go b/internal/resource/resource.go
index 2a01629..1cf451a 100644
--- a/internal/resource/resource.go
+++ b/internal/resource/resource.go
@@ -3,6 +3,7 @@ package resource
 import (
 	"fmt"
 	"log"
+	"sort"
 )
 
 type Applier interface {
@@ -22,12 +23,17 @@ type Resource struct {
 	dependsOn map[string]struct{}
 }
 
-func Register(type_, name string, apply Applier) Resource {
+func Register(type_, name string, apply Applier, deps ...string) Resource {
+	dependsOn := make(map[string]struct{}, len(deps))
+	for _, id := range deps {
+		dependsOn[id] = struct{}{}
+	}
+
 	r := Resource{
 		Type:      type_,
 		Name:      name,
 		applier:   apply,
-		dependsOn: make(map[string]struct{}),
+		dependsOn: dependsOn,
 	}
 
 	if err := getRepository().register(r); err != nil {
@@ -45,6 +51,23 @@ func (r Resource) ID() string {
 	return fmt.Sprintf("%s[%s]", r.Type, r.Name)
 }
 
+// Dependencies returns this resource's own ID. It lets a single Resource be
+// used as a DependsOn target, mirroring Multi.Dependencies.
+func (r Resource) Dependencies() []string {
+	return []string{r.ID()}
+}
+
+// sortedDependsOn returns the IDs this resource depends on, sorted for stable
+// and readable log output.
+func (r Resource) sortedDependsOn() []string {
+	ids := make([]string, 0, len(r.dependsOn))
+	for id := range r.dependsOn {
+		ids = append(ids, id)
+	}
+	sort.Strings(ids)
+	return ids
+}
+
 func (r Resource) Apply() error {
 	return r.applier.Apply()
 }