New input skip_push_if_tag_exists (#472)

Author: Ompragash

cmd/drone-ecr/main.go

@@ -22,6 +22,10 @@ import (
 	docker "github.com/drone-plugins/drone-docker"
 )
 
+type ecrAPI interface {
+	DescribeImages(*ecr.DescribeImagesInput) (*ecr.DescribeImagesOutput, error)
+}
+
 const defaultRegion = "us-east-1"
 
 func main() {
@@ -31,18 +35,19 @@ func main() {
 	}
 
 	var (
-		repo             = getenv("PLUGIN_REPO")
-		registry         = getenv("PLUGIN_REGISTRY")
-		region           = getenv("PLUGIN_REGION", "ECR_REGION", "AWS_REGION")
-		key              = getenv("PLUGIN_ACCESS_KEY", "ECR_ACCESS_KEY", "AWS_ACCESS_KEY_ID")
-		secret           = getenv("PLUGIN_SECRET_KEY", "ECR_SECRET_KEY", "AWS_SECRET_ACCESS_KEY")
-		create           = parseBoolOrDefault(false, getenv("PLUGIN_CREATE_REPOSITORY", "ECR_CREATE_REPOSITORY"))
-		lifecyclePolicy  = getenv("PLUGIN_LIFECYCLE_POLICY")
-		repositoryPolicy = getenv("PLUGIN_REPOSITORY_POLICY")
-		assumeRole       = getenv("PLUGIN_ASSUME_ROLE")
-		externalId       = getenv("PLUGIN_EXTERNAL_ID")
-		scanOnPush       = parseBoolOrDefault(false, getenv("PLUGIN_SCAN_ON_PUSH"))
-		idToken          = os.Getenv("PLUGIN_OIDC_TOKEN_ID")
+		repo                = getenv("PLUGIN_REPO")
+		registry            = getenv("PLUGIN_REGISTRY")
+		region              = getenv("PLUGIN_REGION", "ECR_REGION", "AWS_REGION")
+		key                 = getenv("PLUGIN_ACCESS_KEY", "ECR_ACCESS_KEY", "AWS_ACCESS_KEY_ID")
+		secret              = getenv("PLUGIN_SECRET_KEY", "ECR_SECRET_KEY", "AWS_SECRET_ACCESS_KEY")
+		create              = parseBoolOrDefault(false, getenv("PLUGIN_CREATE_REPOSITORY", "ECR_CREATE_REPOSITORY"))
+		lifecyclePolicy     = getenv("PLUGIN_LIFECYCLE_POLICY")
+		repositoryPolicy    = getenv("PLUGIN_REPOSITORY_POLICY")
+		assumeRole          = getenv("PLUGIN_ASSUME_ROLE")
+		externalId          = getenv("PLUGIN_EXTERNAL_ID")
+		scanOnPush          = parseBoolOrDefault(false, getenv("PLUGIN_SCAN_ON_PUSH"))
+		idToken             = os.Getenv("PLUGIN_OIDC_TOKEN_ID")
+		skipPushIfTagExists = parseBoolOrDefault(false, getenv("PLUGIN_SKIP_PUSH_IF_TAG_EXISTS"))
 	)
 
 	// set the region
@@ -114,6 +119,34 @@ func main() {
 	os.Setenv("DOCKER_PASSWORD", password)
 	os.Setenv("PLUGIN_REGISTRY_TYPE", "ECR")
 
+	// Skip if tag already exits for both mutable and immutable repos
+	if skipPushIfTagExists {
+		tagInput := getenv("PLUGIN_TAG", "PLUGIN_TAGS")
+		var tags []string
+		if tagInput == "" {
+			tags = []string{"latest"}
+		} else {
+			for _, t := range strings.Split(tagInput, ",") {
+				trimmed := strings.TrimSpace(t)
+				if trimmed != "" {
+					tags = append(tags, trimmed)
+				}
+			}
+		}
+
+		repositoryName := trimHostname(repo, registry)
+		for _, t := range tags {
+			exists, err := tagExists(svc, repositoryName, t)
+			if err != nil {
+				logrus.Fatalf("Error checking if image exists for tag %s: %v", t, err)
+			}
+			if exists {
+				logrus.Infof("%s:%s: Image tag exists. Skipping push.", repo, t)
+				os.Exit(0)
+			}
+		}
+	}
+
 	// invoke the base docker plugin binary
 	cmd := exec.Command(docker.GetDroneDockerExecCmd())
 	cmd.Stdout = os.Stdout
@@ -249,3 +282,20 @@ func getECRClient(sess *session.Session, role string, externalId string, idToken
 		})
 	}
 }
+
+func tagExists(svc ecrAPI, repository, tag string) (bool, error) {
+	input := &ecr.DescribeImagesInput{
+		RepositoryName: aws.String(repository),
+		ImageIds: []*ecr.ImageIdentifier{
+			{ImageTag: aws.String(tag)},
+		},
+	}
+	output, err := svc.DescribeImages(input)
+	if err != nil {
+		if aerr, ok := err.(awserr.Error); ok && aerr.Code() == "ImageNotFoundException" {
+			return false, nil
+		}
+		return false, err
+	}
+	return len(output.ImageDetails) > 0, nil
+}