[PLT-8186] add support for ec2 instance profile authentication (#8243)

utils/file_backend_s3.go

@@ -37,7 +37,10 @@ type S3FileBackend struct {
 // disables automatic region lookup.
 func (b *S3FileBackend) s3New() (*s3.Client, error) {
 	var creds *credentials.Credentials
-	if b.signV2 {
+
+	if b.accessKey == "" && b.secretKey == "" {
+		creds = credentials.NewIAM("")
+	} else if b.signV2 {
 		creds = credentials.NewStatic(b.accessKey, b.secretKey, "", credentials.SignatureV2)
 	} else {
 		creds = credentials.NewStatic(b.accessKey, b.secretKey, "", credentials.SignatureV4)
@@ -244,3 +247,19 @@ func s3CopyMetadata(encrypt bool) map[string]string {
 	metaData["x-amz-server-side-encryption"] = "AES256"
 	return metaData
 }
+
+func CheckMandatoryS3Fields(settings *model.FileSettings) *model.AppError {
+	if len(settings.AmazonS3Bucket) == 0 {
+		return model.NewAppError("S3File", "api.admin.test_s3.missing_s3_bucket", nil, "", http.StatusBadRequest)
+	}
+
+	if len(settings.AmazonS3Endpoint) == 0 {
+		return model.NewAppError("S3File", "api.admin.test_s3.missing_s3_endpoint", nil, "", http.StatusBadRequest)
+	}
+
+	if len(settings.AmazonS3Region) == 0 {
+		return model.NewAppError("S3File", "api.admin.test_s3.missing_s3_region", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}

utils/file_backend_s3_test.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2018-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package utils
+
+import (
+	"testing"
+
+	"github.com/mattermost/mattermost-server/model"
+)
+
+func TestCheckMandatoryS3Fields(t *testing.T) {
+	cfg := model.FileSettings{}
+
+	err := CheckMandatoryS3Fields(&cfg)
+	if err == nil || err.Message != "api.admin.test_s3.missing_s3_bucket" {
+		t.Fatal("should've failed with missing s3 bucket")
+	}
+
+	cfg.AmazonS3Bucket = "test-mm"
+	err = CheckMandatoryS3Fields(&cfg)
+	if err == nil || err.Message != "api.admin.test_s3.missing_s3_endpoint" {
+		t.Fatal("should've failed with missing s3 endpoint")
+	}
+
+	cfg.AmazonS3Endpoint = "s3.newendpoint.com"
+	err = CheckMandatoryS3Fields(&cfg)
+	if err == nil || err.Message != "api.admin.test_s3.missing_s3_region" {
+		t.Fatal("should've failed with missing s3 region")
+	}
+
+}