support JSON key and version for secretsmanager secrets specified

for roadmap issue #385
aws/containers-roadmap#385
this commit adds the ability for customers to add parameters
to the secretsmanager ARN specified in containers. agent will be
able to retrieve secret by version or retrieve part of a secret
by json key.
this commit also fixes a minor issue breaking go vet in an unrelated test.

.gitignore

@@ -22,3 +22,4 @@ _bin/
 /misc/v3-task-endpoint-validator/v3-task-endpoint-validator
 /misc/elastic-inference-validator/elastic-inference-validator
 /bin
+*.iml

agent/asm/asm.go

@@ -15,10 +15,12 @@ package asm
 
 import (
 	"encoding/json"
+	"fmt"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/secretsmanager"
 	"github.com/aws/aws-sdk-go/service/secretsmanager/secretsmanageriface"
+	"github.com/cihub/seelog"
 	"github.com/docker/docker/api/types"
 	"github.com/pkg/errors"
 )
@@ -87,6 +89,33 @@ func extractASMValue(out *secretsmanager.GetSecretValueOutput) (types.AuthConfig
 	return dac, nil
 }
 
+func GetSecretFromASMWithInput(input *secretsmanager.GetSecretValueInput,
+	client secretsmanageriface.SecretsManagerAPI, jsonKey string) (string, error) {
+	out, err := client.GetSecretValue(input)
+	if err != nil {
+		return "", errors.Wrapf(err, "secret %s", *input.SecretId)
+	}
+
+	if jsonKey == "" {
+		return aws.StringValue(out.SecretString), nil
+	}
+
+	secretMap := make(map[string]interface{})
+	jsonErr := json.Unmarshal([]byte(*out.SecretString), &secretMap)
+	if jsonErr != nil {
+		seelog.Warnf("Error when treating retrieved secret value with secret id %s as JSON and calling unmarshal.", *input.SecretId)
+		return "", jsonErr
+	}
+
+	secretValue, ok := secretMap[jsonKey]
+	if !ok {
+		err = errors.New(fmt.Sprintf("Retrieved secret from Secrets Manager did not contain json key %s", jsonKey))
+		return "", err
+	}
+
+	return fmt.Sprintf("%v", secretValue), nil
+}
+
 // GetSecretFromASM makes the api call to the AWS Secrets Manager service to
 // retrieve the secret value
 func GetSecretFromASM(secretID string, client secretsmanageriface.SecretsManagerAPI) (string, error) {

agent/asm/asm_test.go

@@ -22,6 +22,17 @@ import (
 	"github.com/aws/aws-sdk-go/service/secretsmanager"
 	"github.com/aws/aws-sdk-go/service/secretsmanager/secretsmanageriface"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	versionID                = "versionId"
+	versionStage             = "versionStage"
+	jsonKey                  = "jsonKey"
+	valueFrom                = "arn:aws:secretsmanager:region:account-id:secret:secretId"
+	secretValue              = "secretValue"
+	jsonSecretValue          = "{\"" + jsonKey + "\": \"" + secretValue + "\",\"some-other-key\": \"secret2\"}"
+	malformedJsonSecretValue = "{\"" + jsonKey + "\": \"" + secretValue
 )
 
 type mockGetSecretValue struct {
@@ -111,11 +122,70 @@ func TestASMGetAuthConfig(t *testing.T) {
 }
 
 func TestGetSecretFromASM(t *testing.T) {
-	asmClient := mockGetSecretValue{
+	asmClient := createASMInterface(secretValue)
+	_, err := GetSecretFromASM("secretName", asmClient)
+	assert.NoError(t, err)
+}
+
+func TestGetSecretFromASMWithJsonKey(t *testing.T) {
+	asmClient := createASMInterface(jsonSecretValue)
+	secretValueInput := createSecretValueInput(toPtr(valueFrom), nil, nil)
+	outSecretValue, _ := GetSecretFromASMWithInput(secretValueInput, asmClient, jsonKey)
+	assert.Equal(t, secretValue, outSecretValue)
+}
+
+func TestGetSecretFromASMWithMalformedJSON(t *testing.T) {
+	asmClient := createASMInterface(malformedJsonSecretValue)
+	secretValueInput := createSecretValueInput(toPtr(valueFrom), nil, nil)
+	outSecretValue, err := GetSecretFromASMWithInput(secretValueInput, asmClient, jsonKey)
+	require.Error(t, err)
+	assert.Equal(t, "", outSecretValue)
+}
+
+func TestGetSecretFromASMWithJSONKeyNotFound(t *testing.T) {
+	asmClient := createASMInterface(jsonSecretValue)
+	secretValueInput := createSecretValueInput(toPtr(valueFrom), nil, nil)
+	nonExistentKey := "nonExistentKey"
+	_, err := GetSecretFromASMWithInput(secretValueInput, asmClient, nonExistentKey)
+	assert.Error(t, err)
+}
+
+func TestGetSecretFromASMWithVersionID(t *testing.T) {
+	asmClient := createASMInterface(secretValue)
+	secretValueInput := createSecretValueInput(toPtr(valueFrom), toPtr(versionID), nil)
+	outSecretValue, err := GetSecretFromASMWithInput(secretValueInput, asmClient, "")
+	require.NoError(t, err)
+	assert.Equal(t, secretValue, outSecretValue)
+}
+
+func TestGetSecretFromASMWithVersionIDAndStage(t *testing.T) {
+	asmClient := createASMInterface(secretValue)
+	secretValueInput := createSecretValueInput(toPtr(valueFrom), toPtr(versionID), toPtr(versionStage))
+	outSecretValue, err := GetSecretFromASMWithInput(secretValueInput, asmClient, "")
+	require.NoError(t, err)
+	assert.Equal(t, secretValue, outSecretValue)
+}
+
+func toPtr(input string) *string {
+	if input == "" {
+		return nil
+	}
+	output := input
+	return &output
+}
+
+func createSecretValueInput(secretID *string, versionID *string, versionStage *string) *secretsmanager.GetSecretValueInput {
+	return &secretsmanager.GetSecretValueInput{
+		SecretId:     secretID,
+		VersionId:    versionID,
+		VersionStage: versionStage,
+	}
+}
+
+func createASMInterface(secretValue string) mockGetSecretValue {
+	return mockGetSecretValue{
 		Resp: secretsmanager.GetSecretValueOutput{
-			SecretString: aws.String("secretValue"),
+			SecretString: aws.String(secretValue),
 		},
 	}
-	_, err := GetSecretFromASM("secretName", asmClient)
-	assert.NoError(t, err)
 }

agent/engine/docker_task_engine_test.go

@@ -2503,7 +2503,7 @@ func TestTaskSecretsEnvironmentVariables(t *testing.T) {
 
 	// metadata required for asm secret resource validation
 	asmSecretName := "myASMSecret"
-	asmSecretValueFrom := "asm/mySecret"
+	asmSecretValueFrom := "arn:aws:secretsmanager:region:account-id:secret:" + asmSecretName
 	asmSecretRetrievedValue := "myASMSecretValue"
 	asmSecretRegion := "us-west-2"
 	asmSecretKey := asmSecretValueFrom + "_" + asmSecretRegion
@@ -2700,7 +2700,7 @@ func TestTaskSecretsEnvironmentVariables(t *testing.T) {
 			}).Return(ssmClientOutput, nil).Times(1)
 
 			mockASMClient.EXPECT().GetSecretValue(gomock.Any()).Do(func(in *secretsmanager.GetSecretValueInput) {
-				assert.Equal(t, aws.StringValue(in.SecretId), asmSecretValueFrom)
+				assert.Equal(t, asmSecretValueFrom, aws.StringValue(in.SecretId))
 			}).Return(asmClientOutput, nil).Times(1)
 
 			require.NoError(t, ssmSecretRes.Create())

agent/engine/engine_unix_integ_test.go

@@ -998,7 +998,7 @@ func TestDockerCfgAuth(t *testing.T) {
 			return nil
 		}
 		data, err := ioutil.ReadFile(path)
-		t.Log("Reading file:%s", path)
+		t.Logf("Reading file:%s", path)
 		if err != nil {
 			return err
 		}

agent/taskresource/asmsecret/asmsecret.go

@@ -30,11 +30,17 @@ import (
 	"github.com/aws/amazon-ecs-agent/agent/credentials"
 	"github.com/aws/amazon-ecs-agent/agent/taskresource"
 	resourcestatus "github.com/aws/amazon-ecs-agent/agent/taskresource/status"
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/arn"
+	"github.com/aws/aws-sdk-go/service/secretsmanager"
 )
 
 const (
 	// ResourceName is the name of the asmsecret resource
-	ResourceName = "asmsecret"
+	ResourceName                       = "asmsecret"
+	arnDelimiter                       = ":"
+	asmARNResourceFormat               = "secret:{secretID}"
+	asmARNResourceWithParametersFormat = "secret:secretID:jsonKey:versionStage:versionID"
 )
 
 // ASMSecretResource represents secrets as a task resource.
@@ -294,8 +300,19 @@ func (secret *ASMSecretResource) retrieveASMSecretValue(apiSecret apicontainer.S
 
 	asmClient := secret.asmClientCreator.NewASMClient(apiSecret.Region, iamCredentials)
 	seelog.Infof("ASM secret resource: retrieving resource for secret %v in region %s for task: [%s]", apiSecret.ValueFrom, apiSecret.Region, secret.taskARN)
-	//for asm secret, ValueFrom can be arn or name
-	secretValue, err := asm.GetSecretFromASM(apiSecret.ValueFrom, asmClient)
+	input, jsonKey, err := getASMParametersFromInput(apiSecret.ValueFrom)
+	if err != nil {
+		errorEvents <- fmt.Errorf("trying to retrieve secret with value %s resulted in error: %v", apiSecret.ValueFrom, err)
+		return
+	}
+
+	if input.SecretId == nil {
+		errorEvents <- fmt.Errorf("could not find a secretsmanager secretID from value %s", apiSecret.ValueFrom)
+		return
+
+	}
+
+	secretValue, err := asm.GetSecretFromASMWithInput(input, asmClient, jsonKey)
 	if err != nil {
 		errorEvents <- fmt.Errorf("fetching secret data from AWS Secrets Manager in region %s: %v", apiSecret.Region, err)
 		return
@@ -309,6 +326,65 @@ func (secret *ASMSecretResource) retrieveASMSecretValue(apiSecret apicontainer.S
 	secret.secretData[secretKey] = secretValue
 }
 
+func pointerOrNil(in string) *string {
+	if in == "" {
+		return nil
+	}
+
+	return aws.String(in)
+}
+
+// Agent follows what Cloudformation does here with using Dynamic References to specify Template Values
+// in the format secret-id:json-key:version-stage:version-id
+// the input will always be a full ARN for ASM
+func getASMParametersFromInput(valueFrom string) (input *secretsmanager.GetSecretValueInput, jsonKey string, err error) {
+	arnObj, err := arn.Parse(valueFrom)
+	if err != nil {
+		seelog.Warnf("Unable to parse ARN %s when trying to retrieve ASM secret", valueFrom)
+		return nil, "", err
+	}
+
+	input = &secretsmanager.GetSecretValueInput{}
+
+	paramValues := strings.Split(arnObj.Resource, arnDelimiter) // arnObj.Resource looks like secret:secretID:...
+	if len(paramValues) == len(strings.Split(asmARNResourceFormat, arnDelimiter)) {
+		input.SecretId = &valueFrom
+		return input, "", nil
+	}
+	if len(paramValues) != len(strings.Split(asmARNResourceWithParametersFormat, arnDelimiter)) {
+		// can't tell what input this is, throw some error
+		err = errors.New("unexpected ARN format with parameters when trying to retrieve ASM secret")
+		return nil, "", err
+	}
+
+	input.SecretId = pointerOrNil(reconstructASMARN(arnObj))
+	jsonKey = paramValues[2]
+	input.VersionStage = pointerOrNil(paramValues[3])
+	input.VersionId = pointerOrNil(paramValues[4])
+
+	return input, jsonKey, nil
+}
+
+// this method is to reconstruct an ASM ARN that has the enhancement parameters
+// attached to it. in order to call secretsmanager:GetSecretValue, the entire ARN
+// (including the 6 character special identifier tacked on by ASM) is required or
+// just the secret name itself is required.
+func reconstructASMARN(arnARN arn.ARN) string {
+	// arn resource should look like secret:secretID:jsonKey:versionStage:versionID
+	secretIDAndParams := strings.Split(arnARN.Resource, arnDelimiter)
+	// reconstruct the secret id without the parameters
+	secretID := fmt.Sprintf("%s%s%s", secretIDAndParams[0], arnDelimiter, secretIDAndParams[1])
+	secretIDARN := arn.ARN{
+		Partition: arnARN.Partition,
+		Service:   arnARN.Service,
+		Region:    arnARN.Region,
+		AccountID: arnARN.AccountID,
+		Resource:  secretID,
+	}.String()
+
+	return secretIDARN
+}
+
 // getRequiredSecrets returns the requiredSecrets field of asmsecret task resource
 func (secret *ASMSecretResource) getRequiredSecrets() map[string]apicontainer.Secret {
 	secret.lock.RLock()