How do I resolve the error that I receive in CloudFormation when I try to publish slow logs to CloudWatch Logs?
Last updated: 2021-03-16
I want to resolve the error that I receive in AWS CloudFormation when I try to publish slow logs to Amazon CloudWatch Logs. The error is: "The Resource Access Policy specified for the CloudWatch Logs log group /aws/aes/domains/search/search-logs does not grant sufficient permissions for Amazon Elasticsearch Service to create a log stream."
Short description
To resolve this error, use a separate policy at the log group level to allow Amazon Elasticsearch Service (Amazon ES) to push logs to CloudWatch Logs. Then, use AccessPolicies in the AWS::Elasticsearch::Domain resource to set permissions for Amazon ES domains.
The following steps show you how to publish slow logs to CloudWatch with CloudFormation by using an AWS Lambda-backed custom resource created in Python 3.6. The custom resource triggers a Lambda function, which triggers the PutResourcePolicy API to publish slow logs.
Note: When CloudFormation enables log publishing to CloudWatch, the AWS::Logs::LogGroup resource doesn't have a property to assign a resource access policy. The resource access policy specified for the CloudWatch Logs log group should grant sufficient permissions for Amazon ES to publish the log stream. You can't create an access policy permission directly using a CloudFormation resource. This is because the PutResourcePolicy API call for the AWS::Logs::LogGroup resource isn't supported by CloudFormation.
Resolution
Note: If you receive errors when running AWS Command Line Interface (AWS CLI) commands, make sure that you’re using the most recent AWS CLI version.
The following CloudFormation template uses a custom resource to get the name of the log group. Then, the template applies the policy that allows the Amazon ES service to make API calls on the log group.
1. Create a CloudFormation template called ESlogsPermission.yaml:
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AWSTemplateFormatVersion: 2010-09-09
Description: AWS cloudFormation template to publish slow logs to Amazon CloudWatch Logs.
Parameters:
LogGroupName:
Type: String
Description: Please don't change the log group name while updating
ESDomainName:
Description: A name for the Amazon Elastic Search domain
Type: String
LambdaFunctionName:
Description: Lambda Function Name
Type: String
Resources:
AwsLogGroup:
Type: 'AWS::Logs::LogGroup'
Properties:
LogGroupName: !Ref LogGroupName
LambdaLogGroup:
Type: 'AWS::Logs::LogGroup'
Properties:
LogGroupName: !Sub '/aws/lambda/${LambdaFunctionName}'
LambdaExecutionRole:
Type: 'AWS::IAM::Role'
Properties:
AssumeRolePolicyDocument:
Version: 2012-10-17
Statement:
- Effect: Allow
Principal:
Service:
- lambda.amazonaws.com
Action:
- 'sts:AssumeRole'
Path: /
Policies:
- PolicyName: root1
PolicyDocument:
Version: 2012-10-17
Statement:
- Effect: Allow
Action:
- 'logs:CreateLogStream'
- 'logs:PutLogEvents'
Resource: !Sub >-
arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/${LambdaFunctionName}:log-stream:*
- PolicyName: root2
PolicyDocument:
Version: 2012-10-17
Statement:
- Effect: Allow
Action:
- 'logs:CreateLogGroup'
Resource:
- !Sub >-
arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/${LambdaFunctionName}
- !Sub >-
arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/${LogGroupName}
- Effect: Allow
Action:
- 'logs:PutResourcePolicy'
- 'logs:DeleteResourcePolicy'
Resource: !Sub 'arn:aws:logs:${AWS::Region}:${AWS::AccountId}:*'
logGroupPolicyFunction:
DependsOn: LambdaLogGroup
Type: 'AWS::Lambda::Function'
Properties:
FunctionName: !Ref LambdaFunctionName
Code:
ZipFile: >
import urllib3
import json
import boto3
http = urllib3.PoolManager()
SUCCESS = "SUCCESS"
FAILED = "FAILED"
def send(event, context, responseStatus, responseData,
physicalResourceId=None, noEcho=False):
responseUrl = event['ResponseURL']
print(responseUrl)
responseBody = {}
responseBody['Status'] = responseStatus
responseBody['Reason'] = 'See the details in CloudWatch Log Stream: ' + context.log_stream_name
responseBody['PhysicalResourceId'] = physicalResourceId or context.log_stream_name
responseBody['StackId'] = event['StackId']
responseBody['RequestId'] = event['RequestId']
responseBody['LogicalResourceId'] = event['LogicalResourceId']
responseBody['NoEcho'] = noEcho
responseBody['Data'] = responseData
json_responseBody = json.dumps(responseBody)
print("Response body:\n" + json_responseBody)
headers = {
'content-type' : '',
'content-length' : str(len(json_responseBody))
}
try:
response = http.request('PUT',responseUrl,body=json_responseBody.encode('utf-8'),headers=headers)
print("Status code: " + response.reason)
except Exception as e:
print("send(..) failed executing requests.put(..): " + str(e))
def handler(event, context):
logsgroup_policy_name=event['ResourceProperties']['CWLOGS_NAME']
cw_log_group_arn=event['ResourceProperties']['CWLOG_ARN']
cwlogs = boto3.client('logs')
loggroup_policy={
"Version": "2012-10-17",
"Statement": [{
"Sid": "",
"Effect": "Allow",
"Principal": { "Service": "es.amazonaws.com"},
"Action":[
"logs:PutLogEvents",
" logs:PutLogEventsBatch",
"logs:CreateLogStream"
],
'Resource': f'{cw_log_group_arn}'
}]
}
loggroup_policy = json.dumps(loggroup_policy)
if(event['RequestType'] == 'Delete'):
print("Request Type:",event['RequestType'])
cwlogs.delete_resource_policy(
policyName=logsgroup_policy_name
)
responseData={}
send(event, context, SUCCESS, responseData)
elif(event['RequestType'] == 'Create'):
try:
cwlogs.put_resource_policy(
policyName = logsgroup_policy_name,
policyDocument = loggroup_policy
)
responseData={}
print("Sending response to custom resource")
send(event, context, SUCCESS, responseData)
except Exception as e:
print('Failed to process:', e)
send(event, context, FAILED, responseData)
elif(event['RequestType'] == 'Update'):
try:
responseData={}
print("Update is not supported on this resource")
send(event, context, SUCCESS, responseData)
except Exception as e:
print('Failed to process:', e)
send(event, context, FAILED, responseData)
Handler: index.handler
Role: !GetAtt
- LambdaExecutionRole
- Arn
Runtime: python3.6
logGroupPolicycustomresource:
Type: 'Custom::LogGroupPolicy'
Properties:
ServiceToken: !GetAtt
- logGroupPolicyFunction
- Arn
CWLOGS_NAME: !Ref LogGroupName
CWLOG_ARN: !GetAtt
- AwsLogGroup
- Arn
ElasticsearchDomain:
Type: 'AWS::Elasticsearch::Domain'
DependsOn: logGroupPolicycustomresource
Properties:
DomainName: !Ref ESDomainName
ElasticsearchVersion: '6.2'
EBSOptions:
EBSEnabled: true
VolumeSize: 10
VolumeType: gp2
LogPublishingOptions:
SEARCH_SLOW_LOGS:
CloudWatchLogsLogGroupArn: !GetAtt
- AwsLogGroup
- Arn
Enabled: true
2. To launch a CloudFormation stack with the ESlogsPermission.yaml file, use the CloudFormation console or the following AWS CLI command:
aws cloudformation create-stack --stack-name yourStackName --template-body file://yourTemplateName --parameters ParameterKey=LogGroupName,ParameterValue=Your-LogGroup-Name, ParameterKey=ESDomainName,ParameterValue=Your-ES-Name --capabilities CAPABILITY_NAMED_IAM --region yourRegion
Note: Replace yourStackName, yourTemplateName, Your-LogGroup-Name, Your-ES-Name, and yourRegion with your values.
The CloudFormation template does the following for you:
2. Creates a Lambda function. The Lambda function gets the log group name from the Parameters section of the CloudFormation template by using a custom resource. The Lambda function calls the PutResourcePolicy API for the log group name. The log group must have a policy to allow the Amazon ES domain to put the logs.
3. Creates a Lambda-backed custom resource to invoke the Lambda function created in step 2. The custom resource helps apply PutResourcePolicy on the log group Amazon Resource Name (ARN) so that Amazon ES can stream logs. In the template, CloudFormation uses a custom resource to create an Amazon ES domain with the LogPublishingOption.
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