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Lambda Promtail

Deploy with CloudFormation

Open source

Deploy with CloudFormation

Deploy Lambda Promtail with the CloudFormation templates in the lambda-promtail repository.

The repository provides the following templates:

lambda-promtail.yaml: Forwards Amazon CloudWatch logs. It subscribes one CloudWatch log group to the function.
aws-eventbridge-logs.yaml: Forwards S3-based logs using EventBridge. Use this template to work around the S3 bucket notification limitation described in Forward S3 logs with EventBridge.
aws-alb-logs.yaml: Forwards Application Load Balancer access logs from S3 using EventBridge.

If you define your infrastructure with CloudFormation and forward S3-based logs, use the EventBridge template for easier deployment.

Before you begin

Make sure that you have the following:

The AWS CLI configured with permissions to create the required resources.
A Loki write endpoint, such as a Grafana Cloud Loki URL or a self-managed Loki cluster.
The function code available to CloudFormation. The templates load the function from an S3 bucket, so download the lambda-promtail.zip archive from the releases page, upload it to a bucket, and provide the S3BucketName and S3KeyName parameters.

Deploy the CloudWatch template

Use aws cloudformation create-stack with the lambda-promtail.yaml template. Set the CloudWatch log group to subscribe with the LogGroupToSubscribe parameter.

Select a highlighted placeholder in the following commands to enter your own value, such as WriteAddress, which is your Loki write endpoint. The value you enter fills in automatically across all the examples on this page.

aws cloudformation create-stack \
  --stack-name lambda-promtail \
  --template-body file://lambda-promtail.yaml \
  --capabilities CAPABILITY_IAM CAPABILITY_NAMED_IAM \
  --region us-east-2 \
  --parameters \
    ParameterKey=WriteAddress,ParameterValue=https://@@@LOKI_ENDPOINT@@@/loki/api/v1/push \
    ParameterKey=Username,ParameterValue=@@@USERNAME@@@ \
    ParameterKey=Password,ParameterValue=@@@PASSWORD@@@ \
    ParameterKey=S3BucketName,ParameterValue=@@@S3_BUCKET_NAME@@@ \
    ParameterKey=LogGroupToSubscribe,ParameterValue=@@@LOG_GROUP_NAME@@@

To subscribe more than one CloudWatch log group, copy the MainLambdaPromtailSubscriptionFilter resource in the template and modify it for each log group:

MainLambdaPromtailSubscriptionFilter:
  Type: AWS::Logs::SubscriptionFilter
  DependsOn: LambdaPromtailPermissions
  Properties:
    DestinationArn: !GetAtt LambdaPromtailFunction.Arn
    FilterPattern: ""
    LogGroupName: "@@@ADDITIONAL_LOG_GROUP_NAME@@@"

Deploy the EventBridge template for S3 logs

Use the aws-eventbridge-logs.yaml template to forward S3-based logs, such as ALB, VPC flow, or CloudFront access logs. Set the source bucket with the EventSourceS3Bucket parameter.

aws cloudformation create-stack \
  --stack-name lambda-promtail-stack \
  --template-body file://aws-eventbridge-logs.yaml \
  --capabilities CAPABILITY_IAM CAPABILITY_NAMED_IAM \
  --region us-east-2 \
  --parameters \
    ParameterKey=WriteAddress,ParameterValue=https://@@@LOKI_ENDPOINT@@@/loki/api/v1/push \
    ParameterKey=Username,ParameterValue=@@@USERNAME@@@ \
    ParameterKey=Password,ParameterValue=@@@PASSWORD@@@ \
    ParameterKey=BearerToken,ParameterValue=@@@BEARER_TOKEN@@@ \
    ParameterKey=ExtraLabels,ParameterValue="name1,value1,name2,value2" \
    ParameterKey=TenantID,ParameterValue=@@@TENANT_ID@@@ \
    ParameterKey=SkipTlsVerify,ParameterValue="false" \
    ParameterKey=S3BucketName,ParameterValue=@@@S3_BUCKET_NAME@@@ \
    ParameterKey=EventSourceS3Bucket,ParameterValue=@@@LOG_SOURCE_BUCKET@@@

Set optional parameters

The templates support the following optional parameters. Availability depends on the template, so check the Parameters section of the template that you use.

KeepStream: Set to true to keep the log stream label.
ExtraLabels: A comma-separated list in the format name1,value1,name2,value2 to add extra labels.
OmitExtraLabelsPrefix: Set to true to omit the __extra_ prefix from extra labels.
TenantID: A tenant ID to add when writing logs.
SkipTlsVerify: Set to true for development only, to skip TLS certificate verification.
ReservedConcurrency: The maximum number of concurrent executions to reserve for the function.