Set up CloudWatch logging for REST APIs in API Gateway
To help debug issues related to request execution or client access to your API, you can enable Amazon CloudWatch Logs to log API calls. For more information about CloudWatch, see Monitor REST API execution with Amazon CloudWatch metrics.
CloudWatch log formats for API Gateway
There are two types of API logging in CloudWatch: execution logging and access logging. In execution logging, API Gateway manages the CloudWatch Logs. The process includes creating log groups and log streams, and reporting to the log streams any caller's requests and responses.
The logged data includes errors or execution traces (such as request or response parameter values or payloads), data used by Lambda authorizers (formerly known as custom authorizers), whether API keys are required, whether usage plans are enabled, and other information. API Gateway redacts authorization headers, API key values, and similar sensitive request parameters from the logged data.
When you deploy an API, API Gateway creates a log group and log streams under the log group. The log group is named
following the API-Gateway-Execution-Logs_{rest-api-id}/{stage_name}
format. Within each log group,
the logs are further divided into log streams, which are ordered by Last Event Time as logged
data is reported.
In access logging, you, as an API developer, want to log who has accessed your API and how the caller accessed the API. You can create your own log group or choose an existing log group that could be managed by API Gateway. To specify the access details, you select $context variables, a log format, and a log group destination.
The access log
format must include at least $context.requestId
or $context.extendedRequestId
. As a best
practice, include $context.requestId
and $context.extendedRequestId
in your log format.
$context.requestId
-
This logs the value in the
x-amzn-RequestId
header. Clients can override the value in thex-amzn-RequestId
header with a value in the format of a universally unique identifier (UUID). API Gateway returns this request ID in thex-amzn-RequestId
response header. API Gateway replaces overridden request IDs that aren't in the format of a UUID with
in your access logs.UUID
_REPLACED_INVALID_REQUEST_ID $context.extendedRequestId
-
The extendedRequestID is a unique ID that API Gateway generates. API Gateway returns this request ID in the
x-amz-apigw-id
response header. An API caller can't provide or override this request ID. You might need to provide this value to Amazon Support to help troubleshoot your API. For more information, see $context Variables for data models, authorizers, mapping templates, and CloudWatch access logging.
Note
Only $context
variables are supported.
Choose a log format that is also adopted by your analytic backend, such as Common Log Format
Examples of some commonly used access log formats are shown in the API Gateway console and are listed as follows.
-
CLF
(Common Log Format): $context.identity.sourceIp $context.identity.caller $context.identity.user [$context.requestTime]"$context.httpMethod $context.resourcePath $context.protocol" $context.status $context.responseLength $context.requestId $context.extendedRequestId
-
JSON
:{ "requestId":"$context.requestId", "extendedRequestId":"$context.extendedRequestId","ip": "$context.identity.sourceIp", "caller":"$context.identity.caller", "user":"$context.identity.user", "requestTime":"$context.requestTime", "httpMethod":"$context.httpMethod", "resourcePath":"$context.resourcePath", "status":"$context.status", "protocol":"$context.protocol", "responseLength":"$context.responseLength" }
-
XML
:<request id="$context.requestId"> <extendedRequestId>$context.extendedRequestId</extendedRequestId> <ip>$context.identity.sourceIp</ip> <caller>$context.identity.caller</caller> <user>$context.identity.user</user> <requestTime>$context.requestTime</requestTime> <httpMethod>$context.httpMethod</httpMethod> <resourcePath>$context.resourcePath</resourcePath> <status>$context.status</status> <protocol>$context.protocol</protocol> <responseLength>$context.responseLength</responseLength> </request>
-
CSV
(comma-separated values):$context.identity.sourceIp,$context.identity.caller,$context.identity.user,$context.requestTime,$context.httpMethod,$context.resourcePath,$context.protocol,$context.status,$context.responseLength,$context.requestId,$context.extendedRequestId
Permissions for CloudWatch logging
To enable CloudWatch Logs, you must grant API Gateway permission to read and write logs to CloudWatch for
your account. The AmazonAPIGatewayPushToCloudWatchLogs
managed policy (with
an ARN of
arn:aws:iam::aws:policy/service-role/AmazonAPIGatewayPushToCloudWatchLogs
)
has all the required permissions:
{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "logs:CreateLogGroup", "logs:CreateLogStream", "logs:DescribeLogGroups", "logs:DescribeLogStreams", "logs:PutLogEvents", "logs:GetLogEvents", "logs:FilterLogEvents" ], "Resource": "*" } ] }
Note
API Gateway calls Amazon Security Token Service in order to assume the IAM role, so make sure that Amazon STS is enabled for the Region. For more information, see Managing Amazon STS in an Amazon Region.
To grant these permissions to your account, create an IAM role with
apigateway.amazonaws.com
as its trusted entity, attach the preceding
policy to the IAM role, and set the IAM role ARN on the cloudWatchRoleArn
property on your Account. You must
set the cloudWatchRoleArn property separately for each Amazon Region in which you
want to enable CloudWatch Logs.
If you receive an error when setting the IAM role ARN, check your Amazon Security Token Service account settings to make sure that Amazon STS is enabled in the Region that you're using. For more information about enabling Amazon STS, see Managing Amazon STS in an Amazon Region in the IAM User Guide.
Set up CloudWatch API logging using the API Gateway console
To set up CloudWatch API logging, you must have deployed the API to a stage. You must also have configured an appropriate CloudWatch Logs role ARN for your account.
Sign in to the API Gateway console at https://console.amazonaws.cn/apigateway
. -
On the main navigation pane, choose Settings, and then under Logging, choose Edit.
-
For CloudWatch log role ARN, enter an ARN of an IAM role with appropriate permissions. You need to do this once for each Amazon Web Services account that creates APIs using API Gateway.
-
In the main navigation pane, choose APIs, and then do one of the following:
-
Choose an existing API, and then choose a stage.
-
Create an API, and then deploy it to a stage.
-
In the main navigation pane, choose Stages.
-
In the Logs and tracing section, choose Edit.
-
To enable execution logging:
-
Select a logging level from the CloudWatch Logs dropdown menu. The logging levels are the following:
-
Off – Logging is not turned on for this stage.
-
Errors only – Logging is enabled for errors only.
-
Errors and info logs – Logging is enabled for all events.
Full request and response logs – Detailed logging is enabled for all events. This can be useful to troubleshoot APIs, but can result in logging sensitive data.
Note
We recommend that you don't use Full request and response logs for production APIs.
-
-
If desired, select Detailed metrics to turn on detailed CloudWatch metrics.
For more information about CloudWatch metrics, see Monitor REST API execution with Amazon CloudWatch metrics.
-
-
To enable access logging:
-
Turn on Custom access logging.
-
For Access log destination ARN, enter the ARN of a log group. The ARN format is
arn:aws:logs:
.{region}
:{account-id}
:log-group:log-group-name
-
For Log Format, enter a log format. You can choose CLF, JSON, XML, or CSV. To learn more about example log formats, see CloudWatch log formats for API Gateway.
-
-
Choose Save changes.
Note
You can enable execution logging and access logging independently of each other.
API Gateway is now ready to log requests to your API. You don't need to redeploy the API when you update the stage settings, logs, or stage variables.
Set up CloudWatch API logging using Amazon CloudFormation
Use the following example Amazon CloudFormation template to create an Amazon CloudWatch Logs log group and configure execution and access logging for a stage. To enable CloudWatch Logs, you must grant API Gateway permission to read and write logs to CloudWatch for your account. To learn more, see Associate account with IAM role in the Amazon CloudFormation User Guide.
TestStage: Type: AWS::ApiGateway::Stage Properties: StageName: test RestApiId: !Ref MyAPI DeploymentId: !Ref Deployment Description: "test stage description" MethodSettings: - ResourcePath: "/*" HttpMethod: "*" LoggingLevel: INFO AccessLogSetting: DestinationArn: !GetAtt MyLogGroup.Arn Format: $context.extendedRequestId $context.identity.sourceIp $context.identity.caller $context.identity.user [$context.requestTime] "$context.httpMethod $context.resourcePath $context.protocol" $context.status $context.responseLength $context.requestId MyLogGroup: Type: AWS::Logs::LogGroup Properties: LogGroupName: !Join - '-' - - !Ref MyAPI - access-logs