StartLiveTail - Amazon CloudWatch Logs (original) (raw)
Starts a Live Tail streaming session for one or more log groups. A Live Tail session returns a stream of log events that have been recently ingested in the log groups. For more information, see Use Live Tail to view logs in near real time.
The response to this operation is a response stream, over which the server sends live log events and the client receives them.
The following objects are sent over the stream:
- A single LiveTailSessionStart object is sent at the start of the session.
- Every second, a LiveTailSessionUpdate object is sent. Each of these objects contains an array of the actual log events.
If no new log events were ingested in the past second, theLiveTailSessionUpdateobject will contain an empty array.
The array of log events contained in aLiveTailSessionUpdatecan include as many as 500 log events. If the number of log events matching the request exceeds 500 per second, the log events are sampled down to 500 log events to be included in eachLiveTailSessionUpdateobject.
If your client consumes the log events slower than the server produces them, CloudWatch Logs buffers up to 10LiveTailSessionUpdateevents or 5000 log events, after which it starts dropping the oldest events. - A SessionStreamingException object is returned if an unknown error occurs on the server side.
- A SessionTimeoutException object is returned when the session times out, after it has been kept open for three hours.
Note
The StartLiveTail API routes requests tostreaming-logs._Region_.amazonaws.com using SDK host prefix injection. VPC endpoint support is not available for this API.
Important
You can end a session before it times out by closing the session stream or by closing the client that is receiving the stream. The session also ends if the established connection between the client and the server breaks.
For examples of using an SDK to start a Live Tail session, see Start a Live Tail session using an AWS SDK.
Request Syntax
{
"logEventFilterPattern": "string",
"logGroupIdentifiers": [ "string" ],
"logStreamNamePrefixes": [ "string" ],
"logStreamNames": [ "string" ]
}Request Parameters
For information about the parameters that are common to all actions, see Common Parameters.
The request accepts the following data in JSON format.
An optional pattern to use to filter the results to include only log events that match the pattern. For example, a filter pattern of error 404 causes only log events that include both error and 404 to be included in the Live Tail stream.
Regular expression filter patterns are supported.
For more information about filter pattern syntax, see Filter and Pattern Syntax.
Type: String
Length Constraints: Minimum length of 0. Maximum length of 1024.
Required: No
An array where each item in the array is a log group to include in the Live Tail session.
Specify each log group by its ARN.
If you specify an ARN, the ARN can't end with an asterisk (*).
Note
You can include up to 10 log groups.
Type: Array of strings
Array Members: Minimum number of 1 item. Maximum number of 10 items.
Length Constraints: Minimum length of 1. Maximum length of 2048.
Pattern: [\w#+=/:,.@-]*
Required: Yes
If you specify this parameter, then only log events in the log streams that have names that start with the prefixes that you specify here are included in the Live Tail session.
If you specify this field, you can't also specify the logStreamNames field.
Note
You can specify this parameter only if you specify only one log group inlogGroupIdentifiers.
Type: Array of strings
Array Members: Minimum number of 1 item. Maximum number of 100 items.
Length Constraints: Minimum length of 1. Maximum length of 512.
Pattern: [^:*]*
Required: No
If you specify this parameter, then only log events in the log streams that you specify here are included in the Live Tail session.
If you specify this field, you can't also specify the logStreamNamePrefixes field.
Note
You can specify this parameter only if you specify only one log group inlogGroupIdentifiers.
Type: Array of strings
Array Members: Minimum number of 1 item. Maximum number of 100 items.
Length Constraints: Minimum length of 1. Maximum length of 512.
Pattern: [^:*]*
Required: No
Response Syntax
{
"responseStream": {
"sessionStart": {
"logEventFilterPattern": "string",
"logGroupIdentifiers": [ "string" ],
"logStreamNamePrefixes": [ "string" ],
"logStreamNames": [ "string" ],
"requestId": "string",
"sessionId": "string"
},
"SessionStreamingException": {
},
"SessionTimeoutException": {
},
"sessionUpdate": {
"sessionMetadata": {
"sampled": boolean
},
"sessionResults": [
{
"ingestionTime": number,
"logGroupIdentifier": "string",
"logStreamName": "string",
"message": "string",
"timestamp": number
}
]
}
}
}Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
An object that includes the stream returned by your request. It can include both log events and exceptions.
Type: StartLiveTailResponseStream object
Errors
For information about the errors that are common to all actions, see Common Errors.
AccessDeniedException
You don't have sufficient permissions to perform this action.
HTTP Status Code: 400
InvalidOperationException
The operation is not valid on the specified resource.
HTTP Status Code: 400
InvalidParameterException
A parameter is specified incorrectly.
HTTP Status Code: 400
LimitExceededException
You have reached the maximum number of resources that can be created.
HTTP Status Code: 400
ResourceNotFoundException
The specified resource does not exist.
HTTP Status Code: 400
See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following: