2025/07/18 - Amazon CloudWatch Logs - 1 new3 updated api methods
Changes CloudWatchLogs launches GetLogObject API with streaming support for efficient log data retrieval. Logs added support for new AccountPolicy type METRIC_EXTRACTION_POLICY. For more information, see CloudWatch Logs API documentation
Retrieves a large logging object (LLO) and streams it back. This API is used to fetch the content of large portions of log events that have been ingested through the PutOpenTelemetryLogs API. When log events contain fields that would cause the total event size to exceed 1MB, CloudWatch Logs automatically processes up to 10 fields, starting with the largest fields. Each field is truncated as needed to keep the total event size as close to 1MB as possible. The excess portions are stored as Large Log Objects (LLOs) and these fields are processed separately and LLO reference system fields (in the format @ptr.$[path.to.field]) are added. The path in the reference field reflects the original JSON structure where the large field was located. For example, this could be @ptr.$['input']['message'], @ptr.$['AAA']['BBB']['CCC']['DDD'], @ptr.$['AAA'], or any other path matching your log structure.
See also: AWS API Documentation
Request Syntax
client.get_log_object(
unmask=True|False,
logObjectPointer='string'
)
boolean
A boolean flag that indicates whether to unmask sensitive log data. When set to true, any masked or redacted data in the log object will be displayed in its original form. Default is false.
string
[REQUIRED]
A pointer to the specific log object to retrieve. This is a required parameter that uniquely identifies the log object within CloudWatch Logs. The pointer is typically obtained from a previous query or filter operation.
dict
The response of this operation contains an :class:`.EventStream` member. When iterated the :class:`.EventStream` will yield events based on the structure below, where only one of the top level keys will be present for any given event.
Response Syntax
{
'fieldStream': EventStream({
'fields': {
'data': b'bytes'
},
'InternalStreamingException': {
'message': 'string'
}
})
}
Response Structure
(dict) --
The response from the GetLogObject operation.
fieldStream (:class:`.EventStream`) --
A stream of structured log data returned by the GetLogObject operation. This stream contains log events with their associated metadata and extracted fields.
fields (dict) --
A structure containing the extracted fields from a log event. These fields are extracted based on the log format and can be used for structured querying and analysis.
data (bytes) --
The actual log data content returned in the streaming response. This contains the fields and values of the log event in a structured format that can be parsed and processed by the client.
InternalStreamingException (dict) --
An internal error occurred during the streaming of log data. This exception is thrown when there's an issue with the internal streaming mechanism used by the GetLogObject operation.
message (string) --
{'policyType': {'METRIC_EXTRACTION_POLICY'}}
Deletes a CloudWatch Logs account policy. This stops the account-wide policy from applying to log groups in the account. If you delete a data protection policy or subscription filter policy, any log-group level policies of those types remain in effect.
To use this operation, you must be signed on with the correct permissions depending on the type of policy that you are deleting.
To delete a data protection policy, you must have the logs:DeleteDataProtectionPolicy and logs:DeleteAccountPolicy permissions.
To delete a subscription filter policy, you must have the logs:DeleteSubscriptionFilter and logs:DeleteAccountPolicy permissions.
To delete a transformer policy, you must have the logs:DeleteTransformer and logs:DeleteAccountPolicy permissions.
To delete a field index policy, you must have the logs:DeleteIndexPolicy and logs:DeleteAccountPolicy permissions.
If you delete a field index policy, the indexing of the log events that happened before you deleted the policy will still be used for up to 30 days to improve CloudWatch Logs Insights queries.
See also: AWS API Documentation
Request Syntax
client.delete_account_policy(
policyName='string',
policyType='DATA_PROTECTION_POLICY'|'SUBSCRIPTION_FILTER_POLICY'|'FIELD_INDEX_POLICY'|'TRANSFORMER_POLICY'|'METRIC_EXTRACTION_POLICY'
)
string
[REQUIRED]
The name of the policy to delete.
string
[REQUIRED]
The type of policy to delete.
None
{'policyType': {'METRIC_EXTRACTION_POLICY'}}
Response {'accountPolicies': {'policyType': {'METRIC_EXTRACTION_POLICY'}}}
Returns a list of all CloudWatch Logs account policies in the account.
To use this operation, you must be signed on with the correct permissions depending on the type of policy that you are retrieving information for.
To see data protection policies, you must have the logs:GetDataProtectionPolicy and logs:DescribeAccountPolicies permissions.
To see subscription filter policies, you must have the logs:DescribeSubscriptionFilters and logs:DescribeAccountPolicies permissions.
To see transformer policies, you must have the logs:GetTransformer and logs:DescribeAccountPolicies permissions.
To see field index policies, you must have the logs:DescribeIndexPolicies and logs:DescribeAccountPolicies permissions.
See also: AWS API Documentation
Request Syntax
client.describe_account_policies(
policyType='DATA_PROTECTION_POLICY'|'SUBSCRIPTION_FILTER_POLICY'|'FIELD_INDEX_POLICY'|'TRANSFORMER_POLICY'|'METRIC_EXTRACTION_POLICY',
policyName='string',
accountIdentifiers=[
'string',
],
nextToken='string'
)
string
[REQUIRED]
Use this parameter to limit the returned policies to only the policies that match the policy type that you specify.
string
Use this parameter to limit the returned policies to only the policy with the name that you specify.
list
If you are using an account that is set up as a monitoring account for CloudWatch unified cross-account observability, you can use this to specify the account ID of a source account. If you do, the operation returns the account policy for the specified account. Currently, you can specify only one account ID in this parameter.
If you omit this parameter, only the policy in the current account is returned.
(string) --
string
The token for the next set of items to return. (You received this token from a previous call.)
dict
Response Syntax
{
'accountPolicies': [
{
'policyName': 'string',
'policyDocument': 'string',
'lastUpdatedTime': 123,
'policyType': 'DATA_PROTECTION_POLICY'|'SUBSCRIPTION_FILTER_POLICY'|'FIELD_INDEX_POLICY'|'TRANSFORMER_POLICY'|'METRIC_EXTRACTION_POLICY',
'scope': 'ALL',
'selectionCriteria': 'string',
'accountId': 'string'
},
],
'nextToken': 'string'
}
Response Structure
(dict) --
accountPolicies (list) --
An array of structures that contain information about the CloudWatch Logs account policies that match the specified filters.
(dict) --
A structure that contains information about one CloudWatch Logs account policy.
policyName (string) --
The name of the account policy.
policyDocument (string) --
The policy document for this account policy.
The JSON specified in policyDocument can be up to 30,720 characters.
lastUpdatedTime (integer) --
The date and time that this policy was most recently updated.
policyType (string) --
The type of policy for this account policy.
scope (string) --
The scope of the account policy.
selectionCriteria (string) --
The log group selection criteria that is used for this policy.
accountId (string) --
The Amazon Web Services account ID that the policy applies to.
nextToken (string) --
The token to use when requesting the next set of items. The token expires after 24 hours.
{'policyType': {'METRIC_EXTRACTION_POLICY'}}
Response {'accountPolicy': {'policyType': {'METRIC_EXTRACTION_POLICY'}}}
Creates an account-level data protection policy, subscription filter policy, field index policy, transformer policy, or metric extraction policy that applies to all log groups or a subset of log groups in the account.
To use this operation, you must be signed on with the correct permissions depending on the type of policy that you are creating.
To create a data protection policy, you must have the logs:PutDataProtectionPolicy and logs:PutAccountPolicy permissions.
To create a subscription filter policy, you must have the logs:PutSubscriptionFilter and logs:PutAccountPolicy permissions.
To create a transformer policy, you must have the logs:PutTransformer and logs:PutAccountPolicy permissions.
To create a field index policy, you must have the logs:PutIndexPolicy and logs:PutAccountPolicy permissions.
To create a metric extraction policy, you must have the logs:PutMetricExtractionPolicy and logs:PutAccountPolicy permissions.
Data protection policy
A data protection policy can help safeguard sensitive data that's ingested by your log groups by auditing and masking the sensitive log data. Each account can have only one account-level data protection policy.
If you use PutAccountPolicy to create a data protection policy for your whole account, it applies to both existing log groups and all log groups that are created later in this account. The account-level policy is applied to existing log groups with eventual consistency. It might take up to 5 minutes before sensitive data in existing log groups begins to be masked.
By default, when a user views a log event that includes masked data, the sensitive data is replaced by asterisks. A user who has the logs:Unmask permission can use a GetLogEvents or FilterLogEvents operation with the unmask parameter set to true to view the unmasked log events. Users with the logs:Unmask can also view unmasked data in the CloudWatch Logs console by running a CloudWatch Logs Insights query with the unmask query command.
For more information, including a list of types of data that can be audited and masked, see Protect sensitive log data with masking.
To use the PutAccountPolicy operation for a data protection policy, you must be signed on with the logs:PutDataProtectionPolicy and logs:PutAccountPolicy permissions.
The PutAccountPolicy operation applies to all log groups in the account. You can use PutDataProtectionPolicy to create a data protection policy that applies to just one log group. If a log group has its own data protection policy and the account also has an account-level data protection policy, then the two policies are cumulative. Any sensitive term specified in either policy is masked.
Subscription filter policy
A subscription filter policy sets up a real-time feed of log events from CloudWatch Logs to other Amazon Web Services services. Account-level subscription filter policies apply to both existing log groups and log groups that are created later in this account. Supported destinations are Kinesis Data Streams, Firehose, and Lambda. When log events are sent to the receiving service, they are Base64 encoded and compressed with the GZIP format.
The following destinations are supported for subscription filters:
An Kinesis Data Streams data stream in the same account as the subscription policy, for same-account delivery.
An Firehose data stream in the same account as the subscription policy, for same-account delivery.
A Lambda function in the same account as the subscription policy, for same-account delivery.
A logical destination in a different account created with PutDestination, for cross-account delivery. Kinesis Data Streams and Firehose are supported as logical destinations.
Each account can have one account-level subscription filter policy per Region. If you are updating an existing filter, you must specify the correct name in PolicyName. To perform a PutAccountPolicy subscription filter operation for any destination except a Lambda function, you must also have the iam:PassRole permission.
Transformer policy
Creates or updates a log transformer policy for your account. You use log transformers to transform log events into a different format, making them easier for you to process and analyze. You can also transform logs from different sources into standardized formats that contain relevant, source-specific information. After you have created a transformer, CloudWatch Logs performs this transformation at the time of log ingestion. You can then refer to the transformed versions of the logs during operations such as querying with CloudWatch Logs Insights or creating metric filters or subscription filters.
You can also use a transformer to copy metadata from metadata keys into the log events themselves. This metadata can include log group name, log stream name, account ID and Region.
A transformer for a log group is a series of processors, where each processor applies one type of transformation to the log events ingested into this log group. For more information about the available processors to use in a transformer, see Processors that you can use.
Having log events in standardized format enables visibility across your applications for your log analysis, reporting, and alarming needs. CloudWatch Logs provides transformation for common log types with out-of-the-box transformation templates for major Amazon Web Services log sources such as VPC flow logs, Lambda, and Amazon RDS. You can use pre-built transformation templates or create custom transformation policies.
You can create transformers only for the log groups in the Standard log class.
You can have one account-level transformer policy that applies to all log groups in the account. Or you can create as many as 20 account-level transformer policies that are each scoped to a subset of log groups with the selectionCriteria parameter. If you have multiple account-level transformer policies with selection criteria, no two of them can use the same or overlapping log group name prefixes. For example, if you have one policy filtered to log groups that start with my-log, you can't have another field index policy filtered to my-logpprod or my-logging.
You can also set up a transformer at the log-group level. For more information, see PutTransformer. If there is both a log-group level transformer created with PutTransformer and an account-level transformer that could apply to the same log group, the log group uses only the log-group level transformer. It ignores the account-level transformer.
Field index policy
You can use field index policies to create indexes on fields found in log events in the log group. Creating field indexes can help lower the scan volume for CloudWatch Logs Insights queries that reference those fields, because these queries attempt to skip the processing of log events that are known to not match the indexed field. Good fields to index are fields that you often need to query for and fields or values that match only a small fraction of the total log events. Common examples of indexes include request ID, session ID, user IDs, or instance IDs. For more information, see Create field indexes to improve query performance and reduce costs
To find the fields that are in your log group events, use the GetLogGroupFields operation.
For example, suppose you have created a field index for requestId. Then, any CloudWatch Logs Insights query on that log group that includes requestId = value or requestId in [value, value, ...] will attempt to process only the log events where the indexed field matches the specified value.
Matches of log events to the names of indexed fields are case-sensitive. For example, an indexed field of RequestId won't match a log event containing requestId.
You can have one account-level field index policy that applies to all log groups in the account. Or you can create as many as 20 account-level field index policies that are each scoped to a subset of log groups with the selectionCriteria parameter. If you have multiple account-level index policies with selection criteria, no two of them can use the same or overlapping log group name prefixes. For example, if you have one policy filtered to log groups that start with my-log, you can't have another field index policy filtered to my-logpprod or my-logging.
If you create an account-level field index policy in a monitoring account in cross-account observability, the policy is applied only to the monitoring account and not to any source accounts.
If you want to create a field index policy for a single log group, you can use PutIndexPolicy instead of PutAccountPolicy. If you do so, that log group will use only that log-group level policy, and will ignore the account-level policy that you create with PutAccountPolicy.
Metric extraction policy
A metric extraction policy controls whether CloudWatch Metrics can be created through the Embedded Metrics Format (EMF) for log groups in your account. By default, EMF metric creation is enabled for all log groups. You can use metric extraction policies to disable EMF metric creation for your entire account or specific log groups.
When a policy disables EMF metric creation for a log group, log events in the EMF format are still ingested, but no CloudWatch Metrics are created from them.
Each account can have either one account-level metric extraction policy that applies to all log groups, or up to 5 policies that are each scoped to a subset of log groups with the selectionCriteria parameter. The selection criteria supports filtering by LogGroupName and LogGroupNamePrefix using the operators IN and NOT IN. You can specify up to 50 values in each IN or NOT IN list.
The selection criteria can be specified in these formats:
LogGroupName IN ["log-group-1", "log-group-2"]
LogGroupNamePrefix NOT IN ["/aws/prefix1", "/aws/prefix2"]
If you have multiple account-level metric extraction policies with selection criteria, no two of them can have overlapping criteria. For example, if you have one policy with selection criteria LogGroupNamePrefix IN ["my-log"], you can't have another metric extraction policy with selection criteria LogGroupNamePrefix IN ["/my-log-prod"] or LogGroupNamePrefix IN ["/my-logging"], as the set of log groups matching these prefixes would be a subset of the log groups matching the first policy's prefix, creating an overlap.
When using NOT IN, only one policy with this operator is allowed per account.
When combining policies with IN and NOT IN operators, the overlap check ensures that policies don't have conflicting effects. Two policies with IN and NOT IN operators do not overlap if and only if every value in the IN ``policy is completely contained within some value in the ``NOT IN policy. For example:
If you have a NOT IN policy for prefix "/aws/lambda", you can create an IN policy for the exact log group name "/aws/lambda/function1" because the set of log groups matching "/aws/lambda/function1" is a subset of the log groups matching "/aws/lambda".
If you have a NOT IN policy for prefix "/aws/lambda", you cannot create an IN policy for prefix "/aws" because the set of log groups matching "/aws" is not a subset of the log groups matching "/aws/lambda".
See also: AWS API Documentation
Request Syntax
client.put_account_policy(
policyName='string',
policyDocument='string',
policyType='DATA_PROTECTION_POLICY'|'SUBSCRIPTION_FILTER_POLICY'|'FIELD_INDEX_POLICY'|'TRANSFORMER_POLICY'|'METRIC_EXTRACTION_POLICY',
scope='ALL',
selectionCriteria='string'
)
string
[REQUIRED]
A name for the policy. This must be unique within the account.
string
[REQUIRED]
Specify the policy, in JSON.
Data protection policy
A data protection policy must include two JSON blocks:
The first block must include both a DataIdentifer array and an Operation property with an Audit action. The DataIdentifer array lists the types of sensitive data that you want to mask. For more information about the available options, see Types of data that you can mask. The Operation property with an Audit action is required to find the sensitive data terms. This Audit action must contain a FindingsDestination object. You can optionally use that FindingsDestination object to list one or more destinations to send audit findings to. If you specify destinations such as log groups, Firehose streams, and S3 buckets, they must already exist.
The second block must include both a DataIdentifer array and an Operation property with an Deidentify action. The DataIdentifer array must exactly match the DataIdentifer array in the first block of the policy. The Operation property with the Deidentify action is what actually masks the data, and it must contain the "MaskConfig": {} object. The "MaskConfig": {} object must be empty.
For an example data protection policy, see the Examples section on this page.
In addition to the two JSON blocks, the policyDocument can also include Name, Description, and Version fields. The Name is different than the operation's policyName parameter, and is used as a dimension when CloudWatch Logs reports audit findings metrics to CloudWatch.
The JSON specified in policyDocument can be up to 30,720 characters long.
Subscription filter policy
A subscription filter policy can include the following attributes in a JSON block:
DestinationArn The ARN of the destination to deliver log events to. Supported destinations are:
An Kinesis Data Streams data stream in the same account as the subscription policy, for same-account delivery.
An Firehose data stream in the same account as the subscription policy, for same-account delivery.
A Lambda function in the same account as the subscription policy, for same-account delivery.
A logical destination in a different account created with PutDestination, for cross-account delivery. Kinesis Data Streams and Firehose are supported as logical destinations.
RoleArn The ARN of an IAM role that grants CloudWatch Logs permissions to deliver ingested log events to the destination stream. You don't need to provide the ARN when you are working with a logical destination for cross-account delivery.
FilterPattern A filter pattern for subscribing to a filtered stream of log events.
Distribution The method used to distribute log data to the destination. By default, log data is grouped by log stream, but the grouping can be set to Random for a more even distribution. This property is only applicable when the destination is an Kinesis Data Streams data stream.
Transformer policy
A transformer policy must include one JSON block with the array of processors and their configurations. For more information about available processors, see Processors that you can use.
Field index policy
A field index filter policy can include the following attribute in a JSON block:
Fields The array of field indexes to create.
It must contain at least one field index.
The following is an example of an index policy document that creates two indexes, RequestId and TransactionId.
"policyDocument": "{ \"Fields\": [ \"RequestId\", \"TransactionId\" ] }"
string
[REQUIRED]
The type of policy that you're creating or updating.
string
Currently the only valid value for this parameter is ALL, which specifies that the data protection policy applies to all log groups in the account. If you omit this parameter, the default of ALL is used.
string
Use this parameter to apply the new policy to a subset of log groups in the account.
Specifying selectionCriteria is valid only when you specify SUBSCRIPTION_FILTER_POLICY, FIELD_INDEX_POLICY or TRANSFORMER_POLICY``for ``policyType.
If policyType is SUBSCRIPTION_FILTER_POLICY, the only supported selectionCriteria filter is LogGroupName NOT IN []
If policyType is FIELD_INDEX_POLICY or TRANSFORMER_POLICY, the only supported selectionCriteria filter is LogGroupNamePrefix
The selectionCriteria string can be up to 25KB in length. The length is determined by using its UTF-8 bytes.
Using the selectionCriteria parameter with SUBSCRIPTION_FILTER_POLICY is useful to help prevent infinite loops. For more information, see Log recursion prevention.
dict
Response Syntax
{
'accountPolicy': {
'policyName': 'string',
'policyDocument': 'string',
'lastUpdatedTime': 123,
'policyType': 'DATA_PROTECTION_POLICY'|'SUBSCRIPTION_FILTER_POLICY'|'FIELD_INDEX_POLICY'|'TRANSFORMER_POLICY'|'METRIC_EXTRACTION_POLICY',
'scope': 'ALL',
'selectionCriteria': 'string',
'accountId': 'string'
}
}
Response Structure
(dict) --
accountPolicy (dict) --
The account policy that you created.
policyName (string) --
The name of the account policy.
policyDocument (string) --
The policy document for this account policy.
The JSON specified in policyDocument can be up to 30,720 characters.
lastUpdatedTime (integer) --
The date and time that this policy was most recently updated.
policyType (string) --
The type of policy for this account policy.
scope (string) --
The scope of the account policy.
selectionCriteria (string) --
The log group selection criteria that is used for this policy.
accountId (string) --
The Amazon Web Services account ID that the policy applies to.