This page explains how Cloud Logging processes log entries, and describes the key components of Logging routing and storage.
At a high level, this is how Cloud Logging routes and stores log entries:
Ingesting and routing logs with the Log Router
The following sections explain how logs are ingested by Logging and routed through the Log Router using sinks.
Cloud Logging receives log entries through the Cloud Logging API where they pass through the Log Router. The sinks in the Log Router check each log entry against the existing inclusion filter and exclusion filters that determine which destinations, including Cloud Logging buckets, that the log entry should be sent to. You can use combinations of sinks to route logs to multiple destinations.
To reliably route logs, the Log Router also stores the logs temporarily (not depicted in the image), which buffers against temporary disruptions on any sink. Note that the Log Router's temporary storage is distinct from the longer term storage provided by Logging buckets.
Sinks control how Cloud Logging routes logs. Using sinks, you can route some or all of your logs to supported destinations. Some of the reasons that you might want to control how your logs are routed include the following:
- To store logs that are unlikely to be read but that must be retained for compliance purposes.
- To organize your logs in buckets in a format that is useful to you.
- To use big-data analysis tools on your logs.
- To stream your logs to other applications, other repositories, or third parties.
Sinks belong to a given Google Cloud resource: Cloud projects, billing accounts, folders, and organizations. When the resource receives a log entry, it routes the log entry according to the sinks contained by that resource and, if enabled, any ancestral sinks belonging under the resource hierarchy. The log entry is sent to the destination associated with each matching sink.
Cloud Logging provides two predefined sinks for each Cloud project,
billing account, folder, and organization:
_Default. All logs
that are generated in a resource are automatically processed through these two
sinks and then are stored either in the correspondingly named
Sinks act independently of each other. Regardless of how the predefined sinks process your log entries, you can create your own sinks to route some or all of your logs to various supported destinations or to exclude them from being stored by Cloud Logging.
The routing behavior for each sink is controlled by configuring the inclusion filter and exclusion filters for that sink. Depending on the sink's configuration, every log entry received by Cloud Logging falls into one or more of these categories:
Stored in Cloud Logging and not routed elsewhere.
Stored in Cloud Logging and routed to a supported destination.
Not stored in Cloud Logging but routed to a supported destination.
Neither stored in Cloud Logging nor routed elsewhere.
You can't route log entries that Logging received before your sink was created because routing happens as logs pass through the Logging API, and new routing rules only apply to logs written after those rules have been created. If you need to route log entries retroactively, see Copy logs.
For any new sink, if you don't specify filters, all logs match and are routed to the sink's destination. You can configure the sink to select specific logs by setting an inclusion filter. You can also set one or more exclusion filters to exclude logs from the sink's destination.
Every log entry received by Logging is routed based on these filtering rules:
The sink's exclusion filters override any of its defined inclusion filters. If a log matches any exclusion filter in the sink, then it doesn't match the sink regardless of any inclusion filters defined. The log entry isn't routed to that sink's destination.
If the sink doesn't contain an inclusion filter, then the following happens:
- If the log entry matches any exclusion filter, it isn't routed to the sink's destination.
- If the log entry doesn't match any exclusion filter, it is routed to the sink's destination. An empty inclusion filter selects all logs.
If the sink contains an inclusion filter, then the following happens:
- If the log entry matches the inclusion filter, it is routed to the sink's destination.
- If the log entry doesn't match the inclusion filter, it isn't routed to the sink's destination.
When you create a sink, you can set multiple exclusion filters, letting you exclude matching log entries from being routed to the sink's destination or from being ingested by Cloud Logging. You create exclusion filters by using the Logging query language.
Logs are excluded after they are received by the Logging API.
Therefore, excluding logs doesn't reduce the number of
entries.write API calls.
Excluded log entries aren't available in the Logs Explorer or Cloud Debugger.
Log entries that aren't routed to at least one log bucket, either explicitly with exclusion filters or because they don't match any sinks with a Logging storage destination, are also excluded from Error Reporting.
User-defined logs-based metrics are computed from log entries in both included and excluded logs. For more information, see Monitor your logs.
You can use the Log Router to route certain logs to supported destinations in any Cloud project. Logging supports the following sink destinations:
- Cloud Storage: JSON files stored in Cloud Storage buckets; provides inexpensive, long-term storage.
- BigQuery: Tables created in BigQuery datasets; provides big data analysis capabilities.
- Pub/Sub: JSON-formatted messages delivered to Pub/Sub topics; supports third-party integrations, such as Splunk, with Logging.
- Cloud Logging: Log entries held in log buckets; provides storage in Cloud Logging with customizable retention periods.
For more information on routing logs to supported destinations, see Configure sinks.
Storing, viewing, and managing logs
The following section details how logs are stored in Cloud Logging, and how you can view and manage them.
Cloud Logging uses log buckets as containers in your Google Cloud projects, billing accounts, folders, and organizations to store and organize your logs data. The logs that you store in Cloud Logging are indexed, optimized, and delivered to let you analyze your logs in real time. Cloud Logging buckets are different storage entities than the similarly named Cloud Storage buckets.
For each Cloud project, billing account, folder, and organization,
Logging automatically creates two log buckets:
_Default. Logging automatically creates sinks named
_Default that, in the default configuration, route logs to the
correspondingly named buckets.
You can disable the logs that are routed to the
_Default log bucket. You can't change routing rules for the
Additionally, you can create user-defined buckets for any Cloud project.
You create sinks to route all, or just a subset, of your logs to any log bucket. This flexibility allows you to choose the Cloud project in which your logs are stored and what other logs are stored with them.
For more information, see Configure log buckets.
_Required log bucket
Cloud Logging automatically routes the following types of logs to the
Cloud Logging retains the logs in this bucket for 400 days; you can't change this retention period.
You can't modify or delete the
_Required bucket. You can't disable the
_Required sink, which routes logs to the
Neither ingestion pricing nor storage pricing applies to the logs data stored in
_Required log bucket.
_Default log bucket
Any log entry that isn't ingested by the
_Required bucket is routed by the
_Default sink to the
_Default bucket, unless you disable or otherwise edit
_Default sink. For instructions on modifying sinks, see
You can't delete the
Logs held in the
_Default bucket are retained for
30 days, unless you
configure custom retention for the
Cloud Logging pricing applies
to the logs data held in the
User-defined log buckets
You can also create user-defined log buckets in any Cloud project. By applying sinks to your user-defined log buckets, you can route any subset of your logs to any log bucket, letting you choose which Cloud project your logs are stored in and which other logs are stored with them.
For example, for any log generated in Project-A, you can configure a sink to route that log to user-defined buckets in Project-A or Project-B.
Cloud Logging pricing applies to the logs data held in this bucket, regardless of the log type.
You can configure custom retention for the bucket.
For information on managing your user-defined log buckets, including deleting or updating them, see Configure and manage log buckets.
When you create your log bucket, you can choose to store your logs in any of the following regions:
In addition to these regions, you also have the option to set the location to
global, which means that you don't need to specify where your logs are
You can create an organization policy to ensure that your organization meets your compliance and regulatory needs. Using an organization policy, you can specify in which regions your organization can create new log buckets. You can also restrict your organization from creating new log buckets in specified regions.
Cloud Logging doesn't enforce your newly created organization policy on your existing log bucket; it only enforces the policy on new log buckets.
For information on creating a location-based organization policy, refer to Restrict resource locations.
Cloud Logging retains logs according to retention rules applying to the log bucket type where the logs are held.
You can configure Cloud Logging to retain logs between 1 day and 3650 days. Custom retention rules apply to all the logs in a bucket, regardless of the log type or whether that log has been copied from another location.
For information on setting retention rules for a log bucket, see Configure custom retention.
Log views let you control who has access to the logs within your log buckets.
Cloud Logging automatically creates the
_AllLogs view for every bucket,
which shows all logs. Cloud Logging also creates a view for the
_Default, which shows all logs except Data Access audit logs.
Because log buckets can contain logs from multiple Cloud projects, you might want to control which Cloud projects different users can view logs from. You can create custom log views, which give you more granular access control for those buckets.
For more information, see Manage log views.
Using logs in the Google Cloud ecosystem
The following section provides information on using logs in the broader Google Cloud.
Logs-based metrics are Cloud Monitoring metrics that are based on the content of log entries. If Cloud Logging receives a log entry for a Cloud project that matches the filter of one of the Cloud project's metrics, then that log entry is reflected in the metric data.
Sink exclusion filters aren't applied to log-based metrics. Even if you exclude logs from being ingested by Cloud Logging API and the logs aren't stored in any log buckets, you could see those logs counted in the logs-based metrics.
Log-based metrics apply at the Cloud project level. These metrics are calculated by the Log Router and apply to both ingested and excluded logs only in the Cloud project in which they're received.
For more information, see Overview of logs-based metrics.
Finding logs in supported destinations
To learn about the format of routed log entries and how the logs are organized in destinations, see View logs in sink destinations.
Common use cases
To address common use cases for routing and storing logs, see the following documents and tutorials:
For best practices on using routing for data governance, see the following documents:
To understand ingestion and storage pricing, see the Cloud Logging pricing information.
Cloud Logging doesn't charge to route logs, but destination charges might apply. For details, review the appropriate service's pricing details:
Note also that if you send and then exclude your Virtual Private Cloud flow logs from Cloud Logging, VPC flow log generation charges apply in addition to the destination charges.
To help you route and store Cloud Logging data, see the following documents:
To create sinks to route logs to supported destinations, see Configure sinks.
For routing and sinks troubleshooting information, see Troubleshoot routing and sinks.