Routing and storage overview

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This document explains how Cloud Logging processes log entries, and describes the key components of Logging routing and storage. Routing refers to the process that Cloud Logging uses to determine what to do with a newly-arrived log entry. You can route log entries to destinations like Logging buckets, which store the log entry, or to Pub/Sub. To export your logs into third-party destinations, route your logs to a Pub/Sub topic, and then authorize the third-party destination to subscribe to the Pub/Sub topic.

At a high level, this is how Cloud Logging routes and stores log entries:

Figure illustrating how Cloud Logging routes logs 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 by using sinks.

Log Router

A log entry is sent to the Google Cloud resource specified in its logName field during its entries.write call.

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 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.

Incoming log entries with timestamps that are more than the logs retention period in the past or that are more than 24 hours in the future are discarded.

Sinks

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. For example, if you want to export your logs from Google Cloud so that you can view them on a third-party platform, then configure a sink to route your log entries to Pub/Sub.

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: _Required and _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 _Required or _Default buckets.

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 usually create sinks at the Cloud project level, but if you want to combine and route logs from the resources contained by a Google Cloud organization or folder, you can create aggregated sinks.

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.

Inclusion filters

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.

When you configure sinks, you create inclusion filters by using the Logging query language. Sinks can also contain multiple exclusion filters.

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.

Exclusion filters

When you create a sink, you can set multiple exclusion filters. Exclusion filters let 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.

Log entries are excluded after they are received by the Logging API and therefore these log entries consume entries.write API quota. You can't reduce the number of entries.write API calls by excluding log entries.

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. Therefore, these logs aren't available to help troubleshoot failures.

User-defined log-based metrics are computed from log entries in both included and excluded logs. For more information, see Monitor your logs.

Log entries that aren't excluded might result in charges. For more information, see the Cloud Logging pricing information.

Supported destinations

You can use the Log Router to route certain logs to supported destinations in any Cloud project. Logging supports the following sink destinations:

  • Cloud Logging log buckets: Provides storage in Cloud Logging. A log bucket can store logs ingested by multiple Google Cloud projects. You specify the data retention period, the data storage location, and the log-views on a log bucket. Log views let you control which logs in a log bucket that a user can access. Log buckets are recommended storage when you want to troubleshoot your applications and services, or to analyze your log data. If you need to combine your Cloud Logging data with other data sources, then you can store your logs in log buckets that are upgraded to use Log Analytics, and then link that bucket to BigQuery. For information about viewing logs, see Query and view logs overview and View logs routed to Cloud Logging buckets.
  • Pub/Sub topics: Provides support for third-party integrations, such as Splunk, with Logging. Log entries are formatted into JSON and then delivered to a Pub/Sub topic. For information about viewing these logs, their organization, and how to configure a third-party integration, see View logs routed to Pub/Sub.
  • BigQuery datasets: Provides storage of log entries in BigQuery datasets. You can use big data analysis capabilities on the stored logs. If you need to combine your Cloud Logging data with other data sources, then you can route your logs to BigQuery. An alternative is to store your logs in log buckets that are upgraded to use Log Analytics and then linked to BigQuery. For information about viewing logs routed to BigQuery, see View logs routed to BigQuery.
  • Cloud Storage buckets: Provides inexpensive, long-term storage of log data in Cloud Storage. Log entries are stored as JSON files. For information about viewing these logs, how they are organized, and how late-arriving logs are handled, see View logs routed to Cloud Storage.

For more information, see Route logs to supported destinations.

Storing, viewing, and managing logs

The following section details how logs are stored in Cloud Logging, and how you can view and manage them.

Log buckets

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: _Required and _Default. Logging automatically creates sinks named _Required and _Default that, in the default configuration, route logs to the correspondingly named buckets.

You can disable the _Default sink, which routes logs to the _Default log bucket. To change the behavior of _Default sinks created for any new Cloud projects or folders created in your organization, you can configure default settings for your organization.

You can't change routing rules for the _Required bucket.

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 _Required bucket:

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 _Required bucket.

Neither ingestion pricing nor storage pricing applies to the logs data stored in the _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 the _Default sink. For instructions on modifying sinks, see Manage sinks.

You can't delete the _Default bucket.

Logs held in the _Default bucket are retained for 30 days, unless you configure custom retention for the bucket.

Cloud Logging pricing applies to the logs data held in the _Default bucket.

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 about managing your user-defined log buckets, including deleting or updating them, see Configure and manage log buckets.

Regionalization

Log buckets are regional resources. The infrastructure that stores, indexes, and searches your logs is located in a specific geographical location. Google manages that infrastructure so that your applications are available redundantly across the zones within that region.

When you create a log bucket or set an organization-level regional policy, you can choose to store your logs in any of the following regions:

Americas

Region name Region description
northamerica-northeast1 Montréal
northamerica-northeast2 Toronto
southamerica-east1 São Paulo
southamerica-west1 Santiago
us-central1 Iowa
us-east1 South Carolina
us-east4 North Virginia
us-east5 Columbus
us-south1 Dallas
us-west1 Oregon
us-west2 Los Angeles
us-west3 Salt Lake City
us-west4 Las Vegas

Asia Pacific

Region name Region description
asia-east1 Taiwan
asia-east2 Hong Kong
asia-northeast1 Tokyo
asia-northeast2 Osaka
asia-northeast3 Seoul
asia-south1 Mumbai
asia-south2 Delhi
asia-southeast1 Singapore
asia-southeast2 Jakarta
australia-southeast1 Sydney
australia-southeast2 Melbourne

Europe

Region name Region description
europe-central2 Warsaw
europe-north1 Finland
europe-southwest1 Madrid
europe-west1 Belgium
europe-west2 London
europe-west3 Frankfurt
europe-west4 Netherlands
europe-west6 Zurich
europe-west8 Milan
europe-west9 Paris

Middle East

Region name Region description
me-west1 Tel Aviv

Other

Region name Region description
eu Logs stored in data centers within the European Union; no additional redundancy guarantees
us Logs stored in data centers within the United States; no additional redundancy guarantees
global Logs stored in any data center in the world; no additional redundancy guarantees

In addition to these regions, you can set the location to global, which means that you don't need to specify where your logs are physically stored.

If you want to automatically apply a particular storage region to the _Default and _Required buckets created in your organization, you can configure a default resource location.

For more information about data regionality and where you can store your logs data, see Understand data regions.

Organization policy

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 existing log buckets; it only enforces the policy on new log buckets.

For information about creating a location-based organization policy, see Restrict resource locations.

In addition, you can configure a default resource location to choose which storage region to apply to the _Default and _Required buckets created in your organization.

Retention

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 about setting retention rules for a log bucket, see Configure custom retention.

For information about the retention periods for different types of logs, see Quotas and limits.

Log views

Log views let you control who has access to the logs within your log buckets.

For every log bucket, Cloud Logging automatically creates the _AllLogs view, which shows all logs stored in that bucket. Cloud Logging also creates a view for the _Default bucket called _Default. The _Default view for the _Default bucket shows all logs except Data Access audit logs. The _AllLogs and _Default views aren't editable and you can't delete them.

Custom log views provide you with an advanced and granular way to control access to your logs data. For example, consider a scenario in which you store all of your organization's logs in a central Cloud project. Because log buckets can contain logs from multiple Cloud projects, you might want to control which Cloud projects different users can view logs from. Using custom log views, you can give one user access to logs only from a single Cloud project, while you give another user access to logs from all the Cloud projects.

For information about configuring log views, see Configure bucket-level access.

Using logs in the Google Cloud ecosystem

The following section provides information about how to use logs in the broader Google Cloud.

Log-based metrics

Log-based metrics are Cloud Monitoring metrics that are derived from the content of log entries. For example, if Cloud Logging receives a log entry for a Cloud project that matches the filters of one of the Cloud project's metrics, then that log entry is counted in the metric data.

Log-based metrics interact with routing differently, depending on whether the log-based metrics are defined by the system or by you. The following sections describe these differences.

Log-based metrics and exclusion filters

Sink exclusion filters apply to system-defined log-based metrics, which count only logs that are included for ingestion by the Cloud project.

Sink exclusion filters don't apply to user-defined log-based metrics. Even if you exclude logs from being ingested by Cloud Logging API and the logs aren't stored in any Logging buckets, you could see those logs counted in these metrics.

Scope of log-based metrics

System-defined log-based metrics apply at the Cloud project level. These metrics are calculated by the Log Router and apply to logs only in the Cloud project in which they're received.

User-defined log-based metrics can apply at either the Cloud project level or at the level of a specific log bucket:

  • Project-level metrics are calculated like system-defined log-based metrics; these user-defined log-based metrics apply to logs only in the Cloud project in which they're received.
  • With bucket-level log-based metrics, you can create log-based metrics that can evaluate logs in the following cases:

    • Logs that are routed from one project to a bucket in another project.
    • Logs that are routed into a bucket through an aggregated sink.

For more information, see Log-based metrics overview.

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:

Compliance needs

For best practices about using routing for data governance, see the following documents:

Access control with IAM

For information about how you use Identity and Access Management (IAM) roles and permissions to control access to Cloud Logging data, see the Access control with IAM.

Pricing

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:

What's next

To help you route and store Cloud Logging data, see the following documents: