Trace data exports overview

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This page provides a conceptual overview of exporting trace data using Cloud Trace. You might want to export trace data for the following reasons:

• To store trace data for a period longer than the default retention period of 30 days.

• To let you use BigQuery tools to analyze your trace data. For example, using BigQuery, you can identify span counts and quantiles. For information on the query used to generate the following table, see HipsterShop query.

  

How exports work

Exporting involves creating a sink for a Google Cloud project. A sink defines a BigQuery dataset as the destination.

You can create a sink by using the Cloud Trace API or by using the Google Cloud CLI.

Sink properties and terminology

Sinks are defined for a Google Cloud project and have the following properties:

• Name: A name for the sink. For example, a name might be:

  "projects/PROJECT_NUMBER/traceSinks/my-sink"
  

  where PROJECT_NUMBER is the sink's Google Cloud project number and my-sink is the sink identifier.

• Parent: The resource in which you create the sink. The parent must be a Google Cloud project:

  "projects/PROJECT_ID"
  

  The PROJECT_ID can either be a Google Cloud project identifier or number.

• Destination: A single place to send trace spans. Trace supports exporting traces to BigQuery. The destination can be sink's Google Cloud project or any other Google Cloud project that is in the same organization.

  For example, a valid destination is:

  bigquery.googleapis.com/projects/DESTINATION_PROJECT_NUMBER/datasets/DATASET_ID
  

  where DESTINATION_PROJECT_NUMBER is the Google Cloud project number of the destination, and DATASET_ID is the BigQuery dataset identifier.

• Writer Identity: A service account name. The export destination's owner must give this service account permissions to write to the export destination. When exporting traces, Trace adopts this identity for authorization. For increased security, new sinks get a unique service account:

  [e-mail]
  

  where PROJECT_NUMBER is your Google Cloud project number, in Hex, and GENERATED_VALUE is a randomly generated value.

  You don't create, own, or manage the service account that is identified by the writer identity of a sink. When you create a sink, Trace creates the service account that the sink requires. This service account isn't included in the list of service accounts for your project until it has at least one Identity and Access Management binding. You add this binding when you configure a sink destination.

  For information on using the writer identity, see destination permissions.

How sinks work

Every time a trace span arrives in a project, Trace exports a copy of the span.

Traces that Trace received before the sink was created cannot be exported.

Access control

To create or modify a sink, you must have one of the following Identity and Access Management roles:

• Trace Admin
• Trace User
• Project Owner
• Project Editor

For more information, see Access control.

To export traces to a destination, the sink's writer service account must be permitted to write to the destination. For more information about writer identities, see Sink properties on this page.

Quotas and limits

Cloud Trace utilizes the BigQuery streaming API to send trace spans to the destination. Cloud Trace batches API calls. Cloud Trace doesn't implement a retry or throttling mechanism. Trace spans might not be exported successfully if the amount of data exceeds the destination quotas.

For details on BigQuery quotas and limits, see Quotas and limits.

Pricing

Exporting traces doesn't incur Cloud Trace charges. However, you might incur BigQuery charges. See BigQuery pricing for more information.

Estimating your costs

BigQuery charges for data ingestion and storage. To estimate your monthly BigQuery costs, do the following:

1. Estimate the total number of trace spans that are ingested in a month.

   For information about how to view usage, see View usage by billing account.

2. Estimate the streaming requirements based on the number of trace spans ingested.

   Each span is written to a table row. Each row in BigQuery requires at least 1024 bytes. Therefore, a lower bound on your BigQuery streaming requirements is to assign 1024 bytes to each span. For example, if your Google Cloud project ingested 200 spans, then those spans require at least 20,400 bytes for the streaming insert.

3. Use the Pricing calculator to estimate your BigQuery costs due to storage, streaming inserts, and queries.

Viewing and managing your BigQuery usage

You can use Metrics Explorer to view your BigQuery usage. You can also create an alerting policy that notifies you if your BigQuery usage exceeds predefined limits. The following table contains the settings to create an alerting policy. You can use the settings in the target pane table when creating a chart or when using Metrics Explorer.

To create an alerting policy that triggers when the ingested BigQuery metrics exceed a user-defined level, use the following settings.

Steps to create an alerting policy.

To create an alerting policy, do the following:

1. In the Google Cloud console, go to the  Alerting page:

   Go to Alerting

   If you use the search bar to find this page, then select the result whose subheading is Monitoring.

2. If you haven't created your notification channels and if you want to be notified, then click Edit Notification Channels and add your notification channels. Return to the Alerting page after you add your channels.
3. From the Alerting page, select Create policy.
4. To select the resource, metric, and filters, expand the Select a metric menu and then use the values in the New condition table:
   1. Optional: To limit the menu to relevant entries, enter the resource or metric name in the filter bar.
   2. Select a Resource type. For example, select VM instance.
   3. Select a Metric category. For example, select instance.
   4. Select a Metric. For example, select CPU Utilization.
   5. Select Apply.
5. Click Next and then configure the alerting policy trigger. To complete these fields, use the values in the Configure alert trigger table.
6. Click Next.

7. Optional: To add notifications to your alerting policy, click Notification channels. In the dialog, select one or more notification channels from the menu, and then click OK.

   To be notified when incidents are openend and closed, check Notify on incident closure. By default, notifications are sent only when incidents are openend.

8. Optional: Update the Incident autoclose duration. This field determines when Monitoring closes incidents in the absence of metric data.
9. Optional: Click Documentation, and then add any information that you want included in a notification message.
10. Click Alert name and enter a name for the alerting policy.
11. Click Create Policy.

New condition Field	Value
Resource and Metric	In the Resources menu, select BigQuery Dataset. In the Metric categories menu, select Storage. Select a metric from the Metrics menu. Metrics specific to usage include Stored bytes, Uploaded bytes, and Uploaded bytes billed. For a full list of available metrics, see BigQuery metrics.
Filter	project_id: Your Google Cloud project ID. dataset_id: Your dataset ID.
Across time series Time series group by	dataset_id: Your dataset ID.
Across time series Time series aggregation	sum
Rolling window	1 m
Rolling window function	mean

Configure alert trigger Field	Value
Condition type	Threshold
Alert trigger	Any time series violates
Threshold position	Above threshold
Threshold value	You determine the acceptable value.
Retest window	1 minute

What's next

To configure a sink, see Exporting traces.