View traces across projects

By default, the Trace Explorer page only searches your selected project for trace data. When a trace has data stored in multiple projects, as might occur when an application in one project makes a call into an application hosted by another project, you need to perform the following steps to view all spans in the trace:

1. Create a trace scope that lists the Google Cloud projects that store the spans in a trace. For information about trace scopes, see Create and manage trace scopes.

2. Update the observability scope.

   Note: To facilitate correlation between log and trace data, set the observability scope. This scope specifies which of your trace scopes and log scopes to use when the corresponding explorer pages open. If you don't configure the observability scope to list the resources that store your data, then you might not be able to correlate your trace and log data. To learn more, see Configure observability scopes for multi-project queries.

3. Open the Trace Explorer page to view your trace data. This page automatically searches the resources listed in the default trace scope for trace data. If the default trace scope scope isn't accessible, then the page searches your Google Cloud project.

   To change which resources are searched for trace data, go to the toolbar and use the Scope element. For more information, see Configure which projects are searched for span data.

   Your Identity and Access Management (IAM) roles on the projects listed in the trace scope and the time-range setting determine what data is displayed. The trace scope only specifies which resources are searched.