AGENTS.md

1# GCP Authentication Filter
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3This directory contains a client-side filter for adding GCP authentication to gRPC calls.
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5## Overarching Purpose
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7The GCP authentication filter provides a mechanism for authenticating to Google Cloud services using service account credentials. It is designed to be used in conjunction with xDS for service discovery and configuration.
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9## Files
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11*   `gcp_authentication_filter.h`, `gcp_authentication_filter.cc`: These files define the `GcpAuthenticationFilter` class, a client-side filter that adds GCP authentication to outgoing requests.
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13## Major Classes
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15*   `grpc_core::GcpAuthenticationFilter`: The channel filter implementation.
16*   `grpc_core::GcpAuthenticationFilter::CallCredentialsCache`: A cache for storing `grpc_call_credentials` objects.
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18## Notes
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20*   This filter is tightly coupled with xDS. It relies on the `XdsConfig` to determine the audience for GCP authentication based on the cluster that the call is being sent to.
21*   The filter uses a cache to store `grpc_call_credentials` objects, which helps to improve performance by avoiding the need to create new credentials for each call.
22*   This filter is an essential component for any gRPC application that needs to securely communicate with Google Cloud services.
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