snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

credentials/jwt/doc.go

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+/*
+ *
+ * Copyright 2025 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package jwt implements JWT token file-based call credentials.
+//
+// This package provides support for A97 JWT Call Credentials, allowing gRPC
+// clients to authenticate using JWT tokens read from files. While originally
+// designed for xDS environments, these credentials are general-purpose.
+//
+// The credentials can be used directly in gRPC clients or configured via xDS.
+//
+// # Token Requirements
+//
+// JWT tokens must:
+//   - Be valid, well-formed JWT tokens with header, payload, and signature
+//   - Include an "exp" (expiration) claim
+//   - Be readable from the specified file path
+//
+// # Considerations
+//
+// - Tokens are cached until expiration to avoid excessive file I/O
+// - Transport security is required (RequireTransportSecurity returns true)
+// - Errors in reading tokens or parsing JWTs will result in RPC UNAVAILALBE or
+// UNAUTHENTICATED errors. The errors are cached and retried with exponential
+// backoff.
+//
+// This implementation is originally intended for use in service mesh
+// environments like Istio where JWT tokens are provisioned and rotated by the
+// infrastructure.
+//
+// # Experimental
+//
+// Notice: All APIs in this package are experimental and may be removed in a
+// later release.
+package jwt