Remove enforcement of BUFBUILD_AUTH_TOKEN

It appears a Buf token is not mandatory anymore to fetch descriptors set from Buf API anymore. There is probably rate limits but outside of this, seems that it's possible to fetch it without a token.

If we see that we start to have some rate limit errors, we shall re-introduced a specific handling to ask use to provide a `BUFBUILD_AUTH_TOKEN`.

docs/release-notes/change-log.md

@@ -11,12 +11,18 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## Unreleased
 
+### Server
+
 * Limit parallel execution of a stage's layer.
 
   Previously, the engine was executing modules in a stage's layer all in parallel. We now change that behavior, development mode will from now on execute every sequentially and when in production mode will limit parallelism to 2 (hard-coded) for now.
 
   The auth plugin can control that value dynamically by providing a trusted header `X-Sf-Substreams-Stage-Layer-Parallel-Executor-Max-Count`.
 
+### CLI
+
+* Removed enforcement of `BUFBUILD_AUTH_TOKEN` environment variable when using descriptor sets. It appears there is now a public free tier to query those which should work in most cases.
+
 ## v1.12.4
 
 ### Server

manifest/protobuf.go

@@ -130,11 +130,6 @@ func loadDescriptorSets(pkg *pbsubstreams.Package, manif *Manifest) ([]*desc.Fil
 			continue
 		}
 
-		authToken := os.Getenv("BUFBUILD_AUTH_TOKEN")
-		if authToken == "" {
-			return nil, fmt.Errorf("missing BUFBUILD_AUTH_TOKEN; go into your account at https://buf.build/settings/user to create an API key")
-		}
-
 		client := reflectv1beta1connect.NewFileDescriptorSetServiceClient(
 			http.DefaultClient,
 			"https://buf.build",
@@ -146,7 +141,11 @@ func loadDescriptorSets(pkg *pbsubstreams.Package, manif *Manifest) ([]*desc.Fil
 			Version: descriptor.Version,
 		})
 
-		request.Header().Set("Authorization", "Bearer "+authToken)
+		authToken := os.Getenv("BUFBUILD_AUTH_TOKEN")
+		if authToken != "" {
+			request.Header().Set("Authorization", "Bearer "+authToken)
+		}
+
 		fileDescriptorSet, err := client.GetFileDescriptorSet(context.Background(), request)
 		if err != nil {
 			return nil, fmt.Errorf("getting file descriptor set for %s: %w", descriptor.Module, err)