Docs fixes: unary response correction, a note on adapter_opts.cred (#484)

* docs: Request, not Reply

* add documentation on how to set up TLS

Points one to the GRPC.Credential module, notes the key in adapter_opts
to use. The documentation that would have saved me 15 minutes of reading
source code.

* link into grpc_client now that it has been moved there

* expand the server quickstart guide with supervision, cred, and some words on what endpoints are

Author: aseigo

README.md

@@ -205,7 +205,7 @@ iex> GRPC.Stream.from([1, 2])
 ...>   {:error, {:exception, _reason}} ->
 ...>     {:error, GRPC.RPCError.exception(message: "Booomm")}
 ...> end)
-``` 
+```
 
 In this example:
 
@@ -233,7 +233,7 @@ def say_unary_hello(request, _materializer) do
 
     {:error, reason} ->
       {:error, GRPC.RPCError.exception(message: "error calling external process: #{inspect(reason)}")}
-    
+
     error ->
       Logger.error("Unknown error")
       error
@@ -297,12 +297,12 @@ children = [
 
 opts = [strategy: :one_for_one, name: MyApp.Supervisor]
 Supervisor.start_link(children, opts)
-``` 
+```
 
 You can also start it manually in scripts or test environments:
 ```elixir
 {:ok, _pid} = DynamicSupervisor.start_link(strategy: :one_for_one, name: GRPC.Client.Supervisor)
-``` 
+```
 
 Then connect with gRPC server:
 
@@ -331,7 +331,7 @@ iex> {:ok, reply} = channel |> Helloworld.GreetingServer.Stub.say_unary_hello(re
 
 ## Target Schemes and Resolvers
 
-The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](lib/grpc/client/resolver.ex).  
+The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](grpc_client/lib/grpc/client/resolver.ex).
 You can connect using `DNS`, `Unix Domain sockets`, `IPv4/IPv6`, or even `xDS-based endpoints`.
 
 ### Supported formats:
@@ -377,7 +377,7 @@ iex> {:ok, channel} =
 
 ## Client Adapters
 
-By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.  
+By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.
 You can switch to **Mint** (pure Elixir HTTP/2) or other adapters as needed.
 
 ### Using Mint Adapter

grpc_client/README.md

@@ -91,12 +91,12 @@ children = [
 
 opts = [strategy: :one_for_one, name: MyApp.Supervisor]
 Supervisor.start_link(children, opts)
-``` 
+```
 
 You can also start it manually in scripts or test environments:
 ```elixir
 {:ok, _pid} = DynamicSupervisor.start_link(strategy: :one_for_one, name: GRPC.Client.Supervisor)
-``` 
+```
 
 Then connect with gRPC server:
 
@@ -125,7 +125,7 @@ iex> {:ok, reply} = channel |> Helloworld.GreetingServer.Stub.say_unary_hello(re
 
 ## Target Schemes and Resolvers
 
-The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](lib/grpc/client/resolver.ex).  
+The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](grpc_client/lib/grpc/client/resolver.ex).
 You can connect using `DNS`, `Unix Domain sockets`, `IPv4/IPv6`, or even `xDS-based endpoints`.
 
 ### Supported formats:
@@ -171,7 +171,7 @@ iex> {:ok, channel} =
 
 ## Client Adapters
 
-By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.  
+By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.
 You can switch to **Mint** (pure Elixir HTTP/2) or other adapters as needed.
 
 ### Using Mint Adapter

grpc_server/README.md

@@ -98,7 +98,7 @@ defmodule HelloworldStreams.Server do
   def say_unary_hello(request, materializer) do
     request
     |> GRPC.Stream.unary(materializer: materializer)
-    |> GRPC.Stream.map(fn %HelloReply{} = reply ->
+    |> GRPC.Stream.map(fn %HelloRequest{} = reply ->
       %HelloReply{message: "[Reply] #{reply.message}"}
     end)
     |> GRPC.Stream.run()
@@ -195,7 +195,7 @@ iex> GRPC.Stream.from([1, 2])
 ...>   {:error, {:exception, _reason}} ->
 ...>     {:error, GRPC.RPCError.exception(message: "Booomm")}
 ...> end)
-``` 
+```
 
 In this example:
 
@@ -223,7 +223,7 @@ def say_unary_hello(request, _materializer) do
 
     {:error, reason} ->
       {:error, GRPC.RPCError.exception(message: "error calling external process: #{inspect(reason)}")}
-    
+
     error ->
       Logger.error("Unknown error")
       error
@@ -269,6 +269,20 @@ defmodule Helloworld.Application do
 end
 ```
 
+A TLS configuration can be defined by assigning a `%GRPC.Credential{}` struct, typically created by calling
+`GRPC.Credential.new/1`, to the `cred` key in the `adapter_opts` option. For example:
+
+```elixir
+  {
+    GRPC.Server.Supervisor, [
+      endpoint: Helloworld.Endpoint,
+      port: 50051,
+      start_server: true,
+      adapter_opts: [cred: GRPC.Credential.new(ssl: Application.get_env(:my_app, :ssl))]
+    ]
+  }
+```
+
 # Client Usage
 
 This section demonstrates how to establish client connections and perform RPC calls using the Elixir gRPC client.
@@ -287,12 +301,12 @@ children = [
 
 opts = [strategy: :one_for_one, name: MyApp.Supervisor]
 Supervisor.start_link(children, opts)
-``` 
+```
 
 You can also start it manually in scripts or test environments:
 ```elixir
 {:ok, _pid} = DynamicSupervisor.start_link(strategy: :one_for_one, name: GRPC.Client.Supervisor)
-``` 
+```
 
 Then connect with gRPC server:
 
@@ -321,7 +335,7 @@ iex> {:ok, reply} = channel |> Helloworld.GreetingServer.Stub.say_unary_hello(re
 
 ## Target Schemes and Resolvers
 
-The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](lib/grpc/client/resolver.ex).  
+The `connect/2` function supports URI-like targets that are resolved via the internal **gRPC** [Resolver](grpc_client/lib/grpc/client/resolver.ex).
 You can connect using `DNS`, `Unix Domain sockets`, `IPv4/IPv6`, or even `xDS-based endpoints`.
 
 ### Supported formats:
@@ -367,7 +381,7 @@ iex> {:ok, channel} =
 
 ## Client Adapters
 
-By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.  
+By default, `GRPC.Stub.connect/2` uses the **Gun** adapter.
 You can switch to **Mint** (pure Elixir HTTP/2) or other adapters as needed.
 
 ### Using Mint Adapter

grpc_server/guides/getting_started/quickstart.livemd

@@ -101,6 +101,9 @@ end
 
 ## Endpoint with Interceptor
 
+Endpoints allow starting one or more servers via the `run` directive along with
+optional middleware which are registered using the `intercept` directive.
+
 ```elixir
 defmodule HelloEndpoint do
   use GRPC.Endpoint
@@ -110,6 +113,9 @@ defmodule HelloEndpoint do
 end
 ```
 
+Interceptors are called in the order they appear, allowing for pluggable logging,
+authentication, etc. to be applied to incoming requests.
+
 ---
 
 ## Starting the Server
@@ -123,6 +129,42 @@ Here we start the GRPC server under supervision at port `50051`.
 IO.puts("gRPC Server running on port 50051")
 ```
 
+A TLS configuration can be defined by assigning a `%GRPC.Credential{}` struct, typically created by calling
+`GRPC.Credential.new/1`, to the `cred` key in the `adapter_opts` option. For example:
+
+```elixir
+  adapter_opts: [cred: GRPC.Credential.new(ssl: Application.get_env(:my_app, :ssl))]
+```
+
+### As part of a supervision tree
+
+Typically the server will be started as part of a supervision tree rather than started
+manually:
+
+```elixir
+defmodule Helloworld.Application do
+  @moduledoc false
+  use Application
+
+  @impl true
+  def start(_type, _args) do
+    children = [
+      {
+        GRPC.Server.Supervisor, [
+          endpoint: HelloEndpoint,
+          port: 50051,
+          start_server: true,
+          adapter_opts: [cred: GRPC.Credential.new(ssl: Application.get_env(:my_app, :ssl))]
+        ]
+      }
+    ]
+
+    opts = [strategy: :one_for_one, name: Helloworld.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end
+```
+
 ---
 
 ## Create a Client and Test the RPC