Replace deprecated tctl plugin example with codec server. (#238)

* Replace deprecated tctl plugin example with codec server.

encryption/README.md

@@ -1,8 +1,8 @@
 ### Steps to run this sample:
 1) You need a Temporal service running. See details in README.md
-2) Compile the encryption plugin for tctl
+2) Run the following command to start the remote codec server
 ```
-go build -o ../bin/encryption-plugin plugin/main.go
+go run ./codec-server
 ```
 3) Run the following command to start the worker
 ```
@@ -12,9 +12,14 @@ go run worker/main.go
 ```
 go run starter/main.go
 ```
-5) Run the following command and see the encrypted payloads
+5) Run the following command and see the payloads cannot be decoded
 ```
-export PATH="../bin:$PATH" TEMPORAL_CLI_PLUGIN_DATA_CONVERTER=encryption-plugin
 tctl workflow show --wid encryption_workflowID
 ```
-Note: plugins should normally be available in your PATH, we include the current directory in the path here for ease of testing.
+6) Run the following command and see the decoded payloads
+```
+tctl --codec_endpoint 'http://localhost:8081/' workflow show --wid encryption_workflowID
+```
+
+Note: The codec server provided in this sample does not support decoding payloads for the Temporal Web UI, only tctl.
+Please see the [codec-server](../codec-server/) sample for a more complete example of a codec server which provides UI decoding and oauth.

encryption/codec-server/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net/http"
+	"os"
+	"os/signal"
+	"strconv"
+
+	"github.com/temporalio/samples-go/encryption"
+
+	"go.temporal.io/sdk/converter"
+)
+
+var portFlag int
+
+func init() {
+	flag.IntVar(&portFlag, "port", 8081, "Port to listen on")
+}
+
+func main() {
+	flag.Parse()
+
+	// This example codec server does not support varying config per namespace,
+	// decoding for the Temporal Web UI or oauth.
+	// For a more complete example of a codec server please see the codec-server sample at:
+	// ../../codec-server.
+	handler := converter.NewPayloadCodecHTTPHandler(&encryption.Codec{}, converter.NewZlibCodec(converter.ZlibCodecOptions{AlwaysEncode: true}))
+
+	srv := &http.Server{
+		Addr:    "0.0.0.0:" + strconv.Itoa(portFlag),
+		Handler: handler,
+	}
+
+	errCh := make(chan error, 1)
+	go func() { errCh <- srv.ListenAndServe() }()
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, os.Interrupt)
+
+	select {
+	case <-sigCh:
+		_ = srv.Close()
+	case err := <-errCh:
+		log.Fatal(err)
+	}
+}