Refactor all gRPC proxy code into a single class.

appengine/swarming/doc/Magic-Values.md

Index: appengine/swarming/doc/Magic-Values.md
diff --git a/appengine/swarming/doc/Magic-Values.md b/appengine/swarming/doc/Magic-Values.md
index 28c47a4c1927a051a9a38c9358e755f07feea927..fb167d81582e8d4f2f48b3a332c75e8dd2618a3b 100644
--- a/appengine/swarming/doc/Magic-Values.md
+++ b/appengine/swarming/doc/Magic-Values.md
@@ -44,6 +44,15 @@ always set:
 The following environment variables may be set to alter bot behavior:
 
   - `SWARMING_EXTERNAL_BOT_SETUP=1` disables bot_config.setup_bot hook.
+  - `SWARMING_GRPC_PROXY=<url>` and `ISOLATED_GRPC_PROXY=<url>` override the
+    same value in the bot config.
+  - `GRPC_PROXY_TLS_ROOTS=<file>` and points to a .crt file containing
+    certificate authorities. `GRPC_PROXY_TLS_OVERRIDE=<name>` specifies the name
+    of the server in the certificate. These are useful for testing a gRPC proxy
+    running on localhost but with TLS enabled. Unlike the `*_GRPC_PROXY` env
+    vars, these are shared between Swarming and Isolated since they're only used
+    in the limited case when you need to override TLS. See
+    /client/utils/grpc_proxy.py for more information.

[M-A Ruel, 2017/08/04 02:05:37]

you can link directly with:
 [/client/utils/grpc_proxy.py](../../../client/utils/grpc_proxy.py)

[aludwin, 2017/08/04 14:53:10]

Done.

 
 
 ### dimensions