From 44bb7343da9c0c6141124a420a48048ea0223ecb Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Fri, 9 Sep 2016 08:44:05 -0700
Subject: [PATCH 1/2] Add documentation for GRPC_ environment variables

---
 doc/environment_variables.md | 61 ++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 doc/environment_variables.md

diff --git a/doc/environment_variables.md b/doc/environment_variables.md
new file mode 100644
index 00000000000..18269ef0415
--- /dev/null
+++ b/doc/environment_variables.md
@@ -0,0 +1,61 @@
+gRPC environment variables
+--------------------------
+
+gRPC C core based implementations (those contained in this repository) expose
+some configuration as environment variables that can be set.
+
+* GRPC_ABORT_ON_LEAKS
+  A debugging aid to cause a call to abort() when gRPC objects are leaked past
+  grpc_shutdown()
+
+* GRPC_GOOGLE_CREDENTIALS_ENV_VAR
+  The path to find the credentials to use when Google credentials are created
+
+* GRPC_SSL_CIPHER_SUITES
+  A colon separated list of cipher suites to use with OpenSSL
+
+* GRPC_POLL_STRATEGY [posix-style environments only]
+  Declares which polling engines to try when starting gRPC.
+  This is a comma-separated list of engines, which are tried in priority order
+  first -> last.
+  Available polling engines include:
+  - epoll (linux-only) - a polling engine based around the epoll family of
+    system calls
+  - poll - a portable polling engine based around poll(), intended to be a
+    fallback engine when nothing better exists
+  - legacy - the (deprecated) original polling engine for gRPC
+
+* GRPC_TRACE
+  A comma separated list of tracers that provide additional insight into how
+  gRPC C core is processing requests via debug logs. Available tracers include:
+  - api - traces api calls to the C core
+  - channel - traces operations on the C core channel stack
+  - combiner - traces combiner lock state
+  - compression - traces compression operations
+  - connectivity_state - traces connectivity state changes to channels
+  - channel_stack_builder - traces information about channel stacks being built
+  - http - traces state in the http2 transport engine
+  - http1 - traces HTTP/1.x operations performed by gRPC
+  - flowctl - traces http2 flow control
+  - op_failure - traces error information when failure is pushed onto a
+    completion queue
+  - pending_tags - [debug builds only] traces still-in-progress tags on
+    completion queues
+  - round_robin - traces the round_robin load balancing policy
+  - glb - traces the grpclb load balancer
+  - queue_pluck
+  - queue_timeout
+  - secure_endpoint - traces bytes flowing through encrypted channels
+  - transport_security - traces metadata about secure channel establishment
+  - tcp - traces bytes in and out of a channel
+  'all' can additionally be used to turn all traces on.
+  Individual traces can be disabled by prefixing them with '-'.
+  Example:
+   export GRPC_TRACE=all,-pending_tags
+
+* GRPC_VERBOSITY
+  Default gRPC logging verbosity - one of:
+  - DEBUG - log all gRPC messages
+  - INFO - log INFO and ERROR message
+  - ERROR - log only errors
+

From 18c09bf2916c631cdd38cfe6980151653eec38bd Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Fri, 9 Sep 2016 13:07:17 -0700
Subject: [PATCH 2/2] Review feedback

---
 doc/environment_variables.md | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/doc/environment_variables.md b/doc/environment_variables.md
index 18269ef0415..578bfe7eb77 100644
--- a/doc/environment_variables.md
+++ b/doc/environment_variables.md
@@ -6,13 +6,16 @@ some configuration as environment variables that can be set.
 
 * GRPC_ABORT_ON_LEAKS
   A debugging aid to cause a call to abort() when gRPC objects are leaked past
-  grpc_shutdown()
+  grpc_shutdown(). Set to 1 to cause the abort, if unset or 0 it does not
+  abort the process.
 
 * GRPC_GOOGLE_CREDENTIALS_ENV_VAR
   The path to find the credentials to use when Google credentials are created
 
 * GRPC_SSL_CIPHER_SUITES
   A colon separated list of cipher suites to use with OpenSSL
+  Defaults to:
+    ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-GCM-SHA384
 
 * GRPC_POLL_STRATEGY [posix-style environments only]
   Declares which polling engines to try when starting gRPC.