[FAB-9961]Fix docs about Chaincode's log level control

FAB-9961 fixes the document to explain the logging level control
within Chaincode container correctly.

According to the update in FAB-3232, two environment
variables are used. CORE_CHAINCODE_LOGGING_LEVEL sets the default
logging level for all modules. CORE_CHAINCODE_LOGGING_SHIM
overrides the level for the 'shim' logging module.

This CR updates the document to reflect the change above and
explain how to set up logging level with core.yaml.

This CR also updates environment variables used in comments of
fabric/core/chaincode/shim/chaincode.go

Change-Id: Ib6e4a24cb932dfd2f341f9d3dc845a8e86c52cb3
Signed-off-by: Yuki Kondo <yuki.kondo@hal.hitachi.com>

Author: yuki-kon

core/chaincode/shim/chaincode.go

@@ -165,8 +165,8 @@ func IsEnabledForLogLevel(logLevel string) bool {
 }
 
 // SetupChaincodeLogging sets the chaincode logging format and the level
-// to the values of CORE_CHAINCODE_LOGFORMAT and CORE_CHAINCODE_LOGLEVEL set
-// from core.yaml by chaincode_support.go
+// to the values of CORE_CHAINCODE_LOGGING_FORMAT, CORE_CHAINCODE_LOGGING_LEVEL
+// and CORE_CHAINCODE_LOGGING_SHIM set from core.yaml by chaincode_support.go
 func SetupChaincodeLogging() {
 	viper.SetEnvPrefix("CORE")
 	viper.AutomaticEnv()

docs/source/logging-control.rst

@@ -177,18 +177,35 @@ control is currently based on the *name* provided when the
 logger *name* will appear in all log messages created by the logger. The
 ``shim`` logs as "shim".
 
+The default logging level for loggers within the Chaincode container can
+be set in the
+`core.yaml <https://github.com/hyperledger/fabric/blob/master/sampleconfig/core.yaml>`__
+file. The key ``chaincode.logging.level`` sets the default level for all
+loggers within the Chaincode container. The key ``chaincode.logging.shim``
+overrides the default level for the ``shim`` module.
+
+::
+
+    # Logging section for the chaincode container
+    logging:
+      # Default level for all loggers within the chaincode container
+      level:  info
+      # Override default level for the 'shim' module
+      shim:   warning
+
+The default logging level can be overridden by using environment
+variables. ``CORE_CHAINCODE_LOGGING_LEVEL`` sets the default logging
+level for all modules. ``CORE_CHAINCODE_LOGGING_SHIM`` overrides the
+level for the ``shim`` module.
+
 Go language chaincodes can also control the logging level of the
 chaincode ``shim`` interface through the ``SetLoggingLevel`` API.
 
 ``SetLoggingLevel(LoggingLevel level)`` - Control the logging level of
 the shim
 
-The default logging level for the shim is ``LogDebug``.
-
 Below is a simple example of how a chaincode might create a private
-logging object logging at the ``LogInfo`` level, and also control the
-amount of logging provided by the ``shim`` based on an environment
-variable.
+logging object logging at the ``LogInfo`` level.
 
 ::
 
@@ -197,9 +214,6 @@ variable.
     func main() {
 
         logger.SetLevel(shim.LogInfo)
-
-        logLevel, _ := shim.LogLevel(os.Getenv("SHIM_LOGGING_LEVEL"))
-        shim.SetLoggingLevel(logLevel)
         ...
     }