Add information in manual about logging

Author: Seung Woo Kim

docs/configuration.rst

@@ -30,99 +30,158 @@ In order to test CodeChain alone, one may want to change ``change_type`` into So
 
 CLI Options for CodeChain client
 ================================
-::
-
- --config-path = [PATH]
+ ``--config-path=[PATH]``
  Specify the certain config file path that you want to use to configure CodeChain to your needs.
 
- --port = [PORT]
+ ``--port=[PORT]``
  Listen for connections on PORT. (default: 3485)
 
- --bootstrap-addresses = [BOOTSTRAP_ADDRESSES]
+ ``--bootstrap-addresses=[BOOTSTRAP_ADDRESSES]``
  Bootstrap addresses to connect.
 
- --no-network
+ ``--no-network``
  Do not open network socket.
 
- --min-peers = [NUM]
+ ``--min-peers=[NUM]``
  Sets the minimum number of connections the user would like. (default: 10)
 
- --max-peers = [NUM]
+ ``--max-peers=[NUM]``
  Sets the maximum number of connections the user would like. (default: 30)
 
- --instance-id = [ID]
+ ``--instance-id=[ID]``
  Specify instance id for logging. Used when running multiple instances of CodeChain.
 
- --quiet
+ ``--quiet``
  Do not show any synchronization information in the console.
 
- --chain = [CHAIN]
+ ``--chain=[CHAIN]``
  Sets the blockchain type out of solo, solo_authority, tendermint or a path to chain spec file. (default: tendermint)
 
- --db-path = [PATH]
+ ``--db-path=[PATH]``
  Specify the database directory path.
 
- --no-sync
+ ``--no-sync``
  Do not run block sync extension.
 
- --no-parcel-relay
+ ``--no-parcel-relay``
  Do not relay parcels.
 
- --jsonrpc-port = [PORT]
+ ``--jsonrpc-port=[PORT]``
  Listen for rpc connections on PORT. (default: 8080)
 
- --no-jsonrpc
+ ``--no-jsonrpc``
  Do not run jsonrpc.
 
- --secret-key = [KEY]
+ ``--secret-key=[KEY]``
  Secret key used by node.
 
- --author = [ADDRESS]
+ ``--author=[ADDRESS]``
  Specify the block's author (aka "coinbase") address for sending block rewards from 
  sealed blocks.
 
- --engine-signer = [ADDRESS]
+ ``--engine-signer=[ADDRESS]``
  Specify the address which should be used to sign consensus messages and 
  issue blocks.
 
- --no-discovery
+ ``--no-discovery``
  Do not use discovery. No automated peer finding.
 
- --discovery = "kademlia" | "unstructured"
- Decides which p2p discovery extension to use. Options are kademlia and unstructured. 
+ ``--discovery="kademlia" | "unstructured"``
+ Decides which p2p discovery extension to use. Options are `kademlia <https://github.com/CodeChain-io/codechain/wiki/Kademlia-Extension>`_ and unstructured.
+ In a testing environment, an unstructured p2p network is desirable because it is
+ more than sufficient when there are a few users.
  (default: unstructured)
 
- --discovery-bucket-size = [NUM]
+ ``--discovery-bucket-size=[NUM]``
  Bucket size for discovery. Choose how many addresses to exchange at a time
  during discovery.
 
- --discovery-refresh = [ms]
+ ``--discovery-refresh=[ms]``
  Refresh timeout of discovery (ms). It may conflict with:`` --no-discovery``.
 
- Subcommands
+Subcommands
+-----------
+
+CodeChain has a subcommand called ``account``. It has subcommands of its own, which are the following:
+
+ ``create``
+ create account
+
+ ``--passphrase <PASSWORD>``
+ account passphrase
+
+ ``import``
+ import private key
+
+ ``--passphrase <PASSWORD>``
+ set account passphrase
+
+ ``--raw-key <RAW-KEY>``
+ specify key to import
+
+ ``list``
+ list managed accounts
+
+For example, if you want to create an account with a password of '1234', run the following:
+::
 
- CodeChain has a subcommand called ``account``. ``amount``is the account managing commands 
- of CodeChain, and also has subcommands of its own, which are the following:
+ ./target/release/codechain account create --passphrase 1234
 
- Subcommands of codechain account:
- create
- create account
- --passphrase = []
- account passphrase
 
- import
- import private key
- --passphrase = []
- account passphrase
+Logging
+=======
+For logging, run the following to configure:
+``$ RUST_LOG=<level> codechain``
 
- --raw-key = []
- key to import
+Log Levels
+----------
+CodeChain currently offers five different ``<level>``. They are error, warn, info, debug, and trace.
 
- list
- list managed accounts
+For example, the log level will be set to debug, if you run the following:
 
- lock
- lock account
+``$ RUST_LOG="debug" codechain``
+
+* The **error** level represents an event where something can be dangerous, but can still run. In the case in which it cannot run anymore, it must crash ASAP instead of logging.
+
+* The **warn** level represents an event which can be potentially dangerous.
+
+* The **info** level represents an event which is not dangerous, but can be useful information for users.
+
+* The **debug** level represents an event that is useful for developers, but not for users.
+
+* The **trace** level is used for tracing.
+
+Log Targets
+-----------
+
+Log levels can be set differently for each log targets. For example, you can run the following to set ``tx``'s log level as ``trace`` and ``parcel``'s 
+log level as ``info`` with the following code:
+
+``$ RUST_LOG="tx=trace, parcel=info" codechain``
+
+The possible log targets are as follows:
+::
 
- unlock
- unlock account
+ "blockchain"
+ "client"
+ "discovery"
+ "engine"
+ "external_parcel"
+ "io"
+ "miner"
+ "net"
+ "netapi"
+ "own_parcel"
+ "parcel_queue"
+ "poa"
+ "shutdown"
+ "snapshot"
+ "solo_authoirty"
+ "spec"
+ "state"
+ "state_db"
+ "stratum"
+ "sync"
+ "test_script"
+ "trie"
+ "tx"