[fix] #4030, #4063, #4064, #4079: re-architect logger and dynamic configuration

CONTRIBUTING.md

@@ -231,7 +231,7 @@ Follow these commit guidelines:
 
 <details> <summary> Expand to learn how to change the log level or write logs to a JSON.</summary>
 
-If one of your tests is failing, you may want to decrease the maximum logging level. By default, Iroha only logs `INFO` level messages, but retains the ability to produce both `DEBUG` and `TRACE` level logs. This setting can be changed either using the `MAX_LOG_LEVEL` environment variable for code-based tests, or using the `/configuration` endpoint on one of the peers in a deployed network.
+If one of your tests is failing, you may want to decrease the maximum logging level. By default, Iroha only logs `INFO` level messages, but retains the ability to produce both `DEBUG` and `TRACE` level logs. This setting can be changed either using the `LOG_LEVEL` environment variable for code-based tests, or using the `/configuration` endpoint on one of the peers in a deployed network.
 
 While logs printed in the `stdout` are sufficient, you may find it more convenient to produce `json`-formatted logs into a separate file and parse them using either [node-bunyan](https://www.npmjs.com/package/bunyan) or [rust-bunyan](https://crates.io/crates/bunyan).
 
@@ -251,16 +251,16 @@ In this case you should compile iroha with support of tokio console like that:
 RUSTFLAGS="--cfg tokio_unstable" cargo build --features tokio-console
 ```
 
-Port for tokio console can by configured through `TOKIO_CONSOLE_ADDR` configuration parameter (or environment variable).
-Using tokio console require log level to be `TRACE`, can be enabled through configuration parameter or environment variable `MAX_LOG_LEVEL`.
+Port for tokio console can by configured through `LOG_TOKIO_CONSOLE_ADDR` configuration parameter (or environment variable).
+Using tokio console require log level to be `TRACE`, can be enabled through configuration parameter or environment variable `LOG_LEVEL`.
 
 Example of running iroha with tokio console support using `scripts/test_env.sh`:
 
 ```bash
 # 1. Compile iroha
 RUSTFLAGS="--cfg tokio_unstable" cargo build --features tokio-console
 # 2. Run iroha with TRACE log level
-MAX_LOG_LEVEL=TRACE ./scripts/test_env.sh setup
+LOG_LEVEL=TRACE ./scripts/test_env.sh setup
 # 3. Access iroha. Peers will be available on ports 5555, 5556, ...
 tokio-console http://127.0.0.1:5555
 ```

README.md

@@ -169,7 +169,7 @@ For a list of all endpoints, available operations, and ways to customize them wi
 
 By default, Iroha provides logs in a human-readable format and prints them out to `stdout`.
 
-The logging level can be changed either via a [configuration option](./docs/source/references/config.md#loggermax_log_level) or at run-time using the `configuration` endpoint.
+The logging level can be changed either via the [`logger.level` configuration parameter](./docs/source/references/config.md#loggerlevel) or at run-time using the `configuration` endpoint.
 
 <details><summary>Example: changing log level</summary>
 
@@ -178,17 +178,13 @@ For example, if your Iroha instance is running at `127.0.0.1:8080` and you want
 curl -X POST \
     -H 'content-type: application/json' \
     http://127.0.0.1:8080/configuration \
-    -d '{"LogLevel": "DEBUG"}' -i
+    -d '{"logger": {"level": "DEBUG"}}' -i
 ```
 </details>
 
-#### JSON Logging Mode
+The log format might be configured via the [`logger.format` configuration parameter](./docs/source/references/config.md#loggerformat). Possible values are: `full` (default), `compact`, `pretty`, and `json`.
 
-Additionally, Iroha supports a JSON logging mode.
-
-To enable it, provide the [logging file](./docs/source/references/config.md#loggerlog_file_path) to store the logs in. On UNIX, you can also specify `/dev/stdout` or `/dev/stderr` if you prefer to pipe the output to [`bunyan`](https://www.npmjs.com/package/bunyan).
-
-[Log rotation](https://www.commandlinux.com/man-page/man5/logrotate.conf.5.html) is the responsibility of the peer administrator.
+Output goes to `/dev/stdout`. Piping to files or [log rotation](https://www.commandlinux.com/man-page/man5/logrotate.conf.5.html) is the responsibility of the peer administrator.
 
 ### Monitoring