Package: jloglevel
# jloglevel[![Build Status](https://travis-ci.org/ivanyu/jloglevel.svg?branch=master)](https://travis-ci.org/ivanyu/jloglevel)`jloglevel` is a command line tool for changing the logging level in JVM apps in runtime via [Jolokia](https://jolokia.org/).## How it worksJVM has a technology [Java Management Extensions (JMX)](https://en.wikipedia.org/wiki/Java_Management_Extensions) that allows to monitor and manage JVM applications in runtime. This is done via components called MBeans (managed beans). MBeans have attributes that can be read and operations (methods) that can be executed with JMX.JVM logging libraries expose MBeans which apart from other features allow control of the logging level in runtime. That means that we can change the logging level of loggers inside the application without restart or modification of files.JMX has a drawback: it doesn't go well with firewalls, especially in dynamic cloud environments. To overcome this issues, JMX-HTTP bridges exist, and [Jolokia](https://jolokia.org/) is probably the most popular of them. It exposes JMX MBeans over HTTP and allows us to read attributes and call methods using simple GETs and POSTs.Combining all this together, jloglevel makes it easy to get and set the logging level on a number of JVM applications (e.g. a scaled-out service).Currently, only [Logback](https://logback.qos.ch/) library is supported.## Installation```bash$ pip3 install jloglevel```## Usage prerequisites1. Jolokia agent needs to be attached to a JVM (or JVMs) you are going to work with. Follow the [Jolokia documentation](https://jolokia.org/documentation.html) for the details.2. Logback must be configured to expose its control via JMX.Technically only `<jmxConfigurator />` needs tp be added to `logback.xml`. See [JMX Configurator page](https://logback.qos.ch/manual/jmxConfig.html) in the documentation for the details.## Usage### Common optionsThere are two common options in every command:`-h` or `--host` to specify the IP address and the port where Jolokia agent is listening for incoming connections. Can be multiple. _Example:_ `-h 192.168.2.1:8778 -h 192.168.2.2:8778 -h 192.168.2.3:8778``--socks5` for specifying the SOCKS5 proxy IP address and port (if needed). _Example_: `--socks5 127.0.0.1:9999`This might be useful with SSH.### Listing all loggersTo list the loggers use `list-loggers` command:```bash$ jloglevel list-loggers -h 192.168.2.1:8778http://192.168.2.1:8778/ROOTmeme.ivanyume.ivanyu.agenthostme.ivanyu.agenthost.App```### Getting the logging levelTo get the logging levels use `get` command:```bash$ jloglevel get -h 192.168.2.1:8778 -h 192.168.2.2:8778 -h 192.168.2.3:8778Logger ROOThttp://192.168.2.1:8778/	DEBUGhttp://192.168.2.2:8778/	DEBUGhttp://192.168.2.3:8778/	DEBUG```By default, the logger is `ROOT`. You can get the logging level of another logger using `-l/--logger` option:```bash$ jloglevel get -h 192.168.2.1:8778 -l me.ivanyu.testapp.AppLogger me.ivanyu.testapp.Apphttp://192.168.2.1:8778/	DEBUG```### Setting the logging levelTo set the logging levels use `set` command:```bash$ jloglevel set -h 192.168.2.1:8778 -h 192.168.2.2:8778 -h 192.168.2.3:8778 TRACELogger ROOThttp://192.168.2.1:8778/	OKhttp://192.168.2.2:8778/	OKhttp://192.168.2.3:8778/	OK```Starting from this moment, the logging level of the ROOT logger is `TRACE`.As with `get` command, you can specify a logger different from the default `ROOT` using `-l/--logger` option:```bash$ jloglevel set -h 192.168.2.1:8778 -l me.ivanyu.testapp.App TRACELogger me.ivanyu.testapp.Apphttp://192.168.2.1:8778/	OK```## Authors and ContributorsThe project is started and maintained by [Ivan Yurchenko](https://ivanyu.me/) (ivan0yurchenko@gmail.com).Contributions are welcome!## License```Copyright 2017 Ivan YurchenkoLicensed under the Apache License, Version 2.0 (the "License");you may not use this file except in compliance with the License.You may obtain a copy of the License athttp://www.apache.org/licenses/LICENSE-2.0Unless required by applicable law or agreed to in writing, softwaredistributed under the License is distributed on an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.See the License for the specific language governing permissions andlimitations under the License.```