openeuler/log4cpp repository overview

⁠Quick reference

• The official log4cpp docker image.

• Maintained by: openEuler CloudNative SIG⁠.

• Where to get help: openEuler CloudNative SIG⁠, openEuler⁠.

• Learn more on Log for C++ Project⁠.

⁠log4cpp | openEuler

Current log4cpp docker images are built on the openEuler⁠. This repository is free to use and exempted from per-user rate limits.

Log4cpp is library of C++ classes for flexible logging to files, syslog, IDSA and other destinations. It is modeled after the Log4j Java library, staying as close to their API as is reasonable.

⁠Supported tags and respective Dockerfile links

The tag of each log4cpp docker image is consist of the version of log4cpp and the version of basic image. The details are as follows

⁠Usage

In this usage, users can select the corresponding {Tag} based on their requirements.

• Pull the openeuler/log4cpp image from docker

  docker pull openeuler/log4cpp:{Tag}
  

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• Run with an interactive shell

  Start a container with an interactive shell to build and run your own C++ programs with log4cpp.

  docker run -it --rm openeuler/log4cpp:{Tag} bash
  

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• Sample code

  The following simple example is taken from the official website. It logs onto the console and into the file program.log.

  main.cpp

  // main.cpp
  
  #include "log4cpp/Category.hh"
  #include "log4cpp/Appender.hh"
  #include "log4cpp/FileAppender.hh"
  #include "log4cpp/OstreamAppender.hh"
  #include "log4cpp/Layout.hh"
  #include "log4cpp/BasicLayout.hh"
  #include "log4cpp/Priority.hh"
  
  int main(int argc, char** argv) {
  	log4cpp::Appender *appender1 = new log4cpp::OstreamAppender("console", &std::cout);
  	appender1->setLayout(new log4cpp::BasicLayout());
  
  	log4cpp::Appender *appender2 = new log4cpp::FileAppender("default", "program.log");
  	appender2->setLayout(new log4cpp::BasicLayout());
  
  	log4cpp::Category& root = log4cpp::Category::getRoot();
  	root.setPriority(log4cpp::Priority::WARN);
  	root.addAppender(appender1);
  
  	log4cpp::Category& sub1 = log4cpp::Category::getInstance(std::string("sub1"));
  	sub1.addAppender(appender2);
  
  	// use of functions for logging messages
  	root.error("root error");
  	root.info("root info");
  	sub1.error("sub1 error");
  	sub1.warn("sub1 warn");
  
  	// printf-style for logging variables
  	root.warn("%d + %d == %s ?", 1, 1, "two");
  
  	// use of streams for logging messages
  	root << log4cpp::Priority::ERROR << "Streamed root error";
  	root << log4cpp::Priority::INFO << "Streamed root info";
  	sub1 << log4cpp::Priority::ERROR << "Streamed sub1 error";
  	sub1 << log4cpp::Priority::WARN << "Streamed sub1 warn";
  
  	// or this way:
  	root.errorStream() << "Another streamed error";
  
  	return 0;
  }
  

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• Compile and run

  The headers are installed under /usr/include/orocos and the shared library name is orocos-log4cpp.

  g++ main.cpp -I/usr/include/orocos -lorocos-log4cpp -o main
  ./main
  

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  Console output for that example:

  1352973121 ERROR  : root error
  1352973121 ERROR sub1 : sub1 error
  1352973121 WARN sub1 : sub1 warn
  1352973121 WARN  : 1 + 1 == two ?
  1352973121 ERROR  : Streamed root error
  1352973121 ERROR sub1 : Streamed sub1 error
  1352973121 WARN sub1 : Streamed sub1 warn
  1352973121 ERROR  : Another streamed error
  

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• Check container logs

  docker logs <container>
  

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• Exec into a running container

  docker exec -it <container> bash
  

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⁠Question and answering

If you have any questions or want to use some special features, please submit an issue or a pull request on openeuler-docker-images⁠.