Sahil Suri, Author at The Linux Juggernaut

Understanding Linux system logging

Posted by Sahil Suri | Aug 14, 2019 | Administration, Basics |

Introduction In this article, we will explain some of the important aspects of logging in Linux. As the case with many aspects of technology, logging mechanisms are being transitioned, modified and improved. It is also noteworthy that systemd, the default system startup and service manager for RHEL 7/Centos 7 provides it’s own logging mechanism in the form of a binary log called journald. Both Syslog and rsyslog use a similar methodology for tracking where certain programs should store their logs and that is managed through facilities and priorities. Please note that we will be using the terms Syslog and rsyslog interchangeably in this article. We’ll be working with a Centos 6 system for all practical purposes which uses rsyslog as it’s logging system. Understanding Syslog terminology: facilities, priorities, and actions If every service running on the system writes every type of log it generates to a single log file then it would be tedious to parse that data. So, a sort of labeling system was devised wherein all programs that could generate log messages would send their corresponding logs messages to a system logger. The system logger would identify the received log message based on two attribute and these attributes are facilities and priorities. Given below is the list of available facilities and priorities that we may use with Syslog facilities: auth (security or authorization related messages) user (user-level...

Docker architecture explained

Posted by Sahil Suri | Aug 12, 2019 | Devops, Docker |

Introduction We’ve touched base upon different aspects of Docker in our previous posts. In this post, we’ll talk about Docker’s architecture in a little more detail and introduce the different components that make up the docker ecosystem. Docker is based on a client-server architecture which means that the docker client and the docker daemon are separate binaries. The client can be used to communicate with different daemons. We use the docker client to execute the commands but the docker daemon is performing the majority of the work behind the scenes. The docker daemon is responsible for building, running and distributing Docker containers. Both the daemon and the client communicate using a REST API which could be accomplished through a UNIX socket or a network interface. What happens when we run a docker command? When we run a docker command, it communicates with the API using a request and tells the Docker daemon to execute the action. The docker daemon (dockerd) dockerd is a persistent process that manages containers. It listens to Docker API requests and performs actions on docker objects. These objects include: Images Containers Networks Volumes The docker client(docker) The docker client is what we use to interact with the daemon. From the command line standpoint, docker is the command that we’ll be executing. For example, let’s say we execute ‘docker container run’, in this case,...

Using cockpit tool for server Linux management part 2 (Adding clients to be managed by cockpit)

Posted by Sahil Suri | Aug 7, 2019 | Administration, Basics |

Introduction In our previous article we demonstrated how we could install the cockpit tool on a Centos 7 machine and manage various aspects of the system using the cockpit web interface. We also mentioned that we could centrally manage other client machines as well from cockpit. In this article we will demonstrate how we would add a client machine to be managed with the cockpit web interface which we installed in the previous article. Prerequisites In order to add clients to cockpit we need to install the cockpit-dashboard rpm which does not get installed when we install cockpit on the system by default. So, first let’s install the cockpit-dashboard rpm on our cockpit management server. [root@linuxnix ~]# sudo yum install cockpit-dashboard -y Loaded plugins: fastestmirror, langpacks, product-id, search-disabled-repos, subscription-manager This system is not registered with an entitlement server. You can use subscription-manager to register. Loading mirror speeds from cached hostfile * base: mirror.sunnyvision.com * extras: centos.communilink.net * updates: centos.communilink.net Resolving Dependencies --> Running transaction check ---> Package cockpit-dashboard.x86_64 0:172-2.el7.centos will be installed --> Processing Dependency: libssh >= 0.7.1 for package: cockpit-dashboard-172-2.el7.centos.x86_64 --> Processing Dependency: libssh.so.4()(64bit) for package: cockpit-dashboard-172-2.el7.centos.x86_64 --> Running transaction check ---> Package libssh.x86_64 0:0.7.1-3.el7 will be installed --> Finished Dependency Resolution Dependencies Resolved =========================================================================================================================================================================================== Package Arch Version Repository Size =========================================================================================================================================================================================== Installing: cockpit-dashboard x86_64 172-2.el7.centos extras 202 k Installing for dependencies: libssh x86_64 0.7.1-3.el7 extras 194 k Transaction...

Author: Sahil Suri

Understanding Linux system logging

Docker architecture explained

Using cockpit tool for server Linux management part 2 (Adding clients to be managed by cockpit)

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