Linux Tips, Hacks, Tricks, and Tutorials
Before you can deploy a registry, you need to install Docker on the host. A registry is an instance of the registry image, and runs within Docker. Install docker service with bellow commands. dnf config-manager –add-repo=https://download.docker.com/linux/centos/docker-ce.repo dnf install -y docker-ce –nobest systemctl enable –now docker dockerstatus=`systemctl status docker | grep “active (running)”` echo “Docker Service […]
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Follow the below steps to export all docker images and import them to another system. Step #1 Export or save all images to one tar file. docker save $(docker images –format ‘{{.Repository}}:{{.Tag}}’) -o allimages.tar Step #2 scp -i key.pem rocky@192.168.1.1:/tmp/allimages.tar . Step #3 Load all images to docker on new host. docker load -i allimages.tar
1. Install kernel-modules-extra and SCTP for the currently installed kernel; yum install kernel-modules-extra-`uname -r` yum install -y lksctp-tools lksctp-tools-devel lksctp-tools-doc 2. Add sctp to /etc/modules-load.d/* to load sctp before systemd-sysctl.service during boot. Loading sctp before systemd-sysctl.service allows the sctp sysctl.conf settings to be effective; # cat /etc/modules-load.d/sctp.conf sctp 3. sctp is blacklisted by default on […]
Galera Arbitrator <http://galeracluster.com/documentation-webpages/arbitrator.html> is a member of Percona XtraDB Cluster that is used for voting in case you have a small number of servers (usually two) and don’t want to add any more resources. Galera Arbitrator does not need a dedicated server. It can be installed on a machine running some other application. Just make sure it has […]
Cluster Configuration In this example configuration of two nodes, we assume that the servers are connected over private network. This allows direct connections without requiring SSH tunnels. The most important parts is to enable listening on IP protocol and to configure addresses and names of the cluster nodes. The config files are similar for each […]
Standard macros that are available in Nagios are listed here. On-demand macros and macros for custom variables are described here. Macro Validity Although macros can be used in all commands you define, not all macros may be “valid” in a particular type of command. For example, some macros may only be valid during service notification commands, […]
As well as receiving SNMP traps in Nagios, you can send SNMP traps from Nagios to a remote SNMP management station like HP OpenView (NNM) or the like. The easiest way to do this is to create a notification command that generates an SNMP trap. This way, you can use an SNMP management station as […]
Docker Terms This section defines some of the most useful Docker terms. Docker Image: A set of read-only files. These files are a part of an operating system that is required to run a Docker container. Dockerfile: A simple text file that contains all the commands a user could call in the command line to […]
You can check if an SSL certificate matches a Private Key by using the 3 easy commands below. For your SSL certificate: openssl x509 -noout -modulus -in <file>.crt | openssl md5 For your RSA private key: openssl rsa -noout -modulus -in <file>.key | openssl md5 For your CSR: openssl req -noout -modulus -in <file>.csr | […]
Notes and Tips To list all services firewalld is aware in an easy to read format use command firewall-cmd –get-services | tr ” ” “\n” Default firewalld service .xml files can be found under /usr/lib/firewalld/services For all commands that support the –zone= option if no zone is provided it will use the default zone. To make changes persistent add […]