Red Hat is offering a few official docker images for RHEL8. One can now use or build images based on the latest operating system from Red Hat. Here is how to do it in 3 simple steps
RHEL8 and Ansible
Red Hat EL8 is available now since May 7th. It’s not particularly exciting IMO. Many “new” features have been available on other distros quite a while ago. Here, I want to evaluate how easy it is to adopt my existing ansible playbooks on this new version of Red Hat.
Rsync backup with BTRFS
There are plenty of backup tools in the community but I still prefer rsync for desktop backup. It only copies the changes and it does not require any catalog. I’ve been using that for years, rsync-ing my files to a USB drive. While it works fine and it saved my day a couple times, my script only keeps 1 version of backup. It’d be nice if I can have at…
UID > INT_MAX
From thehackernews, it was said when the UID is larger than INT_MAX, which is 2147483647, privilege validation is improperly handled and that gives the user right to run systemctl commands as if he/she is a privileged user. What is my INT_MAX? Though it’s hard to imagine who would use such an UID when they usually starts with 1000. However, if Linux is integrated with AD, the AD users ID are mapped…
AMD EPYC on cloud
The new AMD-based instance types are made available in Nov 2018. It’s damn impressive. Here is a quick benchmark using openssl. The first is from EPYC, second from ARM, third from Intel.
Cool feature on Azure – Run Command Script
I don’t think I’ve ever said anything good about Azure, but I’ve finally ran into one today. Someone screwed up sshd_config and the service would not start anymore. With the run script tool, I was able to revert the config to the original version and restart the service. Fortunately, the changes were checked into RCS, which made recovery relatively easy. Here, I checked out the original version of the config…
tmux send input to all panes
Run tmux and have it split into 2 panes, each running a separate process, and send input to all panes. Here I start up one container in each pane, then turn on input broadcast. One can easily modify the commands and have tmux gives control over a cluster of servers. Or ssh to different servers and manage them all at once.
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tmux new 'docker run -it --name sh1 5182e96772bf' \; \ split-window 'docker run -it --name sh2 5182e96772bf' \; \ setw sync |
This is trememdously useful for myself. To turn…
Add security group to all ec2 instances
If you ever need to take over management of an AWS farm, it’s very likely you will need to attach SG to all instances. Be that for monitoring or access. Here is a bash script to add 1 SG to all instances. You will need to first setup a profile on awscli. Then run the script with the profile name as first argument, and the SG id as the second.…
Building my first Linux package
Let’s take a look at how to build a really simple Linux package. The most common package formats are definitely .deb and .rpm. One will find them on Debian-variants and Redhat-variants respectively. In the following examples, a package will be created and it will contain 1 script.The script depends on Python so I want the package management tool to handle that for me too. The script’s name is goldenRatio.sh and…
php debugging
There are a couple ways to debug php applications. We can enable core dump and/or install Xdebug. Enable php core dump on php-fpm First instruct the kernel to write core dumps to /tmp. On some system, dumps are fed to abrtd.
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echo '/tmp/core-%e.%p' > /proc/sys/kernel/core_pattern |
In php-fpm.conf, add the following
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rlimit_core = unlimited |
Restart php-fpm and use gdb to debug the dump files. To get the most out of the dump files, install the debuginfo…