Tag: web hosting

How to disable IPv6 on CentOS / RHEL 7

Sometimes I miss the good old days …

Recently, I had an issue with one of the servers, where a bunch of services were attaching to IPv6 ports instead of the IPv4 ones. Rather than editing the configuration of each of these services, I wanted to simply disabled IPv6 on the machine.

In the old good days, things like these were easily done via the sysctl. I surely tried that option too, but it wasn’t enough. Turns out, the proper way these days is to do this via Grub, as per this blog post:

  1. Vim /etc/default/grub file
  2. Change: GRUB_CMDLINE_LINUX=”ipv6.disable=1 crashkernel=auto rhgb quiet”
  3. Regenerate and overwrite Grub config with: grub2-mkconfig -o /boot/grub2/grub.cfg
  4. Reboot.

That sounds a bit too excessive. But then again a reboot is also required for the proper disabling of SELinux, so I guess its’ fine.

Zabbix 4.2 is out!

Zabbix 4.2 has been released and it brings an impressive array of new features and improvements. Some of these are:

  • Built-in support of Prometheus data collection
  • Efficient high-frequency monitoring
  • Validation of collected data and error handling
  • Preprocessing data with JavaScript
  • Test preprocessing rules from UI
  • Test media type from Web UI
  • Support of TimescaleDB
  • Simplified tag management
  • More flexible auto-registration
  • Support for HTML emails
  • Animations and easy external services access on network maps
  • Extracting data from HTTP headers (like authentication tokens)
  • Non-destructive resizing and reordering of dashboard widgets
  • … and a lot more

If you were waiting for a good reason to upgrade – this is it!

Configuring HA Kubernetes cluster on bare metal servers

Alexey Nizhegolenko has an excellent 3-part series of articles that cover the setup of Kubernetes on the bare metal servers. Here are the parts:

If that’s not a hand-holding walk-through guide, then I don’t know what is.

Kraken – p2p Docker registry

Kraken by Uber:

Kraken is a P2P-powered Docker registry that focuses on scalability and availability. It is designed for Docker image management, replication and distribution in a hybrid cloud environment. With pluggable backend support, Kraken can easily integrate into existing Docker registry setups as the distribution layer.
Kraken has been in production at Uber since early 2018. In our busiest cluster, Kraken distributes more than 1 million blobs per day, including 100k 1G+ blobs. At its peak production load, Kraken distributes 20K 100MB-1G blobs in under 30 sec.

htrace.sh – HTTP/HTTPS troubleshooting and profiling tool

htrace.sh is a handy command-line tool for HTTP/HTTPS troubleshooting and profiling. It also integrates with a number of other security tools, like nmap, SSL Labs, subfinder, etc.