If you run a lot of Virtual Machines using qemu, you probably can save a lot of memory, at the expense of CPU cycles, by enabling Kernel Samepage Merging (KSM).
If you just want to test it and run only on the current boot run the following:
echo 1 > /sys/kernel/mm/ksm/run
After testing if you want to enable it permanently you can use systemd temporary files.
Continue reading “Enable KSM Centos7/Debian”
A Self-hosted installation of GitLab comes with an extremely interesting and useful tool that is disabled by default, the Mattermost chat server, think of it as a self-hosted and better Slack.
If you installed GitLab using the Omnibus package, the recommended way, you can enable it and set up a letsencrypt certificate in a few steps as described bellow.
Open the file ‘/etc/gitlab/gitlab.rb’ and find the line:
Continue reading “Enabling Mattermost on the Gitlab Instalation”
The installation of a self hosted Gitlab instance using SSL certificates from Let’sEncrypt on a Centos 7 is simple and straightforward.
Run as root the following, remember to change Gitlab.example.com with the domain you intend to use for your Gitlab installation
Continue reading “Gitlab on-premisses install + Let’s Encrypt”
Sometimes it’s interesting to get the hash of the head of the current git repository, with it you can check if you are running an up-to-date version or postfix it in URLs with ‘?version=(hash)’ so you won’t have problems with browser/proxies caches.
Continue reading “Get Git Head via PHP script”
If you’ve been bitten by the following bug during the installation of the certbot DNS auth plugin for route53.
---> Package python2-boto3.noarch 0:1.4.6-1.el7 will be installed
--> Processing Dependency: python2-s3transfer >= 0.1.10 for package: python2-boto3-1.4.6-1.el7.noarch
Package python2-s3transfer is obsoleted by python-s3transfer, but obsoleting package does not provide for requirements
--> Finished Dependency Resolution
Error: Package: python2-boto3-1.4.6-1.el7.noarch (epel)
Requires: python2-s3transfer >= 0.1.10
Available: python2-s3transfer-0.1.10-1.el7.noarch (epel)
python2-s3transfer = 0.1.10-1.el7
Continue reading “Install python2-certbot-dns-route53 centos 7”
One annoying “feature” of the windows 10 NFS client is that by default the anonymous user uid and gid is set to -2, and so you can create new files and directories on your NFS server, but you can’t edit or remove existing files.
To fix it, you can paste the code bellow in a text file and save it with a ‘.reg’ extension, run it and reboot the machine.
Continue reading “Enable(fix) write permissions on a NFS share mounted on Windows 10”
If you want to give the zswap kernel extension a try you can enable it just for the current boot with the following
echo 1 > /sys/module/zswap/parameters/enabled
If you want to make the change permanent, it’s simple to do it adding a kernel boot parameter on the grub bootloader
Continue reading “Enable zswap in Linux”
The Simplest reverse proxy configuration possible is the code below, with this configuration your server will proxy all requests from example.com
ServerAdmin [email protected]
Allow from all
Continue reading “Apache Reverse Proxy Example”
If for any reason you want to disable ipv6 and don’t want to do it with the sysctl directive, another easy route is to append ‘ipv6.disable=1’ to the kernel boot parameters.
The grub Way
Open /etc/default/grub and edit the line that starts with GRUB_CMDLINE_LINUX_DEFAULT.
Add the entry ‘ipv6.disable=1’ to the arguments that are already there.
Save and run
Continue reading “Disable IPv6 on Linux Via Kernel Boot Parameters”
In this guide we’ll create a generic apache config file to ‘automatically’ create virtual hosts for a specific domain in your server
Sometimes you have a development server with one primary domain, and some sub-domains with your projects and/or stuff that still need to be validated
Firstly you will need to disable SELinux or configure the folders appropriately ( not covered in this guide ).
Continue reading “Apache auto-create Virtual-Hosts*”