today's howtos
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Specify Name (Save As) When Saving File in vi / vim
The vi (or vim) text editor is a very effective text editor for Linux / UNIX systems. It has been around since 1976 and you either love it or hate it. In order to be effective with the editor, it is important to know all the commands. One such command is specifying the name, or save as, of the file before you write it to disk. Let’s take a look at how to use the “save as” feature in vim.
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Josef Strzibny: Download RPM packages locally with DNF
Sometimes, you only want to download RPM packages without installing them. This is now super easy with DNF.
If you remember Yum, you had to resolve to installing a yum-plugin-downloadonly plugin or a separate tool to be able to download them for inspection.
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Arturo Borrero González: Openstack Neutron L3 failover issues
In the Cloud Services team at the Wikimedia Foundation we use Openstack Neutron to build our virtual network, and in particular, we rely on the neutron-l3-agent for implementing all the L3 connectivity, topology and policing. This includes basic packet firewalling and NAT.
As of this writing, we are using Openstack version Train. We run the neutron-l3-agent on standard linux hardware servers with 10G NICs, and in general it works really well. Our setup is rather simple: we have a couple of servers for redundancy (note: upstream recommends having 3) and each server runs an instance of neutron-l3-agent. We don’t use DVR, so all ingress/egress network traffic (or north-south traffic) flows using these servers. Today we use a flat network topology in our cloud. This means that all of our virtual machines share the same router gateway. Therefore, we only have one software-defined router.
Neutron does a very smart thing: each software-defined router is implemented on a linux network namespace (netns). Each router living on its own netns, the namespace contains all IP addresses, routes, interfaces, netfilter firewalling rules, NAT configuration, etc.
Additionally, we configure the agents and software-defined routers to be deployed on an high availability fashion. Neutron implements this by running an instance of keepalived (VRRP) inside each router netns. The gateway IP is therefore a virtual address that can move between the two instances of the neutron-l3-agent.
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Prepare for successful container adoption with these tips
IT teams use containers to build more dynamic applications and support modern microservice architectures. And containers are a critical tool for IT organizations to take advantage of innovations, such as cloud services, Agile methodology, DevOps collaboration and mobile apps.
As businesses turn to containers to fuel development and support infrastructures, they must identify which workloads benefit from containerization, as well as strategize automation benefits and deploy the right tools for management.
As a result, IT teams are better positioned to evaluate savings potential, adopt key DevOps processes and apply IT training where necessary. In this article, we explore containerization's history and its uses, assess ideal workloads, potential operational savings and key management approaches.
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How to Install VirtualBox 6.1 On Linux?
Virtual Machines are software used to run other operating systems within a pre-installed operating system. This self-contained OS runs as a separate computer that has no relation to the host OS. VirtualBox is an open-source cross-platform software that can help you run multiple guest operating systems on a single computer. In this article, let’s look at how to install VirtualBox 6.1 on Linux, easily.
Why Install VirtualBox?
One of the most important use cases of VirtualBox is its ability to try out/test various operating systems without fiddling with your internal storage. VirtualBox creates a virtual environment that utilizes system resources like RAM and CPU to power the OS inside a container.
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