Separation Anxiety: A Tutorial for Isolating Your System with Linux Namespaces

With the advent of tools like Docker, Linux Containers, and others, it has become super easy to isolate Linux processes into their own little system environments. This makes it possible to run a whole range of applications on a single real Linux machine and ensure no two of them can interfere with each other, without having to resort to using virtual machines. These tools have been a huge boon to PaaS providers. But what exactly happens under the hood?

ansible with docker dynamic inventory

So, I have a few dockers. Every now and then I want to run some command on all of them. Doing ‘docker exec’ is tiresome. I found this neat solution with ansible that I thought I should share with you.

To get started, you need to have the “docker.py” script. This script will be used as python script inventory for ansible. So, use the following command and get the script:

supernova – manage multiple openstack environment

supernova is an easy to use tool that helps manage multiple openstack environments.

Details –

Name        : supernova

Arch        : noarch

Epoch       : 0

Version     : 2.2.0

Release     : 2.fc24

Size        : 62 k

Repo        : @System

From repo   : fedora

Summary     : Use novaclient with multiple OpenStack nova environments the easy way

URL         : https://github.com/major/supernova

License     : ASL 2.0

Description : supernova manages multiple nova environments without sourcing

novarc files or mucking with environment variables.

To get started, start with installing supernova with

Install virtual machines in one line

To install a VM from command line, you can use the following command. Change the required parameters as need but you need to change at-least CDROM iso image and disk-path.

virt-install \
    -n myVM \
    --description "Test VM" \
    --os-type=Linux \
        --os-variant=centos7 \
        --ram=2048 \
        --vcpus=2 \
        --disk path=./myVM.img,bus=virtio,size=10 \
        --graphics none \
        --cdrom  <Image installtion CDROM>.iso \
        --net user

Python script to manage virtual machines with python API for libvirt.

Most of times I use virt-manager to manage VMs but sometimes, I have to manage VMs on other hosts over ssh when connected over VPN or while I am working remotely. GUI like virt-manager thus becomes slow, and hence I like to use cli commands and nothing is better than virsh. But here is simple script that I use sometimes to manage the VMs with CLI based menu. Hope you find it useful.

Most simple and fast lightweight container with Fedora systemd

If you need to have a quick bash shell in sandbox with not network as well, then the most simple command I could find so far is:

sudo virt-sandbox -c lxc:/// /bin/bash

For this you will need to have libvirt-sandbox installed which you can do with the following command:

sudo yum install libvirt-sandbox

virsh – show ip address of all running VMs

If you are using the libvirt and associated tools, then you must be aware about virt-manager. However this being a GUI tools, it is not possible to always use this. “virsh” is a good option for this.

To start with, if you need to know all the VMs all the running VMs, then you can use (to only view the names):

virsh list --name

Extending this to make it more useful is the case if you need to know the IP address for the running VMs. Here is a simple code that you can put in alias or function that can be used to get the IP address of the running VM’s.