Jason Salter - My Blog

Adding Ingress Rules to an AWS Security Group

In this post we will look at how to modify the ingress rules for a security group using the AWS CLI to add and remove http and ssh access. In order to test and verify we'll create an EC2 instance running a basic webpage

Running AWS CLI Client in Docker

In this post, which is a followup to the one here we'll run the AWS CLI client in a Docker container rather then install it on our host machine. The lab assumes that Docker is already installed and running on the machine we are

Installation of AWS CLI

There are a number of ways of interacting with AWS and in this post we'll run through the installation of the CLI client under Ubuntu 20.04. This will allow the running of AWS commands within a standard Bash terminal. In this post we'll

Adding a New User to an AWS Account

In this Lab we will create a new AWS user that will have access to an existing AWS account (165541912265) to create EC2 Virtual Machines and S3 Object Storage. This involves setting up a new user with the IAM service and giving it the

OpenVPN using PFSense

This post is a follow up to the previous one that described the use of tunnelling of an OpenVPN link to encrypt a connection from a client on the 192.168.200.0/24 network to a web server on 172.16.0.0/

OpenVPN using Vagrant

OpenVPN is a popular opensource VPN solution and in this post we'll set up a Lab with a Virtual Machine acting as a gateway to securely access a Web Server running on the 172.16.0.0/24 network from a client. The lab

My Experience of the CKA Exam

This is a quick overview of my experience in sitting and passing the Certified Kubernetes Administrator exam, the first time I have sat a Linux Foundation certification. The exam was taken at home, another thing that I have not experienced before which was of

Custom Column Reports using Kubectl

The standard output options available with the kubectl command allow gathering of information about our Kubernetes cluster and what is running within it. In many circumstances this may be sufficient but sometimes there is a need to display information not part of the standard

Using Netcat for Testing Container Connectivity

This post examines making use of the netcat utility to confirm connectivity between containers running within a Kubernetes cluster. Netcat is a really useful tool for testing network connectivity which is part of the standard Busybox image. The tool can be used for setting

Using Kubernetes RBAC for Creation of New User

The user that kubeadm creates when building a cluster has full access, allowing the creation and deletion of anything within the cluster. In this post we will create a new user, salterje, which only has the ability to gather information about running Pods running

Basic Overview of Multipass

Multipass is a tool created by Canonical that makes it easy to create Virtual Machines which by default run the latest LTS version of Ubuntu. On Linux it uses KVM as it's hypervisor and if it isn't already present on the Host can be

Busybox as a web CGI Server within Kubernetes

Busybox as a web CGI Server within Kubernetes

It is always useful to have basic tools for testing when working with Pods and services within Kubernetes. In this post I'll be taking a look at using Busybox the

Creating Dynamic Routers in Linux

Creating Dynamic Routers in Linux

In this post we will create two Virtual Machines that will act as Routers running OSPF using FRRouting which is a fork of the older Quagga package. The Routers will

Adding a New Node to a Cluster using Kubeadm

In this post we are going to use kubeadm to add a newly created Node to an existing cluster. The Lab consists of a cluster of Virtual Machines running on a Host under Virtualbox which has been built using Vagrant. This means that each

Overview of Ingress Resources in Kubernetes

By default most inter-component communication within Kubernetes is internal to the cluster without any form of NAT. Pods within the cluster can be created and destroyed at any time meaning inter-pod communication is done via services allowing a static IP address to be created

Cron Jobs within Kubernetes

In a normal Kubernetes Deployment PODs will be typically created and continue to run. Jobs in Kubernetes are slightly differerent and are designed to run a particular task, complete their work and then exit. A Job will create a number of PODs ensuring at

Using init Containers in Kubernetes

PODs within Kubernetes often have just a single container within them but it is perfectly possible to have multiple containers within the same POD. All the containers within the POD will share the same IP address and can also share a volume to exchange

Creating an HAProxy Load Balancer

In this post we'll set up a simple Load Balancer, using HAProxy, that will connect two Virtual Machines running NGINX. Each of the backend machines will serve a slightly different page to confirm they are both reachable via the ingress of HAProxy. The lab

Quotas and Resource Limits in Kubernetes

It is always best to have capacity management on any system, particularly when resources are shared. This is particularly important for memory and CPU use as potentially a rogue application can impact other users. Thankfully containerised solutions make use of underlying technology such as

Node Selection in Kubernetes

The normal Kubernetes scheduler will select a suitable Node within the cluster but it is possible to manually schedule PODs on particular Nodes. This is useful if a particular application needs to be run on particular hardware or there are reasons that it should

Network Policies in Kubernetes

In normal operation Kubernetes will allow all PODs within a cluster to communicate, meaning that all ingress and egress traffic will be allowed. Network policies allow rules to be written that will define how groups of PODs can communicate with one another as well

Updating Images within PODs

Updating Images within Deployments One of the drivers for any kind of containerised system is the ability to have all dependencies self-contained within an image. This image can then be used to create running instances of the code with the confidence that it should

Adjust Number of POD Replicas

Updating Deployment Replicas The use of Deployments allows us to define a particular number of PODs that we would like to be running by adjusting the Replicas value within the Deployment. Deployments make use of the ReplicaSet object to set the number of replicas

Services in Kubernetes

Services are means of providing connectivity to PODs that by their nature may be deleted and re-created with different IP addresses within the cluster. This means that inter-POD connectivity cannot rely on using the IP address of the PODs themselves. There are a number

Mounting an NFS Volume in Kubernetes

Best practice dictates that we should not store data within a container as by their nature they are empheral. At any point the container may be destroyed and hopefully a replacement created using a suitable object such as a ReplicaSet. This would still mean