In house or out sourced cloud

In this article, I’d like to make a case for doing away with private cloud and suggest alternatives including Amazon virtual private cloud and masquerading public cloud as private.

First, customers are falsely attracted to “private cloud” offerings. What they really want are the benefits of cloud computing such as scalability, elasticity, rolling applications and virtual machines, etc.  but most of them are misled into thinking a “public cloud” is less secure  and costlier than a “private cloud”. I will make a case that there is a total cost of ownership in a private cloud that makes it less attractive than alternatives.

Second, as an IT provider, it is easier to provision new compute and storage using traditional hosting albeit in the form of datacenters. This generally allows secure, dynamic, scale-able and reusable architecture that can host the business applications from the customers. Yet this does not necessarily result in cost savings, more flexibility or even more security as much as the robust, reliable and comprehensive public cloud from vendors such as Amazon Web Services.

In this article, we will explore the technical feasibility of alternatives (and skip the cost comparison for later between existing and proposed solution)

Amazon Virtual Private Cloud lets us provision an isolated set of virtual machines in a private network but still hosted on AWS cloud. This is similar in nature to the private cloud hosted in data centers but with the benefits of using a scaleable infrastructure. And we have complete control over the virtual network. Generally they are used when we don't want internet access in private facing subnet. 

A sample use case may be where the application and the database servers are separated into subnets with the forward facing application on the public cloud and the isolated database servers in a private VPC. This adds a layer of security to the database servers since they don't have internet connectivity. 

Moreover, security can be increased in a VPC with the use of security groups, network access control lists (ACLs) and flow logs. The security groups control both the inbound and outbound traffic at the instance level. The network ACLs control both the inbound and outbound traffic at the subnet level.  Flow logs capture information about the IP traffic going to and from the network interfaces.

In a VPC, all aspects of a network can be controlled, we can select its IP address range, create subnets, and configure route tables, network gateways, and security settings. We can control how the instances launched into a VPC access resources outside the VPC. An internet gateway is available  to enable our instances to connect to the internet through the Amazon EC2 network edge.

If we want to add corpnet connectivity of the VPC instances to the company, we could make use of AWS directory services.  AWS directory services makes it easy to setup and run Microsoft AD in AWS cloud or connect AWS resources with an existing on-premises Microsoft Active Directory.  This helps manage users and groups, provide single sign on to applications and services, create and apply group policy, domain join EC2 instances, as well as simplify the deployment and management of cloud based Linux and Microsoft Windows workloads.

AWS automatically brings compliance and governance standards that would have otherwise taken more labour and time on the private cloud. AWS also cares about data privacy and provides simple tools to manage ownership and control of sensitive customer content

#codingexercise
Given a bst and two boundary values. Prune the tree if the node data lies outside the boundary values

Node trimRange( node root, int min, int max)

{

If (root == null) return root;

root.left = trimRange(root.left, min,max);

root.right = trimRange(root.right, min, max);

If (root.data < min)

{

Var right = root.right;

 delete root;

  Return right;

}

If(root.data > max)

{

Var left = root.left

delete root;

Return left;

}

Return root;

}

If we were to find only one end of the range, we would exclude just the check towards the end of the method above