Infrastructure Concepts

External

• http://www.infrastructures.org
• Infrastructure as Code: Dynamic Systems for the Cloud Age by Kief Morris

Internal

• Infrastructure as Code
• Infrastructure as Code Concepts

Overview

In a cloud environment, infrastructure, as viewed by the user, is no longer represented by hardware, but by virtual constructs like servers, subnets and block devices. The hardware still exists, but infrastructure elements accessible to users "float" across it, can be manipulated by the infrastructure platform APIs and can be created, duplicated, changed and destroyed at will. They are referred to as infrastructure resources. Infrastructure resources can be instantiated, changed and destroyed by infrastructure as code to provide the infrastructure foundation for application runtimes and applications.

Application

Applications and services provide domain-specific capabilities to organizations and users. They exist in the form of application packages, container instances or serverless code. The underlying layers (application runtime, infrastructure platform) exist to enable this layer. Applications can be directly offered to users as part of a cloud service delivery model, under the generic name of Software-as-a-Service (SaaS). The users do not need to manage anything, but they also do not control anything, including the design of the application. This works well, unless the customer needs functionality that is not available in the application. Examples: Intuit Quickbooks, batch services based on Spark, aimed at data scientists, salesforce.com, etc.

Application Runtime

The application runtime layer provides services and capabilities to the application layer. It consists of container clusters, serverless execution environments, application servers, messaging systems, databases and operating systems. An application runtime is laid upon the infrastructure platform layer and it is assembled from infrastructure resources. This layer is also referred to as Platform as a Service (PaaS) or "cloud application platform" and can be exposed directly to users, as it is the case for EKS, AKS, OpenShift, GKS, etc.

Resources:

• InfoQ: Netflix Adrian Cockcroft on Architecture for the Cloud
• salesforce.com: What is PaaS?

Infrastructure Platform

An infrastructure platform is a set of infrastructure resources and the tools and services that manage them. The infrastructure platform lets its users to provision compute, storage, networking and other infrastructure resources on which they can run operating systems and applications. The infrastructure resources are managed dynamically via an API, which is a definitely characteristic of a cloud. This is also the essential element that allows expressing the resources as code. The infrastructure platform abstracts out the hardware and the virtualization layers. The service users do not control the underlying hardware resources except select networking configuration or perhaps the physical location of the resources at gross geographical level. On the other hand, they control - but they must install and manage - the operating system, the middleware and the application code. Infrastructure as a service is targeted at teams that are building out infrastructure. The infrastructure platforms are also known as Infrastructure as a Service (IaaS). Examples: AWS, Azure, GCP.

Infrastructure Resources

Infrastructure resources consist of compute, network and storage. An infrastructure platform abstracts infrastructure resources from physical hardware. Infrastructure resources are assembled to provide application runtime instances. Infrastructure resources can be expressed as code and grouped in stacks.

Cloud

NIST cloud definition:

Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model promotes availability and is composed of five essential characteristics (On-demand self-service, Broad network access, Resource pooling, Rapid elasticity, Measured Service); three service models (Cloud Software as a Service (SaaS), Cloud Platform as a Service (PaaS), Cloud Infrastructure as a Service (IaaS)); and, four deployment models (Private cloud, Community cloud, Public cloud, Hybrid cloud). Key enabling technologies include: (1) fast wide-area networks, (2) powerful, inexpensive server computers, and (3) high-performance virtualization for commodity hardware.

• NIST definition: https://www.nist.gov/programs-projects/nist-cloud-computing-program-nccp
• NIST definition of Cloud Computing http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf

Cluster

Cluster as code.

Configuration Drift

Configuration drift is variation that happens over time across systems that were once identical. Manually making changes in configuration (performance optimizations, permissions, fixes), even if the base was laid down by automation, causes configuration drift. Selectively using automation on some of the initially identical systems, but not on others, also causes configuration drift. This is how snowflake systems come into existence. Also see Minimize Variation. Once manually-introduced configuration drift occurs, the trust in automation goes down, because people are not sure how an automation will modify a manually-changed system. Interestingly, manual configuration creeps in because the automation is not run frequently and consistently, leading to a vicious circle. To avoid this spiral, make everything reproducible automatically and consistently run automation. Operational automation combined with good monitoring exposes configuration drift.

Governance

Lightweight Architectural Governance

Lightweight architectural governance aims to balance autonomy and centralized control. More in EDGE: Value-Driven Digital Transformation by Jim Robert Highsmith, Linda Luu, David Robinson and the The Goldilocks zone of lightweight architectural governance Jonny LeRoy talk.

Organizatorium

• Integration points