Infrastructure Concepts

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Revision as of 20:54, 30 December 2021 by Ovidiu (talk | contribs) (→‎Application)
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External

Internal

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. 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. An application runtime is laid upon the infrastructure platform layer and it is assembled from infrastructure resources. The application runtime instance may include container clusters, serverless execution environments, application servers, messaging systems, databases and operating systems. 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:

Infrastructure Platform

An infrastructure platform lets the user of the service to provision compute, storage, networking and other infrastructure resources on which they can run operating systems and applications. 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

A cloud infrastructure platform abstracts infrastructure resources (compute, network, storage) from physical hardware. Infrastructure resources are assembled to provide application runtime instances.

Infrastructure Services

Infrastructure Stack

  • Stack integration point.

Cloud

Environment

Containers

Cluster

Cluster as code.

Container Cluster

Server

Serverless Execution Environment

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