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Terraform
# Infrastructure as code
## Problem with manual configuration
Manual configuration of cloud infastructe allows you easily start using service offerings however there are downsides to this approach:
* It is hard to reproduce the same configuration in different environments
* It is hard to track changes in configuration
* It is hard to share configuration with other team members
* It is hard to automate configuration changes
* It is hard to recover from disaster
* It is hard to scale
and many more...
## Solution to the problem
Infrastructure as code is a process of managing and provisioning computing infrastructure and configuration through machine-readable definition files, rather than physical hardware configuration or the use of interactive configuration tools.
* IaC is a blueprint of your infrastructure
* IaC is a version controlled
* IaC is shareable and reproducable
## IaC tools
### Declaritive tools
* What you see is what you get. EXPLICIT.
* More verbose, but easier to read and understand.
* Uses scripting languages like YAML, JSON, HCL.
* Examples:
* Terraform
* CloudFormation - AWS
* Cloud Deployment Manager - GCP
* Azure Blueprints - Azure
* ARM Templates - Azure
### Imperative tools
* You say what you want, and the rest is taken care of. IMPLICIT.
* Less verbose, but harder to read and understand.
* Uses scripting languages like Python, Ruby, Go, etc.
* Examples:
* AWS Cloud Development Kit (CDK)
* Pulumi
* Ansible
### Choosing between imperative and declaritive tools
* Declaritive tools are better for managing infrastructure
* Imperative tools are better for managing configuration
## Terraform
### What is Terraform?
Terraform is an open-source infrastructure as code software tool created by HashiCorp. It enables users to define and provision a datacenter infrastructure using a high-level configuration language known as Hashicorp Configuration Language (HCL), or optionally JSON.
## Terraform is declaritive tool but it also has some imperative features.
Terraform is a declaritive language but it also has some imperative features. For example, you can use `count` and `for_each` to create multiple resources. You can also use `for` and `for_each` to iterate over lists, maps, and sets. You can also use `dynamic` blocks to create nested blocks.
Terraform Supports:
* Conditionals
* Functions
* Expressions
* Variables
* Modules
* Providers
* Complex data types
* Maps
* Lists
* Sets
* Objects
* Tuples
## Infrastructure lifecycle
### What is infrastructure lifecycle?
Infrastructure lifecycle is a process of managing infrastructure from plan, design, implement, operate, and decommission of cloud infrastructure.
### What is day 0, day 1, and day 2 operations?
* Day 0 - Planning and design
* Day 1 - Provisioning and deployment
* Day 2 - Operations and management
## How does IaC enhance infrastructure lifecycle?
### Reliability
* IaC is repeatable and consistent: identical copies of infrastructure can be created in different environments
**Idemptotency** - the ability to run the same code multiple times and get the same result
### Manageability
* Enable mutative operations: infrastructure can be updated and changed
* Revision control: infrastructure can be version controlled with minimal changes
### Sensibility
* avoid finanical waste: infrastructure can be destroyed when not needed
* avoid human errors: infrastructure can be created and destroyed automatically
## Idempotent vs Non-Idempotent
**Non-idempotent** - the ability to run the same code multiple times and get different results (e.g. when i update my IaC and deploy again after launching 2 virtual machines, it will launch 2 more virtual machines)
**Idempotent** - the ability to run the same code multiple times and get the same result (e.g. when i update my IaC and deploy again after launching 2 virtual machines, it will update the existing 2 virtual machines)
## Provisioning vs Orchestration vs Deployment
### Provisioning
* Provisioning is the process of setting up the infrastructure
* You can provision a server using configuration managmeent tools like Ansible, Chef, Puppet, SaltStack, bash scripts, powershell scripts, cloud-init, etc.
* When you launch a cloud service and configure, you are provisioning the service.
### Orchestration
* Orchestration is the process of managing multiple systems and services as a single unit. You can use orchestration tools like Kubernetes, Docker Swarm, Nomad, etc.
* Orchestration tools are commonly used when working with microservices, containers, and serverless, k8s, etc.
### Deployment
* Deployment is the act of delivering a version of an application to run provisioned infrastructure.
* Deployment cloud be performeve via CI/CD tools like Jenkins, GitLab, CircleCI, etc.
## Confiuration drift
### What is configuration drift?
* Configuration drift is a state of inconsistency between the actual configuration of a system and the expected configuration.
* Configuration drift can occur when manual changes are made to a system, when one system is manually configured differently from another system, or when there are unintended changes to systems due to human error, hardware failure, software failure, or malware.
* Configuration drift can be avoided by using IaC tools like Terraform, Ansible, etc.
**Configuration drift going unnoticed could be a loss or breach of services and residing data or result in intterrpution of services leading to unexpected downtime.**
## Detecting Configuration Drift
* Compliance tools that can detect configuration drift
### How to fix configuration drift?
* Compliance tools that can remediate misconfiguration and configuration drift
* Chef Inspec
* Puppet
* Ansible
* Terraform
* AWS Config
* Azure Policy
* GCP Config
* etc.
* Terraform refresh and plan commands can be used to detect configuration drift
* Manually correcting the configuration (not recommended)
* Tear down and rebuild the infrastructure
### How to prevent configuration drift?
* Immutable infrastructure, always create and destroy, never update, Blue/Green deployment strategy
* Servers are never modified after they're deployed
* Instead of updating existing servers, you deploy new servers with the updates using AMI, GCP Templates, etc.
* AMI - Amazon Machine Image
* GCP Templates - Google Cloud Platform Templates
* This approach is more reliable and secure
* This approach is more scalable
* Using GitOps to version control IaC, and peer review every single pull request change before applying them
## Mutable vs Immutable Infrastructure
### Mutable Infrastructure
* Mutable infrastructure is a traditional approach to managing infrastructure
* Mutable infrastructure is updated by modifying the existing infrastructure
* Develop --> Deploy --> Configure
* Example: A virtual machine is deployed then a configuration management tool like Ansible, Chef, Salt, Cloud-Init, etc. is used to configure the virtual machine
* No guarentee that the infrastructure will be in the same state as it was before the update
### Immutable Infrastructure
* Immutable infrastructure is a modern approach to managing infrastructure
* Immutable infrastructure is updated by replacing the existing infrastructure
* Develop --> Deploy --> Destroy --> Deploy
* Example: A virtual machine is deployed then a configuration management tool like Terraform, CloudFormation, etc. When an update is required, the existing virtual machine is destroyed and a new virtual machine is deployed with the updated configuration.
* Use tools like packer to create immutable images
* Immutable infrastructure is more reliable and secure
## What is GitOps?
* GitOps is a way to do Continuous Delivery, it works by using Git as a single source of truth for declarative infrastructure and applications.
* With Git at the center of your delivery pipelines, developers can make pull requests to accelerate and simplify application deployments and operations tasks to Kubernetes.
* GitOps is a way to do Infrastructure as Code (IaC) and Continuous Delivery (CD).
## GitOps Workflow
* Developers make changes to the Git repository
* A CI/CD pipeline detects the changes and deploys the changes to the infrastructure
* The infrastructure is updated and the changes are reflected in the production environment
* Example: A developer makes changes to the Git repository, a CI/CD pipeline detects the changes and deploys the changes to the infrastructure, the infrastructure is updated and the changes are reflected in the production environment
* Example tools: ArgoCD, FluxCD, Jenkins X, etc.
## Immutable Infrastructe Guarantees
Terraform encourage you towards an immutable infrastructure approach by making it difficult to modify infrastructure after it has been created.
* Terraform does not allow you to modify infrastructure after it has been created
Cloud Resource Failure - What if a cloud resource fails?
Application Failure - What if an application fails?
Time to Deploy - What if you need to deploy a new version of your application?
Worst Case Scenarios
* Accidental Deletions
* Compromised by malicious actors
* Natural Disasters - Need to change regions (region outages)
Configuring after deployment does not guarentee 1:1 parity between environments
Every time cloud-init runs post deploy there is no guarentee that the configuration will be the same as it was before
* Cloud-init is a tool that is used to configure virtual machines after they are deployed
* Cloud-init is used to configure virtual machines in AWS, GCP, Azure, etc.
What if everything fails?
* Terraform state file is stored in a remote backend
* Terraform state file is version controlled
* Terraform state file is backed up
* Terraform state file is encrypted
* Terraform state file is locked
## Hashicorp
* Hashicorp is a company that creates open source tools for cloud infrastructure automation
* Hashicorp tools are used by millions of users and companies
* Hashicorp tools are used by 75% of the Fortune 100
* Hashicorp tools are used by 50% of the Forbes Cloud 100
What is Hashicorp Cloud Platform (HCP)?
HCP is a unified cloud platform that offers managed services for Hashicorp tools
HCP services are cloud agnostic
**Agnostic** - not limited to a particular domain or system; not bound by a particular set of ideas, principles, or systems.
* Support for the major cloud service providers (AWS, GCP, Azure)
* Highly suitable for multi-cloud and hybrid cloud environments
* Can be leveraged in traditional on-premises data centers such as VMware vSphere
Tools under HCP include:
* Consul
* Nomad
* Vault
* Terraform
* Waypoint
### Terraform
* Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently
### Terraform Cloud
* Terraform Cloud is a hosted service for Terraform that provides remote state management, API-driven runs, policy management, and more
### Terraform Enterprise
* Terraform Enterprise is a self-hosted distribution of Terraform Cloud that can be run in an air-gapped environment or in your own cloud account
### Boundary
* Boundary is a secure remote access solution for dynamic infrastructure
### Consul
* Consul is a service networking solution to connect and secure services across any runtime platform and public or private cloud
### Nomad
* Nomad is a highly available, distributed, datacenter-aware cluster and application scheduler designed to support the modern datacenter with support for long-running services, batch jobs, and much more
### Packer
* Packer is a tool for creating machine and container images for multiple platforms from a single source configuration
### Vault
* Vault is a tool for secrets management, encryption as a service, and privileged access management
### Vagrant
* Vagrant is a tool for building and distributing development environments
### Waypoint
* Waypoint is a tool that enables developers to build, deploy, and release any application on any platform with a single workflow
## Terraform
### What is Terraform?
* Terraform is an open-source infrastructure as code software tool created by HashiCorp. It enables users to define and provision a datacenter infrastructure using a high-level configuration language known as Hashicorp Configuration Language (HCL), or optionally JSON.
* Terraform is a declaritive language
***Notable Features***
* Installable modules
* Remote state management
* Resource Graph
* Change Automation - Plan and predict changes before applying them
* Terraform Registry - A public registry of Terraform modules with over 1000 providers
## What is Terraform Cloud?
* Terraform Cloud is a hosted service for Terraform that provides remote state management, API-driven runs, policy management, and more
* Terraform Cloud is a SaaS (Software as a Service) platform
* Terraform Cloud is a paid service
Terraform Cloud Offers:
* Remote state management
* Version control integration
* Flexible workflows
* Collaboration on infrastructure changes in a single unified web portal.
* Majority of cases you should be using Terraform Cloud
* Cases where you may not want to use it to manage your state file is your company has many regulatory requirements along with a long procurement process. In this case you may want to use Terraform Enterprise, Standard remote backend, Atlantis, etc.