39 lines
2.0 KiB
Markdown
39 lines
2.0 KiB
Markdown
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---
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layout: "intro"
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page_title: "Terraform vs. CloudFormation, Heat, etc."
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sidebar_current: "vs-other-cloudformation"
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---
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# Terraform vs. CloudFormation, Heat, etc.
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Tools like CloudFormation, Heat, etc allow the details of an infrastructure
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to be codified into a configuration file. The configuration files allow
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the infrastructure to be elastically created, modified and destroyed. Terraform
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is inspired by the problems they solve.
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Terraform similarly uses configuration files to detail the infrastructure
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setup, but it goes further, by being both cloud agnostic and enabling
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multiple providers and services to be combined and composed. For example,
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Terraform can be used to orchestrate an AWS and OpenStack cluster simultaneously,
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while enabling 3rd party services like CloudFlare and DNSimple to be integrated
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to provide CDN and DNS services. This enables Terraform to represent and
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manage the entire infrastructure and it's supporting services, instead of
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only the subset that exists within a single provider. It provides a single
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unified syntax, instead of requiring operators to use independent and
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non-interoperable tools for each platform and service.
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Terraform also seperates the planning phase from the execution phase,
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by using the concept of an execution plan. By running `terraform plan`,
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the current state is refreshed and the configuration is consulted to
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generate an action plan. The plan includes all actions to be taken:
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which resources will be created, destroyed or modified. It can be
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inspected by operators to ensure it is exactly what is expected. Using
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`terraform graph`, the plan can be visualized to show dependent ordering.
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Once the plan is captured, the execution phase can be limited to only
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the actions in the plan. Other tools combine the planning and execution
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phases, meaning operators are forced to mentally reason about the effects
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of a change, which quickly becomes intractable in large infrastructures.
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Terraform lets operators apply changes with confidence, as they know exactly
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what will happen before running.
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