# README
Terraform Plugin SDK
This SDK enables building Terraform plugin which allows Terraform's users to manage existing and popular service providers as well as custom in-house solutions.
Terraform itself is a tool for building, changing, and versioning infrastructure safely and efficiently. You can find more about Terraform on its website and its GitHub repository.
Terraform CLI Compatibility
The v1 major release of the Terraform Plugin SDK supports Terraform 0.11 and later.
It cannot, however, take advantage of all newer features and capabilities in releases of Terraform after 0.11.
Testing using the reattach-based binary test driver, which is opt-in, requires the test runner to be using Terraform 0.12.26 or later. Only test runners, not users, have this requirement.
Go Compatibility
The Terraform Plugin SDK is built in Go, and uses the support policy of Go as its support policy. The two latest major releases of Go are supported by the SDK.
Documentation
See Extending Terraform section on the website.
Scope (Providers VS Core)
Terraform Core
- acts as gRPC client
- interacts with the user
- parses (HCL/JSON) configuration
- manages state as whole, asks Provider(s) to mutate provider-specific parts of state
- handles backends & provisioners
- handles inputs, outputs, modules, and functions
- discovers Provider(s) and their versions per configuration
- manages Provider(s) lifecycle (i.e. spins up & tears down provider process)
- passes relevant parts of parsed (valid JSON/HCL) and interpolated configuration to Provider(s)
- decides ordering of (Create, Read, Update, Delete) operations on resources and data sources
- ...
Terraform Provider (via this SDK)
- acts as gRPC server
- executes any domain-specific logic based on received parsed configuration
- (Create, Read, Update, Delete, Import, Validate) a Resource
- Read a Data Source
- tests domain-specific logic via provided acceptance test framework
- provides Core updated state of a resource or data source and/or appropriate feedback in the form of validation or other errors
Migrating to SDK v1 from built-in SDK
Migrating to the standalone SDK v1 is covered on the Plugin SDK section of the website.
Versioning
The Terraform Plugin SDK is a Go module versioned using semantic versioning. See SUPPORT.md for information on our support policies.