89b05050ec
Previously terraform.Context was built in an unfortunate way where all of the data was provided up front in terraform.NewContext and then mutated directly by subsequent operations. That made the data flow hard to follow, commonly leading to bugs, and also meant that we were forced to take various actions too early in terraform.NewContext, rather than waiting until a more appropriate time during an operation. This (enormous) commit changes terraform.Context so that its fields are broadly just unchanging data about the execution context (current workspace name, available plugins, etc) whereas the main data Terraform works with arrives via individual method arguments and is returned in return values. Specifically, this means that terraform.Context no longer "has-a" config, state, and "planned changes", instead holding on to those only temporarily during an operation. The caller is responsible for propagating the outcome of one step into the next step so that the data flow between operations is actually visible. However, since that's a change to the main entry points in the "terraform" package, this commit also touches every file in the codebase which interacted with those APIs. Most of the noise here is in updating tests to take the same actions using the new API style, but this also affects the main-code callers in the backends and in the command package. My goal here was to refactor without changing observable behavior, but in practice there are a couple externally-visible behavior variations here that seemed okay in service of the broader goal: - The "terraform graph" command is no longer hooked directly into the core graph builders, because that's no longer part of the public API. However, I did include a couple new Context functions whose contract is to produce a UI-oriented graph, and _for now_ those continue to return the physical graph we use for those operations. There's no exported API for generating the "validate" and "eval" graphs, because neither is particularly interesting in its own right, and so "terraform graph" no longer supports those graph types. - terraform.NewContext no longer has the responsibility for collecting all of the provider schemas up front. Instead, we wait until we need them. However, that means that some of our error messages now have a slightly different shape due to unwinding through a differently-shaped call stack. As of this commit we also end up reloading the schemas multiple times in some cases, which is functionally acceptable but likely represents a performance regression. I intend to rework this to use caching, but I'm saving that for a later commit because this one is big enough already. The proximal reason for this change is to resolve the chicken/egg problem whereby there was previously no single point where we could apply "moved" statements to the previous run state before creating a plan. With this change in place, we can now do that as part of Context.Plan, prior to forking the input state into the three separate state artifacts we use during planning. However, this is at least the third project in a row where the previous API design led to piling more functionality into terraform.NewContext and then working around the incorrect order of operations that produces, so I intend that by paying the cost/risk of this large diff now we can in turn reduce the cost/risk of future projects that relate to our main workflow actions. |
||
|---|---|---|
| .circleci | ||
| .github | ||
| docs | ||
| internal | ||
| scripts | ||
| tools | ||
| version | ||
| website | ||
| .gitignore | ||
| .go-version | ||
| .tfdev | ||
| BUGPROCESS.md | ||
| CHANGELOG.md | ||
| CODEOWNERS | ||
| Dockerfile | ||
| LICENSE | ||
| Makefile | ||
| README.md | ||
| checkpoint.go | ||
| codecov.yml | ||
| commands.go | ||
| go.mod | ||
| go.sum | ||
| help.go | ||
| main.go | ||
| main_test.go | ||
| plugins.go | ||
| provider_source.go | ||
| signal_unix.go | ||
| signal_windows.go | ||
| version.go | ||
README.md
Terraform
- Website: https://www.terraform.io
- Forums: HashiCorp Discuss
- Documentation: https://www.terraform.io/docs/
- Tutorials: HashiCorp's Learn Platform
- Certification Exam: HashiCorp Certified: Terraform Associate
Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently. Terraform can manage existing and popular service providers as well as custom in-house solutions.
The key features of Terraform are:
-
Infrastructure as Code: Infrastructure is described using a high-level configuration syntax. This allows a blueprint of your datacenter to be versioned and treated as you would any other code. Additionally, infrastructure can be shared and re-used.
-
Execution Plans: Terraform has a "planning" step where it generates an execution plan. The execution plan shows what Terraform will do when you call apply. This lets you avoid any surprises when Terraform manipulates infrastructure.
-
Resource Graph: Terraform builds a graph of all your resources, and parallelizes the creation and modification of any non-dependent resources. Because of this, Terraform builds infrastructure as efficiently as possible, and operators get insight into dependencies in their infrastructure.
-
Change Automation: Complex changesets can be applied to your infrastructure with minimal human interaction. With the previously mentioned execution plan and resource graph, you know exactly what Terraform will change and in what order, avoiding many possible human errors.
For more information, see the introduction section of the Terraform website.
Getting Started & Documentation
Documentation is available on the Terraform website:
If you're new to Terraform and want to get started creating infrastructure, please check out our Getting Started guides on HashiCorp's learning platform. There are also additional guides to continue your learning.
Show off your Terraform knowledge by passing a certification exam. Visit the certification page for information about exams and find study materials on HashiCorp's learning platform.
Developing Terraform
This repository contains only Terraform core, which includes the command line interface and the main graph engine. Providers are implemented as plugins, and Terraform can automatically download providers that are published on the Terraform Registry. HashiCorp develops some providers, and others are developed by other organizations. For more information, see Extending Terraform.
To learn more about compiling Terraform and contributing suggested changes, please refer to the contributing guide.
To learn more about how we handle bug reports, please read the bug triage guide.