terraform/website/guides/core-workflow.html.md

---
layout: "guides"
page_title: "The Core Terraform Workflow - Guides"
sidebar_current: "guides-core-workflow"
description: |-
  This guide provides an overview of the core Terraform workflow and how it
  applies in individual, team, and organization contexts across Terraform open
  source and Terraform Enterprise.
---

# The Core Terraform Workflow

The core Terraform workflow has three steps:

1. **Write** - Author infrastructure as code.
2. **Plan** - Preview changes before applying.
3. **Apply** - Provision reproducible infrastructure.

This guide walks through how each of these three steps plays out in the context
of working as an individual practitioner, how they evolve when a team is
collaborating on infrastructure, and how Terraform Enterprise enables this
workflow to run smoothly for entire organizations.

## Working as an Individual Practitioner
 
Let's first walk through how these parts fit together as an individual working
on infrastructure as code.

### Write

You write Terraform configuration just like you write code: in your editor of
choice. It's common practice to store your work in a version controlled
repository even when you're just operating as an individual.

```sh
# Create repository
$ git init my-infra && cd my-infra

Initialized empty Git repository in /.../my-infra/.git/

# Write initial config
$ vim main.tf

# Initialize Terraform
$ terraform init

Initializing provider plugins...
# ...
Terraform has been successfully initialized!
```

As you make progress on authoring your config, repeatedly running plans can help
flush out syntax errors and ensure that your config is coming together as you
expect.

```sh
# Make edits to config
$ vim main.tf

# Review plan
$ terraform plan

# Make additional edits, and repeat
$ vim main.tf
```

This parallels working on application code as an individual, where a tight
feedback loop between editing code and running test commands is useful.

### Plan

When the feedback loop of the Write step has yielded a change that looks good,
it's time to commit your work and review the final plan.

```sh
$ git add main.tf
$ git commit -m 'Managing infrastructure as code!'

[master (root-commit) f735520] Managing infrastructure as code!
 1 file changed, 1 insertion(+)
```

Because `terraform apply` will display a plan for confirmation before
proceeding to change any infrastructure, that's the command you run for final
review.

```sh
$ terraform apply

An execution plan has been generated and is shown below.
# ...
```

### Apply

After one last check, you are ready to tell Terraform to provision real
infrastructure.

```sh
Do you want to perform these actions?

  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.
  Enter a value: yes

# ...

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
```

At this point, it's common to push your version control repository to a remote
location for safekeeping.

```sh
$ git remote add origin https://github.com/*user*/*repo*.git
$ git push origin master
```

This core workflow is a loop; the next time you want to make changes, you start
the process over from the beginning.

Notice how closely this workflow parallels the process of writing application
code or scripts as an individual? This is what we mean when we talk about
Terraform enabling infrastructure as code.

## Working as a Team

Once multiple people are collaborating on Terraform configuration, new steps
must be added to each part of the core workflow to ensure everyone is working
together smoothly. You'll see that many of these steps parallel the workflow
changes we make when we work on application code as teams rather than as
individuals.

### Write

While each individual on a team still makes changes to Terraform configuration
in their editor of choice, they save their changes to version control _branches_
to avoid colliding with each other's work. Working in branches enables team
members to resolve mutually incompatible infrastructure changes using their
normal merge conflict workflow.

```sh
$ git checkout -b add-load-balancer

Switched to a new branch 'add-load-balancer'
```

Running iterative plans is still useful as a feedback loop while authoring
configuration, though having each team member's computer able to run them
becomes more difficult with time. As the team and the infrastructure grows, so
does the number of sensitive input variables (e.g. API Keys, SSL Cert Pairs)
required to run a plan.

To avoid the burden and the security risk of each team member arranging all
sensitive inputs locally, it's common for teams to migrate to a model in which
Terraform operations are executed in a shared Continuous Integration (CI)
environment. The work needed to create such a CI environment is nontrivial, and
is outside the scope of this core workflow overview, but a full deep dive on
this topic can be found in our
[Running Terraform in Automation](https://www.terraform.io/guides/running-terraform-in-automation.html)
guide.

This longer iteration cycle of committing changes to version control and then
waiting for the CI pipeline to execute is often lengthy enough to prohibit using
speculative plans as a feedback loop while authoring individual Terraform
configuration changes. Speculative plans are still useful before new Terraform
changes are applied or even merged to the main development branch, however, as
we'll see in a minute.

### Plan

For teams collaborating on infrastructure, Terraform's plan output creates an
opportunity for team members to review each other's work. This allows the team
to ask questions, evaluate risks, and catch mistakes before any potentially
harmful changes are made.

The natural place for these reviews to occur is alongside pull requests within
version control--the point at which an individual proposes a merge from their
working branch to the shared team branch. If team members review proposed
config changes alongside speculative plan output, they can evaluate whether the
intent of the change is being achieved by the plan.

The problem becomes producing that speculative plan output for the team to
review. Some teams that still run Terraform locally make a practice that pull
requests should include an attached copy of speculative plan output generated
by the change author. Others arrange for their CI system to post speculative
plan output to pull requests automatically.

![Screenshot of Pull Request with manually posted Terraform plan output](guides/core-workflow/manually-pasted-plan-output.png)

In addition to reviewing the plan for the proper expression of its author's
intent, the team can also make an evaluation whether they want this change to
happen now. For example, if a team notices that a certain change could result
in service disruption, they may decide to delay merging its pull request until
they can schedule a maintenance window.

### Apply

Once a pull request has been approved and merged, it's important for the team
to review the final concrete plan that's run against the shared team branch and
the latest version of the state file.

This plan has the potential to be different than the one reviewed on the pull
request due to issues like merge order or recent infrastructural changes. For
example, if a manual change was made to your infrastructure since the plan was
reviewed, the plan might be different when you merge.

It is at this point that the team asks questions about the potential
implications of applying the change. Do we expect any service disruption from
this change? Is there any part of this change that is high risk? Is there
anything in our system that we should be watching as we apply this? Is there
anyone we need to notify that this change is happening?

Depending on the change, sometimes team members will want to watch the apply
output as it is happening. For teams that are running Terraform locally, this
may involve a screen share with the team. For teams running Terraform in CI,
this may involve gathering around the build log.

Just like the workflow for individuals, the core workflow for teams is a loop
that plays out for each change. For some teams this loop happens a few times a
week, for others, many times a day.

## The Core Workflow Enhanced by Terraform Enterprise

While the above described workflows enable the safe, predictable, and
reproducible creating or changing of infrastructure, there are multiple
collaboration points that can be streamlined, especially as teams and
organizations scale.  We designed Terraform Enterprise to support and enhance
the core Terraform workflow for anyone collaborating on infrastructure, from
small teams to large organizations. Let's look at how Terraform Enterprise makes
for a better experience at each step.

### Write

Terraform Enterprise provides a centralized and secure location for storing
input variables and state while also bringing back a tight feedback loop for
speculative plans for config authors. Terraform configuration interacts with
Terraform Enterprise via the ["remote" backend](/docs/backends/types/remote.html).

```
terraform {
  backend "remote" {
    organization = "my-org"
    workspaces {
      prefix = "my-app-"
    }
  }
}
```

Once the backend is wired up, a Terraform Enterprise API key is all that's
needed by team members to be able to edit config and run speculative plans
against the latest version of the state file using all the remotely stored
input variables.

```sh
$ terraform workspace select my-app-dev
Switched to workspace "my-app-dev".

$ terraform plan

Running plan remotely in Terraform Enterprise.

Output will stream here. To view this plan in a browser, visit:

https://app.terraform.io/my-org/my-app-dev/.../

Refreshing Terraform state in-memory prior to plan...

# ...

Plan: 1 to add, 0 to change, 0 to destroy.
```

With the assistance of this plan output, team members can each work on
authoring config until it is ready to propose as a change via a pull request.

### Plan

Once a pull request is ready for review, Terraform Enterprise makes the process
of reviewing a speculative plan easier for team members. First, the plan is
automatically run when the pull request is created. Status updates to the pull
request indicate while the plan is in progress.

Once the plan is complete, the status update indicates whether there were any
changes in the speculative plan, right from the pull request view.

![Screenshot of Pull Request with resource changes in the status update](guides/core-workflow/pull-request.png)

For certain types of changes, this information is all that's needed for a team
member to be able to approve the pull request. When a teammate needs to do a
full review of the plan, clicking the link to Terraform Enterprise brings up a
view that allows them to quickly analyze the full plan details.

![Screenshot of Pull Request run in Terraform Enterprise](guides/core-workflow/pr-plan.png)

This page allows the reviewer to quickly determine if the plan is matching the
config author's intent and evaluate the risk of the change.

### Apply

After merge, Terraform Enterprise presents the concrete plan to the team for
review and approval.

![Screenshot of concrete plan](guides/core-workflow/concrete-plan.png)

The team can discuss any outstanding questions about the plan before the change
is made.

![Screenshot of back-and-forth in TFE comments](guides/core-workflow/plan-comments.png)

Once the Apply is confirmed, Terraform Enterprise displays the progress live
to anyone who'd like to watch.

![Screenshot of in-progress Apply](guides/core-workflow/in-progress-apply.png)

<!--

TODO: Add this back in w/ screenshot of notification

And after the change completes, the team can be notified of its outcome.

    [ Multi-screenshot of Slack alert indicating Apply completed successfully and
    with error; except it's not gonna be Slack anymore? ]

-->

## Conclusion

There are many different ways to use Terraform: as an individual user, a single
team, or an entire organization at scale. Choosing the best approach for the
density of collaboration needed will provide the most return on your investment
in the core Terraform workflow. For organizations using Terraform at scale,
Terraform Enterprise introduces new layers that build on this core workflow to
solve problems unique to teams and organizations.