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Migrating to Terraform v0.10.x

When it comes to managing cloud-based resources, it’s hard to find a better tool than Hashicorp’s Terraform. Terraform is an ‘infrastructure as code’ application, marrying configuration files with backing APIs to provide a nearly seamless layer over your various cloud environments. It allows you to declaratively define your environments and their resources through a process that is structured, controlled, and collaborative.

One key advantage Terraform provides over other tools (like AWS CloudFormation) is having a rapid development and release cycle fueled by the open source community. This has some major benefits: features and bug fixes are readily available, new products from resource providers are quickly incorporated, and you’re able to submit your own changes to fulfill your own requirements.

Hashicorp recently released v0.10.0 of Terraform, introducing some fundamental changes in the application’s architecture and functionality. We’ll review the three most notable of these changes and how to incorporate them into your existing Terraform projects when migrating to Terraform v.0.10.x.

  1. Terraform Providers are no longer distributed as part of the main Terraform distribution
  2. New auto-approve flag for terraform apply
  3. Existing terraform env commands replaced by terraform workspace

A brief note on Terraform versions:

Even though Terraform uses a style of semantic versioning, their ‘minor’ versions should be treated as ‘major’ versions.

1. Terraform Providers are no longer distributed as part of the main Terraform distribution

The biggest change in this version is the removal of provider code from the core Terraform application.

Terraform Providers are responsible for understanding API interactions and exposing resources for a particular platform (AWS, Azure, etc). They know how to initialize and call their applications or CLIs, handle authentication and errors, and convert HCL into the appropriate underlying API calls.

It was a logical move to split the providers out into their own distributions. The core Terraform application can now add features and release bug fixes at a faster pace, new providers can be added without affecting the existing core application, and new features can be incorporated and released to existing providers without as much effort. Having split providers also allows you to update your provider distribution and access new resources without necessarily needing to update Terraform itself. One downside of this change is that you have to keep up to date with features, issues, and releases of more projects.

The provider repos can be accessed via the Terraform Providers organization in GitHub. For example, the AWS provider can be found here.

Custom Providers

An extremely valuable side-effect of having separate Terraform Providers is the ability to create your own, custom providers. A custom provider allows you to specify new or modified attributes for existing resources in existing providers, add new or unsupported resources in existing providers, or generate your own resources for your own platform or application.

You can find more information on creating a custom provider from the Terraform Provider Plugin documentation.

1.1 Configuration

The nicest part of this change is that it doesn’t really require any additional modifications to your existing Terraform code if you were already using a Provider block.

If you don’t already have a provider block defined, you can find their configurations from the Terraform Providers documentation.

You simply need to call the terraform init command before you can perform any other action. If you fail to do so, you’ll receive an error informing you of the required actions (img 1a).

After successfully reinitializing your project, you will be provided with the list of providers that were installed as well as the versions requested (img 1b).

You’ll notice that Terraform suggests versions for the providers we are using – this is because we did not specify any specific versions of our providers in code. Since providers are now independently released entities, we have to tell Terraform what code it should download and use to run our project.

(Image 1a: Notice of required reinitialization)










(Image 1b: Response from successful reinitialization)










Providers are released separately from Terraform itself, and maintain their own version numbers.

You can specify the version(s) you want to target in your existing provider blocks by adding the version property (code block 1). These versions should follow the semantic versioning specification (similar to node’s package.json or python’s requirements.txt).

For production use, it is recommended to limit the acceptable provider versions to ensure that new versions with breaking changes are not automatically installed.

(Code Block 1: Provider Config)

provider "aws" {
  version = "0.1.4"
  allowed_account_ids = ["1234567890"]
  region = "us-west-2"

 (Image 1c: Currently defined provider configuration)










2. New auto-approve flag for terraform apply

In previous versions, running terraform apply would immediately apply any changes between your project and saved state.

Your normal workflow would likely be:
run terraform plan followed by terraform apply and hope nothing changed in between.

This version introduced a new auto-approve flag which will control the behavior of terraform apply.

Deprecation Notice

This flag is set to true to maintain backwards compatibility, but will quickly change to false in the near future.

2.1 auto-approve=true (current default)

When set to true, terraform apply will work like it has in previous versions.

If you want to maintain this functionality, you should upgrade your scripts, build systems, etc now as this default value will change in a future Terraform release.

(Code Block 2: Apply with default behavior)

# Apply changes immediately without plan file
terraform apply --auto-approve=true

2.2 auto-approve=false

When set to false, Terraform will present the user with the execution plan and pause for interactive confirmation (img 2a).

If the user provides any response other than yes, terraform will exit without applying any changes.

If the user confirms the execution plan with a yes response, Terraform will then apply the planned changes (and only those changes).

If you are trying to automate your Terraform scripts, you might want to consider producing a plan file for review, then providing explicit approval to apply the changes from the plan file.

(Code Block 3: Apply plan with explicit approval)

# Create Plan
terraform plan -out=tfplan

# Apply approved plan
terraform apply tfplan --auto-approve=true

(Image 2a: Terraform apply with execution plan)








3. Existing terraform env commands replaced by terraform workspace

The terraform env family of commands were replaced with terraform workspace to help alleviate some confusion in functionality. Workspaces are very useful, and can do much more than just split up environment state (which they aren’t necessarily used for). I recommend checking them out and seeing if they can improve your projects.

There is not much to do here other than switch the command invocation, but the previous commands still currently work for now (but are deprecated).


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— Steve Byerly, Principal SDE (IV), Cloud, 2nd Watch


Migrating Terraform Remote State to a “Backend” in Terraform v.0.9+

(AKA: Where the heck did ‘terraform remote config’ go?!!!)

If you are working with cloud-based architectures or working in a DevOps shop, you’ve no doubt been managing your infrastructure as code. It’s also likely that you are familiar with tools like Amazon CloudFormation and Terraform for defining and building your cloud architecture and infrastructure. For a good comparison on Amazon CloudFormation and Terraform check out Coin Graham’s blog on the matter: AWS CFT vs. Terraform: Advantages and Disadvantages.

If you are already familiar with Terraform, then you may have encountered a recent change to the way remote state is handled, starting with Terraform v0.9. Continue reading to find out more about migrating Terraform Remote State to a “Backend” in Terraform v.0.9+.

First off… if you are unfamiliar with what remote state is check out this page.

Remote state is a big ol’ blob of JSON that stores the configuration details and state of your Terraform configuration and infrastructure that has actually been deployed. This is pretty dang important if you ever plan on changing your environment (which is “likely”, to put it lightly) and especially important if you want to have more than one person managing/editing/maintaining the infrastructure, or if you have even the most basic rationale as it pertains to backup and recovery.

Terraform supports almost a dozen backend types (as of this writing) including:

  • Artifactory
  • Azure
  • Consul
  • Etcd
  • Gcs
  • Http
  • Manta
  • S3
  • Swift
  • Terraform Enterprise (AKA: Atlas)


Why not just keep the Terraform state in the same git repo I keep the Terraform code in?

You also don’t want to store the state file in a code repository because it may contain sensitive information like DB passwords, or simply because the state is prone to frequent changes and it might be easy to forget to push those changes to your git repo any time you run Terraform.

So, what happened to terraform remote anyway?

If you’re like me, you probably run the la version of HashiCorp’s Terraform tool as soon as it is available (we actually have a hook in our team Slack channel that notifies us when a new version is released). With the release of Terraform v.0.9 last month, we were endowed with the usual heaping helping of excellent new features and bug-fixes we’ve come to expect from the folks at HashiCorp, but were also met with an unexpected change in the way remote state is handled.

Unless you are religious about reading the release notes, you may have missed an important change in v.0.9 around the remote state. While the release notes don’t specifically call out the removal (not even deprecation, but FULL removal) of the prior method (e.g. with Terraform remote config, the Upgrade Guide specifically calls out the process in migrating from the legacy method to the new method of managing remote state). More specifically, they provide a link to a guide for migrating from the legacy remote state config to the new backend system. The steps are pretty straightforward and the new approach is much improved over the prior method for managing remote state. So, while the change is good, a deprecation warning in v.0.8 would have been much appreciated. At least it is still backwards compatible with the legacy remote state files (up to version 0.10), making the migration process much less painful.

Prior to v.0.9, you may have been managing your Terraform remote state in an S3 bucket utilizing the Terraform remote config command. You could provide arguments like: backend and backend-config to configure things like the S3 region, bucket, and key where you wanted to store your remote state. Most often, this looked like a shell script in the root directory of your Terraform directory that you ran whenever you wanted to initialize or configure your backend for that project.

Something like…

Terraform Legacy Remote S3 Backend Configuration Example
export AWS_PROFILE=myprofile
terraform remote config \
--backend=s3 \
--backend-config="bucket=my-tfstates" \
--backend-config="key=projectX.tfstate" \

This was a bit clunky but functional. Regardless, it was rather annoying having some configuration elements outside of the normal terraform config (*.tf) files.

Along came Terraform v.0.9

The introduction of Terraform v.0.9 with its new fangled “Backends” makes things much more seamless and transparent.  Now we can replicate that same remote state backend configuration with a Backend Resource in a Terraform configuration like so:

Terraform S3 Backend Configuration Example
terraform {
  backend "s3" {
    bucket = "my-tfstates"
    key    = "projectX.tfstate"
    region = "us-west-2"
A Migration Example

So, using our examples above let’s walk through the process of migrating from a legacy “remote config” to a “backend”.  Detailed instructions for the following can be found here.

1. (Prior to upgrading to Terraform v.0.9+) Pull remote config with pre v.0.9 Terraform

> terraform remote pull
Local and remote state in sync

2. Backup your terraform.tfstate file

> cp .terraform/terraform.tfstate 

3. Upgrade Terraform to v.0.9+

4. Configure the new backend

terraform {
  backend "s3" {
    bucket = "my-tfstates"
    key    = "projectX.tfstate"
    region = "us-west-2"

5. Run Terraform init

> terraform init
Downloading modules (if any)...
Initializing the backend...
New backend configuration detected with legacy remote state!
Terraform has detected that you're attempting to configure a new backend.
At the same time, legacy remote state configuration was found. Terraform will
first configure the new backend, and then ask if you'd like to migrate
your remote state to the new backend.
Do you want to copy the legacy remote state from "s3"?
  Terraform can copy the existing state in your legacy remote state
  backend to your newly configured backend. Please answer "yes" or "no".
  Enter a value: no
Successfully configured the backend "s3"! Terraform will automatically
use this backend unless the backend configuration changes.
Terraform has been successfully initialized!
You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.
If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your environment. If you forget, other
commands will detect it and remind you to do so if necessary.

6. Verify the new state is copacetic

> terraform plan
No changes. Infrastructure is up-to-date.
This means that Terraform did not detect any differences between your
configuration and real physical resources that exist. As a result, Terraform
doesn't need to do anything.

7.  Commit and push

In closing…

Managing your infrastructure as code isn’t rocket science, but it also isn’t trivial.  Having a solid understanding of cloud architectures, the Well Architected Framework, and DevOps best practices can greatly impact the success you have.  A lot goes into architecting and engineering solutions in a way that maximizes your business value, application reliability, agility, velocity, and key differentiators.  This can be a daunting task, but it doesn’t have to be!  2nd Watch has the people, processes, and tools to make managing your cloud infrastructure as code a breeze! Contact us today to find out how.


— Ryan Kennedy, Principal Cloud Automation Architect, 2nd Watch