Upgrade to TF version 0.13.6

Background

Cumulus pins its support to a specific version of Terraform see: deployment documentation. The reason for only supporting one specific Terraform version at a time is to avoid deployment errors than can be caused by deploying to the same target with different Terraform versions.

Cumulus is upgrading its supported version of Terraform from 0.12.12 to 0.13.6. This document contains instructions on how to perform the upgrade for your deployments.

Prerequisites

• Follow the Terraform guidance for what to do before upgrading, notably ensuring that you have no pending changes to your Cumulus deployments before proceeding.
  • You should do a terraform plan to see if you have any pending changes for your deployment (for both the data-persistence-tf and cumulus-tf modules), and if so, run a terraform apply before doing the upgrade to Terraform 0.13.6
• Review the Terraform v0.13 release notes to prepare for any breaking changes that may affect your custom deployment code. Cumulus' deployment code has already been updated for compatibility with version 0.13.
• Install Terraform version 0.13.6. We recommend using Terraform Version Manager tfenv to manage your installed versons of Terraform, but this is not required.

Upgrade your deployment code

Terraform 0.13 does not support some of the syntax from previous Terraform versions, so you need to upgrade your deployment code for compatibility.

Terraform provides a 0.13upgrade command as part of version 0.13 to handle automatically upgrading your code. Make sure to check out the documentation on batch usage of 0.13upgrade, which will allow you to upgrade all of your Terraform code with one command.

Run the 0.13upgrade command until you have no more necessary updates to your deployment code.

Upgrade your deployment

1. Ensure that you are running Terraform 0.13.6 by running terraform --version. If you are using tfenv, you can switch versions by running tfenv use 0.13.6.

2. For the data-persistence-tf and cumulus-tf directories, take the following steps:

   1. Run terraform init --reconfigure. The --reconfigure flag is required, otherwise you might see an error like:

      Error: Failed to decode current backend config
      
      The backend configuration created by the most recent run of "terraform init"
      could not be decoded: unsupported attribute "lock_table". The configuration
      may have been initialized by an earlier version that used an incompatible
      configuration structure. Run "terraform init -reconfigure" to force
      re-initialization of the backend.

   2. Run terraform apply to perform a deployment.

      caution

      Even if Terraform says that no resource changes are pending, running the apply using Terraform version 0.13.6 will modify your backend state from version 0.12.12 to version 0.13.6 without requiring approval. Updating the backend state is a necessary part of the version 0.13.6 upgrade, but it is not completely transparent.