container.training/slides/terraform/intro.md

Terraform

“An open-source infrastructure as code software tool created by HashiCorp¹.”

• Other products in that space: Pulumi, Cloud Formation...

• Very rich ecosystem

• Supports many cloud providers

.footnote[¹Also creators of Consul, Nomad, Packer, Vagrant, Vault...]

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Infrastructure as code?

1. Write configuration files that describe resources, e.g.:

   • some GKE and Kapsule Kubernetes clusters
   • some S3 buckets
   • a bunch of Linode/Digital Ocean instances
   • ...and more

2. Run terraform apply to create all these things

3. Make changes to the configuration files

4. Run terraform apply again to create/update/delete resources

(Vagrant, Packer, Consul, Vault, Nomad...)

5. Run terraform destroy to delete all these things

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What Terraform is not

• It's not a tool to abstract the differences between cloud providers

  (“I want to move my AWS workloads to Scaleway!”)

• It's not a configuration management tool

  (“I want to install and configure packages on my servers!”)

• It's not an application deployment tool

  (“I want to deploy a new build of my app!”

• It can be used for these things anyway (more or less succesfully)

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Vocabulary

• Configuration = a set of Terraform files

  • typically in HCL (HashiCorp Config Language), .tf extension

  • can also be JSON

• Resource = a thing that will be managed by Terraform

  • e.g. VM, cluster, load balancer...

• Provider = plugin to manage a family of resources

  • example: google provider to talk with GCP APIs

  • example: tls provider to generate keys