How to upgrade Terraform provider plugins and modules
Since Terraform v0.10, Terraform providers are distributed separately from the Terraform binary. This lets them update at different paces, and allows a wider group of people to collaborate on the providers. This is mostly good, but it does introduce a new step for upgrading providers. It is slightly counterintuitive, but to upgrade your providers, run
terraform init -upgrade
To upgrade your modules, run
terraform get -update