Intro
Terraform Cli users before v0.11.15 can have issues with using new providers.
terraform init stops with error message Error installing provider "external": openpgp: signature made by unknown entity
Problem description
Allowed list of terraform providers OpenPGP signatures for terraform was changed.
Terraform versions before v0.11.15 doesn't accept new signatures and throws error message.
terraform init is downloading latest external provider binary but new signature is accepted only after terraform version v0.11.15
Solution
It's not possible to use newer providers with Terraform Cli version that is "End of Life".
In order to make terraform init work you should downgrade provider version to one which had older signature and it's accepted by Terraform before v0.11.15.
For example provider external downgrade would look like
provider "external" {
version "< 2.1.0"
}
Additional notes
Current solution is dedicated to quick fix terraform code which broke.
Please upgrade your code and Terraform CLI to recent version.
Using End Of Life terraform cli and outdated providers can lead to unexpected run results.