Using environment variables was a mistake, because they must be set again
manually each time we want to re-apply the Terraform configurations.
Instead, put the variables in a tfvars file.
Each time we call that script, we must set a few env vars
beforehand. Let's make these vars optional parameters to
the script instead.
Also add helper scripts to list the locations (zones or
regions) available to each provider.
GCP quotas are fairly limited (on my account, I can only
use 8 public IP addresses per zone, which means that I cannot
deploy many public clusters in a single zone). I tried to
use private clusters, but that causes other problems.
This refactoring makes it possible to spread clusters
across multiple zones. Since I have access to 20+ zones
in Europe and 20+ zones in the US, this lets me create a
lot of public clusters and simplifies the module quite a bit.
Instead of doing a local-exec to 'kubectl get nodes ... > stage2/externalips.X',
we use an external provisioner. And to decouple things, the external provisioner
depends on nodes being ready, and node readiness is implemented with a null
resource. That way we don't need to re-execute the whole 'wait for nodes; dump
node addresses' dance each time we re-run that configuration.
This is a new provisioning mechanism. Right now, it can
provision clusters on:
- Digital Ocean
- Linode
- Oracle Cloud
- Scaleway
Others should be relatively straightforward to add.
Check the README in the prepare-tf subdirectory for details.
