docs: provide setup and usage instructions

This still needs to be extended with some information on how to obtain the IP addresses of each
VM.

README.md

@@ -8,6 +8,49 @@ If you are interested in deploying your own testnets, or using the tool to deplo
 
 Since we use Ansible, if you want to use the tool on Windows, you'll need to use WSL.
 
+## Setup
+
+The tool makes use of Terraform to create either droplets on Digital Ocean or EC2 instances on AWS, so you need an installation of that on your platform. It is very likely available in your platform's package manager.
+
+We make use of Ansible for provisioning the VMs. Since Ansible is a Python application, it is advisable to install it in a virtualenv. If this sounds unfamiliar, I would recommend asking ChatGPT something along the lines of, "How can I install Ansible in a virtualenv created and managed by virtualenvwrapper?" The virtualenv must be activated any time you use the tool.
+
+After you've installed these tools, run our `setup` command:
+```
+cargo run -- setup
+```
+
+This will gather a bunch of values that are written to a `.env` file, which is read when the tool starts.
+
+You only need to run this command once.
+
+## Deploying a Testnet
+
+After completing the setup, you can deploy a testnet like so:
+```
+cargo run -- deploy --name beta
+```
+
+This will deploy a testnet named 'beta' to Digital Ocean, with 10 VMs and 20 node processes on each VM, and the latest version of the `safenode` binary.
+
+If you want more VMs or nodes, use the `--vm-count` and `--node-count` arguments to vary those values to suit your needs:
+```
+cargo run -- deploy --name beta --vm-count 100 --node-count 30
+```
+
+You may want to deploy a custom version of the `safenode` binary. To do so, use the `--branch` and `--repo-owner` arguments:
+```
+cargo run -- deploy --name beta --vm-count 100 --node-count 30 --repo-owner jacderida --branch custom_branch 
+```
+
+## Clean Up
+
+To remove the testnet, use the following command:
+```
+cargo run -- clean --name beta --provider "digital-ocean"
+```
+
+This will use Terraform to tear down all the droplets it created.
+
 ## License
 
 This repository is licensed under the BSD-3-Clause license.

src/lib.rs

@@ -381,6 +381,8 @@ impl TestnetDeploy {
         self.create_infra(name, vm_count, repo_owner.is_some())
             .await?;
         if repo_owner.is_some() {
+            // I think the use of `unwrap` here is justified because we've already checked they are
+            // in a valid state.
             self.build_custom_safenode(
                 name,
                 &repo_owner.as_ref().unwrap(),