doc: Add a CLI example

This is mostly a sense-check the the API is reasonably nice and complete.

examples/cli.rs

@@ -0,0 +1,81 @@
+use std::{convert::TryInto, env, process};
+
+use cloudformatious::{ApplyStackInput, CloudFormatious, DeleteStackInput, TemplateSource};
+use futures_util::StreamExt;
+use rusoto_cloudformation::CloudFormationClient;
+use rusoto_core::Region;
+
+const USAGE: &str = "Usage: cargo run --example cli -- <apply|delete> <stack_name> [template_body]";
+
+enum Op {
+    Apply,
+    Delete,
+}
+
+impl std::str::FromStr for Op {
+    type Err = ();
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "apply" => Ok(Self::Apply),
+            "delete" => Ok(Self::Delete),
+            _ => Err(()),
+        }
+    }
+}
+
+#[tokio::main]
+async fn main() {
+    if let Err(error) = try_main().await {
+        eprintln!("{}", error);
+        process::exit(1);
+    }
+}
+
+async fn try_main() -> Result<(), Box<dyn std::error::Error>> {
+    let [op, stack_name]: [_; 2] = env::args()
+        .skip(1)
+        .take(2)
+        .collect::<Vec<_>>()
+        .try_into()
+        .map_err(|_| USAGE)?;
+    let op = op.parse().map_err(|()| USAGE)?;
+
+    let client = CloudFormationClient::new(Region::default());
+
+    match op {
+        Op::Apply => {
+            let template_body = env::args().nth(3).ok_or(USAGE)?;
+
+            let input = ApplyStackInput::new(stack_name, TemplateSource::inline(template_body));
+            let mut apply = client.apply_stack(input);
+
+            let mut events = apply.events();
+            while let Some(event) = events.next().await {
+                eprintln!("{:?}", event);
+            }
+
+            let output = apply.await?;
+            eprintln!("=== Operation succeeded ===");
+            eprintln!("{:#?}", output);
+            eprintln!();
+        }
+        Op::Delete => {
+            if env::args().nth(3).is_some() {
+                return Err(USAGE.into());
+            }
+
+            let input = DeleteStackInput::new(stack_name);
+            let mut delete = client.delete_stack(input);
+
+            let mut events = delete.events();
+            while let Some(event) = events.next().await {
+                eprintln!("{:?}", event);
+            }
+
+            delete.await?;
+            eprintln!("=== Operation succeeded ===");
+        }
+    }
+
+    Ok(())
+}