From 288205e302d9f6afa06b8602184e983d2080a5b6 Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Tue, 17 Oct 2023 21:17:55 -0400
Subject: CLI tool for updating Route53 DNS for an ASG.

---
 src/dns.rs | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 src/dns.rs

(limited to 'src/dns.rs')

diff --git a/src/dns.rs b/src/dns.rs
new file mode 100644
index 0000000..13e3650
--- /dev/null
+++ b/src/dns.rs
@@ -0,0 +1,75 @@
+use std::convert::TryFrom;
+use std::fmt::Debug;
+
+use anyhow::anyhow;
+use aws_sdk_autoscaling::types::{AutoScalingGroup, Instance, LifecycleState};
+use trust_dns_proto::rr::Name;
+
+use crate::result::{Error, Result};
+
+#[derive(Debug)]
+pub struct AutoScalingGroupConfig {
+    pub name: String,
+    pub live_instance_ids: Vec<String>,
+}
+
+impl AutoScalingGroupConfig {
+    fn live_instance_ids<'a>(instances: impl IntoIterator<Item = &'a Instance>) -> Vec<String> {
+        instances
+            .into_iter()
+            .filter(|instance| match instance.lifecycle_state() {
+                // See <https://docs.aws.amazon.com/autoscaling/ec2/userguide/AutoScalingGroupLifecycle.html>
+                //
+                // Include pending instances so that they can obtain certs, etc.
+                Some(LifecycleState::Pending) => true,
+                Some(LifecycleState::PendingWait) => true,
+                Some(LifecycleState::PendingProceed) => true,
+                Some(LifecycleState::InService) => true,
+                _ => false,
+            })
+            .flat_map(|instance| instance.instance_id())
+            .map(ToOwned::to_owned)
+            .collect()
+    }
+}
+
+impl TryFrom<&AutoScalingGroup> for AutoScalingGroupConfig {
+    type Error = Error;
+
+    fn try_from(autoscaling_group: &AutoScalingGroup) -> Result<Self> {
+        let name = autoscaling_group
+            .auto_scaling_group_name()
+            .ok_or(anyhow!("Autoscaling group returned from AWS with no name"))?
+            .to_owned();
+
+        let instances = autoscaling_group.instances().unwrap_or(&[]);
+
+        let live_instance_ids = Self::live_instance_ids(instances);
+
+        Ok(Self {
+            name,
+            live_instance_ids,
+        })
+    }
+}
+
+pub fn suffixes(mut name: Name) -> Vec<Name> {
+    let mut names = Vec::new();
+
+    loop {
+        names.push(name.clone());
+        if name.is_root() {
+            break;
+        } else {
+            name = name.base_name();
+        }
+    }
+
+    names
+}
+
+pub fn absolute(name: Name) -> Result<Name> {
+    let root = &Name::root();
+    let absolute = name.append_name(root)?;
+    Ok(absolute)
+}
-- 
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