From 2996d2b6268a320fafc512fcbee03a1b6182c521 Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Wed, 24 Jul 2024 22:16:39 -0400
Subject: Normalize the target DNS name much earlier in the program.

Also clean up some naming.
---
 src/cli.rs |  3 ++-
 src/ec2.rs | 31 +++++++++++++++----------------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/cli.rs b/src/cli.rs
index 0362b5e..340d537 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -7,6 +7,7 @@ use trust_dns_proto::rr::Name;
 use crate::apply::ApplyMode;
 use crate::aws_context::AwsContext;
 use crate::converge::named_asg_changes;
+use crate::dns::absolute;
 
 /// Synchronize a DNS entry with an autoscaling group's running instances.
 ///
@@ -48,7 +49,7 @@ impl Args {
         let changes = named_asg_changes(
             &aws_context,
             &args.autoscaling_group,
-            &args.dns_name,
+            &absolute(args.dns_name)?,
             args.dns_ttl,
         )
         .await?;
diff --git a/src/ec2.rs b/src/ec2.rs
index 44719ed..0c55a20 100644
--- a/src/ec2.rs
+++ b/src/ec2.rs
@@ -8,7 +8,6 @@ use aws_sdk_route53::types::{ResourceRecord, ResourceRecordSet, RrType};
 use itertools::Itertools;
 use trust_dns_proto::rr::Name;
 
-use crate::dns::absolute;
 use crate::hashable::Hashable;
 
 pub trait Ec2 {
@@ -18,13 +17,15 @@ pub trait Ec2 {
 pub async fn instance_recordsets<C>(
     aws_context: &C,
     asg_name: &str,
-    dns_suffix: &Name,
+    dns_name: &Name,
     dns_ttl: i64,
     live_instance_ids: &[String],
 ) -> Result<HashSet<Hashable<ResourceRecordSet>>>
 where
     C: Ec2,
 {
+    assert!(dns_name.is_fqdn());
+
     // If there's nothing running, then (a) we don't need to ask AWS about
     // running instances, and (b) we can't anyways as the API call requires at
     // least one instance ID. Abort here.
@@ -37,8 +38,8 @@ where
         .values(asg_name)
         .build();
 
-    let mut apex_ip4 = HashSet::new();
-    let mut apex_ip6 = HashSet::new();
+    let mut ip4 = HashSet::new();
+    let mut ip6 = HashSet::new();
 
     let mut instances_paginator = aws_context
         .ec2()
@@ -53,7 +54,7 @@ where
         let instances = reservation.instances();
         for instance in instances {
             // Mild abuse of the fact that optional values are also iterable
-            apex_ip4.extend(instance.public_ip_address().map(String::from));
+            ip4.extend(instance.public_ip_address().map(String::from));
 
             let instance_interfaces = instance.network_interfaces();
             let instance_ip6: Vec<_> = instance_interfaces
@@ -64,25 +65,23 @@ where
                 .to_owned()
                 .collect();
 
-            apex_ip6.extend(instance_ip6.iter().map(ToOwned::to_owned).map(String::from));
+            ip6.extend(instance_ip6.iter().map(ToOwned::to_owned).map(String::from));
         }
     }
 
-    let apex_hostname = absolute(dns_suffix.clone())?;
-    let apex_hostname = apex_hostname.to_ascii();
-
-    let apex_ip4_recordset = apex_recordset(&apex_hostname, dns_ttl, RrType::A, apex_ip4)?;
-    let apex_ip6_recordset = apex_recordset(&apex_hostname, dns_ttl, RrType::Aaaa, apex_ip6)?;
+    let dns_name = dns_name.to_ascii();
+    let ip4_recordset = host_recordset(&dns_name, dns_ttl, RrType::A, ip4)?;
+    let ip6_recordset = host_recordset(&dns_name, dns_ttl, RrType::Aaaa, ip6)?;
 
-    Ok(apex_ip4_recordset
+    Ok(ip4_recordset
         .into_iter()
-        .chain(apex_ip6_recordset.into_iter())
+        .chain(ip6_recordset.into_iter())
         .map(Hashable::from)
         .collect())
 }
 
-fn apex_recordset(
-    apex_hostname: &str,
+fn host_recordset(
+    dns_name: &str,
     dns_ttl: i64,
     rr_type: RrType,
     addresses: HashSet<impl Into<String>>,
@@ -97,7 +96,7 @@ fn apex_recordset(
             .try_collect()?;
 
         let record_set = ResourceRecordSet::builder()
-            .name(apex_hostname)
+            .name(dns_name)
             .r#type(rr_type)
             .ttl(dns_ttl)
             .set_resource_records(Some(records))
-- 
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