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/converge.rs | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 src/converge.rs

(limited to 'src/converge.rs')

diff --git a/src/converge.rs b/src/converge.rs
new file mode 100644
index 0000000..073e9e6
--- /dev/null
+++ b/src/converge.rs
@@ -0,0 +1,85 @@
+use std::fmt::Debug;
+
+use anyhow::anyhow;
+use aws_sdk_autoscaling::types::AutoScalingGroup;
+use aws_sdk_route53::types::ResourceRecordSet;
+use futures::try_join;
+use trust_dns_proto::rr::Name;
+
+use crate::autoscaling::{asg_by_name, AutoScaling};
+use crate::dns::AutoScalingGroupConfig;
+use crate::ec2::{instance_recordsets, Ec2};
+use crate::hashable::Hashable;
+use crate::result::Result;
+use crate::route53::{zone_for_domain, zone_suffix_recordsets, Route53};
+
+#[derive(Debug)]
+pub struct Changes<T> {
+    pub zone_id: String,
+    pub remove: T,
+    pub insert: T,
+}
+
+async fn changes<C>(
+    aws_context: &C,
+    auto_scaling_group: &AutoScalingGroup,
+    dns_name: &Name,
+    dns_ttl: i64,
+) -> Result<Changes<impl IntoIterator<Item = ResourceRecordSet> + Debug>>
+where
+    C: Ec2 + Route53,
+{
+    let AutoScalingGroupConfig {
+        name: asg_name,
+        live_instance_ids,
+    } = AutoScalingGroupConfig::try_from(auto_scaling_group)?;
+
+    let zone = zone_for_domain(dns_name, aws_context).await?;
+    let zone_id = zone
+        .id()
+        .ok_or(anyhow!("No ID for hosted zone for name: {}", dns_name))?;
+
+    let (intended_records, actual_records) = try_join!(
+        instance_recordsets(
+            &asg_name,
+            dns_name,
+            dns_ttl,
+            &live_instance_ids,
+            aws_context
+        ),
+        zone_suffix_recordsets(dns_name, zone_id, aws_context),
+    )?;
+
+    let remove_records = actual_records.difference(&intended_records);
+    let insert_records = intended_records.difference(&actual_records);
+
+    let remove_records = remove_records.map(Hashable::as_ref);
+    let insert_records = insert_records.map(Hashable::as_ref);
+
+    let remove_records = remove_records.map(ToOwned::to_owned);
+    let insert_records = insert_records.map(ToOwned::to_owned);
+
+    let remove_records: Vec<_> = remove_records.collect();
+    let insert_records: Vec<_> = insert_records.collect();
+
+    Ok(Changes {
+        zone_id: zone_id.into(),
+        remove: remove_records,
+        insert: insert_records,
+    })
+}
+
+pub async fn named_asg_changes<C>(
+    aws_context: &C,
+    name: &str,
+    dns_name: &Name,
+    dns_ttl: i64,
+) -> Result<Changes<impl IntoIterator<Item = ResourceRecordSet> + Debug>>
+where
+    C: AutoScaling + Ec2 + Route53,
+{
+    let auto_scaling_group = asg_by_name(aws_context, name).await?;
+
+    let changes = changes(aws_context, &auto_scaling_group, dns_name, dns_ttl).await?;
+    Ok(changes)
+}
-- 
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