1 files changed, 70 insertions, 0 deletions
diff --git a/src/cli.rs b/src/cli.rs
new file mode 100644
index 0000000..75bb5ef
--- /dev/null
+++ b/src/cli.rs
@@ -0,0 +1,70 @@
+use std::fmt::Debug;
+
+use clap::Parser;
+use trust_dns_proto::rr::Name;
+
+use crate::apply::ApplyMode;
+use crate::aws_context::AwsContext;
+use crate::converge::named_asg_changes;
+
+/// Synchronize a DNS entry with an autoscaling group's running instances.
+///
+/// The given DNS name's A and AAAA records in Route53 will be rewritten to exactly
+/// match the list of pending and in-service EC2 instances in the specified
+/// autoscaling group. Records of other types (including CNAMEs) will not be
+/// modified, so this can be used alongside DNS ACME verification, SPF, and other
+/// DNS applications.
+#[derive(Parser, Debug)]
+pub struct Args {
+    /// The name of the autoscaling group to synchronize.
+    #[arg(long)]
+    autoscaling_group: String,
+
+    /// The DNS domain name to synchronize. The most specific Route53 zone that
+    /// contains this name will be modified.
+    #[arg(long)]
+    dns_name: Name,
+
+    /// The TTL (in seconds) for newly-created records.
+    #[arg(long, default_value_t = 60)]
+    dns_ttl: i64,
+
+    /// Print the affected zone ID and pending changes, without applying them (default).
+    #[arg(long, conflicts_with = "apply")]
+    dry_run: bool,
+
+    /// Apply the changes to Route53.
+    #[arg(long)]
+    apply: bool,
+}
+
+pub type Result = crate::result::Result<()>;
+
+impl Args {
+    pub async fn run(self) -> Result {
+        let args = Args::parse();
+        let name = args.autoscaling_group;
+
+        let aws_context = AwsContext::from_env().await;
+
+        let apply_mode = if args.dry_run {
+            ApplyMode::DryRun
+        } else if args.apply {
+            ApplyMode::Apply
+        } else {
+            ApplyMode::DryRun
+        };
+
+        let changes = named_asg_changes(&aws_context, &name, &args.dns_name, args.dns_ttl).await?;
+        apply_mode
+            .apply(
+                &aws_context,
+                &changes.zone_id,
+                changes.remove,
+                changes.insert,
+            )
+            .await?;
+
+        Ok(())
+    }
+}