From a8bc5b3b6d4d01e320e22a0a9decca80a7320960 Mon Sep 17 00:00:00 2001
From: Marco Neumann <marco@crepererum.net>
Date: Wed, 8 Dec 2021 19:01:45 +0100
Subject: [PATCH] fix: allow setting the same server ID twice

This is important for idempotence and simplifies clients and helper
scripts a lot.
---
 .../tests/end_to_end_cases/deployment_api.rs  | 11 +++++++-
 server/src/lib.rs                             | 25 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/influxdb_iox/tests/end_to_end_cases/deployment_api.rs b/influxdb_iox/tests/end_to_end_cases/deployment_api.rs
index 4bf225d035..894ba05b4d 100644
--- a/influxdb_iox/tests/end_to_end_cases/deployment_api.rs
+++ b/influxdb_iox/tests/end_to_end_cases/deployment_api.rs
@@ -129,7 +129,16 @@ async fn assert_set_get_server_id(server_fixture: ServerFixture) {
     let got = client.get_server_id().await.expect("get ID failed");
     assert_eq!(got, Some(test_id));
 
-    // setting server ID a second time should fail
+    // setting server ID to same ID should be OK
+    client
+        .update_server_id(test_id)
+        .await
+        .expect("set ID again failed");
+
+    let got = client.get_server_id().await.expect("get ID failed");
+    assert_eq!(got, Some(test_id));
+
+    // setting server ID to a different ID should fail
     let result = client
         .update_server_id(NonZeroU32::try_from(13).unwrap())
         .await;
diff --git a/server/src/lib.rs b/server/src/lib.rs
index 95c4ce8c51..b513f85985 100644
--- a/server/src/lib.rs
+++ b/server/src/lib.rs
@@ -470,6 +470,15 @@ impl Server {
         let mut state = self.shared.state.write();
         let startup = match &**state {
             ServerState::Startup(startup) => startup.clone(),
+            state
+                if state
+                    .server_id()
+                    .map(|existing| existing == server_id)
+                    .unwrap_or_default() =>
+            {
+                // already set to same ID
+                return Ok(());
+            }
             _ => return Err(Error::IdAlreadySet),
         };
 
@@ -2459,4 +2468,20 @@ mod tests {
             ])
             .unwrap();
     }
+
+    #[tokio::test]
+    async fn set_server_id_twice() {
+        test_helpers::maybe_start_logging();
+        let server = make_server(make_application());
+
+        server.set_id(ServerId::try_from(1).unwrap()).unwrap();
+        server.wait_for_init().await.unwrap();
+
+        server.set_id(ServerId::try_from(1).unwrap()).unwrap();
+
+        assert_error!(
+            server.set_id(ServerId::try_from(2).unwrap()),
+            Error::IdAlreadySet
+        );
+    }
 }