From 6923ff1a1bfc595b6fa4b8afb04481bea34d7816 Mon Sep 17 00:00:00 2001
From: Scott Leggett <scott@sl.id.au>
Date: Thu, 20 Jul 2023 11:16:10 +0800
Subject: [PATCH] fix: avoid duplicate log lines edge case

---
 internal/k8s/logs.go | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/internal/k8s/logs.go b/internal/k8s/logs.go
index d95811ce..7b1ec723 100644
--- a/internal/k8s/logs.go
+++ b/internal/k8s/logs.go
@@ -101,6 +101,19 @@ func (c *Client) readLogs(ctx context.Context, egSend *errgroup.Group,
 			linewiseCopy(ctx, fmt.Sprintf("[pod/%s/%s]", p.Name, cName), logs,
 				logStream)
 			fmt.Println("done linewiseCopy")
+			// The k8s API sometimes sends an event showing a healthy pod even though
+			// the pod is terminating. This seems to occur sometimes on scale down of
+			// a deployment. When this happens there is a race that occurs where the
+			// existing log stream closes (linewiseCopy() returns), then the
+			// "healthy" event comes in and the container log streaming is started
+			// again, only to return immediately. This can result in duplicated log
+			// lines being returned.
+			// To hack around this behaviour, pause for a couple of seconds here
+			// before exiting. This means that the container ID is retained in
+			// c.logCIDs for a brief period after logs stop streaming which causes
+			// "healthy pod" events from the k8s API to be ignored for that period
+			// and thereby avoiding duplicate log lines being returned.
+			time.Sleep(2)
 			return nil
 		})
 	}
@@ -116,10 +129,11 @@ func (c *Client) podEventHandler(ctx context.Context,
 	// panic if obj is not a pod, since this is specifically a pod informer
 	pod := obj.(*corev1.Pod)
 	spew.Dump(pod.Status)
-	if !slices.ContainsFunc(pod.Status.Conditions, func(cond corev1.PodCondition) bool {
-		return (pod.Status.Phase == corev1.PodRunning) &&
-			(cond.Type == corev1.ContainersReady && cond.Status == corev1.ConditionTrue)
-	}) {
+	if !slices.ContainsFunc(pod.Status.Conditions,
+		func(cond corev1.PodCondition) bool {
+			return cond.Type == corev1.ContainersReady &&
+				cond.Status == corev1.ConditionTrue
+		}) {
 		fmt.Println("pod not ready")
 		return
 	}