From 384034d91f204e1a0bb0ed67ddee05936d355627 Mon Sep 17 00:00:00 2001
From: GitHubPang <61439577+GitHubPang@users.noreply.github.com>
Date: Tue, 25 Feb 2020 08:49:37 +0800
Subject: [PATCH] Fixed ArgumentNullException in ContainerTracker.cs

Fixed crash (ArgumentNullException) caused by resources.BlkioStats.IoServiceBytesRecursive being null when other docker containers keep getting restarted.
---
 ContainerTracker.cs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/ContainerTracker.cs b/ContainerTracker.cs
index 62eb7b6..f109675 100644
--- a/ContainerTracker.cs
+++ b/ContainerTracker.cs
@@ -187,16 +187,16 @@ namespace DockerExporter
             }
             else
             {
-                var readEntries = resources.BlkioStats.IoServiceBytesRecursive
+                var readEntries = resources.BlkioStats.IoServiceBytesRecursive?
                     .Where(entry => entry.Op.Equals("read", StringComparison.InvariantCultureIgnoreCase))
                     .ToArray();
 
-                var writeEntries = resources.BlkioStats.IoServiceBytesRecursive
+                var writeEntries = resources.BlkioStats.IoServiceBytesRecursive?
                     .Where(entry => entry.Op.Equals("write", StringComparison.InvariantCultureIgnoreCase))
                     .ToArray();
 
-                var totalRead = readEntries.Any() ? readEntries.Sum(entry => (long)entry.Value) : 0;
-                var totalWrite = writeEntries.Any() ? writeEntries.Sum(entry => (long)entry.Value) : 0;
+                var totalRead = readEntries == null ? 0 : readEntries.Any() ? readEntries.Sum(entry => (long)entry.Value) : 0;
+                var totalWrite = writeEntries == null ? 0 : writeEntries.Any() ? writeEntries.Sum(entry => (long)entry.Value) : 0;
 
                 metrics.TotalDiskBytesRead.Set(totalRead);
                 metrics.TotalDiskBytesWrite.Set(totalWrite);