fix: Update regex parsing for CGroup v1 to match agent spec. (#2286)

Author: tippmar-nr

src/Agent/NewRelic/Agent/Core/Utilization/VendorInfo.cs

@@ -24,8 +24,7 @@ public class VendorInfo
     {
         private const string ValidateMetadataRegex = @"^[a-zA-Z0-9-_. /]*$";
 #if NETSTANDARD2_0
-        private const string ContainerIdV1Regex = @".*:cpu:/docker/([0-9a-f]{64}).*";
-        private const string ContainerIdV1FallbackRegex = @"([0-9a-f]{64})"; // This is the old regex that just looks for any 64-char hexadecimal string
+        private const string ContainerIdV1Regex = @".*cpu.*([0-9a-f]{64})";
         private const string ContainerIdV2Regex = ".*/docker/containers/([0-9a-f]{64})/.*";
 #endif
 
@@ -321,11 +320,6 @@ private IVendorModel TryGetDockerCGroupV1(string fileContent)
             {
                 return new DockerVendorModel(id);
             }
-            matches = Regex.Matches(fileContent, ContainerIdV1FallbackRegex);
-            if (TryGetIdFromRegexMatch(matches, out id))
-            {
-                return new DockerVendorModel(id);
-            }
             return null;
         }
 

tests/Agent/UnitTests/Core.UnitTest/Utilization/VendorInfoTests.cs

@@ -373,8 +373,9 @@ public void GetVendors_GetDockerVendorInfo_ParsesV1_IfV2LookupFailsToParseFile()
         }
 
         // See https://new-relic.atlassian.net/browse/NR-221128 and https://new-relic.atlassian.net/browse/NR-230908
+        // The sample files below are from a customer issue where the cgroup file was not being parsed correctly
         [Test]
-        public void GetVendors_GetDockerVendorInfo_ParsesV1WithFallback_IfCpuMissing()
+        public void GetVendors_GetDockerVendorInfo_ParsesV1_ForCustomerIssue()
         {
             var vendorInfo = new VendorInfo(_configuration, _agentHealthReporter, _environment, _vendorHttpApiRequestor);
             var mockFileReaderWrapper = Mock.Create<IFileReaderWrapper>();