Add exception handling for non-Dockerfile formats

src/Microsoft.ComponentDetection.Detectors/dockerfile/DockerfileComponentDetector.cs

@@ -3,13 +3,16 @@ namespace Microsoft.ComponentDetection.Detectors.Dockerfile;
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
+using System.Reactive.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.ComponentDetection.Common;
 using Microsoft.ComponentDetection.Contracts;
 using Microsoft.ComponentDetection.Contracts.Internal;
 using Microsoft.ComponentDetection.Contracts.TypedComponent;
 using Microsoft.Extensions.Logging;
+using Sprache;
 using Valleysoft.DockerfileModel;
 
 public class DockerfileComponentDetector : FileComponentDetector, IExperimentalDetector
@@ -41,6 +44,15 @@ public DockerfileComponentDetector(
 
     public override int Version => 1;
 
+    protected override IList<string> SkippedFolders => ["node_modules"];
+
+    protected override Task<IObservable<ProcessRequest>> OnPrepareDetectionAsync(
+        IObservable<ProcessRequest> processRequests,
+        IDictionary<string, string> detectorArgs,
+        CancellationToken cancellationToken = default) =>
+        Task.FromResult(processRequests.Where(processRequest =>
+            !this.IsInSkippedFolder(processRequest.ComponentStream.Location)));
+
     protected override async Task OnFileFoundAsync(ProcessRequest processRequest, IDictionary<string, string> detectorArgs, CancellationToken cancellationToken = default)
     {
         var singleFileComponentRecorder = processRequest.SingleFileComponentRecorder;
@@ -59,12 +71,22 @@ protected override async Task OnFileFoundAsync(ProcessRequest processRequest, ID
             var stageNameMap = new Dictionary<string, string>();
             var dockerFileComponent = this.ParseDockerFileAsync(contents, file.Location, singleFileComponentRecorder, stageNameMap);
         }
+        catch (ParseException e)
+        {
+            this.Logger.LogWarning(e, "Ignoring file that doesn't appear to be a Dockerfile: {Location}", filePath);
+        }
         catch (Exception e)
         {
-            this.Logger.LogError(e, "The file doesn't appear to be a Dockerfile: {Location}", filePath);
+            this.Logger.LogError(e, "Failed to process Dockerfile: {Location}", filePath);
         }
     }
 
+    private bool IsInSkippedFolder(string filePath)
+    {
+        var pathSegments = filePath.Split(['/', '\\'], StringSplitOptions.RemoveEmptyEntries);
+        return this.SkippedFolders.Any(skippedFolder => pathSegments.Contains(skippedFolder, StringComparer.OrdinalIgnoreCase));
+    }
+
     private Task ParseDockerFileAsync(string fileContents, string fileLocation, ISingleFileComponentRecorder singleFileComponentRecorder, Dictionary<string, string> stageNameMap)
     {
         var dockerfileModel = Dockerfile.Parse(fileContents);

test/Microsoft.ComponentDetection.Detectors.Tests/DockerfileComponentDetectorTests.cs

@@ -1,13 +1,16 @@
 #nullable enable
 namespace Microsoft.ComponentDetection.Detectors.Tests;
 
+using System;
+using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using AwesomeAssertions;
 using Microsoft.ComponentDetection.Contracts;
 using Microsoft.ComponentDetection.Contracts.TypedComponent;
 using Microsoft.ComponentDetection.Detectors.Dockerfile;
 using Microsoft.ComponentDetection.TestsUtilities;
+using Microsoft.Extensions.Logging;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Moq;
 
@@ -210,6 +213,51 @@ public async Task TestDockerfile_PrefixedFilenameAsync()
         componentRecorder.GetDetectedComponents().Should().ContainSingle();
     }
 
+    [TestMethod]
+    [DataRow("dockerfile.mjs")]
+    [DataRow("dockerfile.d.mts")]
+    public async Task TestDockerfile_ShikiLanguageDefinitionIsIgnoredAsync(string fileName)
+    {
+        var loggerMock = new Mock<ILogger<DockerfileComponentDetector>>();
+
+        var (scanResult, componentRecorder) = await this.DetectorTestUtility
+            .WithFile(fileName, "export default Object.freeze({ name: 'dockerfile' });")
+            .AddServiceMock(loggerMock)
+            .ExecuteDetectorAsync();
+
+        scanResult.ResultCode.Should().Be(ProcessingResultCode.Success);
+        componentRecorder.GetDetectedComponents().Should().BeEmpty();
+        loggerMock.Verify(
+            logger => logger.Log(
+                LogLevel.Warning,
+                It.IsAny<EventId>(),
+                It.IsAny<It.IsAnyType>(),
+                It.IsAny<Exception>(),
+                It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+            Times.Once);
+        loggerMock.Verify(
+            logger => logger.Log(
+                LogLevel.Error,
+                It.IsAny<EventId>(),
+                It.IsAny<It.IsAnyType>(),
+                It.IsAny<Exception>(),
+                It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+            Times.Never);
+    }
+
+    [TestMethod]
+    public async Task TestDockerfile_UnderNodeModulesIsIgnoredAsync()
+    {
+        var fileLocation = Path.Combine(Path.GetTempPath(), "node_modules", "shiki", "dist", "langs", "dockerfile.mjs");
+
+        var (scanResult, componentRecorder) = await this.DetectorTestUtility
+            .WithFile("dockerfile.mjs", "FROM redis:7-alpine", fileLocation: fileLocation)
+            .ExecuteDetectorAsync();
+
+        scanResult.ResultCode.Should().Be(ProcessingResultCode.Success);
+        componentRecorder.GetDetectedComponents().Should().BeEmpty();
+    }
+
     [TestMethod]
     public async Task TestDockerfile_NoFromInstructionsAsync()
     {