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Added CGroupv2 support into Docker Extensions #839

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merged 18 commits into from
Jan 9, 2023
Merged

Added CGroupv2 support into Docker Extensions #839

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15b1b51
Initial changes
anoopbabu29 Dec 6, 2022
4cb146d
Adding cgroupv2 to test and updating the approach such that it checks…
anoopbabu29 Dec 15, 2022
cb8f573
Merge branch 'main' of https://github.com/anoopbabu29/opentelemetry-d…
anoopbabu29 Dec 16, 2022
7ff1941
Merge branch 'open-telemetry:main' into cgroupv2-sup
anoopbabu29 Dec 16, 2022
aad5630
Merge branch 'cgroupv2-sup' of https://github.com/anoopbabu29/opentel…
anoopbabu29 Dec 19, 2022
94be6e9
Respoding to Comments and build checks
anoopbabu29 Dec 19, 2022
856fed7
Merge branch 'main' into cgroupv2-sup
anoopbabu29 Dec 19, 2022
fd0c8e4
Adjusted build such that Detect checks both versions, and BuildResour…
anoopbabu29 Dec 22, 2022
5ba7994
Merge branch 'cgroupv2-sup' of https://github.com/anoopbabu29/opentel…
anoopbabu29 Dec 22, 2022
78a5a62
Merge branch 'main' into cgroupv2-sup
anoopbabu29 Dec 22, 2022
14ce9b1
Adjusting BuildResource at suggestion
anoopbabu29 Dec 23, 2022
492552d
Merge branch 'cgroupv2-sup' of https://github.com/anoopbabu29/opentel…
anoopbabu29 Dec 23, 2022
a3647b3
Added same tests as the go version as well as their regex expression
anoopbabu29 Jan 4, 2023
9e05aba
Merge branch 'main' into cgroupv2-sup
anoopbabu29 Jan 4, 2023
b5857f0
Addressing Comments by adding Enums and cleaning up tests
anoopbabu29 Jan 5, 2023
7b7e580
Merge branch 'main' into cgroupv2-sup
anoopbabu29 Jan 6, 2023
ba6b6ab
Fix parse mode version in test
anoopbabu29 Jan 6, 2023
d043c33
Merge branch 'main' into cgroupv2-sup
utpilla Jan 9, 2023
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91 changes: 85 additions & 6 deletions src/OpenTelemetry.Extensions.Docker/Resources/DockerResourceDetector.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,24 +28,32 @@ namespace OpenTelemetry.Extensions.Docker.Resources;
public class DockerResourceDetector : IResourceDetector
{
private const string FILEPATH = "/proc/self/cgroup";
private const string FILEPATHV2 = "/proc/self/mountinfo";
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I don't see any usage of FILEPATHV2 in detector. I'd guess, that ExtractContainerIdV2 should use it, instead of FILEPATH. Proper fix for it will also solve problem mentioned by @alexeypukhov , as that functions should check different file.

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Change has been made to check both versions in the Detect method and assuming the version being used in the BuildResource method. This way, the problem mentioned by @alexeypukhov would be solved as you mentioned since no container id would be able to be found when checking for cgroupv1 if cgroupv2 is being used.

private const string HOSTNAME = "hostname";

/// <summary>
/// Detects the resource attributes from Docker.
/// </summary>
/// <returns>Resource with key-value pairs of resource attributes.</returns>
public Resource Detect()
{
return this.BuildResource(FILEPATH);
var cGroupBuild = this.BuildResourceV1(FILEPATH);
if (cGroupBuild == Resource.Empty)
{
cGroupBuild = this.BuildResourceV2(FILEPATHV2);
}

return cGroupBuild;
}

/// <summary>
/// Builds the resource attributes from Container Id in file path.
/// Builds the resource attributes from Container Id in file path of cgroupv1.
/// </summary>
/// <param name="path">File path where container id exists.</param>
/// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
internal Resource BuildResource(string path)
internal Resource BuildResourceV1(string path)
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Source for BuildResourceV1 / BuildResourceV2 are very similar, same as ExtractContainerIdV1 / ExtractContainerIdV2.
To have less duplicated code, I'd probably create enum ParseMode {V1, V2} and pass it as second argument to BuildResource / ExtractContainerId with different logic called when you fetch string containerId = ... in ExtractContainerId.

{
var containerId = this.ExtractContainerId(path);
var containerId = this.ExtractContainerIdV1(path);

if (string.IsNullOrEmpty(containerId))
{
Expand All @@ -58,11 +66,30 @@ internal Resource BuildResource(string path)
}

/// <summary>
/// Extracts Container Id from path.
/// Builds the resource attributes from Container Id in file path of cgroupv2.
/// </summary>
/// <param name="path">File path where container id exists.</param>
/// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
internal Resource BuildResourceV2(string path)
{
var containerId = this.ExtractContainerIdV2(path);

if (string.IsNullOrEmpty(containerId))
{
return Resource.Empty;
}
else
{
return new Resource(new List<KeyValuePair<string, object>>() { new KeyValuePair<string, object>(DockerSemanticConventions.AttributeContainerID, containerId), });
}
}

/// <summary>
/// Extracts Container Id from path using the cgroupv1 format.
/// </summary>
/// <param name="path">cgroup path.</param>
/// <returns>Container Id, Null if not found or exception being thrown.</returns>
private string ExtractContainerId(string path)
private string ExtractContainerIdV1(string path)
{
try
{
Expand All @@ -88,6 +115,37 @@ private string ExtractContainerId(string path)
return null;
}

/// <summary>
/// Extracts Container Id from path using the cgroupv2 format.
/// </summary>
/// <param name="path">File path where container id exists.</param>
/// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
private string ExtractContainerIdV2(string path)
{
try
{
if (!File.Exists(path))
{
return null;
}

foreach (string line in File.ReadLines(path))
{
string containerId = (!string.IsNullOrEmpty(line) && line.Contains(HOSTNAME)) ? this.GetIdFromLineV2(line) : null;
if (!string.IsNullOrEmpty(containerId))
{
return containerId;
}
}
}
catch (Exception ex)
{
DockerExtensionsEventSource.Log.ExtractResourceAttributesException($"{nameof(DockerResourceDetector)} : Failed to extract Container id from path", ex);
}

return null;
}

/// <summary>
/// Gets the Container Id from the line after removing the prefix and suffix.
/// </summary>
Expand Down Expand Up @@ -116,6 +174,27 @@ private string GetIdFromLine(string line)
return containerId;
}

private string GetIdFromLineV2(string line)
{
int hostnameIndex = line.LastIndexOf("/" + HOSTNAME);
if (hostnameIndex < 0)
{
return null;
}

string earlierSection = line.Substring(0, hostnameIndex);
int startIndex = earlierSection.LastIndexOf('/');

string containerId = this.RemovePrefixAndSuffixIfneeded(earlierSection, startIndex, hostnameIndex);

if (string.IsNullOrEmpty(containerId) || !EncodingUtils.IsValidHexString(containerId))
{
return null;
}

return containerId;
}

private string RemovePrefixAndSuffixIfneeded(string input, int startIndex, int endIndex)
{
startIndex = (startIndex == -1) ? 0 : startIndex + 1;
Expand Down
25 changes: 19 additions & 6 deletions test/OpenTelemetry.Extensions.Docker.Tests/Resources/DockerResourceDetectorTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,13 @@ public class DockerResourceDetectorTests
private const string CONTAINERID =
"d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";

// cgroupv2 line with container Id
private const string CGROUPLINEV2 =
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do you also need to check suffix or prefix for cgroup v2?
Also just a thought. Should we check prefix and suffix end to end, I mean with reading from file? If GetContainerId works with extracted cgroup string no matter V1 or V2, maybe we should have a separate test just for this function and do not mix it with reading the line from the file and parsing it depending on V1 or V2

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I can check for them as they are separate implementations. I figured that most of the functionality was similar enough to warrant not having them but I believe you are correct that they should exist, although the suffix isn't a necessary test in my opinion since its not a real case I believe.

"13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356/hostname";

// Expected Container Id
private const string CONTAINERIDV2 = "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";

[Fact]
public void TestValidContainer()
{
Expand All @@ -65,25 +72,31 @@ public void TestValidContainer()
using (TempFile tempFile = new TempFile())
{
tempFile.Write(CGROUPLINEWITHPREFIX);
Assert.Equal(CONTAINERIDWITHPREFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
Assert.Equal(CONTAINERIDWITHPREFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResourceV1(tempFile.FilePath)));
}

using (TempFile tempFile = new TempFile())
{
tempFile.Write(CGROUPLINEWITHSUFFIX);
Assert.Equal(CONTAINERIDWITHSUFFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
Assert.Equal(CONTAINERIDWITHSUFFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResourceV1(tempFile.FilePath)));
}

using (TempFile tempFile = new TempFile())
{
tempFile.Write(CGROUPLINEWITHPREFIXandSUFFIX);
Assert.Equal(CONTAINERIDWITHPREFIXANDSUFFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
Assert.Equal(CONTAINERIDWITHPREFIXANDSUFFIXREMOVED, this.GetContainerId(dockerResourceDetector.BuildResourceV1(tempFile.FilePath)));
}

using (TempFile tempFile = new TempFile())
{
tempFile.Write(CGROUPLINE);
Assert.Equal(CONTAINERID, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
Assert.Equal(CONTAINERID, this.GetContainerId(dockerResourceDetector.BuildResourceV1(tempFile.FilePath)));
}

using (TempFile tempFile = new TempFile())
{
tempFile.Write(CGROUPLINEV2);
Assert.Equal(CONTAINERIDV2, this.GetContainerId(dockerResourceDetector.BuildResourceV2(tempFile.FilePath)));
}
}

Expand All @@ -96,11 +109,11 @@ public void TestInvalidContainer()
using (TempFile tempFile = new TempFile())
{
tempFile.Write(INVALIDCGROUPLINE);
Assert.Equal(dockerResourceDetector.BuildResource(tempFile.FilePath), Resource.Empty);
Assert.Equal(dockerResourceDetector.BuildResourceV1(tempFile.FilePath), Resource.Empty);
}

// test invalid file
Assert.Equal(dockerResourceDetector.BuildResource(Path.GetTempPath()), Resource.Empty);
Assert.Equal(dockerResourceDetector.BuildResourceV1(Path.GetTempPath()), Resource.Empty);
}

private string GetContainerId(Resource resource)
Expand Down