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parse containerid for a pid from cgroup as a hex chain #589

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merged 3 commits into from
Feb 6, 2024
Merged

parse containerid for a pid from cgroup as a hex chain #589

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503be23
parse containerid for a pid from cgroup as a hex chain
esara Jan 31, 2024
c2c5af3
Fix tests
mariomac Feb 6, 2024
3a27dd9
Merge pull request #1 from mariomac/containeridforpid
esara Feb 6, 2024
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23 changes: 18 additions & 5 deletions pkg/internal/helpers/container/container.go
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Original file line number Diff line number Diff line change
Expand Up @@ -24,14 +24,18 @@ type Info struct {
PIDNamespace uint32
}

// A docker cgroup entry is a string like:
// 0::/docker/<hex...>/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-besteffort.slice/
// kubelet-kubepods-besteffort-pod<hex...>.slice/cri-containerd-<hex...>.scope
// A docker cgroup entry is a string like - when running beyla as a process on the node:
// 0::/docker/<hex...>/kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-besteffort.slice/kubelet-kubepods-besteffort-pod<hex...>.slice/cri-containerd-<hex...>.scope
// where the last <hex...> chain is the container ID inside its Pod
// The /docker/<hex...> part might not be visible inside the Pod (e.g. deploying Beyla
// as a sidecar). That's why we search for the "kubelet.slice" string.
var dockerCgroup = regexp.MustCompile(`^\d+:.*:.*/.*-([\da-fA-F]+)\.scope`)

// A k8s cgroup entry is a string like - when running beyla as daemonset in k8s:
// GKE: /kubepods/burstable/pod4a163a05-439d-484b-8e53-2968bc15824f/cde6dfaf5007ed65aad2d6aed72af91b0f3d95813492f773286e29ae145d20f4
// GKE-containerd: /kubepods/burstable/podb53dfa9e2dc9b890f7fadb2770857b03/bb959773d06ad1a07d469bced637bbc49b6f8573c493fd0548d7f5810eb3e5a8
// EKS: /kubepods.slice/kubepods-burstable.slice/kubepods-burstable-poddde1244b_5bb5_4297_b544_85f3bc0d80bf.slice/cri-containerd-acb62391578595ec849d87d8556369cee7f935f0425097fd5f870df0e8aabd3c.scope
// Containerd: /kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7260904bbd08e72e4dff95d9fccd2ee8.slice/cri-containerd-d36686f9785534531160dc936aec9d711a26eb37f4fc7752a2ae27d0a24345c1.scope
var k8sCgroup = regexp.MustCompile(`^\d+:.*:/kubepods.*([0-9a-f]{64})`)

// InfoForPID returns the container ID and PID namespace for the given PID.
func InfoForPID(pid uint32) (Info, error) {
ns, err := namespaceFinder(int32(pid))
Expand All @@ -43,12 +47,21 @@ func InfoForPID(pid uint32) (Info, error) {
if err != nil {
return Info{}, fmt.Errorf("reading %s: %w", cgroupFile, err)
}
// We look for the docker cgroup entry first, as it's the most common
for _, cgroupEntry := range bytes.Split(cgroupBytes, []byte{'\n'}) {
submatches := dockerCgroup.FindSubmatch(cgroupEntry)
if len(submatches) < 2 {
continue
}
return Info{PIDNamespace: ns, ContainerID: string(submatches[1])}, nil
}
// If we didn't find a docker entry, we look for a k8s entry
for _, cgroupEntry := range bytes.Split(cgroupBytes, []byte{'\n'}) {
submatches := k8sCgroup.FindSubmatch(cgroupEntry)
if len(submatches) < 2 {
continue
}
return Info{PIDNamespace: ns, ContainerID: string(submatches[1])}, nil
}
return Info{}, fmt.Errorf("%s: couldn't find any docker entry for process with PID %d", cgroupFile, pid)
}
8 changes: 8 additions & 0 deletions pkg/internal/helpers/container/container_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,14 @@ var fixturesWithContainer = map[uint32]string{
0::/system.slice/containerd.service`,
789: `0::/../cri-containerd-40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9.scope`,
999: `0::/system.slice/docker-40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9.scope/kubepods/burstable/podc55ba69a-e39f-44af-925d-c4794fd57878/264c1e319d1f6080a48a9fabcf9ac8fd9afd9a5930cf35e8d0eeb03b258c3152`,
// GKE cgroup entry
589: `0::/kubepods/burstable/pod4a163a05-439d-484b-8e53-2968bc15824f/40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9`,
// GKE-containerd cgroup entry
689: `0::/kubepods/burstable/podb53dfa9e2dc9b890f7fadb2770857b03/40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9`,
// EKS cgroup entry
788: `0::/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-poddde1244b_5bb5_4297_b544_85f3bc0d80bf.slice/cri-containerd-40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9.scope`,
// Containerd cgroup entry
889: `0::/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod7260904bbd08e72e4dff95d9fccd2ee8.slice/cri-containerd-40c03570b6f4c30bc8d69923d37ee698f5cfcced92c7b7df1c47f6f7887378a9.scope`,
}

var fixturesWithoutContainer = map[uint32]string{
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