112 строки
2.8 KiB
Go
112 строки
2.8 KiB
Go
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package main
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import (
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"bufio"
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"context"
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"fmt"
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"io"
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"os/exec"
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"strings"
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)
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// A ContainerPath identifies a container in Kubernetes
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type ContainerPath struct {
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PodNamespace string
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PodName string
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ContainerName string
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}
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// A DockerContainer connects a container's docker ID and its
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// Kubernetes ContainerPath
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type DockerContainer struct {
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kubePath ContainerPath
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dockerId string
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}
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// parseDockerContainerList parses the output of
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// `docker ps --format "{{.ID}} {{.Labels}}"`
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// and returns a list of DockerContainers
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//
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// There will be one Docker container per pod with the special
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// container_name 'POD'. This container holds the cgroups for the pod,
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// but doesn't correspond to any Kubernetes container.
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func parseDockerContainerList(docker_out io.Reader) ([]DockerContainer, error) {
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var result []DockerContainer
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var scanner = bufio.NewScanner(docker_out)
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for scanner.Scan() {
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line := scanner.Text()
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columns := strings.SplitN(line, " ", 2)
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if len(columns) != 2 {
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return nil, fmt.Errorf("Couldn't parse Docker output line %v", line)
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}
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container_id := columns[0]
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labels := strings.Split(columns[1], ",")
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container_path := ContainerPath{}
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for _, label := range labels {
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if strings.Contains(label, "=") {
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parts := strings.SplitN(label, "=", 2)
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if len(parts) != 2 {
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return nil, fmt.Errorf("Couldn't parse container label %v", label)
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}
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key := parts[0]
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value := parts[1]
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switch key {
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case "io.kubernetes.pod.name":
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container_path.PodName = value
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case "io.kubernetes.pod.namespace":
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container_path.PodNamespace = value
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case "io.kubernetes.container.name":
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container_path.ContainerName = value
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}
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}
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}
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result = append(result, DockerContainer{kubePath: container_path,
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dockerId: container_id})
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}
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return result, nil
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}
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// Build a map from host PIDs to ContainerPaths.
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func buildPidMap() (map[int]ContainerPath, error) {
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ctx, _ := context.WithTimeout(context.Background(), subprocessTimeout)
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dockerPsOut, err := exec.CommandContext(ctx, "docker", "ps", "--format", "{{.ID}} {{.Labels}}").Output()
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if err != nil {
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return nil, err
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}
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dockerContainers, err := parseDockerContainerList(strings.NewReader(string(dockerPsOut)))
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if err != nil {
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return nil, err
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}
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pidMap := make(map[int]ContainerPath)
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for _, container := range dockerContainers {
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ctx, _ := context.WithTimeout(context.Background(), subprocessTimeout)
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dockerInspectOut, err := exec.CommandContext(
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ctx, "docker", "inspect", "--format", "{{.State.Pid}}", container.dockerId).Output()
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if err != nil {
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// We expect errors here if a container was
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// deleted between `docker ps` and here.
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continue
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}
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var rootPid int
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_, err = fmt.Fscan(strings.NewReader(string(dockerInspectOut)), &rootPid)
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if err != nil {
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return nil, err
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}
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pidMap[rootPid] = container.kubePath
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}
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return pidMap, nil
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}
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