From eb8f941ba60b7b74a9ceca40f2a0f07f125cb89b Mon Sep 17 00:00:00 2001
From: Rohit Jnagal <jnagal@google.com>
Date: Thu, 4 Jun 2015 08:24:50 +0000
Subject: [PATCH] Make process listing work when cadvisor is running in docker.

Use /rootfs/proc to build the process listing.
---
 manager/container.go | 40 +++++++++++++++++++++-------------------
 manager/manager.go   | 12 +++++++++++-
 2 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/manager/container.go b/manager/container.go
index 70adbf17..e19e8b5c 100644
--- a/manager/container.go
+++ b/manager/container.go
@@ -132,26 +132,22 @@ func (c *containerData) getCgroupPath(cgroups string) (string, error) {
 	return string(matches[1]), nil
 }
 
-func (c *containerData) GetProcessList() ([]v2.ProcessInfo, error) {
+func (c *containerData) GetProcessList(cadvisorContainer string, inHostNamespace bool) ([]v2.ProcessInfo, error) {
 	// report all processes for root.
 	isRoot := c.info.Name == "/"
-	pidMap := map[int]bool{}
-	if !isRoot {
-		pids, err := c.handler.ListProcesses(container.ListSelf)
-		if err != nil {
-			return nil, err
-		}
-		for _, pid := range pids {
-			pidMap[pid] = true
-		}
-	}
 	// TODO(rjnagal): Take format as an option?
 	format := "user,pid,ppid,stime,pcpu,pmem,rss,vsz,stat,time,comm,cgroup"
-	args := []string{"-e", "-o", format}
+	args := []string{}
+	command := "ps"
+	if !inHostNamespace {
+		command = "/usr/sbin/chroot"
+		args = append(args, "/rootfs", "ps")
+	}
+	args = append(args, "-e", "-o", format)
 	expectedFields := 12
-	out, err := exec.Command("ps", args...).Output()
+	out, err := exec.Command(command, args...).Output()
 	if err != nil {
-		return nil, fmt.Errorf("failed to execute ps command: %v", err)
+		return nil, fmt.Errorf("failed to execute %q command: %v", command, err)
 	}
 	processes := []v2.ProcessInfo{}
 	lines := strings.Split(string(out), "\n")
@@ -187,15 +183,21 @@ func (c *containerData) GetProcessList() ([]v2.ProcessInfo, error) {
 		if err != nil {
 			return nil, fmt.Errorf("invalid virtual size %q: %v", fields[7], err)
 		}
+		cgroup, err := c.getCgroupPath(fields[11])
+		if err != nil {
+			return nil, fmt.Errorf("could not parse cgroup path from %q: %v", fields[10], err)
+		}
+		// Remove the ps command we just ran from cadvisor container.
+		// Not necessary, but makes the cadvisor page look cleaner.
+		if !inHostNamespace && cadvisorContainer == cgroup && fields[10] == "ps" {
+			continue
+		}
 		var cgroupPath string
 		if isRoot {
-			cgroupPath, err = c.getCgroupPath(fields[11])
-			if err != nil {
-				return nil, fmt.Errorf("could not parse cgroup path from %q: %v", fields[10], err)
-			}
+			cgroupPath = cgroup
 		}
 
-		if isRoot || pidMap[pid] == true {
+		if isRoot || c.info.Name == cgroup {
 			processes = append(processes, v2.ProcessInfo{
 				User:          fields[0],
 				Pid:           pid,
diff --git a/manager/manager.go b/manager/manager.go
index 2c055d03..7f2688d9 100644
--- a/manager/manager.go
+++ b/manager/manager.go
@@ -18,6 +18,7 @@ package manager
 import (
 	"flag"
 	"fmt"
+	"os"
 	"path"
 	"regexp"
 	"strconv"
@@ -130,12 +131,20 @@ func New(memoryCache *memory.InMemoryCache, sysfs sysfs.SysFs) (Manager, error)
 	if err != nil {
 		return nil, err
 	}
+
+	// If cAdvisor was started with host's rootfs mounted, assume that its running
+	// in its own namespaces.
+	inHostNamespace := false
+	if _, err := os.Stat("/rootfs/proc"); os.IsNotExist(err) {
+		inHostNamespace = true
+	}
 	newManager := &manager{
 		containers:        make(map[namespacedContainerName]*containerData),
 		quitChannels:      make([]chan error, 0, 2),
 		memoryCache:       memoryCache,
 		fsInfo:            fsInfo,
 		cadvisorContainer: selfContainer,
+		inHostNamespace:   inHostNamespace,
 		startupTime:       time.Now(),
 	}
 
@@ -175,6 +184,7 @@ type manager struct {
 	versionInfo            info.VersionInfo
 	quitChannels           []chan error
 	cadvisorContainer      string
+	inHostNamespace        bool
 	dockerContainersRegexp *regexp.Regexp
 	loadReader             cpuload.CpuLoadReader
 	eventHandler           events.EventManager
@@ -671,7 +681,7 @@ func (m *manager) GetProcessList(containerName string, options v2.RequestOptions
 	// TODO(rjnagal): handle count? Only if we can do count by type (eg. top 5 cpu users)
 	ps := []v2.ProcessInfo{}
 	for _, cont := range conts {
-		ps, err = cont.GetProcessList()
+		ps, err = cont.GetProcessList(m.cadvisorContainer, m.inHostNamespace)
 		if err != nil {
 			return nil, err
 		}