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Fix GetCurrentContainerID() and corresponding test #345

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Merged
merged 2 commits into from
Apr 12, 2021
Merged

Fix GetCurrentContainerID() and corresponding test #345

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c6f3145
fix(context): fallback method to get current cid
buchdag Apr 9, 2021
e44864e
fix(test): fix GetCurrentContainerID() tests
buchdag Apr 9, 2021
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87 changes: 59 additions & 28 deletions context.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,11 +2,14 @@ package dockergen

import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"regexp"
"sync"
"fmt"
"github.com/fsouza/go-dockerclient"

docker "github.com/fsouza/go-dockerclient"
)

var (
Expand Down Expand Up @@ -158,57 +161,85 @@ type Docker struct {
CurrentContainerID string
}

func GetCurrentContainerID() string {
filepaths := []string{"/proc/self/cgroup", "/proc/self/mountinfo"}
// GetCurrentContainerID attempts to extract the current container ID from the provided file paths.
// If no files paths are provided, it will default to /proc/1/cpuset, /proc/self/cgroup and /proc/self/mountinfo.
// It attempts to match the HOSTNAME first then use the fallback method, and returns with the first valid match.
func GetCurrentContainerID(filepaths ...string) (id string) {
if len(filepaths) == 0 {
filepaths = []string{"/proc/1/cpuset", "/proc/self/cgroup", "/proc/self/mountinfo"}
}

var files []io.Reader

for _, filepath := range filepaths {
file, err := os.Open(filepath)
if err != nil {
continue
}
reader := bufio.NewReader(file)
scanner := bufio.NewScanner(reader)
scanner.Split(bufio.ScanLines)
for scanner.Scan() {
_, lines, err := bufio.ScanLines([]byte(scanner.Text()), true)
if err == nil {
strLines := string(lines)
if id := matchDockerCurrentContainerID(strLines); id != "" {
return id
} else if id := matchECSCurrentContainerID(strLines); id != "" {
return id
}
defer file.Close()
files = append(files, file)
}

reader := io.MultiReader(files...)
var buffer bytes.Buffer
tee := io.TeeReader(reader, &buffer)

// We try to match a 64 character hex string starting with the hostname first
scanner := bufio.NewScanner(tee)
scanner.Split(bufio.ScanLines)
for scanner.Scan() {
_, lines, err := bufio.ScanLines([]byte(scanner.Text()), true)
if err == nil {
strLines := string(lines)
if id = matchContainerIDWithHostname(strLines); len(id) == 64 {
return
}
}
}

return ""
// If we didn't get any ID that matches the hostname, fall back to matching the first 64 character hex string
scanner = bufio.NewScanner(&buffer)
scanner.Split(bufio.ScanLines)
for scanner.Scan() {
_, lines, err := bufio.ScanLines([]byte(scanner.Text()), true)
if err == nil {
strLines := string(lines)
if id = matchContainerID(strLines); len(id) == 64 {
return
}
}
}

return
}

func matchDockerCurrentContainerID(lines string) string {
func matchContainerIDWithHostname(lines string) string {
hostname := os.Getenv("HOSTNAME")
regex := fmt.Sprintf("(%s[[:alnum:]]{52})", hostname)
re := regexp.MustCompilePOSIX(regex)
re := regexp.MustCompilePOSIX("^[[:alnum:]]{12}$")

if re.MatchString(lines) {
submatches := re.FindStringSubmatch(string(lines))
containerID := submatches[1]
if re.MatchString(hostname) {
regex := fmt.Sprintf("(%s[[:alnum:]]{52})", hostname)
re := regexp.MustCompilePOSIX(regex)

return containerID
if re.MatchString(lines) {
submatches := re.FindStringSubmatch(string(lines))
containerID := submatches[1]

return containerID
}
}
return ""
}

func matchECSCurrentContainerID(lines string) string {
regex := "/ecs\\/[^\\/]+\\/(.+)$"
func matchContainerID(lines string) string {
regex := "([[:alnum:]]{64})"
re := regexp.MustCompilePOSIX(regex)

if re.MatchString(string(lines)) {
if re.MatchString(lines) {
submatches := re.FindStringSubmatch(string(lines))
containerID := submatches[1]

return containerID
}

return ""
}
120 changes: 83 additions & 37 deletions context_test.go
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Original file line number Diff line number Diff line change
@@ -1,52 +1,98 @@
package dockergen

import (
"fmt"
"io/ioutil"
"log"
"os"
"testing"
)

func TestGetCurrentContainerID(t *testing.T) {
currentContainerID := GetCurrentContainerID()
hostname := os.Getenv("HOSTNAME")
defer os.Setenv("HOSTNAME", hostname)

if len(currentContainerID) != 0 && len(currentContainerID) != 64 {
t.Fail()
ids := []string{
"0fa939e22e6938e7517f663de83e79a5087a18b1b997a36e0c933a917cddb295",
"e881f8c51a72db7da515e9d5cab8ed105b869579eb9923fdcf4ee80933160802",
"eede6bd9e72f5d783a4bfb845bd71f310e974cb26987328a5d15704e23a8d6cb",
}
}

func TestGetCurrentContainerID_ECS(t *testing.T) {
cgroup :=
`9:perf_event:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
8:memory:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
7:hugetlb:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
6:freezer:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
5:devices:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
4:cpuset:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
3:cpuacct:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
2:cpu:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f
1:blkio:/ecs/628967a1-46b4-4a8a-84ff-605128f4679e/3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f`

if got, exp := matchECSCurrentContainerID(cgroup), "3c94e08259a6235781bb65f3dec91150c92e9d414ecc410d6245687392d3900f"; got != exp {
t.Fatalf("id mismatch: got %v, exp %v", got, exp)
contents := map[string]string{
"cpuset": fmt.Sprintf("/docker/%v", ids[0]),
"cgroup": fmt.Sprintf(`13:name=systemd:/docker-ce/docker/%[1]v
12:pids:/docker-ce/docker/%[1]v
11:hugetlb:/docker-ce/docker/%[1]v
10:net_prio:/docker-ce/docker/%[1]v
9:perf_event:/docker-ce/docker/%[1]v
8:net_cls:/docker-ce/docker/%[1]v
7:freezer:/docker-ce/docker/%[1]v
6:devices:/docker-ce/docker/%[1]v
5:memory:/docker-ce/docker/%[1]v
4:blkio:/docker-ce/docker/%[1]v
3:cpuacct:/docker-ce/docker/%[1]v
2:cpu:/docker-ce/docker/%[1]v
1:cpuset:/docker-ce/docker/%[1]v`, ids[1]),
"mountinfo": fmt.Sprintf(`705 661 0:96 / / rw,relatime master:192 - overlay overlay rw,lowerdir=/var/lib/docker/overlay2/l/CVAK3VWZFQCUGTLHRJHPEKJ4UL:/var/lib/docker/overlay2/l/XMJZ73SKVWVECU7TJCOY62F3H2:/var/lib/docker/overlay2/l/AVNBXO52GHDY3MZU3R4RCSNMCE:/var/lib/docker/overlay2/l/L4IJZ33E6NAMXJ5W3SKJSVX5TS:/var/lib/docker/overlay2/l/JXAUAD5TDJCXA34FGS6NYGUZKT:/var/lib/docker/overlay2/l/TBQDSAFKBSTFMUS3QCFWN5NRLB:/var/lib/docker/overlay2/l/MXIUXRGB7MU4Y4NUNZE2VXTXIN:/var/lib/docker/overlay2/l/HN7E4YWJG7TMG7BXLZTGICTBOA:/var/lib/docker/overlay2/l/65XQPC72Z5VRY4THGASZIQXS57:/var/lib/docker/overlay2/l/BVQKC7LU6D7MOSLBDKFHY7YSO3:/var/lib/docker/overlay2/l/R4GGX3SFPMLXTNM3WKMVOKDTOY:/var/lib/docker/overlay2/l/VHGYTU73JLTRCGX45ZF2VGW4FK,upperdir=/var/lib/docker/overlay2/e1fab975d5ffd51474b11a964c82c3bfda1c0e82aec6845a1f12c8150bf61419/diff,workdir=/var/lib/docker/overlay2/e1fab975d5ffd51474b11a964c82c3bfda1c0e82aec6845a1f12c8150bf61419/work,index=off
706 705 0:105 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw
707 705 0:106 / /dev rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
708 707 0:107 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=666
709 705 0:108 / /sys ro,nosuid,nodev,noexec,relatime - sysfs sysfs ro
710 709 0:25 / /sys/fs/cgroup ro,nosuid,nodev,noexec,relatime - cgroup2 cgroup rw,nsdelegate,memory_recursiveprot
711 707 0:104 / /dev/mqueue rw,nosuid,nodev,noexec,relatime - mqueue mqueue rw
712 707 0:109 / /dev/shm rw,nosuid,nodev,noexec,relatime - tmpfs shm rw,size=65536k,inode64
713 705 8:3 /var/lib/docker/containers/%[1]v/resolv.conf /etc/resolv.conf rw,relatime - ext4 /dev/sda3 rw
714 705 8:3 /var/lib/docker/containers/%[1]v/hostname /etc/hostname rw,relatime - ext4 /dev/sda3 rw
715 705 8:3 /var/lib/docker/containers/%[1]v/hosts /etc/hosts rw,relatime - ext4 /dev/sda3 rw
716 705 8:3 /var/lib/docker/volumes/ca8074e1a2eb12edc86c59c5108bb48c31bb7ace4b90beb0da8137a9baa45812/_data /etc/nginx/certs rw,relatime master:1 - ext4 /dev/sda3 rw
717 705 8:3 /var/lib/docker/volumes/2cf8a52c907469a56f6e2cc7d1959d74a4dd04131e7edcd53eaf909db28f770f/_data /etc/nginx/dhparam rw,relatime master:1 - ext4 /dev/sda3 rw
662 707 0:107 /0 /dev/console rw,nosuid,noexec,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=666
663 706 0:105 /bus /proc/bus ro,relatime - proc proc rw
664 706 0:105 /fs /proc/fs ro,relatime - proc proc rw
665 706 0:105 /irq /proc/irq ro,relatime - proc proc rw
666 706 0:105 /sys /proc/sys ro,relatime - proc proc rw
667 706 0:105 /sysrq-trigger /proc/sysrq-trigger ro,relatime - proc proc rw
668 706 0:110 / /proc/acpi ro,relatime - tmpfs tmpfs ro,inode64
669 706 0:106 /null /proc/kcore rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
670 706 0:106 /null /proc/keys rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
671 706 0:106 /null /proc/latency_stats rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
672 706 0:106 /null /proc/timer_list rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
673 706 0:106 /null /proc/sched_debug rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,inode64
674 706 0:111 / /proc/scsi ro,relatime - tmpfs tmpfs ro,inode64
675 709 0:112 / /sys/firmware ro,relatime - tmpfs tmpfs ro,inode64`, ids[2]),
}

keys := []string{
"cpuset",
"cgroup",
"mountinfo",
}
}

func TestGetCurrentContainerID_DockerCE(t *testing.T) {
cgroup :=
`13:name=systemd:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
12:pids:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
11:hugetlb:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
10:net_prio:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
9:perf_event:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
8:net_cls:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
7:freezer:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
6:devices:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
5:memory:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
4:blkio:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
3:cpuacct:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
2:cpu:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb
1:cpuset:/docker-ce/docker/18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb`

if got, exp := matchDockerCurrentContainerID(cgroup), "18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb"; got != exp {
t.Fatalf("id mismatch: got %v, exp %v", got, exp)
var filepaths []string
// Create temporary files with test content
for _, key := range keys {
file, err := ioutil.TempFile("", key)
if err != nil {
log.Fatal(err)
}
defer os.Remove(file.Name())
if _, err = file.WriteString(contents[key]); err != nil {
log.Fatal(err)
}
filepaths = append(filepaths, file.Name())
}

// Each time the HOSTNAME is set to a short form ID, GetCurrentContainerID() should match and return the corresponding full ID
for _, id := range ids {
os.Setenv("HOSTNAME", id[0:12])
if got, exp := GetCurrentContainerID(filepaths...), id; got != exp {
t.Fatalf("id mismatch with HOSTNAME %v: got %v, exp %v", id[0:12], got, exp)
}
}

// If the Hostname isn't a short form ID, we should match the first valid ID (64 character hex string) instead
os.Setenv("HOSTNAME", "customhostname")
if got, exp := GetCurrentContainerID(filepaths...), ids[0]; got != exp {
t.Fatalf("id mismatch with custom HOSTNAME: got %v, exp %v", got, exp)
}
}