GetCurrentContainerID from /proc/self/mountinfo nginx-proxy#335 + nginx-proxy#336

Author: bugficks

context.go

@@ -6,7 +6,7 @@ import (
 	"regexp"
 	"sync"
 
-	"github.com/fsouza/go-dockerclient"
+	docker "github.com/fsouza/go-dockerclient"
 )
 
 var (
@@ -161,24 +161,27 @@ type Docker struct {
 }
 
 func GetCurrentContainerID() string {
-	file, err := os.Open("/proc/self/cgroup")
+	filepaths := []string{"/proc/self/cgroup", "/proc/self/mountinfo"}
 
-	if err != nil {
-		return ""
-	}
+	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
+		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
+				}
 			}
 		}
 	}
@@ -187,12 +190,12 @@ func GetCurrentContainerID() string {
 }
 
 func matchDockerCurrentContainerID(lines string) string {
-	regex := "/docker[/-]([[:alnum:]]{64})(\\.scope)?$"
+	regex := "/docker(/containers)?[/-]([[:alnum:]]{64})(/|$)"
 	re := regexp.MustCompilePOSIX(regex)
 
 	if re.MatchString(lines) {
 		submatches := re.FindStringSubmatch(string(lines))
-		containerID := submatches[1]
+		containerID := submatches[len(submatches)-2]
 
 		return containerID
 	}

context_test.go

@@ -48,5 +48,37 @@ func TestGetCurrentContainerID_DockerCE(t *testing.T) {
 	if got, exp := matchDockerCurrentContainerID(cgroup), "18862cabc2e0d24142cf93c46ccb6e070c2ea7b996c81c0311ec0309abcbcdfb"; got != exp {
 		t.Fatalf("id mismatch: got %v, exp %v", got, exp)
 	}
+}
+
+func TestGetCurrentContainerID_DockerCE_mountinfo(t *testing.T) {
+	mountinfo :=
+		`550 209 0:38 / / rw,relatime master:97 - overlay overlay rw,seclabel,lowerdir=/var/lib/docker/overlay2/l/CMLIRGTLVPWATOT2BBGMMWTKPL:/var/lib/docker/overlay2/l/JBJ54L4BQPWTRHZVLNTFAIKIMU:/var/lib/docker/overlay2/l/GKWSGW3V5DTMUG5OV2QF2NDXZM:/var/lib/docker/overlay2/l/KKB7IBA5SXQ6GOHKPC3X2TVPDL,upperdir=/var/lib/docker/overlay2/d3c3d349e227bba0d9f66787a03a5ba8928e6fb8198e787d4d038425afc89fd0/diff,workdir=/var/lib/docker/overlay2/d3c3d349e227bba0d9f66787a03a5ba8928e6fb8198e787d4d038425afc89fd0/work
+551 550 0:47 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw
+552 550 0:48 / /dev rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+553 552 0:49 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,seclabel,gid=5,mode=620,ptmxmode=666
+554 550 0:50 / /sys ro,nosuid,nodev,noexec,relatime - sysfs sysfs ro,seclabel
+555 554 0:27 / /sys/fs/cgroup ro,nosuid,nodev,noexec,relatime - cgroup2 cgroup rw,seclabel,nsdelegate
+556 552 0:46 / /dev/mqueue rw,nosuid,nodev,noexec,relatime - mqueue mqueue rw,seclabel
+557 552 0:51 / /dev/shm rw,nosuid,nodev,noexec,relatime - tmpfs shm rw,seclabel,size=65536k,inode64
+558 550 253:1 /var/lib/docker/containers/bc4ed21e220deb8e759970f0853854b868f0157d1b45caab844c5641435553a4/resolv.conf /etc/resolv.conf rw,relatime - xfs /dev/mapper/fedora_tpdachsserver-root rw,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota
+559 550 253:1 /var/lib/docker/containers/bc4ed21e220deb8e759970f0853854b868f0157d1b45caab844c5641435553a4/hostname /etc/hostname rw,relatime - xfs /dev/mapper/fedora_tpdachsserver-root rw,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota
+560 550 253:1 /var/lib/docker/containers/bc4ed21e220deb8e759970f0853854b868f0157d1b45caab844c5641435553a4/hosts /etc/hosts rw,relatime - xfs /dev/mapper/fedora_tpdachsserver-root rw,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota
+210 551 0:47 /bus /proc/bus ro,relatime - proc proc rw
+211 551 0:47 /fs /proc/fs ro,relatime - proc proc rw
+212 551 0:47 /irq /proc/irq ro,relatime - proc proc rw
+264 551 0:47 /sys /proc/sys ro,relatime - proc proc rw
+265 551 0:47 /sysrq-trigger /proc/sysrq-trigger ro,relatime - proc proc rw
+523 551 0:58 / /proc/asound ro,relatime - tmpfs tmpfs ro,seclabel,inode64
+524 551 0:59 / /proc/acpi ro,relatime - tmpfs tmpfs ro,seclabel,inode64
+529 551 0:48 /null /proc/kcore rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+530 551 0:48 /null /proc/keys rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+531 551 0:48 /null /proc/latency_stats rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+532 551 0:48 /null /proc/timer_list rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+533 551 0:48 /null /proc/sched_debug rw,nosuid - tmpfs tmpfs rw,seclabel,size=65536k,mode=755,inode64
+534 551 0:60 / /proc/scsi ro,relatime - tmpfs tmpfs ro,seclabel,inode64
+535 554 0:61 / /sys/firmware ro,relatime - tmpfs tmpfs ro,seclabel,inode64`
 
+	if got, exp := matchDockerCurrentContainerID(mountinfo), "bc4ed21e220deb8e759970f0853854b868f0157d1b45caab844c5641435553a4"; got != exp {
+		t.Fatalf("id mismatch: got %v, exp %v", got, exp)
+	}
 }