Add OS to docker info

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)

parsers/operatingsystem/operatingsystem.go

@@ -0,0 +1,40 @@
+package operatingsystem
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+)
+
+var (
+	// file to use to detect if the daemon is running in a container
+	proc1Cgroup = "/proc/1/cgroup"
+
+	// file to check to determine Operating System
+	etcOsRelease = "/etc/os-release"
+)
+
+func GetOperatingSystem() (string, error) {
+	b, err := ioutil.ReadFile(etcOsRelease)
+	if err != nil {
+		return "", err
+	}
+	if i := bytes.Index(b, []byte("PRETTY_NAME")); i >= 0 {
+		b = b[i+13:]
+		return string(b[:bytes.IndexByte(b, '"')]), nil
+	}
+	return "", errors.New("PRETTY_NAME not found")
+}
+
+func IsContainerized() (bool, error) {
+	b, err := ioutil.ReadFile(proc1Cgroup)
+	if err != nil {
+		return false, err
+	}
+	for _, line := range bytes.Split(b, []byte{'\n'}) {
+		if len(line) > 0 && !bytes.HasSuffix(line, []byte{'/'}) {
+			return true, nil
+		}
+	}
+	return false, nil
+}

parsers/operatingsystem/operatingsystem_test.go

@@ -0,0 +1,123 @@
+package operatingsystem
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGetOperatingSystem(t *testing.T) {
+	var (
+		backup       = etcOsRelease
+		ubuntuTrusty = []byte(`NAME="Ubuntu"
+VERSION="14.04, Trusty Tahr"
+ID=ubuntu
+ID_LIKE=debian
+PRETTY_NAME="Ubuntu 14.04 LTS"
+VERSION_ID="14.04"
+HOME_URL="http://www.ubuntu.com/"
+SUPPORT_URL="http://help.ubuntu.com/"
+BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"`)
+		gentoo = []byte(`NAME=Gentoo
+ID=gentoo
+PRETTY_NAME="Gentoo/Linux"
+ANSI_COLOR="1;32"
+HOME_URL="http://www.gentoo.org/"
+SUPPORT_URL="http://www.gentoo.org/main/en/support.xml"
+BUG_REPORT_URL="https://bugs.gentoo.org/"
+`)
+		noPrettyName = []byte(`NAME="Ubuntu"
+VERSION="14.04, Trusty Tahr"
+ID=ubuntu
+ID_LIKE=debian
+VERSION_ID="14.04"
+HOME_URL="http://www.ubuntu.com/"
+SUPPORT_URL="http://help.ubuntu.com/"
+BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"`)
+	)
+
+	dir := os.TempDir()
+	defer func() {
+		etcOsRelease = backup
+		os.RemoveAll(dir)
+	}()
+
+	etcOsRelease = filepath.Join(dir, "etcOsRelease")
+	for expect, osRelease := range map[string][]byte{
+		"Ubuntu 14.04 LTS": ubuntuTrusty,
+		"Gentoo/Linux":     gentoo,
+		"":                 noPrettyName,
+	} {
+		if err := ioutil.WriteFile(etcOsRelease, osRelease, 0600); err != nil {
+			t.Fatalf("failed to write to %s: %v", etcOsRelease, err)
+		}
+		s, err := GetOperatingSystem()
+		if s != expect {
+			if expect == "" {
+				t.Fatalf("Expected error 'PRETTY_NAME not found', but got %v", err)
+			} else {
+				t.Fatalf("Expected '%s', but got '%s'. Err=%v", expect, s, err)
+			}
+		}
+	}
+}
+
+func TestIsContainerized(t *testing.T) {
+	var (
+		backup                      = proc1Cgroup
+		nonContainerizedProc1Cgroup = []byte(`14:name=systemd:/
+13:hugetlb:/
+12:net_prio:/
+11:perf_event:/
+10:bfqio:/
+9:blkio:/
+8:net_cls:/
+7:freezer:/
+6:devices:/
+5:memory:/
+4:cpuacct:/
+3:cpu:/
+2:cpuset:/
+`)
+		containerizedProc1Cgroup = []byte(`9:perf_event:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+8:blkio:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+7:net_cls:/
+6:freezer:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+5:devices:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+4:memory:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+3:cpuacct:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+2:cpu:/docker/3cef1b53c50b0fa357d994f8a1a8cd783c76bbf4f5dd08b226e38a8bd331338d
+1:cpuset:/`)
+	)
+
+	dir := os.TempDir()
+	defer func() {
+		proc1Cgroup = backup
+		os.RemoveAll(dir)
+	}()
+
+	proc1Cgroup = filepath.Join(dir, "proc1Cgroup")
+
+	if err := ioutil.WriteFile(proc1Cgroup, nonContainerizedProc1Cgroup, 0600); err != nil {
+		t.Fatalf("failed to write to %s: %v", proc1Cgroup, err)
+	}
+	inContainer, err := IsContainerized()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if inContainer {
+		t.Fatal("Wrongly assuming containerized")
+	}
+
+	if err := ioutil.WriteFile(proc1Cgroup, containerizedProc1Cgroup, 0600); err != nil {
+		t.Fatalf("failed to write to %s: %v", proc1Cgroup, err)
+	}
+	inContainer, err = IsContainerized()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !inContainer {
+		t.Fatal("Wrongly assuming non-containerized")
+	}
+}