Merge pull request #3374 from giuseppe/cgroups

cgroups: add initial support for cgroups v2

1 files changed, 149 insertions, 0 deletions

diff --git a/pkg/cgroups/blkio.go b/pkg/cgroups/blkio.go
new file mode 100644
index 000000000..ca9107d97
--- /dev/null
+++ b/pkg/cgroups/blkio.go
@@ -0,0 +1,149 @@
+package cgroups
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	spec "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+type blkioHandler struct {
+}
+
+func getBlkioHandler() *blkioHandler {
+	return &blkioHandler{}
+}
+
+// Apply set the specified constraints
+func (c *blkioHandler) Apply(ctr *CgroupControl, res *spec.LinuxResources) error {
+	if res.BlockIO == nil {
+		return nil
+	}
+	return fmt.Errorf("blkio apply function not implemented yet")
+}
+
+// Create the cgroup
+func (c *blkioHandler) Create(ctr *CgroupControl) (bool, error) {
+	if ctr.cgroup2 {
+		return false, fmt.Errorf("io create not implemented for cgroup v2")
+	}
+	return ctr.createCgroupDirectory(Blkio)
+}
+
+// Destroy the cgroup
+func (c *blkioHandler) Destroy(ctr *CgroupControl) error {
+	return os.Remove(ctr.getCgroupv1Path(Blkio))
+}
+
+// Stat fills a metrics structure with usage stats for the controller
+func (c *blkioHandler) Stat(ctr *CgroupControl, m *Metrics) error {
+	var ioServiceBytesRecursive []BlkIOEntry
+
+	if ctr.cgroup2 {
+		// more details on the io.stat file format:X https://facebookmicrosites.github.io/cgroup2/docs/io-controller.html
+		values, err := readCgroup2MapFile(ctr, "io.stat")
+		if err != nil {
+			return err
+		}
+		for k, v := range values {
+			d := strings.Split(k, ":")
+			if len(d) != 2 {
+				continue
+			}
+			minor, err := strconv.ParseUint(d[0], 10, 0)
+			if err != nil {
+				return err
+			}
+			major, err := strconv.ParseUint(d[1], 10, 0)
+			if err != nil {
+				return err
+			}
+
+			for _, item := range v {
+				d := strings.Split(item, "=")
+				if len(d) != 2 {
+					continue
+				}
+				op := d[0]
+
+				// Accommodate the cgroup v1 naming
+				switch op {
+				case "rbytes":
+					op = "read"
+				case "wbytes":
+					op = "write"
+				}
+
+				value, err := strconv.ParseUint(d[1], 10, 0)
+				if err != nil {
+					return err
+				}
+
+				entry := BlkIOEntry{
+					Op:    op,
+					Major: major,
+					Minor: minor,
+					Value: value,
+				}
+				ioServiceBytesRecursive = append(ioServiceBytesRecursive, entry)
+			}
+		}
+	} else {
+		BlkioRoot := ctr.getCgroupv1Path(Blkio)
+
+		p := filepath.Join(BlkioRoot, "blkio.throttle.io_service_bytes_recursive")
+		f, err := os.Open(p)
+		if err != nil {
+			if os.IsNotExist(err) {
+				return nil
+			}
+			return errors.Wrapf(err, "open %s", p)
+		}
+		defer f.Close()
+
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			line := scanner.Text()
+			parts := strings.Fields(line)
+			if len(parts) < 3 {
+				continue
+			}
+			d := strings.Split(parts[0], ":")
+			if len(d) != 2 {
+				continue
+			}
+			minor, err := strconv.ParseUint(d[0], 10, 0)
+			if err != nil {
+				return err
+			}
+			major, err := strconv.ParseUint(d[1], 10, 0)
+			if err != nil {
+				return err
+			}
+
+			op := parts[1]
+
+			value, err := strconv.ParseUint(parts[2], 10, 0)
+			if err != nil {
+				return err
+			}
+			entry := BlkIOEntry{
+				Op:    op,
+				Major: major,
+				Minor: minor,
+				Value: value,
+			}
+			ioServiceBytesRecursive = append(ioServiceBytesRecursive, entry)
+		}
+		if err := scanner.Err(); err != nil {
+			return errors.Wrapf(err, "parse %s", p)
+		}
+	}
+	m.Blkio = BlkioMetrics{IoServiceBytesRecursive: ioServiceBytesRecursive}
+	return nil
+}