buildkit/cmd/buildkitd/main_oci_worker.go

// +build linux,!no_oci_worker

package main

import (
	"os/exec"
	"strconv"

	ctdsnapshot "github.com/containerd/containerd/snapshots"
	"github.com/containerd/containerd/snapshots/native"
	"github.com/containerd/containerd/snapshots/overlay"
	"github.com/moby/buildkit/cmd/buildkitd/config"
	"github.com/moby/buildkit/worker"
	"github.com/moby/buildkit/worker/base"
	"github.com/moby/buildkit/worker/runc"
	"github.com/opencontainers/runc/libcontainer/system"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"github.com/urfave/cli"
)

func init() {
	defaultConf, _ := defaultConf()

	enabledValue := func(b *bool) string {
		if b == nil {
			return "auto"
		}
		return strconv.FormatBool(*b)
	}

	if defaultConf.Workers.OCI.Snapshotter == "" {
		defaultConf.Workers.OCI.Snapshotter = "auto"
	}

	flags := []cli.Flag{
		cli.StringFlag{
			Name:  "oci-worker",
			Usage: "enable oci workers (true/false/auto)",
			Value: enabledValue(defaultConf.Workers.OCI.Enabled),
		},
		cli.StringSliceFlag{
			Name:  "oci-worker-labels",
			Usage: "user-specific annotation labels (com.example.foo=bar)",
		},
		cli.StringFlag{
			Name:  "oci-worker-snapshotter",
			Usage: "name of snapshotter (overlayfs or native)",
			Value: defaultConf.Workers.OCI.Snapshotter,
		},
		cli.StringSliceFlag{
			Name:  "oci-worker-platform",
			Usage: "override supported platforms for worker",
		},
	}
	n := "oci-worker-rootless"
	u := "enable rootless mode"
	if system.RunningInUserNS() {
		flags = append(flags, cli.BoolTFlag{
			Name:  n,
			Usage: u,
		})
	} else {
		flags = append(flags, cli.BoolFlag{
			Name:  n,
			Usage: u,
		})
	}
	registerWorkerInitializer(
		workerInitializer{
			fn:       ociWorkerInitializer,
			priority: 0,
		},
		flags...,
	)
	// TODO: allow multiple oci runtimes
}

func applyOCIFlags(c *cli.Context, cfg *config.Config) error {
	if cfg.Workers.OCI.Snapshotter == "" {
		cfg.Workers.OCI.Snapshotter = "auto"
	}

	if c.GlobalIsSet("oci-worker") {
		boolOrAuto, err := parseBoolOrAuto(c.GlobalString("oci-worker"))
		if err != nil {
			return err
		}
		cfg.Workers.OCI.Enabled = boolOrAuto
	}

	labels, err := attrMap(c.GlobalStringSlice("oci-worker-labels"))
	if err != nil {
		return err
	}
	if cfg.Workers.OCI.Labels == nil {
		cfg.Workers.OCI.Labels = make(map[string]string)
	}
	for k, v := range labels {
		cfg.Workers.OCI.Labels[k] = v
	}
	if c.GlobalIsSet("oci-worker-snapshotter") {
		cfg.Workers.OCI.Snapshotter = c.GlobalString("oci-worker-snapshotter")
	}

	if c.GlobalIsSet("rootless") || c.GlobalBool("rootless") {
		cfg.Workers.OCI.Rootless = c.GlobalBool("rootless")
	}
	if c.GlobalIsSet("oci-worker-rootless") {
		cfg.Workers.OCI.Rootless = c.GlobalBool("oci-worker-rootless")
	}

	if platforms := c.GlobalStringSlice("oci-worker-platform"); len(platforms) != 0 {
		cfg.Workers.OCI.Platforms = platforms
	}

	return nil
}

func ociWorkerInitializer(c *cli.Context, common workerInitializerOpt) ([]worker.Worker, error) {
	if err := applyOCIFlags(c, common.config); err != nil {
		return nil, err
	}

	cfg := common.config.Workers.OCI

	if (cfg.Enabled == nil && !validOCIBinary()) || (cfg.Enabled != nil && !*cfg.Enabled) {
		return nil, nil
	}

	snFactory, err := snapshotterFactory(common.config.Root, cfg.Snapshotter)
	if err != nil {
		return nil, err
	}

	if cfg.Rootless {
		logrus.Debugf("running in rootless mode")
	}
	opt, err := runc.NewWorkerOpt(common.config.Root, snFactory, cfg.Rootless, cfg.Labels)
	if err != nil {
		return nil, err
	}
	opt.SessionManager = common.sessionManager
	opt.GCPolicy = getGCPolicy(cfg.GCPolicy, common.config.Root)
	opt.ResolveOptionsFunc = resolverFunc(common.config)

	if platformsStr := cfg.Platforms; len(platformsStr) != 0 {
		platforms, err := parsePlatforms(platformsStr)
		if err != nil {
			return nil, errors.Wrap(err, "invalid platforms")
		}
		opt.Platforms = platforms
	}
	w, err := base.NewWorker(opt)
	if err != nil {
		return nil, err
	}
	return []worker.Worker{w}, nil
}

func snapshotterFactory(commonRoot, name string) (runc.SnapshotterFactory, error) {
	if name == "auto" {
		if err := overlay.Supported(commonRoot); err == nil {
			logrus.Debug("auto snapshotter: using overlayfs")
			name = "overlayfs"
		} else {
			logrus.Debugf("auto snapshotter: using native, because overlayfs is not available for %s: %v", commonRoot, err)
			name = "native"
		}
	}
	snFactory := runc.SnapshotterFactory{
		Name: name,
	}
	switch name {
	case "native":
		snFactory.New = native.NewSnapshotter
	case "overlayfs": // not "overlay", for consistency with containerd snapshotter plugin ID.
		snFactory.New = func(root string) (ctdsnapshot.Snapshotter, error) {
			return overlay.NewSnapshotter(root)
		}
	default:
		return snFactory, errors.Errorf("unknown snapshotter name: %q", name)
	}
	return snFactory, nil
}

func validOCIBinary() bool {
	_, err := exec.LookPath("runc")
	if err != nil {
		logrus.Warnf("skipping oci worker, as runc does not exist")
		return false
	}
	return true
}