buildkit/worker/runc/runc.go

package runc

import (
	"context"
	"os"
	"path/filepath"

	"github.com/boltdb/bolt"
	"github.com/containerd/containerd/content/local"
	"github.com/containerd/containerd/diff/walking"
	ctdmetadata "github.com/containerd/containerd/metadata"
	ctdsnapshot "github.com/containerd/containerd/snapshots"
	"github.com/containerd/containerd/snapshots/overlay"
	"github.com/moby/buildkit/cache/metadata"
	"github.com/moby/buildkit/executor/runcexecutor"
	"github.com/moby/buildkit/snapshot/nogc"
	"github.com/moby/buildkit/worker/base"
)

// NewWorkerOpt creates a WorkerOpt.
// But it does not set the following fields:
//  - SessionManager
func NewWorkerOpt(root string, labels map[string]string) (base.WorkerOpt, error) {
	var opt base.WorkerOpt
	name := "runc-overlayfs"
	root = filepath.Join(root, name)
	if err := os.MkdirAll(root, 0700); err != nil {
		return opt, err
	}
	md, err := metadata.NewStore(filepath.Join(root, "metadata.db"))
	if err != nil {
		return opt, err
	}
	exe, err := runcexecutor.New(filepath.Join(root, "executor"))
	if err != nil {
		return opt, err
	}
	s, err := overlay.NewSnapshotter(filepath.Join(root, "snapshots"))
	if err != nil {
		return opt, err
	}

	c, err := local.NewStore(filepath.Join(root, "content"))
	if err != nil {
		return opt, err
	}

	db, err := bolt.Open(filepath.Join(root, "containerdmeta.db"), 0644, nil)
	if err != nil {
		return opt, err
	}

	mdb := ctdmetadata.NewDB(db, c, map[string]ctdsnapshot.Snapshotter{
		"overlayfs": s,
	})
	if err := mdb.Init(context.TODO()); err != nil {
		return opt, err
	}

	gc := func(ctx context.Context) error {
		_, err := mdb.GarbageCollect(ctx)
		return err
	}

	c = nogc.NewContentStore(mdb.ContentStore(), "buildkit", gc)
	df, err := walking.NewWalkingDiff(c)
	if err != nil {
		return opt, err
	}

	id, err := base.ID(root)
	if err != nil {
		return opt, err
	}
	xlabels := base.Labels("oci", "overlayfs")
	for k, v := range labels {
		xlabels[k] = v
	}
	opt = base.WorkerOpt{
		ID:              id,
		Labels:          xlabels,
		MetadataStore:   md,
		Executor:        exe,
		BaseSnapshotter: nogc.NewSnapshotter(mdb.Snapshotter("overlayfs"), "buildkit", gc),
		ContentStore:    c,
		Applier:         df,
		Differ:          df,
		ImageStore:      nil, // explicitly
	}
	return opt, nil
}