platformtest: dedicated pool per test, Makefile target, maintainer notice

fixes #216
fixes #211

platformtest/platformtest_zpool.go

@@ -0,0 +1,92 @@
+package platformtest
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+	"github.com/zrepl/zrepl/zfs"
+)
+
+type Zpool struct {
+	args ZpoolCreateArgs
+}
+
+type ZpoolCreateArgs struct {
+	PoolName   string
+	ImagePath  string
+	ImageSize  int64
+	Mountpoint string
+}
+
+func (a ZpoolCreateArgs) Validate() error {
+	if !filepath.IsAbs(a.ImagePath) {
+		return errors.Errorf("ImagePath must be absolute, got %q", a.ImagePath)
+	}
+	const minImageSize = 1024
+	if a.ImageSize < minImageSize {
+		return errors.Errorf("ImageSize must be > %v, got %v", minImageSize, a.ImageSize)
+	}
+	if a.Mountpoint != "none" {
+		return errors.Errorf("Mountpoint must be \"none\"")
+	}
+	if a.PoolName == "" {
+		return errors.Errorf("PoolName must not be emtpy")
+	}
+	return nil
+}
+
+func CreateOrReplaceZpool(ctx context.Context, e Execer, args ZpoolCreateArgs) (*Zpool, error) {
+	if err := args.Validate(); err != nil {
+		return nil, errors.Wrap(err, "zpool create args validation error")
+	}
+
+	// export pool if it already exists (idempotence)
+	if _, err := zfs.ZFSGetRawAnySource(args.PoolName, []string{"name"}); err != nil {
+		if _, ok := err.(*zfs.DatasetDoesNotExist); ok {
+			// we'll create it shortly
+		} else {
+			return nil, errors.Wrapf(err, "cannot determine whether test pool %q exists", args.PoolName)
+		}
+	} else {
+		// exists, export it, OpenFile will destroy it
+		if err := e.RunExpectSuccessNoOutput(ctx, "zpool", "export", args.PoolName); err != nil {
+			return nil, errors.Wrapf(err, "cannot destroy test pool %q", args.PoolName)
+		}
+	}
+
+	// idempotently (re)create the pool image
+	image, err := os.OpenFile(args.ImagePath, os.O_CREATE|os.O_RDWR, 0600)
+	if err != nil {
+		return nil, errors.Wrap(err, "create image file")
+	}
+	defer image.Close()
+	if err := image.Truncate(args.ImageSize); err != nil {
+		return nil, errors.Wrap(err, "create image: truncate")
+	}
+	image.Close()
+
+	// create the pool
+	err = e.RunExpectSuccessNoOutput(ctx, "zpool", "create", "-O", "mountpoint=none", args.PoolName, args.ImagePath)
+	if err != nil {
+		return nil, errors.Wrap(err, "zpool create")
+	}
+
+	return &Zpool{args}, nil
+}
+
+func (p *Zpool) Name() string { return p.args.PoolName }
+
+func (p *Zpool) Destroy(ctx context.Context, e Execer) error {
+
+	if err := e.RunExpectSuccessNoOutput(ctx, "zpool", "export", p.args.PoolName); err != nil {
+		return errors.Wrapf(err, "export pool %q", p.args.PoolName)
+	}
+
+	if err := os.Remove(p.args.ImagePath); err != nil {
+		return errors.Wrapf(err, "remove pool image")
+	}
+
+	return nil
+}