vpython: Add CIPD support.

vpython/cipd/cipd.go

Index: vpython/cipd/cipd.go
diff --git a/vpython/cipd/cipd.go b/vpython/cipd/cipd.go
new file mode 100644
index 0000000000000000000000000000000000000000..b6b6b21f85c377d1d4e13dbffb90b9225ed81881
--- /dev/null
+++ b/vpython/cipd/cipd.go
@@ -0,0 +1,168 @@
+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package cipd
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"github.com/luci/luci-go/vpython/api/env"
+	"github.com/luci/luci-go/vpython/venv"
+
+	"github.com/luci/luci-go/cipd/client/cipd"
+	"github.com/luci/luci-go/cipd/client/cipd/common"
+	"github.com/luci/luci-go/cipd/client/cipd/ensure"
+	"github.com/luci/luci-go/common/errors"
+	"github.com/luci/luci-go/common/logging"
+
+	"golang.org/x/net/context"
+)
+
+// PackageLoader is an implementation of venv.PackageLoader that uses the
+// CIPD service to fetch packages.
+//
+// Packages that use the CIPD loader use the CIPD package name as their Path
+// and a CIPD version/tag/ref as their Version.
+type PackageLoader struct {
+	// Options are additional client options to use when generating CIPD clients.
+	Options cipd.ClientOptions
+}
+
+var _ venv.PackageLoader = (*PackageLoader)(nil)
+
+// Resolve implements venv.PackageLoader.
+//
+// The resulting packages slice will be updated in-place with the resolves

[iannucci, 2017/02/23 01:06:56]

resolved

[dnj, 2017/03/11 16:47:24]

Done.

+// package name and instance ID.
+func (pl *PackageLoader) Resolve(c context.Context, root string, packages []*env.Spec_Package) error {
+	if len(packages) == 0 {
+		return nil
+	}
+
+	var ensureFile bytes.Buffer
+	if err := writeEnsureFile(&ensureFile, packages); err != nil {
+		return errors.Annotate(err).Reason("failed to generate manifest").Err()
+	}
+
+	// Generate a CIPD client. Use the supplied root.
+	opts := pl.Options
+	opts.Root = root
+	client, err := cipd.NewClient(opts)
+	if err != nil {
+		return errors.Annotate(err).Reason("failed to generate CIPD client").Err()
+	}
+
+	// Start a CIPD client batch.
+	client.BeginBatch(c)
+	defer client.EndBatch(c)
+
+	// Parse and resolve the CIPD ensure file.
+	logging.Debugf(c, "Resolving CIPD manifest:\n%s", ensureFile.Bytes())
+	ef, err := ensure.ParseFile(&ensureFile)

[iannucci, 2017/02/23 01:06:56]

could just make an ensure.File directly rather than going through the parser.

[dnj, 2017/03/11 16:47:24]

Oh neat! I don't think this was exported the first time I wrote this.

+	if err != nil {
+		return errors.Annotate(err).Reason("failed to process ensure file").Err()
+	}
+
+	resolved, err := ef.Resolve(func(pkg, vers string) (common.Pin, error) {
+		return client.ResolveVersion(c, pkg, vers)
+	})
+	if err != nil {
+		return errors.Annotate(err).Reason("failed to resolve ensure file").Err()
+	}
+
+	// Write the results to "packages". All of them should have been installed
+	// into the root subdir.
+	for i, pkg := range resolved.PackagesBySubdir[""] {
+		packages[i].Path = pkg.PackageName

[iannucci, 2017/02/23 01:06:56]

why is it packages[i].Path? Shouldn't it be Name or something like that?

[dnj, 2017/03/11 16:47:24]

In the protobuf, "package" is an intentionally generic "Path" / "Version"
combination. The way this is constructed, someone could create a PackageLoader
using a non-CIPD service, in which case "Path" could map to someone's Google
Storage bucket URL, or be a full download URL, and the protobuf fields are
applicable there, too.

I didn't want to need to implement first-class support for each possible method
in the proto (e.g., oneof), as that would make the text form more annoying and
also imply the full set of imagined capabilities are available.

Maybe I'll change to "Name" though; it's just as generic and also fits better.

+		packages[i].Version = pkg.InstanceID
+	}
+	return nil
+}
+
+// Ensure implement venv.PackageLoader.
+//
+// The packages must be valid (PackageIsComplete). If they aren't, Ensure will
+// panic.
+//
+// The CIPD client that is used for the operation is generated from the supplied
+// options, opts.
+func (pl *PackageLoader) Ensure(c context.Context, root string, packages []*env.Spec_Package) error {
+	pins, err := packagesToPins(packages)
+	if err != nil {
+		return errors.Annotate(err).Reason("failed to convert packages to CIPD pins").Err()
+	}
+	pinSlice := common.PinSliceBySubdir{
+		"": pins,
+	}
+
+	// Generate a CIPD client. Use the supplied root.
+	opts := pl.Options
+	opts.Root = root
+	client, err := cipd.NewClient(opts)
+	if err != nil {
+		return errors.Annotate(err).Reason("failed to generate CIPD client").Err()
+	}
+
+	// Start a CIPD client batch.
+	client.BeginBatch(c)
+	defer client.EndBatch(c)
+
+	actionMap, err := client.EnsurePackages(c, pinSlice, false)
+	if err != nil {
+		return errors.Annotate(err).Reason("failed to install CIPD packages").Err()
+	}
+	if len(actionMap) > 0 {
+		errorCount := 0
+		for root, action := range actionMap {
+			errorCount += len(action.Errors)
+			for _, err := range action.Errors {
+				logging.Errorf(c, "CIPD root %q action %q for pin %q encountered error: %s", root, err.Action, err.Pin, err)
+			}
+		}
+		if errorCount > 0 {
+			return errors.Reason("CIPD package installation encountered %(count)d error(s)").
+				D("count", errorCount).
+				Err()
+		}
+	}
+	return nil
+}
+
+func writeEnsureFile(out io.Writer, packages []*env.Spec_Package) error {
+	for _, pkg := range packages {
+		if err := validatePackage(pkg); err != nil {
+			panic(errors.Annotate(err).Reason("invalid CIPD package").Err())
+		}
+		if _, err := fmt.Fprintf(out, "%s %s\n", pkg.Path, pkg.Version); err != nil {
+			return errors.Annotate(err).Reason("failed to write manifest line").Err()
+		}
+	}
+	return nil
+}
+
+// validatePackage returns an error if the package does not have all of the
+// required fields to describe a CIPD package.
+func validatePackage(pkg *env.Spec_Package) error {

[iannucci, 2017/02/23 01:06:56]

tbh... Ensure will do this better anyway:
https://github.com/luci/luci-go/blob/master/cipd/client/cipd/client.go#L1255

[dnj, 2017/03/11 16:47:24]

Done.

+	switch {
+	case pkg.Path == "":
+		return errors.New("package must have a path")
+	case pkg.Version == "":
+		return errors.New("package must have a version")
+	default:
+		return nil
+	}
+}
+
+func packagesToPins(packages []*env.Spec_Package) ([]common.Pin, error) {
+	pins := make([]common.Pin, len(packages))
+	for i, pkg := range packages {
+		pins[i] = common.Pin{
+			PackageName: pkg.Path,
+			InstanceID:  pkg.Version,
+		}
+	}
+	return pins, nil
+}