internal: Add helper package to store manifests

Previously we had a bunch of ad-hoc code to store the revision and
roots internally. These changes just add a proper package to deal with
the reading and writing of the revision and roots.

Note, the bundle package itself is still hardcoding the manifest path
but we can fix that in a subsequent PR.

Signed-off-by: Torin Sandall <torinsandall@gmail.com>

internal/manifest/manifest.go

@@ -0,0 +1,82 @@
+// Copyright 2019 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+// Package manifest implements helper functions for the stored manifest.
+package manifest
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/open-policy-agent/opa/bundle"
+	"github.com/open-policy-agent/opa/storage"
+	"github.com/open-policy-agent/opa/util"
+)
+
+var bundlePath = storage.MustParsePath("/system/bundle")
+var manifestPath = storage.MustParsePath("/system/bundle/manifest")
+var revisionPath = storage.MustParsePath("/system/bundle/manifest/revision")
+var rootsPath = storage.MustParsePath("/system/bundle/manifest/roots")
+
+// Write the manifest into the storage. This function is called when
+// the bundle is activated.
+func Write(ctx context.Context, store storage.Store, txn storage.Transaction, m bundle.Manifest) error {
+
+	var value interface{} = m
+
+	if err := util.RoundTrip(&value); err != nil {
+		return err
+	}
+
+	if err := storage.MakeDir(ctx, store, txn, bundlePath); err != nil {
+		return err
+	}
+
+	return store.Write(ctx, txn, storage.AddOp, manifestPath, value)
+}
+
+// ReadBundleRoots returns the roots specified in the currently
+// activated bundle. If there is no activated bundle, this function
+// will return storage NotFound error.
+func ReadBundleRoots(ctx context.Context, store storage.Store, txn storage.Transaction) ([]string, error) {
+
+	value, err := store.Read(ctx, txn, rootsPath)
+	if err != nil {
+		return nil, err
+	}
+
+	sl, ok := value.([]interface{})
+	if !ok {
+		return nil, fmt.Errorf("corrupt manifest roots")
+	}
+
+	roots := make([]string, len(sl))
+
+	for i := range sl {
+		roots[i], ok = sl[i].(string)
+		if !ok {
+			return nil, fmt.Errorf("corrupt manifest root")
+		}
+	}
+
+	return roots, nil
+}
+
+// ReadBundleRevision returns the revision in the currently activated
+// bundle. If there is no activated bundle, ths function will return
+// storage NotFound error.
+func ReadBundleRevision(ctx context.Context, store storage.Store, txn storage.Transaction) (string, error) {
+
+	value, err := store.Read(ctx, txn, revisionPath)
+	if err != nil {
+		return "", err
+	}
+
+	str, ok := value.(string)
+	if !ok {
+		return "", fmt.Errorf("corrupt manifest revision")
+	}
+
+	return str, nil
+}

plugins/bundle/plugin.go

@@ -15,9 +15,9 @@ import (
 	"github.com/open-policy-agent/opa/ast"
 	"github.com/open-policy-agent/opa/bundle"
 	"github.com/open-policy-agent/opa/download"
+	"github.com/open-policy-agent/opa/internal/manifest"
 	"github.com/open-policy-agent/opa/plugins"
 	"github.com/open-policy-agent/opa/storage"
-	"github.com/open-policy-agent/opa/util"
 	"github.com/sirupsen/logrus"
 )
 
@@ -195,7 +195,7 @@ func (p *Plugin) activate(ctx context.Context, b *bundle.Bundle) error {
 			}
 		}
 
-		if roots, err := p.readRoots(ctx, txn); err == nil {
+		if roots, err := manifest.ReadBundleRoots(ctx, p.manager.Store, txn); err == nil {
 			for _, root := range roots {
 				erase[root] = struct{}{}
 			}
@@ -217,11 +217,11 @@ func (p *Plugin) activate(ctx context.Context, b *bundle.Bundle) error {
 			return err
 		}
 
-		if err := p.writeManifest(ctx, txn, b.Manifest); err != nil {
+		if err := p.writeModules(ctx, txn, b.Modules); err != nil {
 			return err
 		}
 
-		if err := p.writeModules(ctx, txn, b.Modules); err != nil {
+		if err := manifest.Write(ctx, p.manager.Store, txn, b.Manifest); err != nil {
 			return err
 		}
 
@@ -314,45 +314,6 @@ func (p *Plugin) writeModules(ctx context.Context, txn storage.Transaction, file
 	return nil
 }
 
-func (p *Plugin) readRoots(ctx context.Context, txn storage.Transaction) ([]string, error) {
-
-	value, err := p.manager.Store.Read(ctx, txn, rootsPath)
-	if err != nil {
-		return nil, err
-	}
-
-	sl, ok := value.([]interface{})
-	if !ok {
-		return nil, fmt.Errorf("corrupt manifest roots")
-	}
-
-	roots := make([]string, len(sl))
-
-	for i := range sl {
-		roots[i], ok = sl[i].(string)
-		if !ok {
-			return nil, fmt.Errorf("corrupt manifest root")
-		}
-	}
-
-	return roots, nil
-}
-
-func (p *Plugin) writeManifest(ctx context.Context, txn storage.Transaction, m bundle.Manifest) error {
-
-	var value interface{} = m
-
-	if err := util.RoundTrip(&value); err != nil {
-		return err
-	}
-
-	if err := storage.MakeDir(ctx, p.manager.Store, txn, bundlePath); err != nil {
-		return err
-	}
-
-	return p.manager.Store.Write(ctx, txn, storage.AddOp, manifestPath, value)
-}
-
 func (p *Plugin) logError(fmt string, a ...interface{}) {
 	logrus.WithFields(p.logrusFields()).Errorf(fmt, a...)
 }
@@ -372,12 +333,6 @@ func (p *Plugin) logrusFields() logrus.Fields {
 	}
 }
 
-var (
-	bundlePath   = storage.MustParsePath("/system/bundle")
-	manifestPath = storage.MustParsePath("/system/bundle/manifest")
-	rootsPath    = storage.MustParsePath("/system/bundle/manifest/roots")
-)
-
 func lookup(path storage.Path, data map[string]interface{}) (interface{}, bool) {
 	if len(path) == 0 {
 		return data, true