Simplestreams: Define a simplestreams type

By defining a simplestreams type we no longer need to pass the factory everywhere as we can just use a type to hold that information.
sdg0919 · Jun 3, 2021 · 6a3173a · 6a3173a
1 parent 71f0554
commit 6a3173a
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Showing 8 changed files with 71 additions and 45 deletions.
diff --git a/environs/gui/simplestreams.go b/environs/gui/simplestreams.go
@@ -66,7 +66,8 @@ func FetchMetadata(stream string, major, minor int, sources ...simplestreams.Dat
 			ValueTemplate:   Metadata{},
 		},
 	}
-	items, _, err := simplestreams.GetMetadata(simplestreams.DefaultDataSourceFactory(), sources, params)
+	ss := simplestreams.NewSimpleStreams(simplestreams.DefaultDataSourceFactory())
+	items, _, err := ss.GetMetadata(sources, params)
 	if err != nil {
 		return nil, errors.Annotate(err, "error fetching simplestreams metadata")
 	}

diff --git a/environs/imagedownloads/simplestreams.go b/environs/imagedownloads/simplestreams.go
@@ -97,7 +97,8 @@ func Fetch(
 			ValueTemplate: Metadata{},
 		},
 	}
-	items, resolveInfo, err := simplestreams.GetMetadata(simplestreams.DefaultDataSourceFactory(), src, params)
+	ss := simplestreams.NewSimpleStreams(simplestreams.DefaultDataSourceFactory())
+	items, resolveInfo, err := ss.GetMetadata(src, params)
 	if err != nil {
 		return nil, resolveInfo, err
 	}

diff --git a/environs/imagemetadata/simplestreams.go b/environs/imagemetadata/simplestreams.go
@@ -216,14 +216,12 @@ func (im *ImageMetadata) productId() string {
 	return fmt.Sprintf("com.ubuntu.cloud%s:server:%s:%s", stream, im.Version, im.Arch)
 }
 
-// Fetch returns a list of images for the specified cloud matching the constraint.
-// The base URL locations are as specified - the first location which has a file is the one used.
-// Signed data is preferred, but if there is no signed data available and onlySigned is false,
-// then unsigned data is used.
-func Fetch(
-	sources []simplestreams.DataSource, cons *ImageConstraint,
-) ([]*ImageMetadata, *simplestreams.ResolveInfo, error) {
-
+// Fetch returns a list of images for the specified cloud matching the
+// constraint. The base URL locations are as specified - the first location
+// which has a file is the one used.
+// Signed data is preferred, but if there is no signed data available and
+// onlySigned is false, then unsigned data is used.
+func Fetch(sources []simplestreams.DataSource, cons *ImageConstraint) ([]*ImageMetadata, *simplestreams.ResolveInfo, error) {
 	params := simplestreams.GetMetadataParams{
 		StreamsVersion:   currentStreamsVersion,
 		LookupConstraint: cons,
@@ -233,7 +231,8 @@ func Fetch(
 			ValueTemplate: ImageMetadata{},
 		},
 	}
-	items, resolveInfo, err := simplestreams.GetMetadata(simplestreams.DefaultDataSourceFactory(), sources, params)
+	ss := simplestreams.NewSimpleStreams(simplestreams.DefaultDataSourceFactory())
+	items, resolveInfo, err := ss.GetMetadata(sources, params)
 	if err != nil {
 		return nil, resolveInfo, err
 	}

diff --git a/environs/simplestreams/simplestreams.go b/environs/simplestreams/simplestreams.go
@@ -110,8 +110,9 @@ func (p LookupParams) Params() LookupParams {
 // Not every model attribute is defined here, only the ones we care about.
 // See the doc/README file in lp:simplestreams for more information.
 
-// Metadata attribute values may point to a map of attribute values (aka aliases) and these attributes
-// are used to override/augment the existing attributes.
+// Metadata attribute values may point to a map of attribute values (aka
+// aliases) and these attributes are used to override/augment the existing
+// attributes.
 type attributeValues map[string]string
 type aliasesByAttribute map[string]attributeValues
 
@@ -307,9 +308,10 @@ func (entries IndexMetadataSlice) filter(match func(*IndexMetadata) bool) IndexM
 	return result
 }
 
-// noMatchingProductsError is used to indicate that metadata files have been located,
-// but there is no metadata satisfying a product criteria.
-// It is used to distinguish from the situation where the metadata files could not be found.
+// noMatchingProductsError is used to indicate that metadata files have been
+// located, but there is no metadata satisfying a product criteria.
+// It is used to distinguish from the situation where the metadata files could
+// not be found.
 type noMatchingProductsError struct {
 	msg string
 }
@@ -337,7 +339,8 @@ const (
 	SignedSuffix           = ".sjson"
 	UnsignedSuffix         = ".json"
 
-	// These constants define the currently supported simplestreams data formats.
+	// These constants define the currently supported simplestreams data
+	// formats.
 	IndexFormat   = "index:1.0"
 	ProductFormat = "products:1.0"
 	MirrorFormat  = "mirrors:1.0"
@@ -348,7 +351,8 @@ const (
 // returned interface slice.
 type AppendMatchingFunc func(DataSource, []interface{}, map[string]interface{}, LookupConstraint) ([]interface{}, error)
 
-// ValueParams contains the information required to pull out from the metadata structs of a particular type.
+// ValueParams contains the information required to pull out from the metadata
+// structs of a particular type.
 type ValueParams struct {
 	// The simplestreams data type key.
 	DataType string
@@ -379,24 +383,44 @@ func UnsignedMirror(streamsVersion string) string {
 	return fmt.Sprintf(unsignedMirror, streamsVersion)
 }
 
+// Simplestreams defines a type for encapsulating the functionality for
+// requesting simplestreams data.
+//
+// TODO (stickupkid): This requires more work. The idea is to localize all
+// package level functions up on to this type. Passing the type through layers
+// becomes simple.
+type Simplestreams struct {
+	factory DataSourceFactory
+}
+
+// NewSimpleStreams creates a new simplestreams accessor.
+func NewSimpleStreams(factory DataSourceFactory) *Simplestreams {
+	return &Simplestreams{
+		factory: factory,
+	}
+}
+
 // GetMetadataParams defines parameters used to load simplestreams metadata.
 type GetMetadataParams struct {
 	StreamsVersion   string
 	LookupConstraint LookupConstraint
 	ValueParams      ValueParams
 }
 
-// GetMetadata returns metadata records matching the specified constraint,looking in each source for signed metadata.
-// If onlySigned is false and no signed metadata is found in a source, the source is used to look for unsigned metadata.
-// Each source is tried in turn until at least one signed (or unsigned) match is found.
-func GetMetadata(factory DataSourceFactory, sources []DataSource, params GetMetadataParams) (items []interface{}, resolveInfo *ResolveInfo, err error) {
+// GetMetadata returns metadata records matching the specified constraint,
+// looking in each source for signed metadata. If onlySigned is false and no
+// signed metadata is found in a source, the source is used to look for
+// unsigned metadata.
+// Each source is tried in turn until at least one signed (or unsigned) match
+// is found.
+func (s Simplestreams) GetMetadata(sources []DataSource, params GetMetadataParams) (items []interface{}, resolveInfo *ResolveInfo, err error) {
 	for _, source := range sources {
 		logger.Tracef("searching for signed metadata in datasource %q", source.Description())
-		items, resolveInfo, err = getMaybeSignedMetadata(factory, source, params, true)
+		items, resolveInfo, err = s.getMaybeSignedMetadata(source, params, true)
 		// If no items are found using signed metadata, check unsigned.
 		if err != nil && len(items) == 0 && !source.RequireSigned() {
 			logger.Tracef("falling back to search for unsigned metadata in datasource %q", source.Description())
-			items, resolveInfo, err = getMaybeSignedMetadata(factory, source, params, false)
+			items, resolveInfo, err = s.getMaybeSignedMetadata(source, params, false)
 		}
 		if err == nil {
 			break
@@ -410,7 +434,7 @@ func GetMetadata(factory DataSourceFactory, sources []DataSource, params GetMeta
 }
 
 // getMaybeSignedMetadata returns metadata records matching the specified constraint in params.
-func getMaybeSignedMetadata(factory DataSourceFactory, source DataSource, params GetMetadataParams, signed bool) ([]interface{}, *ResolveInfo, error) {
+func (s Simplestreams) getMaybeSignedMetadata(source DataSource, params GetMetadataParams, signed bool) ([]interface{}, *ResolveInfo, error) {
 
 	makeIndexPath := func(basePath string) string {
 		pathNoSuffix := fmt.Sprintf(basePath, params.StreamsVersion)
@@ -430,8 +454,7 @@ func getMaybeSignedMetadata(factory DataSourceFactory, source DataSource, params
 	mirrorsPath := fmt.Sprintf(defaultMirrorsPath, params.StreamsVersion)
 	cons := params.LookupConstraint
 
-	indexRef, indexURL, err := fetchIndex(
-		factory,
+	indexRef, indexURL, err := s.fetchIndex(
 		source,
 		indexPath,
 		mirrorsPath,
@@ -446,8 +469,7 @@ func getMaybeSignedMetadata(factory DataSourceFactory, source DataSource, params
 		logger.Tracef("%s not accessed, trying legacy index path: %s", indexPath, legacyIndexPath)
 
 		indexPath = legacyIndexPath
-		indexRef, indexURL, err = fetchIndex(
-			factory,
+		indexRef, indexURL, err = s.fetchIndex(
 			source,
 			indexPath,
 			mirrorsPath,
@@ -481,16 +503,16 @@ func getMaybeSignedMetadata(factory DataSourceFactory, source DataSource, params
 }
 
 // fetchIndex attempts to load the index file at indexPath in source.
-func fetchIndex(factory DataSourceFactory, source DataSource, indexPath string, mirrorsPath string, cloudSpec CloudSpec,
+func (s Simplestreams) fetchIndex(source DataSource, indexPath string, mirrorsPath string, cloudSpec CloudSpec,
 	signed bool, params ValueParams) (indexRef *IndexReference, indexURL string, _ error) {
 	indexURL, err := source.URL(indexPath)
 	if err != nil {
-		// Some providers return an error if asked for the URL of a non-existent file.
-		// So the best we can do is use the relative path for the URL when logging messages.
+		// Some providers return an error if asked for the URL of a non-existent
+		// file. The best we can do is use the relative path for the URL when
+		// logging messages.
 		indexURL = indexPath
 	}
-	indexRef, err = GetIndexWithFormat(
-		factory,
+	indexRef, err = s.GetIndexWithFormat(
 		source,
 		indexPath, IndexFormat,
 		mirrorsPath,
@@ -501,7 +523,8 @@ func fetchIndex(factory DataSourceFactory, source DataSource, indexPath string,
 	return indexRef, indexURL, err
 }
 
-// fetchData gets all the data from the given source located at the specified path.
+// fetchData gets all the data from the given source located at the specified
+// path.
 // It returns the data found and the full URL used.
 func fetchData(source DataSource, path string, requireSigned bool) (data []byte, dataURL string, err error) {
 	rc, dataURL, err := source.Fetch(path)
@@ -541,7 +564,7 @@ func (defaultDataSourceFactory) NewDataSource(cfg Config) DataSource {
 
 // GetIndexWithFormat returns a simplestreams index of the specified format.
 // Exported for testing.
-func GetIndexWithFormat(factory DataSourceFactory, source DataSource,
+func (s Simplestreams) GetIndexWithFormat(source DataSource,
 	indexPath, indexFormat, mirrorsPath string, requireSigned bool,
 	cloudSpec CloudSpec, params ValueParams) (*IndexReference, error) {
 
@@ -580,7 +603,7 @@ func GetIndexWithFormat(factory DataSourceFactory, source DataSource,
 			source, mirrors, params.DataType, params.MirrorContentId, cloudSpec, requireSigned)
 		if err == nil {
 			logger.Debugf("using mirrored products path: %s", path.Join(mirrorInfo.MirrorURL, mirrorInfo.Path))
-			indexRef.Source = factory.NewDataSource(Config{
+			indexRef.Source = s.factory.NewDataSource(Config{
 				Description:          "mirror",
 				BaseURL:              mirrorInfo.MirrorURL,
 				PublicSigningKey:     source.PublicSigningKey(),
@@ -599,7 +622,6 @@ func GetIndexWithFormat(factory DataSourceFactory, source DataSource,
 
 // getMirrorRefs parses and returns a simplestreams mirror reference.
 func getMirrorRefs(source DataSource, baseMirrorsPath string, requireSigned bool) (MirrorRefs, string, error) {
-
 	mirrorsPath := baseMirrorsPath + UnsignedSuffix
 	if requireSigned {
 		mirrorsPath = baseMirrorsPath + SignedSuffix

diff --git a/environs/simplestreams/simplestreams_test.go b/environs/simplestreams/simplestreams_test.go
@@ -343,7 +343,8 @@ func (s *simplestreamsSuite) TestGetMetadataNoMatching(c *gc.C) {
 		ValueParams:      simplestreams.ValueParams{DataType: "image-ids"},
 	}
 
-	items, resolveInfo, err := simplestreams.GetMetadata(sstesting.TestDataSourceFactory(), sources, params)
+	ss := simplestreams.NewSimpleStreams(sstesting.TestDataSourceFactory())
+	items, resolveInfo, err := ss.GetMetadata(sources, params)
 	c.Assert(err, jc.ErrorIsNil)
 	c.Assert(items, gc.HasLen, 0)
 	c.Assert(resolveInfo, gc.DeepEquals, &simplestreams.ResolveInfo{
@@ -493,8 +494,8 @@ func (s *simplestreamsSuite) TestGetMirrorMetadata(c *gc.C) {
 			DataType:        "content-download",
 			MirrorContentId: "com.ubuntu.juju:released:agents",
 		}
-		indexRef, err := simplestreams.GetIndexWithFormat(
-			sstesting.TestDataSourceFactory(),
+		ss := simplestreams.NewSimpleStreams(sstesting.TestDataSourceFactory())
+		indexRef, err := ss.GetIndexWithFormat(
 			s.Source, s.IndexPath(), sstesting.Index_v1,
 			simplestreams.MirrorsPath("v1"), s.RequireSigned, cloud, params)
 		if !c.Check(err, jc.ErrorIsNil) {

diff --git a/environs/simplestreams/testing/testing.go b/environs/simplestreams/testing/testing.go
@@ -718,8 +718,8 @@ func (s *LocalLiveSimplestreamsSuite) GetIndexRef(format string) (*simplestreams
 		DataType:      s.DataType,
 		ValueTemplate: TestItem{},
 	}
-	return simplestreams.GetIndexWithFormat(
-		TestDataSourceFactory(),
+	ss := simplestreams.NewSimpleStreams(TestDataSourceFactory())
+	return ss.GetIndexWithFormat(
 		s.Source, s.IndexPath(),
 		format,
 		simplestreams.MirrorsPath(s.StreamsVersion),

diff --git a/environs/tools/simplestreams.go b/environs/tools/simplestreams.go
@@ -169,7 +169,8 @@ func Fetch(factory simplestreams.DataSourceFactory,
 			ValueTemplate:   ToolsMetadata{},
 		},
 	}
-	items, resolveInfo, err := simplestreams.GetMetadata(factory, sources, params)
+	ss := simplestreams.NewSimpleStreams(factory)
+	items, resolveInfo, err := ss.GetMetadata(sources, params)
 	if err != nil {
 		return nil, nil, err
 	}

diff --git a/provider/vsphere/image_metadata.go b/provider/vsphere/image_metadata.go
@@ -65,7 +65,8 @@ func imageMetadataFetch(sources []simplestreams.DataSource, cons *imagemetadata.
 			ValueTemplate: OvaFileMetadata{},
 		},
 	}
-	items, _, err := simplestreams.GetMetadata(simplestreams.DefaultDataSourceFactory(), sources, params)
+	ss := simplestreams.NewSimpleStreams(simplestreams.DefaultDataSourceFactory())
+	items, _, err := ss.GetMetadata(sources, params)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}