implement /index endpoint (#1630)

* implement /index endpoint

* rename to Module to Path

pkg/stash/stasher.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/gomods/athens/pkg/errors"
+	"github.com/gomods/athens/pkg/index"
 	"github.com/gomods/athens/pkg/log"
 	"github.com/gomods/athens/pkg/module"
 	"github.com/gomods/athens/pkg/observ"
@@ -13,7 +14,7 @@ import (
 )
 
 // Stasher has the job of taking a module
-// from an upstream entity and stashing it to a Storage Backend.
+// from an upstream entity and stashing it to a Storage Backend and Index.
 // It also returns a string that represents a semver version of
 // what was requested, this is helpful if what was requested
 // was a descriptive version such as a branch name or a full commit sha.
@@ -27,8 +28,8 @@ type Wrapper func(Stasher) Stasher
 // New returns a plain stasher that takes
 // a module from a download.Protocol and
 // stashes it into a backend.Storage.
-func New(f module.Fetcher, s storage.Backend, wrappers ...Wrapper) Stasher {
-	var st Stasher = &stasher{f, s, storage.WithChecker(s)}
+func New(f module.Fetcher, s storage.Backend, indexer index.Indexer, wrappers ...Wrapper) Stasher {
+	var st Stasher = &stasher{f, s, storage.WithChecker(s), indexer}
 	for _, w := range wrappers {
 		st = w(st)
 	}
@@ -40,6 +41,7 @@ type stasher struct {
 	fetcher module.Fetcher
 	storage storage.Backend
 	checker storage.Checker
+	indexer index.Indexer
 }
 
 func (s *stasher) Stash(ctx context.Context, mod, ver string) (string, error) {
@@ -71,6 +73,10 @@ func (s *stasher) Stash(ctx context.Context, mod, ver string) (string, error) {
 	if err != nil {
 		return "", errors.E(op, err)
 	}
+	err = s.indexer.Index(ctx, mod, v.Semver)
+	if err != nil {
+		return "", errors.E(op, err)
+	}
 	return v.Semver, nil
 }
 
@@ -80,6 +86,5 @@ func (s *stasher) fetchModule(ctx context.Context, mod, ver string) (*storage.Ve
 	if err != nil {
 		return nil, errors.E(op, err)
 	}
-
 	return v, nil
 }