feat: define Store interface (#38)

Resolves #27

Signed-off-by: Sylvia Lei <lixlei@microsoft.com>

Author: Wwwsylvia

go.mod

@@ -1,3 +1,7 @@
 module github.com/oras-project/oras-credentials-go
 
 go 1.19
+
+require oras.land/oras-go/v2 v2.0.2
+
+require golang.org/x/sync v0.1.0 // indirect

go.sum

@@ -0,0 +1,4 @@
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+oras.land/oras-go/v2 v2.0.2 h1:3aSQdJ7EUC0ft2e9PjJB9Jzastz5ojPA4LzZ3Q4YbUc=
+oras.land/oras-go/v2 v2.0.2/go.mod h1:PWnWc/Kyyg7wUTUsDHshrsJkzuxXzreeMd6NrfdnFSo=

store.go

@@ -0,0 +1,32 @@
+/*
+Copyright The ORAS Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package credentials
+
+import (
+	"context"
+
+	"oras.land/oras-go/v2/registry/remote/auth"
+)
+
+// Store is the interface that any credentials store must implement.
+type Store interface {
+	// Get retrieves credentials from the store for the given server address.
+	Get(ctx context.Context, serverAddress string) (auth.Credential, error)
+	// Put saves credentials into the store for the given server address.
+	Put(ctx context.Context, serverAddress string, cred auth.Credential) error
+	// Delete removes credentials from the store for the given server address.
+	Delete(ctx context.Context, serverAddress string) error
+}