diff --git a/metrics-server/pkg/sources/interfaces.go b/metrics-server/pkg/sources/interfaces.go
new file mode 100644
index 0000000..74a4d14
--- /dev/null
+++ b/metrics-server/pkg/sources/interfaces.go
@@ -0,0 +1,76 @@
+// Copyright 2018 The Kubernetes 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 sources
+
+import (
+	"context"
+	"time"
+
+	"k8s.io/apimachinery/pkg/api/resource"
+)
+
+// MetricsBatch is a single batch of pod, container, and node metrics from some source.
+type MetricsBatch struct {
+	Nodes []NodeMetricsPoint
+	Pods  []PodMetricsPoint
+}
+
+// NodeMetricsPoint contains the metrics for some node at some point in time.
+type NodeMetricsPoint struct {
+	Name string
+	MetricsPoint
+}
+
+// PodMetricsPoint contains the metrics for some pod's containers.
+type PodMetricsPoint struct {
+	Name      string
+	Namespace string
+
+	Containers []ContainerMetricsPoint
+}
+
+// ContainerMetricsPoint contains the metrics for some container at some point in time.
+type ContainerMetricsPoint struct {
+	Name string
+	MetricsPoint
+}
+
+// MetricsPoint represents the a set of specific metrics at some point in time.
+type MetricsPoint struct {
+	Timestamp time.Time
+	// CpuUsage is the CPU usage rate, in cores
+	CpuUsage resource.Quantity
+	// MemoryUsage is the working set size, in bytes.
+	MemoryUsage resource.Quantity
+}
+
+// MetricSource knows how to collect pod, container, and node metrics from some location.
+// It is expected that the batch returned contains unique values (i.e. it does not return
+// the same node, pod, or container as any other source).
+type MetricSource interface {
+	// Collect fetches a batch of metrics.  It may return both a partial result and an error,
+	// and non-nil results thus must be well-formed and meaningful even when accompanied by 
+	// and error.
+	Collect(context.Context) (*MetricsBatch, error)
+	// Name names the metrics source for identification purposes
+	Name() string
+}
+
+// MetricSourceProvider provides metric sources to collect from.
+type MetricSourceProvider interface {
+	// GetMetricSources fetches all sources known to this metrics provider.
+	// It may return both partial results and an error.
+	GetMetricSources() ([]MetricSource, error)
+}