Handle out of disk situation on kubelets.

Kubelet will stop accepting new pods if it detects low disk space on root fs or fs holding docker images.
Running pods are not affected. low-diskspace-threshold-mb is used to configure the low diskspace threshold.

pkg/kubelet/disk_manager_test.go

@@ -0,0 +1,144 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 kubelet
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/cadvisor"
+	cadvisorApi "github.com/google/cadvisor/info/v2"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func testPolicy() DiskSpacePolicy {
+	return DiskSpacePolicy{
+		DockerFreeDiskMB: 250,
+		RootFreeDiskMB:   250,
+	}
+}
+
+func testValidPolicy(t *testing.T) {
+	assert := assert.New(t)
+	policy := testPolicy()
+	c := new(cadvisor.Mock)
+	_, err := newDiskSpaceManager(c, policy)
+	require.NoError(t, err)
+
+	policy = testPolicy()
+	policy.DockerFreeDiskMB = -1
+	_, err = newDiskSpaceManager(c, policy)
+	assert.Error(err)
+
+	policy = testPolicy()
+	policy.RootFreeDiskMB = -1
+	_, err = newDiskSpaceManager(c, policy)
+	assert.Error(err)
+}
+
+func testSpaceAvailable(t *testing.T) {
+	policy := testPolicy()
+	mockCadvisor := new(cadvisor.Mock)
+	dm, err := newDiskSpaceManager(mockCadvisor, policy)
+	require.NoError(t, err)
+	const mb = 1024 * 1024
+	mockCadvisor.On("DockerImagesFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    400 * mb,
+		Capacity: 1000 * mb,
+	}, nil)
+	mockCadvisor.On("RootFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    9 * mb,
+		Capacity: 10 * mb,
+	}, nil)
+	ok, err := dm.IsDockerDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.True(t, ok)
+	ok, err = dm.IsRootDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.True(t, ok)
+}
+
+func testRootFsAvailable(t *testing.T) {
+	policy := testPolicy()
+	policy.RootFreeDiskMB = 10
+	mockCadvisor := new(cadvisor.Mock)
+	dm, err := newDiskSpaceManager(mockCadvisor, policy)
+	require.NoError(t, err)
+
+	const mb = 1024 * 1024
+	// 500MB free
+	mockCadvisor.On("DockerImagesFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    9500 * mb,
+		Capacity: 10000 * mb,
+	}, nil)
+	// 10MB free
+	mockCadvisor.On("RootFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    990 * mb,
+		Capacity: 1000 * mb,
+	}, nil)
+	ok, err := dm.IsDockerDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.True(t, ok)
+	ok, err = dm.IsRootDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.False(t, ok)
+}
+
+func testFsInfoError(t *testing.T) {
+	assert := assert.New(t)
+	policy := testPolicy()
+	policy.RootFreeDiskMB = 10
+	mockCadvisor := new(cadvisor.Mock)
+	dm, err := newDiskSpaceManager(mockCadvisor, policy)
+	require.NoError(t, err)
+
+	mockCadvisor.On("DockerImagesFsInfo").Return(cadvisorApi.FsInfo{}, fmt.Errorf("can't find fs"))
+	mockCadvisor.On("RootFsInfo").Return(cadvisorApi.FsInfo{}, fmt.Errorf("EBUSY"))
+	ok, err := dm.IsDockerDiskSpaceAvailable()
+	assert.Error(err)
+	require.True(t, ok)
+	ok, err = dm.IsRootDiskSpaceAvailable()
+	assert.Error(err)
+	require.True(t, ok)
+}
+
+func testCache(t *testing.T) {
+	policy := testPolicy()
+	mockCadvisor := new(cadvisor.Mock)
+	dm, err := newDiskSpaceManager(mockCadvisor, policy)
+	require.NoError(t, err)
+	const mb = 1024 * 1024
+	mockCadvisor.On("DockerImagesFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    400 * mb,
+		Capacity: 1000 * mb,
+	}, nil).Once()
+	mockCadvisor.On("RootFsInfo").Return(cadvisorApi.FsInfo{
+		Usage:    9 * mb,
+		Capacity: 10 * mb,
+	}, nil).Once()
+	ok, err := dm.IsDockerDiskSpaceAvailable()
+	ok, err = dm.IsRootDiskSpaceAvailable()
+
+	// Checking for space again shouldn't need to mock as cache would serve it.
+	ok, err = dm.IsDockerDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.True(t, ok)
+	ok, err = dm.IsRootDiskSpaceAvailable()
+	require.NoError(t, err)
+	require.True(t, ok)
+}