Add a fake rkt app-level API to rktshim pkg

pkg/kubelet/rktshim/fake-app-interface.go

+/*
+Copyright 2016 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 rktshim
+
+import (
+	"errors"
+	"io"
+	"math/rand"
+	"time"
+
+	kubeletApi "k8s.io/kubernetes/pkg/kubelet/api"
+	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+)
+
+func init() {
+	// Don't randomize due to testing purposes
+	// rand.Seed(time.Now().UnixNano())
+}
+
+func randString(n int) string {
+	runeAlphabet := []rune("abcdefghijklmnopqrstuvwxyz")
+	dictLen := len(runeAlphabet)
+
+	buf := make([]rune, n)
+	for i := range buf {
+		buf[i] = runeAlphabet[rand.Intn(dictLen)]
+	}
+
+	return string(buf)
+}
+
+var (
+	ErrContainerNotFound               = errors.New("rktshim: container not found")
+	ErrInvalidContainerStateTransition = errors.New("rktshim: wrong container operation for current state")
+)
+
+type FakeRuntime struct {
+	Containers containerRegistry
+}
+
+type FakeRuntimeConfig struct{}
+
+func NewFakeRuntime() (kubeletApi.ContainerManager, error) {
+	return &FakeRuntime{Containers: make(containerRegistry)}, nil
+}
+
+type characterStreams struct {
+	In  io.Reader
+	Out io.Writer
+	Err io.Writer
+}
+
+func newCharacterStreams(in io.Reader, out io.Writer, err io.Writer) characterStreams {
+	std := characterStreams{in, out, err}
+
+	return std
+}
+
+type fakeContainer struct {
+	Config *runtimeApi.ContainerConfig
+
+	Status runtimeApi.ContainerStatus
+
+	State runtimeApi.ContainerState
+
+	Streams characterStreams
+}
+
+func (c *fakeContainer) Start() {
+	c.State = runtimeApi.ContainerState_RUNNING
+
+	c.Status.State = &c.State
+}
+
+func (c *fakeContainer) Stop() {
+	c.State = runtimeApi.ContainerState_EXITED
+
+	c.Status.State = &c.State
+
+	exitSuccess := int32(0)
+	c.Status.ExitCode = &exitSuccess
+
+	// c.Status.Reason
+}
+
+func (c *fakeContainer) Exec(cmd []string, in io.Reader, out, err io.WriteCloser) error {
+	// TODO(tmrts): incomplete command execution logic
+	// c.StreamCompare(c.Streams.In, s.InputStream)
+	// c.StreamFlush(c.Streams.Out, s.OutputStream)
+	// c.StreamFlush(c.Streams.Err, s.ErrorStream)
+
+	return nil
+}
+
+type containerRegistry map[string]*fakeContainer
+
+func (r *FakeRuntime) CreateContainer(pid string, cfg *runtimeApi.ContainerConfig, sandboxCfg *runtimeApi.PodSandboxConfig) (string, error) {
+	// TODO(tmrts): allow customization
+	containerIDLength := 8
+
+	cid := randString(containerIDLength)
+
+	r.Containers[cid] = &fakeContainer{
+		Config:  cfg,
+		Streams: newCharacterStreams(nil, nil, nil),
+	}
+
+	return cid, nil
+}
+
+func (r *FakeRuntime) StartContainer(id string) error {
+	c, ok := r.Containers[id]
+	if !ok {
+		return ErrContainerNotFound
+	}
+	switch c.State {
+	case runtimeApi.ContainerState_EXITED:
+		fallthrough
+	case runtimeApi.ContainerState_CREATED:
+		c.Start()
+	case runtimeApi.ContainerState_UNKNOWN:
+		// TODO(tmrts): add timeout to Start API or generalize timeout somehow
+		//<-time.After(time.Duration(timeout) * time.Second)
+		fallthrough
+	default:
+		return ErrInvalidContainerStateTransition
+	}
+
+	return nil
+}
+
+func (r *FakeRuntime) StopContainer(id string, timeout int64) error {
+	c, ok := r.Containers[id]
+	if !ok {
+		return ErrContainerNotFound
+	}
+
+	switch c.State {
+	case runtimeApi.ContainerState_RUNNING:
+		c.State = runtimeApi.ContainerState_EXITED // This state might not be the best one
+	case runtimeApi.ContainerState_UNKNOWN:
+		<-time.After(time.Duration(timeout) * time.Second)
+		fallthrough
+	default:
+		return ErrInvalidContainerStateTransition
+	}
+
+	return nil
+}
+
+func (r *FakeRuntime) RemoveContainer(id string) error {
+	_, ok := r.Containers[id]
+	if !ok {
+		return ErrContainerNotFound
+	}
+
+	// Remove regardless of the container state
+	delete(r.Containers, id)
+
+	return nil
+}
+
+func (r *FakeRuntime) ListContainers(*runtimeApi.ContainerFilter) ([]*runtimeApi.Container, error) {
+	list := []*runtimeApi.Container{}
+
+	// TODO(tmrts): apply the filter
+	for _, c := range r.Containers {
+		list = append(list, &runtimeApi.Container{
+			Id:       c.Status.Id,
+			Name:     c.Config.Name,
+			Labels:   c.Config.Labels,
+			ImageRef: c.Status.ImageRef,
+			State:    &c.State,
+		})
+	}
+
+	return list, nil
+}
+
+func (r *FakeRuntime) ContainerStatus(id string) (*runtimeApi.ContainerStatus, error) {
+	c, ok := r.Containers[id]
+	if !ok {
+		return &runtimeApi.ContainerStatus{}, ErrContainerNotFound
+	}
+
+	return &c.Status, nil
+}
+
+func (r *FakeRuntime) Exec(id string, cmd []string, tty bool, in io.Reader, out, err io.WriteCloser) error {
+	c, ok := r.Containers[id]
+	if !ok {
+		return ErrContainerNotFound
+	}
+
+	// TODO(tmrts): Validate the assumption that container has to be running for exec to work.
+	if c.State != runtimeApi.ContainerState_RUNNING {
+		return ErrInvalidContainerStateTransition
+	}
+
+	return c.Exec(cmd, in, out, err)
+}