openshift源码简析之pod网络配置：Openshift源码分析系列第一篇

1podSandboxID, msg, err = m.createPodSandbox(pod, podContainerChanges.Attempt)

 1// createPodSandbox creates a pod sandbox and returns (podSandBoxID, message, error).
 2func (m *kubeGenericRuntimeManager) createPodSandbox(pod *v1.Pod, attempt uint32) (string, string, error) {
 3    podSandboxConfig, err := m.generatePodSandboxConfig(pod, attempt)
 4    if err != nil {
 5        message := fmt.Sprintf("GeneratePodSandboxConfig for pod %q failed: %v", format.Pod(pod), err)
 6        glog.Error(message)
 7        return "", message, err
 8    }
 9
10    // Create pod logs directory
11    err = m.osInterface.MkdirAll(podSandboxConfig.LogDirectory, 0755)
12    if err != nil {
13        message := fmt.Sprintf("Create pod log directory for pod %q failed: %v", format.Pod(pod), err)
14        glog.Errorf(message)
15        return "", message, err
16    }
17
18    podSandBoxID, err := m.runtimeService.RunPodSandbox(podSandboxConfig)
19    if err != nil {
20        message := fmt.Sprintf("CreatePodSandbox for pod %q failed: %v", format.Pod(pod), err)
21        glog.Error(message)
22        return "", message, err
23    }
24
25    return podSandBoxID, "", nil
26}

 1// RunPodSandbox creates and starts a pod-level sandbox. Runtimes should ensure
 2// the sandbox is in ready state.
 3// For docker, PodSandbox is implemented by a container holding the network
 4// namespace for the pod.
 5// Note: docker doesn't use LogDirectory (yet).
 6func (ds *dockerService) RunPodSandbox(ctx context.Context, r *runtimeapi.RunPodSandboxRequest) (*runtimeapi.RunPodSandboxResponse, error) {
 7    config := r.GetConfig()
 8
 9    // Step 1: Pull the image for the sandbox.
10    image := defaultSandboxImage
11    podSandboxImage := ds.podSandboxImage
12    if len(podSandboxImage) != 0 {
13        image = podSandboxImage
14    }
15
16    // NOTE: To use a custom sandbox image in a private repository, users need to configure the nodes with credentials properly.
17    // see: http://kubernetes.io/docs/user-guide/images/#configuring-nodes-to-authenticate-to-a-private-repository
18    // Only pull sandbox image when it's not present - v1.PullIfNotPresent.
19    if err := ensureSandboxImageExists(ds.client, image); err != nil {
20        return nil, err
21    }
22
23    // Step 2: Create the sandbox container.
24    createConfig, err := ds.makeSandboxDockerConfig(config, image)
25    if err != nil {
26        return nil, fmt.Errorf("failed to make sandbox docker config for pod %q: %v", config.Metadata.Name, err)
27    }
28    createResp, err := ds.client.CreateContainer(*createConfig)
29    if err != nil {
30        createResp, err = recoverFromCreationConflictIfNeeded(ds.client, *createConfig, err)
31    }
32
33    if err != nil || createResp == nil {
34        return nil, fmt.Errorf("failed to create a sandbox for pod %q: %v", config.Metadata.Name, err)
35    }
36    resp := &runtimeapi.RunPodSandboxResponse{PodSandboxId: createResp.ID}
37
38    ds.setNetworkReady(createResp.ID, false)
39    defer func(e *error) {
40        // Set networking ready depending on the error return of
41        // the parent function
42        if *e == nil {
43            ds.setNetworkReady(createResp.ID, true)
44        }
45    }(&err)
46
47    // Step 3: Create Sandbox Checkpoint.
48    if err = ds.checkpointHandler.CreateCheckpoint(createResp.ID, constructPodSandboxCheckpoint(config)); err != nil {
49        return nil, err
50    }
51
52    // Step 4: Start the sandbox container.
53    // Assume kubelet's garbage collector would remove the sandbox later, if
54    // startContainer failed.
55    err = ds.client.StartContainer(createResp.ID)
56    if err != nil {
57        return nil, fmt.Errorf("failed to start sandbox container for pod %q: %v", config.Metadata.Name, err)
58    }
59
60    // Rewrite resolv.conf file generated by docker.
61    // NOTE: cluster dns settings aren't passed anymore to docker api in all cases,
62    // not only for pods with host network: the resolver conf will be overwritten
63    // after sandbox creation to override docker's behaviour. This resolv.conf
64    // file is shared by all containers of the same pod, and needs to be modified
65    // only once per pod.
66    if dnsConfig := config.GetDnsConfig(); dnsConfig != nil {
67        containerInfo, err := ds.client.InspectContainer(createResp.ID)
68        if err != nil {
69            return nil, fmt.Errorf("failed to inspect sandbox container for pod %q: %v", config.Metadata.Name, err)
70        }
71
72        if err := rewriteResolvFile(containerInfo.ResolvConfPath, dnsConfig.Servers, dnsConfig.Searches, dnsConfig.Options); err != nil {
73            return nil, fmt.Errorf("rewrite resolv.conf failed for pod %q: %v", config.Metadata.Name, err)
74        }
75    }
76
77    // Do not invoke network plugins if in hostNetwork mode.
78    if config.GetLinux().GetSecurityContext().GetNamespaceOptions().GetNetwork() == runtimeapi.NamespaceMode_NODE {
79        return resp, nil
80    }
81
82    // Step 5: Setup networking for the sandbox.
83    // All pod networking is setup by a CNI plugin discovered at startup time.
84    // This plugin assigns the pod ip, sets up routes inside the sandbox,
85    // creates interfaces etc. In theory, its jurisdiction ends with pod
86    // sandbox networking, but it might insert iptables rules or open ports
87    // on the host as well, to satisfy parts of the pod spec that aren't
88    // recognized by the CNI standard yet.
89    cID := kubecontainer.BuildContainerID(runtimeName, createResp.ID)
90    err = ds.network.SetUpPod(config.GetMetadata().Namespace, config.GetMetadata().Name, cID, config.Annotations)
91    if err != nil {
92        // TODO(random-liu): Do we need to teardown network here?
93        if err := ds.client.StopContainer(createResp.ID, defaultSandboxGracePeriod); err != nil {
94            glog.Warningf("Failed to stop sandbox container %q for pod %q: %v", createResp.ID, config.Metadata.Name, err)
95        }
96    }
97    return resp, err
98}

 1func ensureSandboxImageExists(client libdocker.Interface, image string) error {
 2    _, err := client.InspectImageByRef(image)
 3    if err == nil {
 4        return nil
 5    }
 6    if !libdocker.IsImageNotFoundError(err) {
 7        return fmt.Errorf("failed to inspect sandbox image %q: %v", image, err)
 8    }
 9
10    repoToPull, _, _, err := parsers.ParseImageName(image)
11    if err != nil {
12        return err
13    }
14
15    keyring := credentialprovider.NewDockerKeyring()
16    creds, withCredentials := keyring.Lookup(repoToPull)
17    if !withCredentials {
18        glog.V(3).Infof("Pulling image %q without credentials", image)
19
20        err := client.PullImage(image, dockertypes.AuthConfig{}, dockertypes.ImagePullOptions{})
21        if err != nil {
22            return fmt.Errorf("failed pulling image %q: %v", image, err)
23        }
24
25        return nil
26    }
27
28    var pullErrs []error
29    for _, currentCreds := range creds {
30        authConfig := credentialprovider.LazyProvide(currentCreds)
31        err := client.PullImage(image, authConfig, dockertypes.ImagePullOptions{})
32        // If there was no error, return success
33        if err == nil {
34            return nil
35        }
36
37        pullErrs = append(pullErrs, err)
38    }
39
40    return utilerrors.NewAggregate(pullErrs)
41}

 1func (d *kubeDockerClient) CreateContainer(opts dockertypes.ContainerCreateConfig) (*dockercontainer.ContainerCreateCreatedBody, error) {
 2    ctx, cancel := d.getTimeoutContext()
 3    defer cancel()
 4    // we provide an explicit default shm size as to not depend on docker daemon.
 5    // TODO: evaluate exposing this as a knob in the API
 6    if opts.HostConfig != nil && opts.HostConfig.ShmSize <= 0 {
 7        opts.HostConfig.ShmSize = defaultShmSize
 8    }
 9    createResp, err := d.client.ContainerCreate(ctx, opts.Config, opts.HostConfig, opts.NetworkingConfig, opts.Name)
10    if ctxErr := contextError(ctx); ctxErr != nil {
11        return nil, ctxErr
12    }
13    if err != nil {
14        return nil, err
15    }
16    return &createResp, nil
17}

1func (d *kubeDockerClient) StartContainer(id string) error {
2    ctx, cancel := d.getTimeoutContext()
3    defer cancel()
4    err := d.client.ContainerStart(ctx, id, dockertypes.ContainerStartOptions{})
5    if ctxErr := contextError(ctx); ctxErr != nil {
6        return ctxErr
7    }
8    return err
9}