// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
func (daemon *Daemon) containerStart(container *container.Container) (err error) {
container.Lock()
defer container.Unlock()
if container.Running {
return nil
}
if container.RemovalInProgress || container.Dead {
return fmt.Errorf("Container is marked for removal and cannot be started.")
}
// if we encounter an error during start we need to ensure that any other
// setup has been cleaned up properly
defer func() {
if err != nil {
container.SetError(err)
// if no one else has set it, make sure we don't leave it at zero
if container.ExitCode == 0 {
container.ExitCode = 128
}
container.ToDisk()
daemon.Cleanup(container)
}
}()
if err := daemon.conditionalMountOnStart(container); err != nil {
return err
}
// Make sure NetworkMode has an acceptable value. We do this to ensure
// backwards API compatibility.
container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)
if err := daemon.initializeNetworking(container); err != nil {
return err
}
spec, err := daemon.createSpec(container)
if err != nil {
return err
}
if err := daemon.containerd.Create(container.ID, *spec, libcontainerd.WithRestartManager(container.RestartManager(true))); err != nil {
errDesc := grpc.ErrorDesc(err)
logrus.Errorf("Create container failed with error: %s", errDesc)
// if we receive an internal error from the initial start of a container then lets
// return it instead of entering the restart loop
// set to 127 for container cmd not found/does not exist)
if strings.Contains(errDesc, "executable file not found") ||
strings.Contains(errDesc, "no such file or directory") ||
strings.Contains(errDesc, "system cannot find the file specified") {
container.ExitCode = 127
}
// set to 126 for container cmd can't be invoked errors
if strings.Contains(errDesc, syscall.EACCES.Error()) {
container.ExitCode = 126
}
container.Reset(false)
return fmt.Errorf("%s", errDesc)
}
return nil
}
// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
func (daemon *Daemon) containerStart(container *container.Container, checkpoint string, resetRestartManager bool) (err error) {
container.Lock()
defer container.Unlock()
if resetRestartManager && container.Running { // skip this check if already in restarting step and resetRestartManager==false
return nil
}
if container.RemovalInProgress || container.Dead {
return fmt.Errorf("Container is marked for removal and cannot be started.")
}
// if we encounter an error during start we need to ensure that any other
// setup has been cleaned up properly
defer func() {
if err != nil {
container.SetError(err)
// if no one else has set it, make sure we don't leave it at zero
if container.ExitCode() == 0 {
container.SetExitCode(128)
}
container.ToDisk()
daemon.Cleanup(container)
// if containers AutoRemove flag is set, remove it after clean up
if container.HostConfig.AutoRemove {
container.Unlock()
if err := daemon.ContainerRm(container.ID, &types.ContainerRmConfig{ForceRemove: true, RemoveVolume: true}); err != nil {
logrus.Errorf("can't remove container %s: %v", container.ID, err)
}
container.Lock()
}
}
}()
if err := daemon.conditionalMountOnStart(container); err != nil {
return err
}
// Make sure NetworkMode has an acceptable value. We do this to ensure
// backwards API compatibility.
container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)
if err := daemon.initializeNetworking(container); err != nil {
return err
}
spec, err := daemon.createSpec(container)
if err != nil {
return err
}
createOptions, err := daemon.getLibcontainerdCreateOptions(container)
if err != nil {
return err
}
if resetRestartManager {
container.ResetRestartManager(true)
}
if err := daemon.containerd.Create(container.ID, checkpoint, container.CheckpointDir(), *spec, container.InitializeStdio, createOptions...); err != nil {
errDesc := grpc.ErrorDesc(err)
logrus.Errorf("Create container failed with error: %s", errDesc)
// if we receive an internal error from the initial start of a container then lets
// return it instead of entering the restart loop
// set to 127 for container cmd not found/does not exist)
if strings.Contains(errDesc, container.Path) &&
(strings.Contains(errDesc, "executable file not found") ||
strings.Contains(errDesc, "no such file or directory") ||
strings.Contains(errDesc, "system cannot find the file specified")) {
container.SetExitCode(127)
}
// set to 126 for container cmd can't be invoked errors
if strings.Contains(errDesc, syscall.EACCES.Error()) {
container.SetExitCode(126)
}
// attempted to mount a file onto a directory, or a directory onto a file, maybe from user specified bind mounts
if strings.Contains(errDesc, syscall.ENOTDIR.Error()) {
errDesc += ": Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type"
container.SetExitCode(127)
}
container.Reset(false)
return fmt.Errorf("%s", errDesc)
}
return nil
}
// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
//容器启动的核心方法。
func (daemon *Daemon) containerStart(container *container.Container) (err error) {
//这里的锁是干什么的？
container.Lock()
defer container.Unlock()
if container.Running {
return nil
}
if container.RemovalInProgress || container.Dead {
return fmt.Errorf("Container is marked for removal and cannot be started.")
}
// if we encounter an error during start we need to ensure that any other
// setup has been cleaned up properly
defer func() {
if err != nil {
container.SetError(err)
// if no one else has set it, make sure we don't leave it at zero
if container.ExitCode == 0 {
container.ExitCode = 128
}
container.ToDisk()
daemon.Cleanup(container)
attributes := map[string]string{
"exitCode": fmt.Sprintf("%d", container.ExitCode),
}
daemon.LogContainerEventWithAttributes(container, "die", attributes)
}
}()
//挂载容器的文件系统。会调用daemon/daemon.go中的Mount()方法。
//不过那个方法比较奇怪，感觉正常情况下并不会做什么事情。
if err := daemon.conditionalMountOnStart(container); err != nil {
return err
}
// Make sure NetworkMode has an acceptable value. We do this to ensure
// backwards API compatibility.
//设置默认的网络模式。
container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)
/*
initializeNetworking() 对网络进行初始化，docker网络模式有三种，分别是 bridge模式
（每个容器用户单独的网络栈），host模式（与宿主机共用一个网络栈），contaier模式
（与其他容器共用一个网络栈，猜测kubernate中的pod所用的模式）；
根据config和hostConfig中的参数来确定容器的网络模式，然后调动libnetwork包来建立网络
*/
if err := daemon.initializeNetworking(container); err != nil {
return err
}
//创建容器关于namespace和cgroup等的运行环境。在daemon/oci_linux.go中。
//Spec中包括了容器的最基本的信息。
spec, err := daemon.createSpec(container)
if err != nil {
return err
}
//运行容器，详细请见libcontainerd/client_linux.go中Create()方法。
if err := daemon.containerd.Create(container.ID, *spec, libcontainerd.WithRestartManager(container.RestartManager(true))); err != nil {
// if we receive an internal error from the initial start of a container then lets
// return it instead of entering the restart loop
// set to 127 for container cmd not found/does not exist)
if strings.Contains(err.Error(), "executable file not found") ||
strings.Contains(err.Error(), "no such file or directory") ||
strings.Contains(err.Error(), "system cannot find the file specified") {
container.ExitCode = 127
err = fmt.Errorf("Container command '%s' not found or does not exist.", container.Path)
}
// set to 126 for container cmd can't be invoked errors
if strings.Contains(err.Error(), syscall.EACCES.Error()) {
container.ExitCode = 126
err = fmt.Errorf("Container command '%s' could not be invoked.", container.Path)
}
container.Reset(false)
// start event is logged even on error
daemon.LogContainerEvent(container, "start")
return err
}
return nil
}