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* Jobs return an integer status instead of a string * Status convention mimics unix process execution: 0=success, 1=generic error, 127="no such command" * Stdout and Stderr support multiple thread-safe data receivers and ring buffer filtering
118 lines
3.5 KiB
Go
118 lines
3.5 KiB
Go
package engine
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import (
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"fmt"
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"github.com/dotcloud/docker/utils"
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"log"
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"os"
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"runtime"
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"strings"
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)
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type Handler func(*Job) Status
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var globalHandlers map[string]Handler
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func init() {
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globalHandlers = make(map[string]Handler)
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}
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func Register(name string, handler Handler) error {
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_, exists := globalHandlers[name]
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if exists {
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return fmt.Errorf("Can't overwrite global handler for command %s", name)
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}
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globalHandlers[name] = handler
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return nil
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}
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// The Engine is the core of Docker.
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// It acts as a store for *containers*, and allows manipulation of these
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// containers by executing *jobs*.
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type Engine struct {
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root string
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handlers map[string]Handler
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hack Hack // data for temporary hackery (see hack.go)
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id string
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}
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func (eng *Engine) Root() string {
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return eng.root
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}
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func (eng *Engine) Register(name string, handler Handler) error {
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eng.Logf("Register(%s) (handlers=%v)", name, eng.handlers)
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_, exists := eng.handlers[name]
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if exists {
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return fmt.Errorf("Can't overwrite handler for command %s", name)
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}
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eng.handlers[name] = handler
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return nil
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}
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// New initializes a new engine managing the directory specified at `root`.
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// `root` is used to store containers and any other state private to the engine.
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// Changing the contents of the root without executing a job will cause unspecified
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// behavior.
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func New(root string) (*Engine, error) {
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// Check for unsupported architectures
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if runtime.GOARCH != "amd64" {
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return nil, fmt.Errorf("The docker runtime currently only supports amd64 (not %s). This will change in the future. Aborting.", runtime.GOARCH)
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}
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// Check for unsupported kernel versions
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// FIXME: it would be cleaner to not test for specific versions, but rather
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// test for specific functionalities.
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// Unfortunately we can't test for the feature "does not cause a kernel panic"
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// without actually causing a kernel panic, so we need this workaround until
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// the circumstances of pre-3.8 crashes are clearer.
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// For details see http://github.com/dotcloud/docker/issues/407
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if k, err := utils.GetKernelVersion(); err != nil {
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log.Printf("WARNING: %s\n", err)
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} else {
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if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {
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log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
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}
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}
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if err := os.MkdirAll(root, 0700); err != nil && !os.IsExist(err) {
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return nil, err
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}
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eng := &Engine{
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root: root,
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handlers: make(map[string]Handler),
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id: utils.RandomString(),
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}
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// Copy existing global handlers
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for k, v := range globalHandlers {
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eng.handlers[k] = v
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}
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return eng, nil
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}
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func (eng *Engine) String() string {
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return fmt.Sprintf("%s|%s", eng.Root(), eng.id[:8])
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}
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// Job creates a new job which can later be executed.
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// This function mimics `Command` from the standard os/exec package.
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func (eng *Engine) Job(name string, args ...string) *Job {
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job := &Job{
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Eng: eng,
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Name: name,
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Args: args,
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Stdin: NewInput(),
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Stdout: NewOutput(),
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Stderr: NewOutput(),
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}
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job.Stdout.Add(utils.NopWriteCloser(os.Stdout))
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job.Stderr.Add(utils.NopWriteCloser(os.Stderr))
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handler, exists := eng.handlers[name]
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if exists {
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job.handler = handler
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}
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return job
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}
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func (eng *Engine) Logf(format string, args ...interface{}) (n int, err error) {
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prefixedFormat := fmt.Sprintf("[%s] %s\n", eng, strings.TrimRight(format, "\n"))
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return fmt.Fprintf(os.Stderr, prefixedFormat, args...)
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}
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