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moby--moby/engine/job.go

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package engine
import (
"bytes"
"io"
"strings"
"fmt"
"encoding/json"
)
// A job is the fundamental unit of work in the docker engine.
// Everything docker can do should eventually be exposed as a job.
// For example: execute a process in a container, create a new container,
// download an archive from the internet, serve the http api, etc.
//
// The job API is designed after unix processes: a job has a name, arguments,
// environment variables, standard streams for input, output and error, and
// an exit status which can indicate success (0) or error (anything else).
//
// One slight variation is that jobs report their status as a string. The
// string "0" indicates success, and any other strings indicates an error.
// This allows for richer error reporting.
//
type Job struct {
Eng *Engine
Name string
Args []string
env []string
Stdin io.ReadCloser
Stdout io.WriteCloser
Stderr io.WriteCloser
handler func(*Job) string
status string
}
// Run executes the job and blocks until the job completes.
// If the job returns a failure status, an error is returned
// which includes the status.
func (job *Job) Run() error {
job.Logf("{")
defer func() {
job.Logf("}")
}()
if job.handler == nil {
job.status = "command not found"
} else {
job.status = job.handler(job)
}
if job.status != "0" {
return fmt.Errorf("%s: %s", job.Name, job.status)
}
return nil
}
// String returns a human-readable description of `job`
func (job *Job) String() string {
s := fmt.Sprintf("%s.%s(%s)", job.Eng, job.Name, strings.Join(job.Args, ", "))
// FIXME: if a job returns the empty string, it will be printed
// as not having returned.
// (this only affects String which is a convenience function).
if job.status != "" {
var okerr string
if job.status == "0" {
okerr = "OK"
} else {
okerr = "ERR"
}
s = fmt.Sprintf("%s = %s (%s)", s, okerr, job.status)
}
return s
}
func (job *Job) Getenv(key string) (value string) {
for _, kv := range job.env {
if strings.Index(kv, "=") == -1 {
continue
}
parts := strings.SplitN(kv, "=", 2)
if parts[0] != key {
continue
}
if len(parts) < 2 {
value = ""
} else {
value = parts[1]
}
}
return
}
func (job *Job) GetenvBool(key string) (value bool) {
s := strings.ToLower(strings.Trim(job.Getenv(key), " \t"))
if s == "" || s == "0" || s == "no" || s == "false" || s == "none" {
return false
}
return true
}
func (job *Job) SetenvBool(key string, value bool) {
if value {
job.Setenv(key, "1")
} else {
job.Setenv(key, "0")
}
}
func (job *Job) GetenvList(key string) []string {
sval := job.Getenv(key)
l := make([]string, 0, 1)
if err := json.Unmarshal([]byte(sval), &l); err != nil {
l = append(l, sval)
}
return l
}
func (job *Job) SetenvList(key string, value []string) error {
sval, err := json.Marshal(value)
if err != nil {
return err
}
job.Setenv(key, string(sval))
return nil
}
func (job *Job) Setenv(key, value string) {
job.env = append(job.env, key + "=" + value)
}
// DecodeEnv decodes `src` as a json dictionary, and adds
// each decoded key-value pair to the environment.
//
// If `text` cannot be decoded as a json dictionary, an error
// is returned.
func (job *Job) DecodeEnv(src io.Reader) error {
m := make(map[string]interface{})
if err := json.NewDecoder(src).Decode(&m); err != nil {
return err
}
for k, v := range m {
if sval, ok := v.(string); ok {
job.Setenv(k, sval)
} else if val, err := json.Marshal(v); err == nil {
job.Setenv(k, string(val))
} else {
job.Setenv(k, fmt.Sprintf("%v", v))
}
}
return nil
}
func (job *Job) EncodeEnv(dst io.Writer) error {
return json.NewEncoder(dst).Encode(job.Environ())
}
func (job *Job) ExportEnv(dst interface{}) error {
var buf bytes.Buffer
if err := job.EncodeEnv(&buf); err != nil {
return err
}
if err := json.NewDecoder(&buf).Decode(dst); err != nil {
return err
}
return nil
}
func (job *Job) ImportEnv(src interface{}) error {
var buf bytes.Buffer
if err := json.NewEncoder(&buf).Encode(src); err != nil {
return err
}
if err := job.DecodeEnv(&buf); err != nil {
return err
}
return nil
}
func (job *Job) Environ() map[string]string {
m := make(map[string]string)
for _, kv := range job.env {
parts := strings.SplitN(kv, "=", 2)
m[parts[0]] = parts[1]
}
return m
}
func (job *Job) Logf(format string, args ...interface{}) (n int, err error) {
prefixedFormat := fmt.Sprintf("[%s] %s\n", job, strings.TrimRight(format, "\n"))
return fmt.Fprintf(job.Stdout, prefixedFormat, args...)
}