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|
package main
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"github.com/dotcloud/docker"
"os"
"strings"
"text/template"
)
var templates = map[string]string{
"upstart": `description "{{.description}}"
author "{{.author}}"
start on filesystem and started lxc-net and started docker
stop on runlevel [!2345]
respawn
exec /home/vagrant/goroot/bin/docker start -a {{.container_id}}
`,
"systemd": `[Unit]
Description={{.description}}
Author={{.author}}
After=docker.service
[Service]
Restart=always
ExecStart=/usr/bin/docker start -a {{.container_id}}
ExecStop=/usr/bin/docker stop -t 2 {{.container_id}}
[Install]
WantedBy=local.target
`,
}
func main() {
// Parse command line for custom options
kind := flag.String("t", "upstart", "Type of manager requested")
author := flag.String("a", "<none>", "Author of the image")
description := flag.String("d", "<none>", "Description of the image")
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "\nUsage: manager <container id>\n\n")
flag.PrintDefaults()
}
flag.Parse()
// We require at least the container ID
if flag.NArg() != 1 {
println(flag.NArg())
flag.Usage()
return
}
// Check that the requested process manager is supported
if _, exists := templates[*kind]; !exists {
panic("Unknown script template")
}
// Load the requested template
tpl, err := template.New("processManager").Parse(templates[*kind])
if err != nil {
panic(err)
}
// Create stdout/stderr buffers
bufOut := bytes.NewBuffer(nil)
bufErr := bytes.NewBuffer(nil)
// Instanciate the Docker CLI
cli := docker.NewDockerCli(nil, bufOut, bufErr, "unix", "/var/run/docker.sock")
// Retrieve the container info
if err := cli.CmdInspect(flag.Arg(0)); err != nil {
// As of docker v0.6.3, CmdInspect always returns nil
panic(err)
}
// If there is nothing in the error buffer, then the Docker daemon is there and the container has been found
if bufErr.Len() == 0 {
// Unmarshall the resulting container data
c := []*docker.Container{{}}
if err := json.Unmarshal(bufOut.Bytes(), &c); err != nil {
panic(err)
}
// Reset the buffers
bufOut.Reset()
bufErr.Reset()
// Retrieve the info of the linked image
if err := cli.CmdInspect(c[0].Image); err != nil {
panic(err)
}
// If there is nothing in the error buffer, then the image has been found.
if bufErr.Len() == 0 {
// Unmarshall the resulting image data
img := []*docker.Image{{}}
if err := json.Unmarshal(bufOut.Bytes(), &img); err != nil {
panic(err)
}
// If no author has been set, use the one from the image
if *author == "<none>" && img[0].Author != "" {
*author = strings.Replace(img[0].Author, "\"", "", -1)
}
// If no description has been set, use the comment from the image
if *description == "<none>" && img[0].Comment != "" {
*description = strings.Replace(img[0].Comment, "\"", "", -1)
}
}
}
/// Old version: Wrtie the resulting script to file
// f, err := os.OpenFile(kind, os.O_CREATE|os.O_WRONLY, 0755)
// if err != nil {
// panic(err)
// }
// defer f.Close()
// Create a map with needed data
data := map[string]string{
"author": *author,
"description": *description,
"container_id": flag.Arg(0),
}
// Process the template and output it on Stdout
if err := tpl.Execute(os.Stdout, data); err != nil {
panic(err)
}
}
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