Fixed bug #1240667: pin priority for cloud-tools

cloudinit/cloudinit.go

 // Copyright 2011, 2013 Canonical Ltd.
 // Licensed under the AGPLv3, see LICENCE file for details.
 
 // The cloudinit package implements a way of creating
 // a cloud-init configuration file.
 // See https://help.ubuntu.com/community/CloudInit.
 package cloudinit
 
 import (
+        "bytes"
+        "text/template"
+
         yaml "launchpad.net/goyaml"
 )
 
 // Config represents a set of cloud-init configuration options.
 type Config struct {
         attrs map[string]interface{}
 }
 
 // New returns a new Config with no options set.
 func New() *Config {
@@ skipping 11 matching lines @@
 
 func (cfg *Config) set(opt string, yes bool, value interface{}) {
         if yes {
                 cfg.attrs[opt] = value
         } else {
                 delete(cfg.attrs, opt)
         }
 }
 
 // AptSource is an apt(8) source, comprising a source location,
-// with an optional Key.
+// with an optional Key, and optional apt_preferences(5).
 type AptSource struct {
-        Source string `yaml:"source"`
-        Key    string `yaml:"key,omitempty"`
+        Source string          `yaml:"source"`
+        Key    string          `yaml:"key,omitempty"`
+        Prefs  *AptPreferences `yaml:"-"`
+}
+
+// AptPreferences is a set of apt_preferences(5) compatible
+// preferences for an apt source. It can be used to override the
+// default priority for the source. Path where the file will be
+// created (usually in /etc/apt/preferences.d/).
+type AptPreferences struct {
+        Path        string
+        Explanation string
+        Package     string
+        Pin         string
+        PinPriority int
+}
+
+// FileContents generates an apt_preferences(5) file from the fields
+// in prefs.
+func (prefs *AptPreferences) FileContents() string {
+        const prefTemplate = `
+Explanation: {{.Explanation}}
+Package: {{.Package}}
+Pin: {{.Pin}}
+Pin-Priority: {{.PinPriority}}
+`
+        var buf bytes.Buffer
+        t := template.Must(template.New("").Parse(prefTemplate[1:]))
+        err := t.Execute(&buf, prefs)
+        if err != nil {
+                panic(err)
+        }
+        return buf.String()
 }
 
 // command represents a shell command.
 type command struct {
         literal string
         args    []string
 }
 
 // GetYAML implements yaml.Getter
 func (t *command) GetYAML() (tag string, value interface{}) {
         if t.args != nil {
                 return "", t.args
         }
         return "", t.literal
 }
 
 type SSHKeyType string
 
 const (
         RSAPrivate SSHKeyType = "rsa_private"
         RSAPublic  SSHKeyType = "rsa_public"
         DSAPrivate SSHKeyType = "dsa_private"
         DSAPublic  SSHKeyType = "dsa_public"
 )