provisioner/chef-solo: ability to specify custom chef template

CHANGELOG.md

 ## 0.3.8 (unreleased)
 
+FEATURES:
+
+* provisioner/chef-solo: Ability to specify a custom Chef configuration
+  template.
+
 IMPROVEMENTS:
 
 * builder/amazon/*: Interrupts work while waiting for AMI to be ready.

provisioner/chef-solo/provisioner.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"github.com/mitchellh/packer/common"
 	"github.com/mitchellh/packer/packer"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -17,6 +18,7 @@ import (
 type Config struct {
 	common.PackerConfig `mapstructure:",squash"`
 
+	ConfigTemplate      string   `mapstructure:"config_template"`
 	CookbookPaths       []string `mapstructure:"cookbook_paths"`
 	ExecuteCommand      string   `mapstructure:"execute_command"`
 	InstallCommand      string   `mapstructure:"install_command"`
@@ -80,7 +82,8 @@ func (p *Provisioner) Prepare(raws ...interface{}) error {
 	errs := common.CheckUnusedConfig(md)
 
 	templates := map[string]*string{
-		"staging_dir": &p.config.StagingDir,
+		"config_template": &p.config.ConfigTemplate,
+		"staging_dir":     &p.config.StagingDir,
 	}
 
 	for n, ptr := range templates {
@@ -121,6 +124,17 @@ func (p *Provisioner) Prepare(raws ...interface{}) error {
 		}
 	}
 
+	if p.config.ConfigTemplate != "" {
+		fi, err := os.Stat(p.config.ConfigTemplate)
+		if err != nil {
+			errs = packer.MultiErrorAppend(
+				errs, fmt.Errorf("Bad config template path: %s", err))
+		} else if fi.IsDir() {
+			errs = packer.MultiErrorAppend(
+				errs, fmt.Errorf("Config template path must be a file: %s", err))
+		}
+	}
+
 	for _, path := range p.config.CookbookPaths {
 		pFileInfo, err := os.Stat(path)
 
@@ -216,7 +230,24 @@ func (p *Provisioner) createConfig(ui packer.Ui, comm packer.Communicator, local
 		cookbook_paths[i] = fmt.Sprintf(`"%s"`, path)
 	}
 
-	configString, err := p.config.tpl.Process(DefaultConfigTemplate, &ConfigTemplate{
+	// Read the template
+	tpl := DefaultConfigTemplate
+	if p.config.ConfigTemplate != "" {
+		f, err := os.Open(p.config.ConfigTemplate)
+		if err != nil {
+			return "", err
+		}
+		defer f.Close()
+
+		tplBytes, err := ioutil.ReadAll(f)
+		if err != nil {
+			return "", err
+		}
+
+		tpl = string(tplBytes)
+	}
+
+	configString, err := p.config.tpl.Process(tpl, &ConfigTemplate{
 		CookbookPaths: strings.Join(cookbook_paths, ","),
 	})
 	if err != nil {

provisioner/chef-solo/provisioner_test.go

@@ -19,6 +19,49 @@ func TestProvisioner_Impl(t *testing.T) {
 	}
 }
 
+func TestProvisionerPrepare_configTemplate(t *testing.T) {
+	var err error
+	var p Provisioner
+
+	// Test no config template
+	config := testConfig()
+	delete(config, "config_template")
+	err = p.Prepare(config)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Test with a file
+	tf, err := ioutil.TempFile("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Remove(tf.Name())
+
+	config = testConfig()
+	config["config_template"] = tf.Name()
+	p = Provisioner{}
+	err = p.Prepare(config)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Test with a directory
+	td, err := ioutil.TempDir("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(td)
+
+	config = testConfig()
+	config["config_template"] = td
+	p = Provisioner{}
+	err = p.Prepare(config)
+	if err == nil {
+		t.Fatal("should have err")
+	}
+}
+
 func TestProvisionerPrepare_cookbookPaths(t *testing.T) {
 	var p Provisioner
 

website/source/docs/provisioners/chef-solo.html.markdown

@@ -32,6 +32,13 @@ The example below is fully functional and expects cookbooks in the
 The reference of available configuration options is listed below. No
 configuration is actually required, but at least `run_list` is recommended.
 
+* `config_template` (string) - Path to a template that will be used for
+  the Chef configuration file. By default Packer only sets configuration
+  it needs to match the settings set in the provisioner configuration. If
+  you need to set configurations that the Packer provisioner doesn't support,
+  then you should use a custom configuration template. See the dedicated
+  "Chef Configuration" section below for more details.
+
 * `cookbook_paths` (array of strings) - This is an array of paths to
   "cookbooks" directories on your local filesystem. These will be uploaded
   to the remote machine in the directory specified by the `staging_directory`.
@@ -70,6 +77,25 @@ configuration is actually required, but at least `run_list` is recommended.
   this folder. If the permissions are not correct, use a shell provisioner
   prior to this to configure it properly.
 
+## Chef Configuration
+
+By default, Packer uses a simple Chef configuration file in order to set
+the options specified for the provisioner. But Chef is a complex tool that
+supports many configuration options. Packer allows you to specify a custom
+configuration template if you'd like to set custom configurations.
+
+The default value for the configuration template is:
+
+```
+cookbook_path [{{.CookbookPaths}}]
+```
+
+This template is a [configuration template](/docs/templates/configuration-templates.html)
+and has a set of variables available to use:
+
+* `CookbookPaths` is the set of cookbook paths ready to embedded directly
+  into a Ruby array to configure Chef.
+
 ## Execute Command
 
 By default, Packer uses the following command (broken across multiple lines