Allow specification of template delimiters

This PR adds support for specifying the delimiters used in the template.

Fixes #2312

api/tasks.go

@@ -181,6 +181,8 @@ type Template struct {
 	ChangeSignal string
 	Splay        time.Duration
 	Perms        string
+	LeftDelim    *string
+	RightDelim   *string
 }
 
 type Vault struct {

client/consul_template.go

@@ -394,6 +394,8 @@ func parseTemplateConfigs(tmpls []*structs.Template, taskDir string,
 		ct.Source = &src
 		ct.Destination = &dest
 		ct.Contents = &tmpl.EmbeddedTmpl
+		ct.LeftDelim = &tmpl.LeftDelim
+		ct.RightDelim = &tmpl.RightDelim
 
 		// Set the permissions
 		if tmpl.Perms != "" {

jobspec/parse.go

@@ -859,7 +859,9 @@ func parseTemplates(result *[]*structs.Template, list *ast.ObjectList) error {
 			"change_signal",
 			"data",
 			"destination",
+			"left_delimiter",
 			"perms",
+			"right_delimiter",
 			"source",
 			"splay",
 		}

jobspec/parse_test.go

@@ -179,6 +179,8 @@ func TestParse(t *testing.T) {
 										ChangeSignal: "",
 										Splay:        5 * time.Second,
 										Perms:        "777",
+										LeftDelim:    "--",
+										RightDelim:   "__",
 									},
 								},
 								Leader: true,

jobspec/test-fixtures/basic.hcl

@@ -147,6 +147,8 @@ job "binstore-storagelocker" {
         source = "bar"
         destination = "bar"
         perms = "777"
+        left_delimiter = "--"
+        right_delimiter = "__"
       }
     }
 

nomad/structs/structs.go

@@ -2611,6 +2611,11 @@ type Template struct {
 
 	// Perms is the permission the file should be written out with.
 	Perms string `mapstructure:"perms"`
+
+	// LeftDelim and RightDelim are optional configurations to control what
+	// delimiter is utilized when parsing the template.
+	LeftDelim  string `mapstructure:"left_delimiter"`
+	RightDelim string `mapstructure:"right_delimiter"`
 }
 
 // DefaultTemplate returns a default template.

website/source/docs/http/json-jobs.html.md

@@ -661,19 +661,6 @@ README][ct].
 
 `Template` object supports following attributes:
 
-* `SourcePath` - Specifies the path to the template to be rendered. `SourcePath`
-  is mutually exclusive with `EmbeddedTmpl` attribute. The source can be fetched
-  using an [`Artifact`](#artifact) resource. The template must exist on the
-  machine prior to starting the task; it is not possible to reference a template
-  inside of a Docker container, for example.
-
-* `EmbeddedTmpl` -  Specifies the raw template to execute. One of `SourcePath`
-  or `EmbeddedTmpl` must be specified, but not both. This is useful for smaller
-  templates, but we recommend using `SourcePath` for larger templates.
-
-* `DestPath` - Specifies the location where the resulting template should be
-  rendered, relative to the task directory.
-
 - `ChangeMode` - Specifies the behavior Nomad should take if the rendered
   template changes. The default value is `"restart"`. The possible values are:
 
@@ -685,9 +672,30 @@ README][ct].
   "SIGUSR1" or "SIGINT". This option is required if the `ChangeMode` is
   `signal`.
 
-* `perms` - Specifies the rendered template's permissions. File permissions are
+* `DestPath` - Specifies the location where the resulting template should be
+  rendered, relative to the task directory.
+
+* `EmbeddedTmpl` -  Specifies the raw template to execute. One of `SourcePath`
+  or `EmbeddedTmpl` must be specified, but not both. This is useful for smaller
+  templates, but we recommend using `SourcePath` for larger templates.
+
+* `LeftDelim` - Specifies the left delimiter to use in the template. The default
+  is "{{" for some templates, it may be easier to use a different delimiter that
+  does not conflict with the output file itself.
+
+* `Perms` - Specifies the rendered template's permissions. File permissions are
   given as octal of the unix file permissions rwxrwxrwx.
 
+* `RightDelim` - Specifies the right delimiter to use in the template. The default
+  is "}}" for some templates, it may be easier to use a different delimiter that
+  does not conflict with the output file itself.
+
+* `SourcePath` - Specifies the path to the template to be rendered. `SourcePath`
+  is mutually exclusive with `EmbeddedTmpl` attribute. The source can be fetched
+  using an [`Artifact`](#artifact) resource. The template must exist on the
+  machine prior to starting the task; it is not possible to reference a template
+  inside of a Docker container, for example.
+
 * `Splay` - Specifies a random amount of time to wait between 0ms and the given
   splay value before invoking the change mode. Should be specified in
   nanoseconds.

website/source/docs/job-specification/template.html.md

@@ -65,9 +65,17 @@ README][ct].
 - `destination` `(string: <required>)` - Specifies the location where the
   resulting template should be rendered, relative to the task directory.
 
+* `left_delimiter` `(string: "{{")` - Specifies the left delimiter to use in the
+  template. The default is "{{" for some templates, it may be easier to use a
+  different delimiter that does not conflict with the output file itself.
+
 - `perms` `(string: "666")` - Specifies the rendered template's permissions.
   File permissions are given as octal of the unix file permissions rwxrwxrwx.
 
+* `right_delimiter` `(string: "}}")` - Specifies the right delimiter to use in the
+  template. The default is "}}" for some templates, it may be easier to use a
+  different delimiter that does not conflict with the output file itself.
+
 - `source` `(string: "")` - Specifies the path to the template to be rendered.
   One of `source` or `data` must be specified, but not both. This source can
   optionally be fetched using an [`artifact`][artifact] resource. This template