New plugin args option

Signed-off-by: Dave Henderson <[email protected]>

docs/content/config.md

@@ -304,15 +304,19 @@ See [`--plugin`](../usage/#plugin).
 A map that configures custom functions for use in the templates. The key is the
 name of the function, and the value configures the plugin. The value is a map
 containing the command (`cmd`) and the options `pipe` (boolean) and `timeout`
-(duration).
+(duration). A list of optional arguments to always pass to the plugin can be set
+with `args` (array of strings).
 
-Alternatively, the value can be a string, which sets `cmd`.
+Alternatively, the value can be a string, which sets only `cmd`.
 
 ```yaml
-in: '{{ "hello world" | figlet | lolcat }}'
+in: '{{ "world" | figlet | lolcat }}'
 plugins:
   figlet:
     cmd: /usr/local/bin/figlet
+    args:
+      - oh
+      - hello
     pipe: true
     timeout: 1s
   lolcat: /home/hairyhenderson/go/bin/lolcat
@@ -322,6 +326,33 @@ plugins:
 
 The path to the plugin executable (or script) to run.
 
+### `args`
+
+An array of optional arguments to always pass to the plugin. These arguments
+will be passed _before_ any arguments provided in the template.
+
+For example:
+
+```yaml
+plugins:
+  echo:
+    cmd: /bin/echo
+    args:
+      - foo
+      - bar
+```
+
+With this template:
+```
+{{ echo "baz" }}
+```
+
+Will result the command being called like this:
+
+```console
+$ /bin/echo foo bar baz
+```
+
 ### `pipe`
 
 Whether to pipe the final argument of the template function to the plugin's

plugins.go

@@ -49,6 +49,10 @@ type PluginOpts struct {
 	// Defaults to os.Stderr.
 	Stderr io.Writer
 
+	// Args are additional arguments to pass to the plugin. These precede any
+	// arguments passed to the plugin function at runtime.
+	Args []string
+
 	// Timeout is the maximum amount of time to wait for the plugin to complete.
 	// Defaults to 5 seconds.
 	Timeout time.Duration
@@ -74,6 +78,7 @@ func PluginFunc(ctx context.Context, cmd string, opts PluginOpts) func(...interf
 	plugin := &plugin{
 		ctx:     ctx,
 		path:    cmd,
+		args:    opts.Args,
 		timeout: timeout,
 		pipe:    opts.Pipe,
 		stderr:  stderr,
@@ -87,6 +92,7 @@ type plugin struct {
 	ctx     context.Context
 	stderr  io.Writer
 	path    string
+	args    []string
 	timeout time.Duration
 	pipe    bool
 }
@@ -122,6 +128,7 @@ func findPowershell() string {
 
 func (p *plugin) run(args ...interface{}) (interface{}, error) {
 	a := conv.ToStrings(args...)
+	a = append(p.args, a...)
 
 	name, a := p.buildCommand(a)
 

plugins_test.go

@@ -73,6 +73,30 @@ func TestRun(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, "", stderr.String())
 	assert.Equal(t, "foo", strings.TrimSpace(out.(string)))
+
+	p = &plugin{
+		ctx:     ctx,
+		timeout: 500 * time.Millisecond,
+		stderr:  stderr,
+		path:    "echo",
+		args:    []string{"foo", "bar"},
+	}
+	out, err = p.run()
+	require.NoError(t, err)
+	assert.Equal(t, "", stderr.String())
+	assert.Equal(t, "foo bar", strings.TrimSpace(out.(string)))
+
+	p = &plugin{
+		ctx:     ctx,
+		timeout: 500 * time.Millisecond,
+		stderr:  stderr,
+		path:    "echo",
+		args:    []string{"foo", "bar"},
+	}
+	out, err = p.run("baz", "qux")
+	require.NoError(t, err)
+	assert.Equal(t, "", stderr.String())
+	assert.Equal(t, "foo bar baz qux", strings.TrimSpace(out.(string)))
 }
 
 func ExamplePluginFunc() {