add variable support.

Readme.md

@@ -157,6 +157,27 @@ events:
  command: robo events gy2d 25
 ```
 
+### Variables
+
+ Robo supports variables via the [text/template](https://golang.org/pkg/text/template/) package. All you have to do is define a map of `variables` and use `{{` `}}` to refer to them.
+
+ Here's an example:
+
+```yml
+stage:
+ summary: Run commands against stage.
+ command: ssh {{.hosts.stage}} -t robo
+
+prod:
+ summary: Run commands against prod.
+ command: ssh {{.hosts.prod}} -t robo
+
+variables:
+ hosts:
+ prod: bastion-prod
+ stage: bastion-stage
+```
+
 ### Templates
 
  Task `list` and `help` output may be re-configured, for example if you

config/config.go

@@ -2,11 +2,14 @@ package config
 
 import "github.com/tj/robo/task"
 import "gopkg.in/yaml.v2"
+import "text/template"
 import "io/ioutil"
+import "bytes"
 
 // Config.
 type Config struct {
  Tasks map[string]*task.Task `yaml:",inline"`
+ Variables map[string]interface{}
  Templates struct {
  List string
  Help string
@@ -27,14 +30,52 @@ func New(file string) (*Config, error) {
 func NewString(s string) (*Config, error) {
  c := new(Config)
 
+ // unmarshal
  err := yaml.Unmarshal([]byte(s), &c)
  if err != nil {
  return nil, err
  }
 
+ // assign .Name
  for name, task := range c.Tasks {
  task.Name = name
  }
 
+ // interpolation
+ for _, task := range c.Tasks {
+ err := interpolate(c.Variables, &task.Command, &task.Summary, &task.Script, &task.Exec)
+ if err != nil {
+ return nil, err
+ }
+ }
+
  return c, nil
 }
+
+// Apply interpolation against the given strings.
+func interpolate(v interface{}, s ...*string) error {
+ for _, p := range s {
+ ret, err := eval(*p, v)
+ if err != nil {
+ return err
+ }
+ *p = ret
+ }
+ return nil
+}
+
+// Evaluate template against `v`.
+func eval(s string, v interface{}) (string, error) {
+ t, err := template.New("task").Parse(s)
+ if err != nil {
+ return "", err
+ }
+
+ var b bytes.Buffer
+ err = t.Execute(&b, v)
+ if err != nil {
+ return "", err
+ }
+
+ return string(b.Bytes()), nil
+}

config/config_test.go

@@ -13,14 +13,30 @@ bar:
  summary: Command bar.
  command: echo "bar"
 
+stage:
+ summary: Run commands against stage.
+ command: ssh {{.hosts.stage}} -t robo
+
+prod:
+ summary: Run commands against prod.
+ command: ssh {{.hosts.prod}} -t robo
+
 templates:
  list: testing
+
+variables:
+ hosts:
+ prod: bastion-prod
+ stage: bastion-stage
 `
 
 func TestNewString(t *testing.T) {
  c, err := config.NewString(s)
  assert.Equal(t, nil, err)
- assert.Equal(t, 2, len(c.Tasks))
+ assert.Equal(t, 4, len(c.Tasks))
+
+ assert.Equal(t, `ssh bastion-stage -t robo`, c.Tasks["stage"].Command)
+ assert.Equal(t, `ssh bastion-prod -t robo`, c.Tasks["prod"].Command)
 
  assert.Equal(t, `foo`, c.Tasks["foo"].Name)
  assert.Equal(t, `Command foo.`, c.Tasks["foo"].Summary)