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Introduce variable map self-interpolation and command variable interp…
…olation. A variable in the variables section can now reference another variable and will get populated before an actual task’s content will get populated. Additionally to self-referencing variables `$()` will run a command and capture the output into a variable.
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Jens Petersohn
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Sep 2, 2020
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,122 @@ | ||
| // Package interpolation provides methods to interpolate user defined variables and robo tasks. | ||
| package interpolation | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "fmt" | ||
| "github.com/tj/robo/task" | ||
| "gopkg.in/yaml.v2" | ||
| "os" | ||
| "os/exec" | ||
| "regexp" | ||
| "strings" | ||
| "text/template" | ||
| ) | ||
|
|
||
| var commandPattern = regexp.MustCompile("\\$\\((.+)\\)") | ||
|
|
||
| // Vars interpolates a given map of interfaces (strings or submaps) with itself | ||
| // returning it mit populated template values. | ||
| func Vars(vars *map[string]interface{}) error { | ||
| b, err := yaml.Marshal(*vars) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| s := string(b) | ||
|
|
||
| err = interpolate("variables", *vars, &s) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| err = interpolateVariableCommands(&s) | ||
| if err != nil { | ||
| return fmt.Errorf("failed replacing variable placeholder with command result") | ||
| } | ||
|
|
||
| err = yaml.Unmarshal([]byte(s), vars) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| return err | ||
| } | ||
|
|
||
| func interpolateVariableCommands(s *string) error { | ||
| // find all commands | ||
| matches := commandPattern.FindAllStringSubmatch(*s, -1) | ||
| for _, match := range matches { | ||
| if len(match) != 2 { | ||
| continue | ||
| } | ||
| cmdOut, err := captureCommandOutput(match[1]) | ||
| if err != nil { | ||
| return fmt.Errorf("error while executing command. Error: %s", err) | ||
| } | ||
| *s = strings.ReplaceAll(*s, match[0], cmdOut) | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // captureCommandOutput executes a command and captures the output which usually gets prompted to stdout. | ||
| func captureCommandOutput(args string) (string, error) { | ||
| var cmd *exec.Cmd | ||
| // try to use the user's default shell. If it is not set via env var fall back to `sh`. | ||
| if defaultShell, ok := os.LookupEnv("SHELL"); ok { | ||
| cmd = exec.Command(defaultShell, "-c", args) | ||
| } else { | ||
| cmd = exec.Command("sh", "-c", args) | ||
| } | ||
| var b bytes.Buffer | ||
| cmd.Stdin = os.Stdin | ||
| cmd.Stdout = &b | ||
| cmd.Stderr = os.Stderr | ||
| err := cmd.Run() | ||
| return strings.TrimSuffix(string(b.Bytes()), "\n"), err | ||
| } | ||
|
|
||
| // Tasks interpolates a given task with a set of data replacing placeholders | ||
| // in the command, summary, script, exec and envs property. | ||
| func Tasks(tasks map[string]*task.Task, data map[string]interface{}) error { | ||
| for _, task := range tasks { | ||
| // interpolate the tasks main fields | ||
| err := interpolate( | ||
| "task", | ||
| data, | ||
| &task.Command, | ||
| &task.Summary, | ||
| &task.Script, | ||
| &task.Exec, | ||
| ) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| // interpolate a tasks environment data | ||
| for i, item := range task.Env { | ||
| if err := interpolate("env-var", data, &item); err != nil { | ||
| return err | ||
| } | ||
| task.Env[i] = item | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // interpolate populates a given slice of templates with actual values provided | ||
| // in the data parameter. | ||
| func interpolate(name string, data interface{}, temps ...*string) error { | ||
| for _, temp := range temps { | ||
| t, err := template.New(name).Parse(*temp) | ||
| if err != nil { | ||
| return err | ||
| } | ||
|
|
||
| var b bytes.Buffer | ||
| err = t.Execute(&b, data) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| *temp = string(b.Bytes()) | ||
| } | ||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,55 @@ | ||
| package interpolation | ||
|
|
||
| import ( | ||
| "github.com/bmizerany/assert" | ||
| "github.com/tj/robo/task" | ||
| "testing" | ||
| ) | ||
|
|
||
| func TestVars_whenValueReferencesOtherKey_shouldReplaceAccordingly(t *testing.T) { | ||
| vars := map[string]interface{}{ | ||
| "foo": "Hello", | ||
| "bar": "{{ .foo }} World!", | ||
| } | ||
| err := Vars(&vars) | ||
|
|
||
| assert.Equal(t, nil, err) | ||
| assert.Equal(t, "Hello", vars["foo"]) | ||
| assert.Equal(t, "Hello World!", vars["bar"]) | ||
| } | ||
|
|
||
| func TestVars_whenValueIsCommand_shouldReplaceWithCommandResult(t *testing.T) { | ||
| vars := map[string]interface{}{ | ||
| "foo": "$(echo Hello)", | ||
| "bar": | ||
| map[string]interface{}{ | ||
| "sub": "$(echo World!)", | ||
| }, | ||
| } | ||
|
|
||
| err := Vars(&vars) | ||
|
|
||
| assert.Equal(t, nil, err) | ||
| assert.Equal(t, "Hello", vars["foo"]) | ||
| assert.Equal(t, "World!", vars["bar"].(map[interface{}]interface{})["sub"]) | ||
| } | ||
|
|
||
| func TestTasks(t *testing.T) { | ||
| tk := task.Task{ | ||
| Summary: "This task handles {{ .foo }} World!", | ||
| Command: "echo {{ .foo }} World!", | ||
| Script: "/path/to/{{ .foo }}.sh", | ||
| Exec: "{{ .foo }} World!", | ||
| Env: []string{"bar={{ .foo }} World!"}, | ||
| } | ||
|
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| vars := map[string]interface{}{"foo": "Hello"} | ||
|
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| err := Tasks(map[string]*task.Task{"tk": &tk}, vars) | ||
| assert.Equal(t, nil, err) | ||
| assert.Equal(t, "This task handles Hello World!", tk.Summary) | ||
| assert.Equal(t, "echo Hello World!", tk.Command) | ||
| assert.Equal(t, "/path/to/Hello.sh", tk.Script) | ||
| assert.Equal(t, "Hello World!", tk.Exec) | ||
| assert.Equal(t, "bar=Hello World!", tk.Env[0]) | ||
| } |