# Drone-convert-starlark and drone-cli uses different versions and script errors are unhelpful **URL:** \ **Category:** Drone Bugs\ **Created:** [March 5, 2020, 12:23pm UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881 "2020-03-05T12:23:15Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![thomasf](https://yyz1.discourse-cdn.com/flex003/user_avatar/drone.discourse.group/thomasf/32/3650_2.png) [@thomasf](https://drone.discourse.group/u/thomasf)\ **Post date:** [March 5, 2020, 12:23pm UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881/1 "2020-03-05T12:23:15Z")
the one in drone-cli go.mod lacks starlark features. In any case I was trying to use the `fail()` builtin to add validation inside a complex build and it isnt defined. Upgrading to latest version in drone cli solved it, I have no idea if the version in the starlark convert plugin is new enough to support it but at least for now I can use `fail` while developing the starlark drone build. ```diff iff --git a/go.mod b/go.mod index ffefde4..80178bc 100644 --- a/go.mod +++ b/go.mod @@ -34,11 +34,11 @@ require ( github.com/pkg/errors v0.8.0 github.com/urfave/cli v1.20.0 github.com/vinzenz/yaml v0.0.0-20170920082545-91409cdd725d - go.starlark.net v0.0.0-20190219202100-4eb76950c5f0 + go.starlark.net v0.0.0-20200203144150-6677ee5c7211 golang.org/x/net v0.0.0-20181005035420-146acd28ed58 golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f - golang.org/x/sys v0.0.0-20181005133103-4497e2df6f9e + golang.org/x/sys v0.0.0-20191002063906-3421d5a6bb1c google.golang.org/appengine v1.3.0 gopkg.in/yaml.v2 v2.2.2 ) ``` the one in the convert plugin is ```auto go.starlark.net v0.0.0-20190820173200-988906f77f65 ``` ```auto ▶13 ~/src/.../api git:drone-starlark?*+ :27 tf@whale!$ watchexec -e .star -- 'drone starlark && drone fmt --save && cat .drone.yml' 2020/03/05 13:27:37 .drone.star:90:5: undefined: fail ^C (...upgrading starlark..) ▶13 ~/src/.../api git:drone-starlark?*+ :27 tf@whale!$ watchexec -e .star -- 'drone starlark && drone fmt --save && cat .drone.yml' 2020/03/05 13:27:50 fail: asd ``` ---
**Author:** ![thomasf](https://yyz1.discourse-cdn.com/flex003/user_avatar/drone.discourse.group/thomasf/32/3650_2.png) [@thomasf](https://drone.discourse.group/u/thomasf)\ **Post date:** [March 5, 2020, 6:16pm UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881/2 "2020-03-05T18:16:17Z")
if its worth anything as far as testing goes I have been converting a thousand+ lines yml file to a many hundred lines long starlark script today and I am going to continue tomorrow and so far I have not seen any issues from upgrading the dep in drone-cli. I will probably continue doing this for a client tomorrow and if it works out well maybe for a few weeks as well ---
**Author:** ![thomasf](https://yyz1.discourse-cdn.com/flex003/user_avatar/drone.discourse.group/thomasf/32/3650_2.png) [@thomasf](https://drone.discourse.group/u/thomasf)\ **Post date:** [March 6, 2020, 9:04am UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881/3 "2020-03-06T09:04:35Z")
I got into a situation where I had a problem where I needed some context form the error output… So I made another small chage in drone-cli ```diff diff --git a/drone/starlark/starlark.go b/drone/starlark/starlark.go index 9ac77a2..b0fa794 100644 --- a/drone/starlark/starlark.go +++ b/drone/starlark/starlark.go @@ -154,6 +154,9 @@ func generate(c *cli.Context) error { }) mainVal, err = starlark.Call(thread, main, args, nil) if err != nil { + if e, ok := err.(*starlark.EvalError); ok { + return fmt.Errorf("starlark eval error:\n%s", e.Backtrace()) + } return err } ``` without changes you get a kind of useless error message: ```auto 2020/03/06 10:03:44 update: got NoneType, want iterable ``` with changes: ```auto 2020/03/06 10:04:14 starlark eval error: Traceback (most recent call last): .drone.star:20:21: in main .drone.star:115:23: in tag_pipeline .drone.star:477:20: in ecs_stage_step .drone.star:436:24: in ecs_step : in update Error: update: got NoneType, want iterable ``` ---
**Author:** ![thomasf](https://yyz1.discourse-cdn.com/flex003/user_avatar/drone.discourse.group/thomasf/32/3650_2.png) [@thomasf](https://drone.discourse.group/u/thomasf)\ **Post date:** [March 6, 2020, 11:10am UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881/4 "2020-03-06T11:10:52Z")
since drone calls starlark at multiple stages I have changed it to this now: ```diff diff --git a/drone/starlark/starlark.go b/drone/starlark/starlark.go index 9ac77a2..cccbba1 100644 --- a/drone/starlark/starlark.go +++ b/drone/starlark/starlark.go @@ -99,6 +99,7 @@ var Command = cli.Command{ } func generate(c *cli.Context) error { + source := c.String("source") target := c.String("target") @@ -114,7 +115,7 @@ func generate(c *cli.Context) error { } globals, err := starlark.ExecFile(thread, source, data, nil) if err != nil { - return err + return prettyStarlarkError(err) } mainVal, ok := globals["main"] @@ -154,9 +155,8 @@ func generate(c *cli.Context) error { }) mainVal, err = starlark.Call(thread, main, args, nil) if err != nil { - return err + return prettyStarlarkError(err) } - buf := new(bytes.Buffer) switch v := mainVal.(type) { case *starlark.List: @@ -304,7 +304,7 @@ func makeLoad() func(thread *starlark.Thread, module string) (starlark.StringDic // Load it. thread := &starlark.Thread{Name: "exec " + module, Load: thread.Load} globals, err := starlark.ExecFile(thread, module, nil, nil) - e = &entry{globals, err} + e = &entry{globals, prettyStarlarkError(err)} // Update the cache. cache[module] = e @@ -312,3 +312,12 @@ func makeLoad() func(thread *starlark.Thread, module string) (starlark.StringDic return e.globals, e.err } } + +// prettyStarlarkError returns a suitable human readable error for a +// starlark.Exec error or returns the error unmodified. +func prettyStarlarkError(err error) error { + if err, ok := err.(*starlark.EvalError); ok { + return fmt.Errorf("starlark eval error:\n%s", err.Backtrace()) + } + return err +} ``` ---
**Author:** ![thomasf](https://yyz1.discourse-cdn.com/flex003/user_avatar/drone.discourse.group/thomasf/32/3650_2.png) [@thomasf](https://drone.discourse.group/u/thomasf)\ **Post date:** [March 7, 2020, 12:23pm UTC](https://drone.discourse.group/t/drone-convert-starlark-and-drone-cli-uses-different-versions-and-script-errors-are-unhelpful/8881/5 "2020-03-07T12:23:15Z")
I made 2 pull requests for this, added backtraces to the error messages of both projects and upped the starlark version to the same latest version that has the fail builtin for sure. > >