Improve WASM runtime error messages by adding a function to retrieve errors from resourceList #978

wleese · 2023-02-20T12:24:24Z

We'd like WASM compiled functions to provide the same information as those run in docker and aims to solve kptdev/kpt#3822

This PR also resolves a panic that can occur when an error is returned in the constructed javascript function.

In order to actually surface the error messages, the kpt wasm function runner needs to be modified.

This can be tested with:

Kptfile

apiVersion: kpt.dev/v1
kind: Kptfile
metadata:
  name: kpt
  annotations:
    config.kubernetes.io/local-config: "true"
info:
  description: this package provides the parent package for your application
pipeline:
  mutators:
    - image: gcr.io/kpt-fn/starlark:v0.4.3
      configPath: starlarkconfig.yaml

resources.yaml

apiVersion: iam.cnrm.cloud.google.com/v1beta1
kind: IAMPolicyMember
metadata:
  name: bucket-read-write-by-service-account-diogotuesday274
  namespace: bb8-tuesdayds

starlarkconfig.yaml

apiVersion: fn.kpt.dev/v1alpha1
kind: StarlarkRun
metadata:
  name: apply-team-name-to-iampolicymember
source: |
  team = ctx.resource_list["functionConfig"]["params"]["team"]

And running:
kpt fn render . --allow-alpha-wasm
and
KPT_FN_WASM_RUNTIME=nodejs kpt fn render . --allow-alpha-wasm

wleese · 2023-02-21T07:31:50Z

functions/go/apply-replacements/run_js.go

-	// Currently error is surfaced as a string.
-	jsonFunc := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+func resourceListProcessorWrapper(resourceList *[]byte) js.Func {
+	jsonFunc := js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) != 1 {
 			return "Invalid number of arguments passed"


Perhaps this entire function could simply either return the resourceList or empty string, always deferring to the other function to get error messages, rather than mixing those approaches. Would require an update to kptdev/kpt#3830 if we take that route.

That's a good point. I think deferring to the other function to get errors makes a lot of sense. Would like to hear @droot @mortent opinion on this.

sdowell · 2023-02-21T19:32:46Z

Thank you for the PR! Could you add some unit/e2e tests to verify and document the behavior of this change?

yuwenma · 2023-02-21T19:37:10Z

Thank you so much for making the change. The PR makes a lot of sense to me. I just have a comment about the potential risk conditions to pull out the ResourceList.Results errors.

Can you also share the your testing steps (test data, command to reproduce) in the PR description?

yuwenma · 2023-02-21T19:37:21Z

cc @natasha41575

yuwenma · 2023-02-21T19:12:07Z

functions/go/apply-setters/generated/docs.go

-  $ kpt fn eval --image gcr.io/kpt-fn/apply-setters:unstable -- image=ubuntu replicas=3
+  $ kpt fn eval --image gcr.io/kpt-fn/apply-setters:unstable -- tag=1.16.2 nginx-replicas=3


qq: do we need to change this example?

(I had no intention of making this change btw. It probably was made when running make)

yuwenma · 2023-02-21T19:18:09Z

functions/go/apply-replacements/run_js.go

-	// Currently error is surfaced as a string.
-	jsonFunc := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+func resourceListProcessorWrapper(resourceList *[]byte) js.Func {
+	jsonFunc := js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) != 1 {
 			return "Invalid number of arguments passed"


That's a good point. I think deferring to the other function to get errors makes a lot of sense. Would like to hear @droot @mortent opinion on this.

yuwenma · 2023-02-21T19:35:46Z

functions/go/apply-replacements/run_js.go

+			return ""
+		}
+		errorMessages := ""
+		for _, r := range(rl.Results) {


When running in a pipeline, the function only appends Results to ResourceList.Results but not override the existing ones. So this resourceListProcessorErrors may get irrelevant error Results (from previous functions' results).

I'd suggest at least adding a comment to notify future contributors about this since it could cause some unexpected failures in certain risk conditions.

wleese · 2023-02-21T19:57:05Z

Thank you so much for making the change. The PR makes a lot of sense to me. I just have a comment about the potential risk conditions to pull out the ResourceList.Results errors.

Can you also share the your testing steps (test data, command to reproduce) in the PR description?

I've added a copy & paste from the linked issue at the top of this PR, as those resources can be used to reproduce.

wleese · 2023-02-21T20:06:13Z

Thank you for the PR! Could you add some unit/e2e tests to verify and document the behavior of this change?

I can do this, although it will take some time (don't have a golang background)

natasha41575 · 2023-02-21T20:26:34Z

Thank you for the PR! Could you add some unit/e2e tests to verify and document the behavior of this change?

I can do this, although it will take some time (don't have a golang background)

@wleese If there is a good way to add unit tests, that would be nice, but I don't think we have an existing e2e framework for wasm functions and I don't want to block this PR on that. Adding e2e tests for wasm functions is a separate issue (kptdev/kpt#3587) that could take a while to do. So if you find yourself stuck on a good way to add tests, don't worry about spending too much time on it and IMO we can still accept this PR without them.

yuwenma · 2023-02-21T22:34:26Z

Thank you for the PR! Could you add some unit/e2e tests to verify and document the behavior of this change?

I can do this, although it will take some time (don't have a golang background)

@wleese If there is a good way to add unit tests, that would be nice, but I don't think we have an existing e2e framework for wasm functions and I don't want to block this PR on that. Adding e2e tests for wasm functions is a separate issue (GoogleContainerTools/kpt#3587) that could take a while to do. So if you find yourself stuck on a good way to add tests, don't worry about spending too much time on it and IMO we can still accept this PR without them.

Good catch and suggestion, @sdowell and @natasha41575 Yeah, I think adding the test steps in the PR description is good enough for this PR. We'd like to help and make the contribution experience easier for active users and contributors.

wleese · 2023-02-22T06:57:10Z

Thanks!

Add a function to retrieve errors

c2b6dc5

wleese requested review from droot, sdowell and yuwenma as code owners February 20, 2023 12:24

wleese mentioned this pull request Feb 20, 2023

Improve wasm errors kptdev/kpt#3830

Merged

wleese commented Feb 21, 2023

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wleese changed the title ~~Add a function to retrieve errors~~ Improve WASM runtime error messages by adding a function to retrieve errors from resourceList Feb 21, 2023

yuwenma reviewed Feb 21, 2023

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yuwenma approved these changes Feb 21, 2023

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yuwenma merged commit 6948151 into GoogleContainerTools:master Feb 21, 2023

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Improve WASM runtime error messages by adding a function to retrieve errors from resourceList #978

Improve WASM runtime error messages by adding a function to retrieve errors from resourceList #978

wleese commented Feb 20, 2023 •

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wleese Feb 21, 2023

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wleese commented Feb 21, 2023

natasha41575 commented Feb 21, 2023 •

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yuwenma commented Feb 21, 2023

wleese commented Feb 22, 2023

		$ kpt fn eval --image gcr.io/kpt-fn/apply-setters:unstable -- image=ubuntu replicas=3
		$ kpt fn eval --image gcr.io/kpt-fn/apply-setters:unstable -- tag=1.16.2 nginx-replicas=3

Improve WASM runtime error messages by adding a function to retrieve errors from resourceList #978

Improve WASM runtime error messages by adding a function to retrieve errors from resourceList #978

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