Bug: Incorrect Implementation of --file Option in kn func invoke

[Assassin141]

Summary

The implementation of the --file option in the kn func invoke command encodes the file content as a base64 string, but it is not decoded before being sent, resulting in errors when invoking functions via HTTP or CloudEvents.

Steps to Reproduce

1. Create a JSON file, e.g., test.json, with the following content:

   {
       "id": 123
   }

2. Invoke the function with the command:

   kn func invoke --file ./test.json --content-type application/json --format http -v

3. The output shows:

   Sending values
     ID: 
     Source: /boson/fn
     Type: boson.fn
     ContentType: application/json
     Data: ewogICAgImlkIjogMTIzCn0=
   

4. Similarly, invoke the function using CloudEvents format:

   kn func invoke --file ./test.json --content-type application/json --format cloudevent -v

5. The resulting error is:

   Error: invalid character 'e' looking for beginning of value
   

Analysis

The sequence of operations in func/cmd/invoke.go shows that when --file is specified, the file content gets read and encoded as a base64 string (m.Data), but this encoded data is not being decoded before being sent in the request. This inconsistency leads to the errors observed.

Relevant code snippet from func/cmd/invoke.go:

if cfg.File != "" {
    content, err := os.ReadFile(cfg.File)
    if err != nil {
        return err
    }
    m.Data = base64.StdEncoding.EncodeToString(content)
}

The data is sent without decoding in the sendEvent and sendPost functions located in func/pkg/functions/invoke.go. For example, in the sendEvent function, the decoding code is as follows:

err = json.Unmarshal([]byte(m.Data), &d)

At this point, m.Data is still a base64 string (e.g., ewogICAgImlkIjogMTIzCn0=), which cannot be decoded into JSON.

Expected Behavior

When using the --file option, the command should read the content of the specified file and send it in the same format as if the --data option had been provided.

Environment

• Knative version:

* Serving
  - serving.knative.dev/v1 (knative-serving v0.42.1-0.20240820122005-5f5f6d820b03)
* Eventing
  - sources.knative.dev/v1 (knative-eventing v0.42.1-0.20240828134450-34f9cd384dea)
  - eventing.knative.dev/v1 (knative-eventing v0.42.1-0.20240828134450-34f9cd384dea)

[lkingland]

Thanks for the bug report!

We'll add this to our development roadmap, but PRs are welcome ;)

[siddhesh0705]

Hi @Assassin141 and @lkingland ,
I’m Siddhesh Sangale, and I’m new to open-source contributions. I’m eager to get started by tackling some beginner-
friendly tasks that can help me build confidence and gain experience. While I’m just beginning my open-source journey, I’m excited to grow my skills and contribute to impactful projects.

I’m looking forward to working on something meaningful and gradually taking on bigger challenges as I learn. I would appreciate any guidance or suggestions for good starting points.

can you appoint me with this issue ?

[tarunsunny3]

Hi @lkingland
Would love to work on this one, if it's unassigned