Failed to run simple rust plugin in playground about extism

[piaoger]

just had more tests and found it caused by following line about config. Take a look at The manifest but still cannot figure out how to use it for testing :)

    // remove to fix runtime error
    // config::get("thing").expect("'thing' key set in config");
    let config = String::from("something");

[bhelx]

Did you copy paste the code from https://extism.org/docs/write-a-plugin/rust-pdk ?

I ran your code through the extism cli:

echo "Hello World" | extism call wasm_web_plugin.wasm count_vowels
Traceback (most recent call last):
  File "/Users/ben/.local/bin/extism", line 558, in <module>
    main()
  File "/Users/ben/.local/bin/extism", line 553, in main
    r = plugin.call(args.function, input, parse=None)
  File "/opt/homebrew/lib/python3.10/site-packages/extism/extism.py", line 201, in call
    self._check_error(
  File "/opt/homebrew/lib/python3.10/site-packages/extism/extism.py", line 183, in _check_error
    raise Error(ffi.string(error).decode())
extism.extism.Error: Call failed

Caused by:
    0: error while executing at wasm backtrace:
           0: 0x74c3 - <unknown>!__rust_start_panic
           1: 0x74b7 - <unknown>!rust_panic
           2: 0x7487 - <unknown>!std::panicking::rust_panic_with_hook::he04cb00575f2a1e3
           3: 0x6b18 - <unknown>!std::panicking::begin_panic_handler::{{closure}}::hb733f0aa505760cf
           4: 0x6a45 - <unknown>!std::sys_common::backtrace::__rust_end_short_backtrace::h6beefa0bcab220bc
           5: 0x70db - <unknown>!rust_begin_unwind
           6: 0x803a - <unknown>!core::panicking::panic_fmt::h586d720a90aa8503
           7: 0x9134 - <unknown>!core::panicking::panic_display::he96fafaefe672510
           8: 0x90ae - <unknown>!core::panicking::panic_str::h8b2f06f6f011655d
           9: 0x907c - <unknown>!core::option::expect_failed::h1e9a9cbb22bbd6ac
          10:  0xcf4 - <unknown>!count_vowels
       note: using the `WASMTIME_BACKTRACE_DETAILS=1` environment variable to may show more debugging information
    1: wasm trap: wasm `unreachable` instruction executed

The line of interest to you should be:

           9: 0x907c - <unknown>!core::option::expect_failed::h1e9a9cbb22bbd6ac

Keep in mind that any of these lines may trap and just there to demonstrate the API:

    let a = var::get("a")?.expect("variable 'a' set");
    let a = String::from_utf8(a).expect("string from varible value");
    let config = config::get("thing").expect("'thing' key set in config");

Here is a simplified version of that example:

use extism_pdk::*;
use serde::Serialize;

const VOWELS: &[char] = &['a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'u', 'U'];

#[derive(Serialize)]
struct TestOutput {
    pub count: i32,
}

#[plugin_fn]
pub unsafe fn count_vowels(input: String) -> FnResult<Json<TestOutput>> {
    let mut count = 0;
    for ch in input.chars() {
        if VOWELS.contains(&ch) {
            count += 1;
        }
    }

    let output = TestOutput {
        count,
    };
    Ok(Json(output))
}

[piaoger]

@bhelx
Thanks for your reply.I had already modified my code and passed the test in playgound.

My current question is about where and how to privide manifest/config.

[nilslice]

@piaoger currently there is no support to add a config through the playground, but you can do it via the CLI using --set-config to pass a map of key/value pairs, or --config to set a single key=value pair.

An example of using --set-config can be seen here:

https://github.com/extism/assemblyscript-pdk/blob/main/.github/workflows/ci.yml#L55

[piaoger]

@nilslice thanks for the information ：）