Go function error handling

If a handler reports a Go function runtime or loading error, the runtime environment automatically captures the error and returns a JSON document with the error type in the response. For more information about the JSON document format, see Calling a function.

The error data is also written to the execution log. You can view it using the YC CLI or management console.

Examples of error handling

Case 1: user code goes outside the array boundaries, a panic is expected. In fact, the handler captures the panic automatically, aggregates information about it, and generates a JSON document that contains an error message (the errorMessage field), error type (the errorType field), and stack trace (the stackTrace field).

Function code:

package main

func Handler () (int, error) {
  array := []int{1, 2, 3, 4, 5}
  return array[15], nil
}

JSON document returned:

{
  "errorMessage": "user code execution causes panic: runtime error: index out of range [15] with length 5",
  "errorType": "UserCodePanic",
  "stackTrace": [
    ...
  ]
}

Case 2: user code reports an error by returning it from the function. In this case, the handler captures this error and generates a JSON document with a user-defined error message (the errorMessage field) and its type (the errorType field).

Function code:

package main

import "fmt"

func Handler () (int, error) {
  return 0, fmt.Errorf("an error")
}

JSON document returned:

{
  "errorMessage": "an error",
  "errorType": "UserCodeError"
}