[pkg/ottl] Allow indexing maps and slices with dynamic values

[marcinsiennicki95]

Component(s)

processor/transform

Is your feature request related to a problem? Please describe.

I want to set a new key-value pair attribute using the value of another attribute

Option 1

transform/combine_scope_type_and_scope_value:
  error_mode: ignore
  log_statements:
    - context: log
      statements:
        - 'set(attributes[attributes["scope.type"]], attributes["scope.value"]) where attributes["scope.type"] != nil and attributes["scope.value"] != nil' 

Option 2

transform/combine_scope_type_and_scope_value:
  error_mode: ignore
  log_statements:
    - context: log
      statements:
        - 'set(${attributes["scope.type"]}, attributes["scope.value"]) where attributes["scope.type"] != nil and attributes["scope.value"] != nil'

When I use option 1 got error
2024/12/02 14:53:40 collector server run finished with error: invalid configuration: processors::transform/combine_scope_type_and_scope_value: unable to parse OTTL statement "set(attributes[attributes[\"scope.type\"]], attributes[\"scope.value\"]) where attributes[\"scope.type\"] != nil and attributes[\"scope.value\"] != nil": statement has invalid syntax: 1:15: unexpected token "[" (expected ")" Key*)

Alternative is

  transform:
    error_mode: ignore
    log_transformations:
       - context: log
         condition:
         - attributes["scope.type"] != nil and attributes["scope.value"] != nil'
         statements:
          - set_attributes:
              - key: '${attributes["scope.type"]}'
                value: '${attributes["scope.value"]}'

But I also have error

Error: failed to get config: cannot resolve the configuration: environment variable "scope.value" has invalid name: must match regex ^[a-zA-Z_][a-zA-Z0-9_]*$
2024/12/02 17:42:16 collector server run finished with error: failed to get config: cannot resolve the configuration: environment variable "scope.value" has invalid name: must match regex ^[a-zA-Z_][a-zA-Z0-9_]*$

The final effect should be
scope.type = enviroment
scope.value = dev

And addition new key-value which will be combination of scope.type and scope.value
enviroment = dev

Describe the solution you'd like

See up

Describe alternatives you've considered

No response

Additional context

No response

[github-actions]

Pinging code owners:

• processor/transform: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[github-actions]

Pinging code owners for pkg/ottl: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley. See Adding Labels via Comments if you do not have permissions to add labels yourself. For example, comment '/label priority:p2 -needs-triaged' to set the priority and remove the needs-triaged label.

[TylerHelmuth]

Dynamic indexing in OTTL is definitely a language feature we’d like.

[odubajDT]

I would like to take a look at this if possible

[odubajDT]

Hello! The PR should be ready, please have a look #36719