Parse custom logs in Elastic cloud

I'm sending custom logs with filebeat to Elasticsearch, but I would like to be able to parse them and extract some information. I see the document on Kibana, but the message is the whole log entry:

[2020-02-12 16:26:23] env.ERROR: Command "xxx" is not defined. {"exception":"[object] (Symfony\Component\Console\Exception\CommandNotFoundException(code: 0): Command "xxx" is not defined. at /path/vendor/symfony/console/Application.php:642)"}

How can I parse those messages? I tried to create a pipeline, but I don't what values should provide for input/output blocks.

Thanks in advance.