DockerOperator / XCOM : `TypeError: Object of type bytes is not JSON serializable`

[AlessioM]

Apache Airflow version: 2.0.0

Kubernetes version (if you are using kubernetes) (use kubectl version): NA

Environment:

• local Ubuntu 18.04 LTS /
• docker-compose version 1.25.3, build d4d1b42b
• docker 20.10.1, build 831ebea

What happened:

when enabling xcom push for a docker operator the following error is thrown after the task finishes succesfully:
TypeError: Object of type bytes is not JSON serializable

What you expected to happen:

• error is not thrown
• if xcom_all is True: xcom contains all log lines
• if xcom_all is False: xcom contains last log line

How to reproduce it:

see docker compose and readme here:
https://github.com/AlessioM/airflow-xcom-issue

[boring-cyborg]

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