If you end up here, the new convenience image now has poetry pre-installed using the recommended method!
~|⇒ docker run -it cimg/python:3.9
circleci@78dde45f7301:~/project$ poetry self update
Updating to 1.1.2
- Downloading poetry-1.1.2-linux.tar.gz 100%
Poetry (1.1.2) is installed now. Great!
circleci@78dde45f7301:~/project$ poetry self update --preview
You are using the latest version