"SyntaxError: invalid syntax" at os_detect_ on Ubuntu 16.04

[130s]

Problem

Dev-installing the latest main on 16.04 (where Python3 is 3.5) I get this. Confirmed on a native host and a Docker container.

Citing the result from Docker container.

$ docker run -it -v /home/noodle/repos/osrf/rocker:/cws/rocker ubuntu:xenial bash

root@f1c29e17b557:/# apt update
# cd %ROCKER% && git log --oneline -2
7351432 (HEAD -> feature-mount, plusone-robotics/feature-mount) Document --volume
a735938 [volume] Rename from 'mount' (addressing https://github.com/osrf/rocker/pull/46#discussion_r301416615)

# pip3 install --user . 
# find ~/.local/ -iname rocker*
/root/.local/bin/rocker
/root/.local/lib/python3.5/site-packages/rocker
/root/.local/lib/python3.5/site-packages/rocker-0.2.3.egg-info

root@f1c29e17b557:/cws/rocker# /root/.local/bin/rocker --help
Traceback (most recent call last):
  File "/root/.local/bin/rocker", line 9, in <module>
    load_entry_point('rocker==0.2.3', 'console_scripts', 'rocker')()
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 542, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2569, in load_entry_point
    return ep.load()
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2229, in load
    return self.resolve()
  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2235, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/root/.local/lib/python3.5/site-packages/rocker/cli.py", line 26, in <module>
    from .os_detector import detect_os
  File "/root/.local/lib/python3.5/site-packages/rocker/os_detector.py", line 60
    tag="rocker:" + f"os_detect_{image_name}".replace(':', '_').replace('/', '_')
                                            ^
SyntaxError: invalid syntax
root@f1c29e17b557:/cws/rocker# python3 --version
Python 3.5.2

Although, this doesn't happen with the version 0.2.3 taken from apt.

Potential fix

Ubuntu 16.04 is ending the life and Py3.5 has EoLed. So I'm not sure how much we want to fix this?

[130s]

Although, this doesn't happen with the version 0.2.3 taken from apt.

The result in OP was from the branch in #142 but even I switched to main, the same happens.

$ git log --oneline -2
9d7a392 (HEAD -> main, origin/master, origin/main, origin/HEAD) add an action to mirror main to master Providing backwards compatibility for renaming master to main
695734c git extension supporting user override and full coverage (#138)

• The line that causes the error was added in Remove intermediate containers and name detect_os images #133, which is NOT yet included in v 0.2.3.
• I also tried on Ubuntu 18.04 and 20.04 but I do NOT confirm this issue happen.

[130s]

Since I have a project with Ubuntu 16.04 and it's unclear when we'd switch to OS with newer Python, I made #144.

[malban]

Although, this doesn't happen with the version 0.2.3 taken from apt.

Now that 0.2.4 is the version apt installs for xenial, the 0.2.4 xenial apt package is broken.

It should be a trivial change to fix:

tag="rocker:" + f"os_detect_{image_name}".replace(':', '_').replace('/', '_')

to

tag="rocker:" + "os_detect_{}".format(image_name).replace(':', '_').replace('/', '_')

[tfoote]

I'm going to close this as xenial is EOL and which was the last python 3.5 platform.