🕰 The command line tool for scheduling Python scripts

Related issue: #5

Here's what this PR brings:

• when an action is successful, print in green (Killed X, Scheduled X);
• when an exception is raised, print in red + hide traceback for commonplace errors (file not found, unsupported platform, hickory specific errors);
• the output of status isn't colored because as a table-like output, it's likely to be passed through a pipe for other purposes (although you could always detect when this happens using os.isatty and not add any colors).
• added hickory/__main__.py to be able to run the package against a specific python runtime: python -m hickory targeting the folder or the installed package.

Coloring is done using colorama, a popular terminal coloring package. It also brings cross-compatibility with Windows since coloring is done through API calls rather than escape sequences in there.

I like the philosophy behind hickory but I'm wondering if it makes sense to add a retry mechanic.

One of the main reasons some of my old clients resorted to airflow was because of the retry mechanics in them. It feels like API-wise we could add two extra flags. One for how often we should attempt a retry and another one for how long to wait between retries.

Describe the bug I followed the readme, but did not succeed. To Reproduce Create a foo.py

import datetime
import time

stamp = datetime.datetime.now().strftime("%H:%M:%S")
time.sleep(5)

print(f"Foo - {stamp} + 5 seconds")

Then schedule with hickory schedule foo.py --every=10s

Then check the status using hickory status

Expected behavior Expect the schedule will work and the show the status of all scheduled jobs

Environment:

• OS: [Linux] (Windows subsystem linux 2)
• Version: [Ubuntu 20.04.1 LTS]

Additional context When I check status, it shows

Traceback (most recent call last):
  File "/home/jake/anaconda3/bin/hickory", line 8, in <module>
    sys.exit(main())
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/cli.py", line 86, in main
    return status()
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/cli.py", line 71, in status
    return status_systemd()
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/systemd.py", line 126, in status_systemd
    info_dicts = [_service_info(s) for s in services]
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/systemd.py", line 126, in <listcomp>
    info_dicts = [_service_info(s) for s in services]
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/systemd.py", line 118, in _service_info
    state = _find_state(short)
  File "/home/jake/anaconda3/lib/python3.8/site-packages/hickory/systemd.py", line 105, in _find_state
    state = re.findall("Active: (.*?)\n", status)[0]
IndexError: list index out of range

I am trying to run hickory on PopOS (which I think is a variant of ubuntu) and it seems to complain about the folder structure.

hickory schedule scripts/grab_issues.py --every 2hours
Traceback (most recent call last):
  File "/home/vincent/Development/gh-dashb/venv/bin/hickory", line 8, in <module>
    sys.exit(main())
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/hickory/cli.py", line 83, in main
    schedule(args.script, args.every)
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/hickory/cli.py", line 35, in schedule
    schedule_systemd(label, working_directory, which_python, script, every)
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/hickory/systemd.py", line 74, in schedule_systemd
    dump_string(service, f"{SYSTEMD_PATH}/{label}.service")
  File "/home/vincent/Development/gh-dashb/venv/lib/python3.7/site-packages/hickory/systemd.py", line 66, in dump_string
    with open(path, "w") as f:
FileNotFoundError: [Errno 2] No such file or directory: '/home/vincent/.config/systemd/user/hickory.3825d9.scripts/grab_issues.py.service'

I can confirm that the /home/vincent/.config/systemd/user path exists, so maybe this is a file that didn't get created?

Environment:

> pip freeze | grep hickory
hickory==1.0.0

> cat /etc/os-release
NAME="Pop!_OS"
VERSION="20.04 LTS"
ID=pop
ID_LIKE="ubuntu debian"
PRETTY_NAME="Pop!_OS 20.04 LTS"
VERSION_ID="20.04"
HOME_URL="https://pop.system76.com"
SUPPORT_URL="https://support.system76.com"
BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
PRIVACY_POLICY_URL="https://system76.com/privacy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
LOGO=distributor-logo-pop-os

Hey @maxhumber Please validate my work, I have added .env file for replacing ur constants and then added logging system. Check them and let me know !!

At the moment the command line only allows you to pass a python file. The merit to this is that things remain simple. But one might wonder, could we also run anything that the command line could run?

That way hickory could also be used to run;

• scripts from non-python languages
• jupyter notebooks
• docker containers

The API might still allow it via something like;

hickory schedule "docker run ..." --every=1hour
hickory schedule "jupyter nbconvert notebook.ipynb" --every=1hour

If this is out of scope of the library I understand. There's merit to keeping a tool small.