uv and PEP 723
uv and PEP 723
I have recently started using uv a lot, specially for quick standalone scripts, most of these scripts are generated by various LLMs for different tasks. The biggest pain point I had with these scripts was to setup a virtual env, installing the packages and asking ChatGPT and other LLMs to give me requirements file/list.
uv changed that by utilizing PEP 723 and embedding these requirement inline to the script.
At Diversio, I frequently use GitHub Copilot a lot, and there I've added a small instruction to make sure it's embedding the requirements in the script itself.
When asked to generate a uv based Python script, at the very top of the file, insert an inline metadata block listing all external packages in this format:
# /// script
# requires-python = ">=3.11"
# dependencies = [
# "requests<3",
# "rich",
# ]
# ///
Now, I gave it the prompt:
Give me a uv based Python script that pings google.com and prints the output in colorful tabular format.
You can see its output here
➜ uv run uv_pep_723_example.py
Installed 9 packages in 207ms
Pinging google.com 5 times...
Ping 1: Success - 221.01 ms
Ping 2: Success - 461.52 ms
Ping 3: Success - 288.88 ms
Ping 4: Success - 216.29 ms
Ping 5: Success - 205.57 ms
HTTP Ping Results for google.com
┏━━━┳━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━━┓
┃ # ┃ Timestamp ┃ Host ┃ Status ┃ Response Time ┃
┡━━━╇━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━━┩
│ 1 │ 2025-03-05 00:25:16 │ google.com │ Success │ 221.01 ms │
│ 2 │ 2025-03-05 00:25:18 │ google.com │ Success │ 461.52 ms │
│ 3 │ 2025-03-05 00:25:19 │ google.com │ Success │ 288.88 ms │
│ 4 │ 2025-03-05 00:25:20 │ google.com │ Success │ 216.29 ms │
│ 5 │ 2025-03-05 00:25:22 │ google.com │ Success │ 205.57 ms │
└───┴─────────────────────┴────────────┴─────────┴───────────────┘
Summary Statistics:
Successful requests: 5/5
Min/Avg/Max: 205.57/278.65/461.52 ms
Standard Deviation: 107.35 ms
Where is uv storing these packages?
➜ ls -l ~/.cache/uv/environments-v2/uv-pep-723-example-af4300630d2aced4/lib/python3.12/site-packages
total 12
drwxr-xr-x 3 monty staff 96 Mar 5 00:25 __pycache__
drwxr-xr-x 8 monty staff 256 Mar 5 00:25 certifi
drwxr-xr-x 9 monty staff 288 Mar 5 00:25 certifi-2025.1.31.dist-info
drwxr-xr-x 17 monty staff 544 Mar 5 00:25 charset_normalizer
drwxr-xr-x 10 monty staff 320 Mar 5 00:25 charset_normalizer-3.4.1.dist-info
drwxr-xr-x 12 monty staff 384 Mar 5 00:25 idna
drwxr-xr-x 8 monty staff 256 Mar 5 00:25 idna-3.10.dist-info
drwxr-xr-x 23 monty staff 736 Mar 5 00:25 markdown_it
drwxr-xr-x 10 monty staff 320 Mar 5 00:25 markdown_it_py-3.0.0.dist-info
drwxr-xr-x 9 monty staff 288 Mar 5 00:25 mdurl
drwxr-xr-x 8 monty staff 256 Mar 5 00:25 mdurl-0.1.2.dist-info
drwxr-xr-x 22 monty staff 704 Mar 5 00:25 pygments
drwxr-xr-x 9 monty staff 288 Mar 5 00:25 pygments-2.19.1.dist-info
drwxr-xr-x 21 monty staff 672 Mar 5 00:25 requests
drwxr-xr-x 9 monty staff 288 Mar 5 00:25 requests-2.32.3.dist-info
drwxr-xr-x 82 monty staff 2624 Mar 5 00:25 rich
drwxr-xr-x 8 monty staff 256 Mar 5 00:25 rich-13.9.4.dist-info
drwxr-xr-x 19 monty staff 608 Mar 5 00:25 urllib3
drwxr-xr-x 8 monty staff 256 Mar 5 00:25 urllib3-2.3.0.dist-info
-rw-r--r-- 1 monty staff 18 Mar 5 00:25 _virtualenv.pth
-rw-r--r-- 1 monty staff 4342 Mar 5 00:25 _virtualenv.py
The cache can be cleaned using the uv cache clean command as specified here.
References
- https://peps.python.org/pep-0723/
- https://docs.astral.sh/uv/guides/scripts/#declaring-script-dependencies
- https://docs.astral.sh/uv/concepts/cache/#clearing-the-cache
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