mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-11-29 09:27:03 -05:00
76 lines
3.5 KiB
Markdown
76 lines
3.5 KiB
Markdown
---
|
|
title: "Quick Python: Check Submodule Load"
|
|
date: 2022-12-01T21:12:03-05:00
|
|
draft: false
|
|
tags: ["Python"]
|
|
math: false
|
|
---
|
|
|
|
Reading other people's code is a great way to learn. Recently, I was looking at the `numpy` repository and they had a hidden gem within their `setup.py`. In large scale repositories like `numpy`, we can have different dependencies that we rely upon via *git submodules*. The following function will check to see that these dependencies are loaded and in a "clean" state.
|
|
|
|
```python
|
|
def check_submodules():
|
|
""" verify that the submodules are checked out and clean
|
|
use `git submodule update --init`; on failure
|
|
"""
|
|
if not os.path.exists('.git'):
|
|
return
|
|
with open('.gitmodules') as f:
|
|
for line in f:
|
|
if 'path' in line:
|
|
p = line.split('=')[-1].strip()
|
|
if not os.path.exists(p):
|
|
raise ValueError('Submodule {} missing'.format(p))
|
|
|
|
proc = subprocess.Popen(['git', 'submodule', 'status'],
|
|
stdout=subprocess.PIPE)
|
|
status, _ = proc.communicate()
|
|
status = status.decode("ascii", "replace")
|
|
for line in status.splitlines():
|
|
if line.startswith('-') or line.startswith('+'):
|
|
raise ValueError('Submodule not clean: {}'.format(line))
|
|
```
|
|
|
|
To get a better idea of what this piece of code is doing, let's trace through its execution. The `.gitmodules` file defines where each of the submodules are stored in the repository. Here's the file for `numpy`'s repository.
|
|
|
|
```ini
|
|
[submodule "doc/source/_static/scipy-mathjax"]
|
|
path = doc/source/_static/scipy-mathjax
|
|
url = https://github.com/scipy/scipy-mathjax.git
|
|
[submodule "numpy/core/src/umath/svml"]
|
|
path = numpy/core/src/umath/svml
|
|
url = https://github.com/numpy/SVML.git
|
|
```
|
|
|
|
The function then checks if each of the `path` locations are defined in the filesystem.
|
|
|
|
```python
|
|
# Check #1
|
|
if not os.path.exists("doc/source/_static/scipy-mathjax"):
|
|
raise ValueError('Submodule {} missing'.format("doc/source/_static/scipy-mathjax"))
|
|
|
|
# Check #2
|
|
if not os.path.exists("numpy/core/src/umath/svml"):
|
|
raise ValueError('Submodule {} missing'.format("numpy/core/src/umath/svml"))
|
|
```
|
|
|
|
Now it is possible for these submodules to be checked out, but be in some sort of unclean state. For example let's say that I edit `numpy/core/src/umath/svml/README.md` and commit that change. Then the `git submodule status` command will look like the following.
|
|
|
|
```bash
|
|
$ git submodule status
|
|
36f4c898f2255e0c98eb6949cd67381552d5ffea ../doc/source/_static/scipy-mathjax (heads/master)
|
|
+1f2b5b3cae704ffa6210a638dfd084946da366bf core/src/umath/svml (heads/main-1-g1f2b5b3)
|
|
```
|
|
|
|
Notice the `+` behind the second submodule. According to the man page for `git submodule`
|
|
|
|
> Show the status of the submodules. This will print the SHA-1 of the currently checked out commit for each submodule, along with the submodule path and the output of git describe for the SHA-1.
|
|
>
|
|
> Each SHA-1 will possibly be prefixed with
|
|
> - **-** if the submodule is not initialized
|
|
> - **+** if the currently checked out submodule commit does not match the SHA-1 found in the index of the containing repository
|
|
> - U if the submodule has merge conflicts.
|
|
|
|
The existence of the `+` would make this check fail. However, no prefixes will make the check succeed.
|
|
|
|
By executing this function within the repositories `setup.py`, it verifies that the needed dependencies are checked out and clean before installing the python package. Checks like these make python packages feel a little more stable.
|