Git Commit Messages¶
Commit messages matter. One of the goals of any repository is to keep the project’s history in good shape.
The main goals of following agreed upon (good) practices on a given project’s repository amounts to these:
Those three characteristics form a symbiosis that leads to traceability, which in turn helps pinpointing the cause of problems when things go wrong (and they do go wrong).
One lamentable episode¶
Once upon a time, I was in the #git IRC chanell at libera.chat (I am still active in IRC) and we were talking about the importance of proper commit messages when this happened (real nicks ommitted):
user_0 Are there "official" git documentation on writing proper commit messages? What I see is people random opinions in posts all over the web (some very sensible, true). I have had little success educating people on writing an informative and concise subject line followed (when appropriate) by some explanation for the reason of that commit. user_1 beyond that, it's up to the development team to implement user_2 yeah, teams should decide what they want to do user_0 People who do not understand and/or read about git and this kind of stuff dislike even attempting to get good at it. user_0 It is hard to explain, argue and have an educated conversation about a subject with people who do not know about that subject. “Ignorance more frequently begets confidence than does knowledge.” I see that all the time. I hope I myself don't do it as much as I seem to watch other people doing it... user_2 if proper commit messages have no purpose other than being proper commit messages.. they're a waste of time user_2 user_0: which problem are you actually trying to solve? user_0 user_2: I am trying to convince people that commit messages matter. That keeping a repo organized, clean, informational, semantic, etc. helps. Helps troubleshooting problems, finding historical stuff, and makes everyone happier. user_2: Then commit messages could be like "first commit", "second commit". user_0 Sure. I add to that that just because you are linking to a ticketing system doesn't relive people for being responsible in writing good code and commit subject and description in general. → Then someone asks this question ← user_3 There is a Git repo where the contents of .gitattributes file is "* java eol=lf" ... is that correct? → nobody answers, the same person insists ← user_3 perhaps the line should be "*.java eol=lf" instead of "* java eol=lf"? user_4 user_3: I think attributes can be free-form (ie. there's no finite list of legal attributes). So in theory it looks like it sets the "java" attribute on all files user_3: try git check-attr -a some/file yep. man gitattributes "DEFINING MACRO ATTRIBUTES" user_3 user_4, is "java" even a real attribute? I'm reading the documentation for gitattributes and it seems maybe "java" can be a "built-in pattern", but not an attribute user_4 user_3: it's an attribute that someone made up user_4 But whatever that attribute does, it sure sounds weird to put in on all files. So I would still guess it's a typo user_3 user_4, okay... I think one of two fixes will work. Either remove the asterisk and let "java" be the first thing on the line which makes it the built-in pattern... or putting a dot between * and java which makes "*.java" the pattern user_4 maybe the commit message has a clue user_0 Good idea. Do a git log -S java -- .gitattributes user_3 user_0, yeah, I saw where they added it. It was on a commit called "spotless applied" whatever that is... I'm not a Java person user_0 user_3: And no extra description on the commit? user_3´ user_0, was a big commit... looks like they applied some auto style formatting user_4 I guess it's a typo. I'm just saying it's technically legal the way it is. user_5 user_2: here's an example where proper commit message and usage of the tool would be invaluable user_0 I will print this conversation. It may help my future arguments with people. user_2 user_5: you don't need to convince me
TL;DR: Someone was struggling understanding something in the repository and
there had been a massive commit with lots of files which went through some
tool to format them, and the only thing the commit message said was “spotless
applied”. But they did more than “apply spotless”. They seem to have changed
.gitattributes file with some strange stuff (or it was a type, god
knows) and nothing in the commit message to give a clue. I’ll refrain myself
from showing here a few other scenarios that I have been through at work lest
I get in trouble with my current or previous employers. The list of situations
like this goes on.
Read the Chris Beans post (linked below) and the others as well.
TODO: We intend to add our own examples where regarding commit messages, atomic commits, squashing commits (when it makes sense, not all the time), etc.