A blog and website by Peter Bengtsson
15 June 2020 0 comments Python
tl;dr hashin 0.15.0 makes package comparison agnostic to underscore or hyphens
See issue #116 for a fuller story. Basically, now it doesn't matter if you write...
hashin python_memcached
...or...
hashin python-memcached
And the same can be said about the contents of your requirements.txt file. Suppose it already had something like this:
python_memcached==1.59 \
--hash=sha256:4dac64916871bd35502 \
--hash=sha256:a2e28637be13ee0bf1a8and you type hashin python-memcached it will do the version comparison on these independent of the underscore or hyphen.
Thank @caphrim007 who implemented this for the benefit of Renovate.
10 June 2020 0 comments Python, Linux, Bash
tl;dr; Here's a useful bash script to avoid starting something when its already running as a ghost process.
Huey is a great little Python library for doing background tasks. It's like Celery but much lighter, faster, and easier to understand.
What cost me almost an hour of hair-tearing debugging today was that I didn't realize that a huey daemon process had gotten stuck in the background with code that wasn't updating as I made changes to the tasks.py file in my project. I just couldn't understand what was going on.
The way I start my project is with honcho
which is a Python Foreman clone. The Procfile looks something like this:
elasticsearch: cd /Users/peterbe/dev/PETERBECOM/elasticsearch-7.7.0 && ./bin/elasticsearch -q
web: ./bin/run.sh web
minimalcss: cd minimalcss && PORT=5000 yarn run start
huey: ./manage.py run_huey --flush-locks --huey-verbose
adminui: cd adminui && yarn start
pulse: cd pulse && yarn run dev
And you start that with simply typing:
When you Ctrl-C
, it kills all those processes but somehow somewhere it doesn't always kill everything. Restarting the computer isn't a fun alternative.
So, to prevent my sanity from draining I wrote this script:
#!/usr/bin/env bash
set -eo pipefail
# This is used to make sure that before you start huey,
# there isn't already one running the background.
# It has happened that huey gets lingering stuck as a
# ghost and it's hard to notice it sitting there
# lurking and being weird.
bad() {
echo "Huey is already running!"
exit 1
}
good() {
echo "Huey is NOT already running"
exit 0
}
ps aux | rg huey | rg -v 'rg huey' | rg -v 'huey-isnt-running.sh' && bad || good
(If you're wondering what rg is; it's short for ripgrep)
And I change my Procfile accordingly:
-huey: ./manage.py run_huey --flush-locks --huey-verbose
+huey: ./bin/huey-isnt-running.sh && ./manage.py run_huey --flush-locks --huey-verbose
There really isn't much rocket science or brain surgery about this blog post but I hope it inspires someone who's been in similar trenches that a simple bash script can make all the difference.
22 May 2020 0 comments Python, MDN
So recently, in MDN, we changed the setting WELCOME_EMAIL_FROM. Seems harmless right? Wrong, it failed horribly in runtime and we didn't notice until it was in production. Here's the traceback:
SMTPSenderRefused: (552, b"5.1.7 The sender's address was syntactically invalid.\n5.1.7 see : http://support.socketlabs.com/kb/84 for more information.", '=?utf-8?q?Janet?=')
(8 additional frame(s) were not displayed)
...
File "newrelic/api/function_trace.py", line 151, in literal_wrapper
return wrapped(*args, **kwargs)
File "django/core/mail/message.py", line 291, in send
return self.get_connection(fail_silently).send_messages([self])
File "django/core/mail/backends/smtp.py", line 110, in send_messages
sent = self._send(message)
File "django/core/mail/backends/smtp.py", line 126, in _send
self.connection.sendmail(from_email, recipients, message.as_bytes(linesep='\r\n'))
File "python3.8/smtplib.py", line 871, in sendmail
raise SMTPSenderRefused(code, resp, from_addr)
SMTPSenderRefused: (552, b"5.1.7 The sender's address was syntactically invalid.\n5.1.7 see : http://support.socketlabs.com/kb/84 for more information.", '=?utf-8?q?Janet?=')
Yikes!
So, to prevent this from happening every again we're putting this check in:
from email.utils import parseaddr
WELCOME_EMAIL_FROM = config("WELCOME_EMAIL_FROM", ...)
# If this fails, SMTP will probably also fail.
assert parseaddr(WELCOME_EMAIL_FROM)[1].count('@') == 1, parseaddr(WELCOME_EMAIL_FROM)
You could go to town even more on this. Perhaps use the email validator within django but for now I'd call that overkill. This is just a decent check before anything gets a chance to go wrong.
19 February 2020 0 comments Python, MacOSX
I'm still working on getting pyenv
in my bloodstream. It seems like totally the right tool for having different versions of Python available on macOS that don't suddenly break when you run brew upgrade periodically. But every thing I tried failed with an error similar to this:
python-build: use openssl from homebrew
python-build: use readline from homebrew
Installing Python-3.7.0...
python-build: use readline from homebrew
BUILD FAILED (OS X 10.15.x using python-build 20XXXXXX)
Inspect or clean up the working tree at /var/folders/mw/0ddksqyn4x18lbwftnc5dg0w0000gn/T/python-build.20190528163135.60751
Results logged to /var/folders/mw/0ddksqyn4x18lbwftnc5dg0w0000gn/T/python-build.20190528163135.60751.log
Last 10 log lines:
./Modules/posixmodule.c:5924:9: warning: this function declaration is not a prototype [-Wstrict-prototypes]
if (openpty(&master_fd, &slave_fd, NULL, NULL, NULL) != 0)
^
./Modules/posixmodule.c:6018:11: error: implicit declaration of function 'forkpty' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
pid = forkpty(&master_fd, NULL, NULL, NULL);
^
./Modules/posixmodule.c:6018:11: warning: this function declaration is not a prototype [-Wstrict-prototypes]
2 warnings and 2 errors generated.
make: *** [Modules/posixmodule.o] Error 1
make: *** Waiting for unfinished jobs....
I read through the Troubleshooting FAQ and the "Common build problems" documentation. xcode was up to date and I had all the related brew packages upgraded. Nothing seemed to work.
Until I saw this comment on an open pyenv issue: "Unable to install any Python version on MacOS"
All I had to do was replace the 10.14 for 10.15 and now it finally worked here on Catalina 10.15. So, the magical line was this:
SDKROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk \
MACOSX_DEPLOYMENT_TARGET=10.15 \
PYTHON_CONFIGURE_OPTS="--enable-framework" \
pyenv install -v 3.7.6
Hopefully, by blogging about it you'll find this from Googling and I'll remember the next time I need it because it did eat 2 hours of precious evening coding time.
14 February 2020 0 comments Python
You can accomplish the same with curl -L but I've had this as a little personal hack script in my ~/bin folder on my computer. Thought I'd make it a public tool. Also, from here, a lot more can be done to this script if you wanna help out with ideas.
▶ redirect-chain http://developer.mozilla.org/en-US/docs/xpcshell
0 http://developer.mozilla.org/en-US/docs/xpcshell 301
1 > https://developer.mozilla.org/en-US/docs/xpcshell 301
2 >> https://developer.mozilla.org/docs/en/XPConnect/xpcshell 302
3 >>> https://developer.mozilla.org/en-US/docs/en/XPConnect/xpcshell 301
4 >>>> https://developer.mozilla.org/en-US/docs/XPConnect/xpcshell 301
5 >>>>> https://developer.mozilla.org/en-US/docs/Mozilla/XPConnect/xpcshell 301
6 >>>>>> https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Language_bindings/XPConnect/xpcshell 200
It basically gives you a pretty summary of redirects from a starting URL.
To install it on your system run:
pipx install redirect-chain
Happy Friday!
07 February 2020 0 comments Python
We use poetry in MDN Kuma. That means there's a pyproject.toml and a poetry.lock file. To add or remove dependencies, you don't touch either file in an editor. For example, to add a package:
poetry add --dev black
It changes pyproject.toml and poetry.lock for you. (Same with yarn add somelib which edits package.json and yarn.lock).
Suppose that you make a pull request to add a new dependency, but someone sneaks a new pull request in before you and have theirs landed in master before. Well, that's how you end up in this place:
So how do you resolve that?
So, you go back to your branch and run something like:
git checkout master
git pull origin master
git checkout my-branch
git merge master
Now you get this in git status:
Unmerged paths:
(use "git add <file>..." to mark resolution)
both modified: poetry.lockAnd the contents of poetry.lock looks something like this:
I wish there just was a way poetry itself could just figure fix this.
What you need to do is to run:
# Get poetry.lock to look like it does in master
git checkout --theirs poetry.lock
# Rewrite the lock file
poetry lock
Now, your poetry.lock file should correctly reflect the pyproject.toml that has been merged from master.
To finish up, resolve the conflict:
git add poetry.lock
git commit -a -m "conflict resolved"
# and most likely needed
poetry install
content-hash
Inside the poetry.lock file there's the lock file's hash. It looks like this:
[metadata]
content-hash = "875b6a3628489658b323851ce6fe8dafacd5f69e5150d8bb92b8c53da954c1be"
So, as can be seen in my screenshot, when git conflicted on this it looks like this:
[metadata]
+<<<<<<< HEAD
+content-hash = "6658b1379d6153dd603bbc27d04668e5e93068212c50e76bd068e9f10c0bec59"
+=======
content-hash = "5c00dce18ddffd5d6f797dfa14e4d56bf32bbc3769d7b761a2b1b3ff14bce287"
+>>>>>>> master
Basically, the content-hash = "5c00dce1... is what you'd find in master and content-hash = "6658b137... is what you would see in your branch before the conflict.
When you run that poetry lock you can validate that the new locking worked because it should be a hash. One that is neither 5c00dce1... or 6658b137....
Notes
I'm still new to poetry and I'm learning. This was just some loud note-to-self so I can remember for next time.
I don't yet know what else can be automated if there's a conflict in pyproject.toml too. And what do you do if there are serious underlying conflicts in Python packages, like they added a package that requires somelib<=0.99 and you added something that requires somelib>=1.11.
Also, perhaps there are ongoing efforts within the poetry project to help out with this.
UPDATE Feb 12, 2020
My colleague informed me that this change was actually NOT what I wanted. poetry lock actually updates some dependencies as it makes a completely new lock file. I didn't immediately notice that in my case because the lock file is large. See this open issue which is about the ability to update the lock file without upgrading any other dependencies.
