DjangoCon JP 2021 発表資料

Djangoで非同期処理を実現するために、よく使われているCelery。ただDjangoほど知見が共有されていないため、なんとなく使っているという方も多いのではないかと思います。そのような場合Celeryを使えるようにするまでは順調でも、実際に運用がはじまったあとに困ることが出てきます。例えば、ログの保存、リトライの設計、デプロイ戦略など。
このトークでは、CeleryをDjangoプロジェクトで実際に運用するうえでの役立つTipsをお伝えします。

• Use **kwargs for your tasks input. This makes it easier to make updates to your tasks once they're already running in production if your input needs to change. 
• Reminders about all of the handy kwargs you can pass to tasks in regards to retry. Especially handy autoretry_for where you can pass a tuple of exceptions that will cause the task to automatically retry

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Base Thoughts 

• I don't think posting should be syndicated automatically on publish. There's a couple of reasons for this: 
  • Tanzawa doesn't support any kind of background tasks. Posts that have a bunch of links take a while to complete it tries to send webmentions. Adding more external requests could increase the response time to longer than the request timeout allows quite easily. This is especially true because webmentions require 2 requests per save (before content update and after content update). We could probably process webmentions concurrently to speed this up, but that feels like a bit much at this point? It may be easy with asyncio, but I'd need to research it.
  • When I was posting with Wordpress there was a syndication checkbox (via brid.gy) and found it you'd get errors if you saved twice as the post had already been syndicated. Because there also wasn't a preview, it was always a bit of a gamble for how it would post.
• Syndication is a separate concern from authoring posts themselves. And as such warrants dedicated screens to make it _right_.  Initially I had thought it might work well to handle syndication via a modal on the edit post page, but the more I think about it, it would box us in.
• Brid.gy is still super handy for backfeeding likes/replies as webmentions. I still think brid.gy is useful / "required" unless we were to build in some kind of polling mechanism, which is difficult without support for cron/background tasks. ( It could be done "easily" with a django management command, I'm hesitant to introduce undue complexity).
• "Syndication" feels a bit jargony to me. Is "Cross post" (or something similar)  a better term to use in the interface?
• Each syndication destination is going to require some kind of settings (API keys, mostly). These can / should be managed via the Django admin?

Workflow

• Creating a new syndication would happen from the edit post button. The button should be on the meta menu (on the right), below the publish  buttons and only display once the post is published (you can't syndicate a draft).
• Clicking this button would take you to dedicated syndication page.
• The top of the page would be a form. The form would display the syndication text and up to 4 photos (with the caption).
  
  The syndication text is free text and pre-filled with either the post title + link or the first 280 chars of the note. Above the text field itself would be a segmented control (tabs? radio button?) that when clicked would let you toggle between the different presets.
  
  You may not want to syndicate each photo, so perhaps a checkbox is warranted to let you select which photos will be sent.
• Finally at the bottom there's some checkboxes for which networks to syndicate to. As you can only syndicate a post once per network, posts that have already been syndicated to would be disabled with text explaining that you've already syndicated to that network for this post.
• Once syndicated they'd store the url of the syndication and create a TSyndication record.

from django.contrib.gis.geos import Point

# Keep our familiar lat/lon ordering without messing up the data point.
point = Point(y=35.31593281000502, x=139.4700015160363)

• A Roller coaster? The Great Crash in 1929? I keep trying to find the right way to describe this week, but I can't. Most everything that was under my control went well. Those that weren't, less so.
• Japan is handling vaccine distribution in a very measured way. There's basically 3 groups of people getting vaccines right now: the elderly, those with pre-existing conditions, and those that work for large companies. If you are none of those, tough luck. To get a vaccine outside of working for a major company, you need a voucher. My voucher is supposed to come sometime next month, but I won't be able to get an appointment until mid-August at the earliest. Which will have me fully vaccinated my October-ish? Maybe?
  
  When I posted  that I found a clinic that would give a vaccine to anyone, even without a vaccine I couldn't believe it. I could get fully vaccinated before the Olympics and take back 3 months of 2021. I had an appointment for 30th.
  
  But then I saw reports that the health authorities found out and told them to start canceling reservations for people outside from outside of the ward. Existing reservations seemed to be fine for a couple of days. Then the health authorities dropped the hammer on them and they've been forced to turn away everything without a voucher and everyone from outside the ward.
  
  And just like that. Poof. My hope for getting vaccinated this summer vanished. Gutted. Who knows, maybe once I get my golden ticket in a couple of weeks  I'll find a clinic that'll let me get vaccinated earlier. 
  
  Silver lining is that I found out I'll get turned away at the door before taking the day off work and making an hour-ish trip train ride into Ikebukuro. I also won't ended up being unable to get a second shot or have to make a trip to Ikebukuro to get a stamp on my voucher so I can get a second shot.
• I joined Leo for his first field trip to Kodomo no kuni ( Kid country?) Check the link, they got all sorts of slides, trains, and so forth. We watched the cows, ran up and down a big hill, and Leo bounced on a white bouncing dome. I definitely want to go back when it's cooler and when we're not with a huge group. I expanded my checkin to a proper blog post, which is something I want to do more often.
• The issue of Web+DB Press that I wrote an article for is finally release for sale. I haven't gained any new followers or gotten mentions, so I assume people aren't running into any issues following along.
• Another work update – I was the guest this week on BPZM, an internal company podcast(?) / show. It was fun to shoot the breeze in Japanese. One thing I'd like to get better at is off-the-cuff explanations of things in Japanese without having to stop and think. The largest issue ( I think) is I think of how to explain in, then have to reverse the order of some of the explanation for it work in Japanese and I derail my train of thought.
• I'm trying to focus less on each day and more on the week. I'm not sure if it's helping, but I did manage to run twice this week. Compared to the previous weeks (months) of 0 runs, it's a vast improvement. Yay me.

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