Sacha Chua - category - tech Emacs, sketches, and life https://sachachua.com/blog/category/tech/feed/atom/index.xml 11ty 2025-08-31T18:05:44Z Nginx maps: How I redirect sketch IDs to blog posts or sketches 2025-08-31T18:05:44Z 2025-08-31T18:05:44Z https://sachachua.com/blog/2025/08/nginx-maps-how-i-redirect-sketch-ids-to-blog-posts-or-sketches/

Assumed audience: I'm mostly writing these notes for myself, because I'd forgotten how this actually works. Maybe it might be interesting for people who also like identifying their posts or sketches and who use Nginx.

Since August 2022, I've been identifying sketches with YYYY-MM-DD-NN, where NN is a number derived from my journaling system. I used to use just YYYY-MM-DD and the title, but sometimes I renamed sketches. Then I used YYYY-MM-DDa (ex: 2022-08-01f). Sometimes optical character recognition had a hard time distinguishing my hand-drawn "d" from "a", though. Numbers were generally more reliable. And besides, that way, there's room for growth in case I have more than 26 journal entries or sketches in a day. (Not that I've gone anywhere near that volume.)

Anyway, I want to have short URLs like sachachua.com/2025-07-31-10 or sach.ac/2025-07-31-10 go to a blog post if one's available, or just the sketch if I haven't written about it yet, like sach.ac/2025-01-16-01. Here's how I do it.

To publish my site, I export HTML files from Org Mode and I use the 11ty static site generator to put them together in a blog.

One of my 11ty files is map.11ty.cjs, which has the following code:

map.11ty.cjs 
module.exports = class AllPosts {
  data() {
    return {
      permalink: '/conf/nginx.map',
      eleventyExcludeFromCollections: true
    };
  }
  async render (data) {
    let list = data.collections._posts;
    let cats = data.siteCategoriesWithParents;
    let nested = cats.filter(o => o.parent);
    let hash = {};
    await list.reduce(async (prev, o) => {
      await prev;
      if (o.data?.zid) {
        hash[o.data.zid] = o.url;
      }
      let matches = (await o.template.inputContent).matchAll(/{% +sketchFull +\"([0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9](-[0-9][0-9]|[a-z]))?/g);
      for (const m of matches) {
        if (m[1] && !hash[m[1]]) {
          hash[m[1]] = o.url;
        }
      }
    });
    let byZIDs = Object.entries(hash).map((o) => `/${o[0]} ${o[1]};\n`).join('');
    let byBlogID = list.filter(o => o.data.id).map((o) => `/blog/p/${o.data.id} ${o.url};`).join("\n") + "\n";
    let nestedCategories = nested.map((o) => {
      let slugPath = o.parentPath.map((p) => p.slug).join('/') + '/' + o.slug;
      let catPage = `/blog/category/${slugPath} /blog/category/${o.slug};\n`;
      let catFeed = `/blog/category/${slugPath}/feed/ /blog/category/${o.slug}/feed/;\n`;
      let catAtom = `/blog/category/${slugPath}/feed/atom/ /blog/category/${o.slug}/feed/atom/;\n`;
      return catAtom + catFeed + catPage;
    }).join('');
    const result = byBlogID + nestedCategories + byZIDs;
    return result;
  }
};

The code analyzes each of my blog posts and looks for full-sized sketches. If it finds a full-size sketch, it writes a rule that redirects that ID to that blog post. This is what part of the resulting nginx.map looks like: 

/2025-07-31-10 /blog/2025/08/monthly-review-july-2025/;
/2025-08-04-01 /blog/2025/08/turning-42-life-as-a-41-year-old/;
/2025-08-03-08 /blog/2025/08/turning-42-life-as-a-41-year-old/;
/2025-08-31-01 /blog/2025/08/emacs-elevator-pitch-tinkerers-unite/;

In my Nginx web server config (nginx.conf), I have: 

http {
  # ...
  include /etc/nginx/redirections.map;
  # ...
}

And that redirections.map uses the map module and looks like this: 

map $request_uri $new_uri {
   default "";
   include /var/www/static-blog/conf/nginx.map;
   / /blog;
   # ...
}

Then in my Nginx site configuration, I redirect to that $new_uri if available. As a fallback, I also detect yyyy-mm-dd-nn URLs and redirect them to my sketchbook. 

server {
   # ... other rules
   if ($new_uri) {
       return 302 $new_uri;
   }
   location ~ ^/([0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9](a-z|-[0-9][0-9])?)$ {
      return 302 https://sketches.sachachua.com/$1;
   }
}

The Node app that runs sketches.sachachua.com searches by ID if it gets one. Here's the code in the Express router: 

router.get('/:filename', controller.serveImagePageByFilename);

which calls this controller: 

exports.serveImagePageByFilename = async (req, res) => {
  if (req.params.filename) {
    let f = await findImageByFilename(req.params.filename);
    if (f) {
      renderSingle(req, res, f);
    } else {
      res.sendStatus(404);
    }
  } else {
    res.sendStatus(404);
  }
};

which uses this function: 

const findImageByFilename = (filename) => {
  return getSketches().then((sketches) => {
    let id = filename.match(/^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]([a-z]|-[0-9][0-9])/);
    let m = filename.match(/^[^#]+/);
    let file = sketches.find((x) => path.parse(x.filename).name == filename);
    if (!file) {
      file = sketches.find((x) => x.filename.startsWith(id));
    }
    if (!file && m) {
      file = sketches.find((x) => x.filename.startsWith(m[0]));
    }
    if (!file) {
      file = sketches.find((x) => path.parse(x.filename).name.replace(' #.*') == filename);
    }
    if (!file) {
      file = sketches.find((x) => x.filename.startsWith(filename));
    }
    return file;
  });
};

(getSketches just reads the JSON I've saved.)

So my workflow for a public sketch is:

  1. Draw the sketch.
  2. In my journaling system, write the title and tags for the sketch. Get an ID.
  3. Write the ID on the sketch.
  4. Export the sketch from the iPad as a JPEG.
  5. Wait for things to sync in the background.
  6. Process the sketch. I can use my-image-rename-current-image-based-on-id to rename it manually, or I can use my-sketch-process to recognize the ID and process the text. (My Emacs configuration)
  7. Wait for things to sync in the background. In the meantime, edit the text version of the sketch.
  8. Reload my public sketches, which regenerates the sketches.json that lists all the sketches.
  9. Use my-write-about-sketch or my-insert-sketch-and-text to include the sketch and the text in a draft blog post. (My Emacs configuration) Do my usual blogging process.

You can comment on Mastodon or e-mail me at sacha@sachachua.com.

]]> Two weeks with the iPad Air (+ SuperNote A5X and Lenovo P52) 2025-03-01T14:55:09Z 2025-02-28T20:42:01Z https://sachachua.com/blog/2025/02/two-weeks-with-the-ipad-air-supernote-a5x-and-lenovo-p52/

[2025-03-01 Sat]: Genaro suggested beorg, so now I've got that on my iPad and it seems to be doing fine for browsing my Org Mode files. I think I'll set up WebDAV on our network-attached storage (NAS) and see what that's like, too.

Also, apparently, it's been about three weeks, whoops!

I've had this iPad Air 13" for about two three weeks now, and I'm slowly settling into how the different pieces of tech can work together and how things can flow.

2025-02-28-01 Getting used to SuperNote A5X and iPad Air 13 -- drawing supernote ipad tech
2025-02-28-01 Getting used to SuperNote A5X and iPad Air 13 -- drawing supernote ipad tech

Text from sketch

Getting used to SuperNote A5X + iPad Air 13"

SuperNote A5X:

  • I prefer it for writing, sketchnotes
    • pen feel
    • strokes: exactly as I expect, no hooks or smoothing
    • lighter weight
    • no backlight
  • Also nice for reading EPUBs, PDFs

iPad Air:

  • Libby for library e-books
  • Procreate, Simply Draw for art
  • NetNewswire for RSS
  • Copying & pasting is nice

Procreate replaces spaces with underscores and doesn't overwrite files. Instead, it adds 2 to the filename.

I want to start building up thought maps so I can see quick summaries and open questions. The laptop is probably the best place to do it.

Org Mode files with sketches, text, and links

  • Export to HTML
  • Also, add export to HTML gallery view?

Private sketches: Available through DS

Private web server on the NAS? I can just run my sketch viewer.

DS: Synology NAS drive

  • Program the server to consolidate files?
  • Consider moving metadata to subdir for easier flipping?

Ideas for next steps:

  • Figure out easier doodling from iPad: resample, autocrop, insert with HTML markup
  • Automate recolour/rename from Dropbox (phone? server?)

On the iPad, I've been mostly using:

Moving data around is a bit of a hodgepodge: internal webserver or Dropbox for the Supernote, Dropbox and Synology's DS Drive for the iPad, and Syncthing for the server. I'm sure that'll settle down eventually as I figure out a better flow.

Untitled_Artwork.jpg

I like how drawing, singing, and playing the piano give me a way to distract myself from the urge to nag A+. Still definitely just starting out, but it's fun anyway. It's nice to be able to breeze through library e-books again, too.

I notice I've been missing the occasional calendar reminder from my phone, so that's probably a sign that I need to (a) set up the iPad for calendar access as well, (b) have more distinct notifications on my phone, and (c) take the phone with me as I go from room to room. On the plus side, that probably means I've been getting in the zone, yay! It seems a little easier to just take the whole stack of phone+Supernote+iPad when I move rooms instead of leaving them in different places and then having to go find them. The laptop is a lot heavier, though, so I tend to move that on an as-needed basis.

I set up a copy of sketches.sachachua.com server on the NAS (so it's just on the local network) pointing to my private sketches directory, so now I can flip through my private sketches fairly easily. They're mostly just various thoughts on parenting and emotions and life. Now I can review them from either my iPad or my laptop, yay!

Ideas for next steps:

  • Keep distracting myself from fretting about A+ by completing various art/music tutorials.
  • Have fun doodling.
  • Contemplate whether I want to read my Org files on the iPad, and what the best way of doing it might be. (Organice? PlainOrg? Just do a PDF/EPUB export of stuff I'm focusing on? - update 2025-03-01: added Beorg)
  • See if A+ is up for field trips to the art gallery or museum.

The iPad Air seems like a good addition. Let's see what I can do with it.

You can view 1 comment or e-mail me at sacha@sachachua.com.

]]> Scaling a BigBlueButton server down to a 1 GB node between uses 2025-01-23T19:53:47Z 2025-01-23T19:53:47Z https://sachachua.com/blog/2025/01/scaling-a-bigbluebutton-server-down-to-a-1-gb-node-between-uses/ Now that we've survived EmacsConf, I've been looking into running a BigBlueButton server so that various Emacs meetups can use it if they like instead of relying on Jitsi or other free video-conferencing services. (I spent some time looking into Galene, but I'm not quite sure that's ready for our uses yet, like this issue that LibrePlanet ran into with recording.)

BigBlueButton requires a server with at least 4 CPU cores and 8 GB of RAM to even start up, and it doesn't like to share with other services. This costs about USD 48+tax/month on Linode or USD 576+tax/year, which is not an efficient use of funds yet. I could delete it after each instance, but I've been having a hard time properly restoring it from backup after deploying to a new IP address. bbb-conf --setip doesn't seem to catch everything, so I was still getting curl errors related to verifying the certificate.

A reasonable in-between is to run it on Linode's lowest plan (1 core, 1GB RAM; USD 60+tax for the year) in between meetups, and then spin things up for maybe 6-12 hours around each meetup. If I go with the 4-core 8 GB setup, that would be an extra USD 0.43 - 0.86 USD per meetup, which is eminently doable. I could even go with the recommended configuration of 8 cores and 16 GB memory on a dedicated CPU plan (USD 0.216/hour, so USD 1.30 to 2.59 per meetup). This was the approach that we used while preparing for EmacsConf. Since I didn't have a lot of programming time, I scaled the node up to 4 core / 8GB RAM whenever I had time to work on it, and I scaled it down to 1GB at the end of each of my working sessions. I scaled it up to dedicated 8 core / 16 GB RAM for EmacsConf, during which we used roughly half of the CPU capacity in order to host a max of 107 simultaneous users over 7 meetings.

I reviewed my BigBlueButton setup notes in the EmacsConf organizers notebook and the 2024 notebook and set up a Linode instance under my account, so that I can handle the billing and also so that Amin Bandali doesn't get spammed by all the notifications (up, down, up, down…). And then I'll be able to just scale it up when EmacsConf comes around again, which is nice.

Anyway, BBB refuses to install on a machine with fewer than 4 cores or 8 GB RAM, but once you set it up, it'll valiantly thrash around even on an underpowered server, which makes working with the server over ssh a lot slower. Besides, that's not friendly to other people using the same server. I wanted to configure the services so that they would only run on a server of the correct size. It turns out that systemd will let you specify either ConditionMemory and ConditionCPUs in the unit configuration file, and that you can use files ending in .conf in a directory named like yourservicename.service.d to override part of the configuration. Clear examples were hard to find, so I wanted to share these notes.

Since ConditionMemory is specified in bytes (ex: 8000000000), I found ConditionCPUs to be easier to read.

I used this command to check if I'd gotten the syntax right: 

systemd-analyze condition 'ConditionCPUs=>=4'

and then I wrote this script to set up the overrides: 

CPUS_REQUIRED=4
for ID in coturn.service redis-server.service bigbluebutton.target multi-user.target bbb-graphql-server.service bbb-rap-resque-worker.service bbb-webrtc-sfu.service bbb-fsesl-akka.service bbb-webrtc-recorder.service bbb-pads.service bbb-export-annotations.service bbb-web.service freeswitch.service etherpad.service bbb-rap-starter.service bbb-rap-caption-inbox.service freeswitch.service bbb-apps-akka.service bbb-graphql-actions postgresql@14-main.service; do
    mkdir -p /etc/systemd/system/$ID.d
    printf "[Unit]\nConditionCPUs=>=$CPUS_REQUIRED\n" > /etc/systemd/system/$ID.d/require-cpu.conf
done
systemctl daemon-reload
systemd-analyze verify bigbluebutton.target

It seems to work. When I use linode-cli to resize to the testing size, BigBlueButton works: 

#!/bin/bash
source /home/sacha/.profile
PATH=/home/sacha/.local/bin/:$PATH
linode-cli linodes resize $BBB_ID --type g6-standard-4 --allow_auto_disk_resize false
sleep 4m
linode-cli linodes boot $BBB_ID
sleep 3m
ssh root@bbb.emacsverse.org "bbb-conf --restart; cd ~/greenlight-v3; docker compose restart"
notify-send "Should be ready"

And when I resize it down to a 1 GB nanode, BigBlueButton doesn't get started and the VPS is nice and responsive when I SSH in. 

#!/bin/bash
source /home/sacha/.profile
PATH=/home/sacha/.local/bin/:$PATH
echo Powering off
linode-cli linodes shutdown $BBB_ID
sleep 60
echo "Resizing BBB node to nanode, dormant"
linode-cli linodes resize $BBB_ID --type g6-nanode-1 --allow_auto_disk_resize false

So now I'm going to coordinate with Ihor Radchenko about when he might want to try this out for OrgMeetup, and I can talk to other meetup organizers to figure out times. People will probably want to test things before announcing it to their meetup groups, so we just need to schedule that. It's BigBlueButton 3.0. I'm not 100% confident in the setup. We had some technical issues with some EmacsConf speakers even though we did a tech check with them before we went live with their session. Not sure what happened there.

I'm still a little nervous about accidentally forgetting to downscale the server and running up a bill, but I've scheduled downscaling with the at command before, so that's helpful. If it turns out to be something we want to do regularly, I might even be able to use a cronjob from my other server so that it happens even if my laptop is off, and maybe set up a backup nginx server with a friendly message (and maybe a list of upcoming meetups) in case people connect before it's been scaled up. Anyway, I think that's a totally good use of part of the Google Open Source Peer Bonus I received last year.

As an aside, you can change a room's friendly_id to something actually friendly. In the Rails console (docker exec -it greenlight-v3 bundle exec rails console), you could do something like this: 

Room.find_by(friendly_id: "CURRENT_ROOM_ID").update_attribute(:friendly_id, "NEW_CUSTOM_ID")

Anyway, let me know if you organize an Emacs meetup and want to give this BigBlueButton instance a try!

You can e-mail me at sacha@sachachua.com.

]]> One month with the SuperNote A5X 2022-08-25T15:44:41Z 2022-08-25T15:44:41Z https://sachachua.com/blog/2022/08/one-month-with-the-supernote-a5x/ I've had my SuperNote A5X for a month now, and I really like it.

Text from my sketch

I use it for:

  • untangling thoughts
  • sketchnoting books
  • planning
  • drafting blog posts
  • drawing

A- uses it for: (she's 6 years old)

  • practising cursive
  • doing mazes and dot-to-dots
  • drawing
  • reading lyrics

Things I'm learning:

  • Exporting PNGs at 200% works well for my workflow. I rename them in Dropbox and upload them to sketches.sachachua.com.
  • Carefully copying & deleting pages lets me preserve page numbers. I use lassoed titles for active thoughts and maintain a manual index for other things.
  • Layouts:
    • Landscape: only easier to review on my laptop
    • Portrait columns: lots of scrolling up and down
    • Portrait rows: a little harder to plan, but easier to review
  • Many books fit into one page each.
  • Google Lens does a decent job of converting my handwriting to text (print or cursive, even with a background). Dropbox → Google Photos → Orgzly → Org
  • Draft blog posts go into new notebooks so that I can delete them once converted.
  • The Super Note helps me reclaim a lot of the time I spend waiting for A-. A digital notebook is really nice. Easy to erase, rearrange, export… It works well for me.
  • Part of my everyday carry kit

Ideas for growth:

  • Settle into monthly pages, bullet journaling techniques
  • Practise drawing; use larger graphic elements & organizers, different shades
  • Integrate into Zettelkasten

2022-08-25-01 One month with the SuperNote A5X #supernote #drawing #decision-review #tech.png
2022-08-25-01 One month with the SuperNote A5X #supernote #drawing #decision-review #tech.png

I put my visual book notes and visual library notes into a Dropbox shared folder so that you can check them out if you have a Supernote. If you don't have a Supernote, you can find my visual book notes at sketches.sachachua.com. Enjoy!

You can e-mail me at sacha@sachachua.com.

]]> Trying out the SuperNote A5X 2022-07-29T14:57:34Z 2022-07-29T14:57:34Z https://sachachua.com/blog/2022/07/trying-out-the-supernote-a5x/

2022-07-25 Trying the SuperNote A5X
2022-07-25 Trying the SuperNote A5X

W- was happy with his SuperNote A5X, so I ordered one for myself on July 18. The company was still doing pre-orders because of the lockdowns in China, but it shipped out on July 20 and arrived on July 25, which was pretty fast.

I noticed that the org-epub export makes verse blocks look double-spaced on the SuperNote, probably because <br> tags are getting extra spacing. I couldn't figure out how to fix it with CSS, so I've been hacking around it by exporting it as a different class without the <br> tags and just using { white-space: pre }. I also ended up redoing the templates I made in Inkscape, since the gray I used was too light to see on the SuperNote.

2022-07-26b SuperNote for now
2022-07-26b SuperNote for now

It was very tempting to dive into the rabbithole of interesting layouts on /r/supernote and various journaling resources, but I still don't have much time, so there's no point in getting all fancy about to-do lists or trackers at the moment. I wanted to focus on just a couple of things: untangling my thoughts and sketching. Sketchnoting books would be a nice bonus (and I actually managed to do one on paper during a recent playdate), but that can also wait until I have more focused time.

2022-07-29a Getting the hang of drawing on the Supernote A5X
2022-07-29a Getting the hang of drawing on the Supernote A5X

I've had the A5X for five days and I really like it. Writing with the Lamy pen feels like less work than writing with a pencil or regular pen. It's smooth but not rubbery. I've still been drawing in landscape form because that feels a little handier for reviewing on my tablet or writing about on my blog, but I should probably experiment with portrait form at some point.

So far, I've:

sketched out my thoughts
I used to use folded-over 8x14" to sketch out two thoughts, but scanning them was a bit of a pain. Sometimes I used the backs of our writing practice sheets in order to reduce paper waste, but then scanning wasn't always as clean. I really like using the SuperNote to sketch out thoughts like this one. It's neat, and I can get the note into my archive pretty easily.
sketched stuff from life
This is easier if I take a quick reference picture on my phone. I could probably even figure out some kind of workflow for making that available as a template for tracing.
received many kiddo drawings
A- loves being able to use the eraser and lasso to modify her drawings. Novelty's probably another key attraction, too. She's made quite a few drawings for me, even experimenting with drawing faces from the side like the way she's been seeing me practice doing.
received many kiddo requests
A- likes to ask me to draw things. She enjoys tracing over them in another layer. More drawing practice for both of us!
used it to help A- practise coding, etc.
A- wanted to do some coding puzzles with her favourite characters. I enjoyed being able to quickly sketch it up, drawing large versions and then scaling down as needed.
played a game of chess
I drew chess pieces just to see if I could, and we ended up using those to play chess. I should share these and maybe add other games as well.
referred to EPUBs and PDFs
I put our favourite songs and poems on it. I've also started using org-chef to keep a cookbook.
doodled sketch elements
boxes, borders, little icons, people… Probably should organize these and share them too.

I've figured out how to publish sketches by using my phone to rotate them and sync them with my online sketches. Now I'm playing around with my writing workflow to see if I can easily post them to my blog. At some point, I think I'll experiment with using my phone to record and automatically transcribe some commentary, which I can pull into the blog post via some other Emacs Lisp code I've written. Whee!

You can e-mail me at sacha@sachachua.com.

]]>