[GauntletWizard]

Possibly because running a bot client is much different from running a webserver. Dialing outbound to connect to slack is much easier than figuring out or configuring your own canonical URL, opening ports, etc.

On the other hand, preparing hands as a single image seems a bad way of doing this; Does the slack API only allow a single image per conversation? I agree with your preparation microservice idea - There should be (and probably are several) a service that allows you to specify a poker hand as a query string and get back an image of the hand. More simply, though: A webfont and https://en.wikipedia.org/wiki/Playing_cards_in_Unicode

[TazeTSchnitzel]

Are images even necessary, anyway?

Unicode has playing card codepoints (the full 52) and playing card house codepoints (️, ️, ️, ️).

Edit: What the hell? Hacker News stripped the Unicode characters?! https://news.ycombinator.com/item?id=10156894

[CharlieHess]

You can't control the font rendering in Slack (it's Lato, at a certain size). The Unicode cards are far too small to read.

[TazeTSchnitzel]

I did think of that. But you could use the symbols for the houses and pair them with a number/letter.

[CharlieHess]

The Slack API only allows a single image URL for attachments. I was also keen on the idea of being able to swap out the card assets whenever. Unicode playing cards is a decent idea, except Slack only renders in Lato.

[icebraining]

Does Slack accept images with data URIs instead of URLs? Seems like it'd give you the best of both worlds.

[OJFord]

    >  preparing hands as a single image seems a bad way of doing this

I don't believe there's another way to display them inline?

[Vexs]

I saw it on HN a while ago- a webservice that does poker hands using a URL; you could pass it cards in the URL and it would display them.

[jeeva]

deckofcardsapi.com, if it's the one I'm thinking of?