Sep 18, 2026, 5:13 PMI was today years old when I learned that Dockerfiles support heredoc-like syntax, and I am furious at every tutorial and presenter that has used a dozen lines with \ instead of that.
- Sep 18, 2026, 5:13 PM
Replies
Stéphane 🏴☠️🐘👨💻🇪🇺🐧️s_hulard@mamot.frSep 18, 2026, 5:16 PM@Crell 😯 how do you use this ? Have you a sample ?
- Sep 18, 2026, 5:17 PM
@s_hulard See https://frankenphp.dev/docs/docker/#running-as-a-non-root-user for example. (That's where I first saw it, an hour ago.)
- Stéphane 🏴☠️🐘👨💻🇪🇺🐧️s_hulard@mamot.frSep 18, 2026, 5:18 PM
@Crell wow that's a lot more readable and expressive, thank you for sharing !
- Alejandro Celayaacelaya@mastodon.socialSep 28, 2026, 3:41 AM
@Crell WTF! I didn't know this either 😅
- Franz Graffgraf@hachyderm.ioSep 18, 2026, 5:19 PM
@Crell WHAT?! and that exists since 2021 ( https://www.docker.com/blog/introduction-to-heredocs-in-dockerfiles/ )
Thanks for sharing - Sep 18, 2026, 5:20 PM
@fgraf iknowright? Excuse me, I have to go switch over a bunch of Dockerfiles...
Stephan Hochdörfershochdoerfer@phpc.socialSep 18, 2026, 5:37 PM@Crell wait, what?
- Sep 18, 2026, 5:37 PM
- Stephan Hochdörfershochdoerfer@phpc.socialSep 18, 2026, 5:38 PM
@Crell ha, read these docs last week and did not realize at all :(
Alerta! Alerta!heiglandreas@phpc.socialSep 18, 2026, 5:40 PM- Alerta! Alerta!heiglandreas@phpc.socialSep 18, 2026, 6:02 PM
As I am right now debugging a DOckerfile I immediately used that.
And what shall I say....
RUN <<INSTALL_BASIC_TOOLS
apt update
apt install curl gpg software-properties-common -y
INSTALL_BASIC_TOOLSnow even allows me to remove the comment as it'S now selfdocumenting!
🎉
- Alerta! Alerta!heiglandreas@phpc.socialSep 18, 2026, 6:15 PM
@shochdoerfer Of course I ran into an issue as I was running docker 20.something - which doesn't understand that ... 🙈
Updating to docker 29.whatever solved the issue
- Stephan Hochdörfershochdoerfer@phpc.socialSep 19, 2026, 6:02 AM
@heiglandreas you and your edge cases :)
Sep 18, 2026, 6:00 PM@Crell learned it last year: game changer
- Sep 18, 2026, 6:00 PM
- AdirelleAdirelle@mastodon.socialSep 18, 2026, 8:57 PM
@Crell I also discovered it recently, but to be fair the syntax of Dockerfiles does evolve over time.
- Sep 19, 2026, 12:15 AM@Crell WHAT?!?
Ben Ramseyramsey@phpc.socialSep 28, 2026, 3:16 AM@Crell @JosephLeedy Wait, what?!!!!
Sep 28, 2026, 3:47 AM@Crell Good news: You can also use shebangs for custom interpreters.
So you can have php in your dockerfile.
I have to imagine there is some sort of drawback to this madness.
- Sep 28, 2026, 3:50 AM
@kboyd 😲 I am both shocked and horrified by this concept.
- maschinenstuermerlukasrotermund@social.lukasrotermund.deSep 28, 2026, 4:13 AM
- Sep 28, 2026, 4:17 AM
@lukasrotermund @Crell Well, sure, if it's `FROM php:8.6-cli` .... :)
