If the aim is simple portability, I think it would be better to use Docker to create a lightweight image. Dagger supports general-purpose programming languages. So it allows you to write powerful logic. Dagger is powerful, but I found the migration challenging because it’s the heavy tool with its quirks. Dagger wasn’t right for my needs. I created a small tool (https://github.com/lask-task-runner/lask) for building lighter, simpler Docker layers. At my work, a simple tool like this was enough.

I like Dagger but it doesn't scale very well for larger workloads. Excellent for small/medium projects, though.

I haven't used Dagger but it looks like a fundamentally different design from traditional CI engines, so some people might have issues moving to it.

I recommend Drone.io or WoodpeckerCI for hosting your own CI. It's a very good design; very simple, easy to run, easy to use, integrates with most systems you'd want to, abstracts away components rather than tightly integrating them, and you don't need to be a programmer to use it. So basically the opposite of Dagger.

Yes, I use Dagger, it's much more than building containers

- Container based workflows are the same in CI and locally (you can run containers too), they become one-liners

- Remote caching out of the box without extra steps

- Multiple language SDKs, unlocks the DAG in BuildKit and containers, real reuse

- Obfuscates secrets from your logs and agents. I've built an agent environment on Dagger, which also includes forking and time travel)

tl;dr - Dagger gives you SDK access to BuildKit and container based DAGs for building or anything else.

v1-beta just released yesterday: https://dagger.io/blog/dagger-10-beta/

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edit: they are replacing BuildKit (for good reasons) and that is already out https://dagger.io/changelog/theseus/