Yurt blueprint isolation

[dhruvbhatia]

Hi there,

I have run into another edge case that I'd like your guidance with.

I have a situation where I've built super-cool-library which uses Yurt to run it's lifecycle.
If I create my-project, a project with mount components, and add super-cool-library as a dep, I find that super-cool-library's yurt/blueprint contains ALL the mount components of the parent project.

This means that starting super-cool-library within a mount component in the parent project results in ALL the mount components starting. In other words, there is no isolation between a Yurt blueprint of a dependency, and the parent project.

Is this by design? If so, is there a way for me to limit a dependancy's lifecycle so that the yurt/blueprint fn doesn't pull in components from other namespaces?

Let me know if my explanation is gibberish - I can try and create a demo project if need be!

[tolitius]

usually libraries are stateless: i.e. they provide functionality with the state passed to them. As a rule of thumb I would generally try to keep libraries stateless.

but of course there are different use cases. I just added building smaller Yurts that would allow your "super-cool-library" to only start its own components: i.e. when it's built, it would not look at the app components.

Let me know if that works for you.

[dhruvbhatia]

Thanks - that works well, appreciate the update!

One more q: is it possible to combine build-only with the ability to swap alternative implementations (as per build-with)?

[tolitius]

sure, glad it worked for you!

build-only & build-with not right now, but maybe later when I have more time to work on it :)

[dhruvbhatia]

No probs - I've sent a PR #4 adding yurt/build-only-with which combines :only and :swap. There is also a relevant test showing how this works.

Let me know your thoughts? My code probably isn't the most elegant, but it works as expected!

[tolitius]

I enhanced build / destroy a little to optionally take a map with options:

(yurt/build (yurt/blueprint) {:swap {"neo.conf/config" test-config}
                              :only ["neo.conf/config" "neo.db/db"]})

so now we can combine them easily in one call to build.

see whether it works for you (0.1.2-SNAPSHOT), I'll release it with docs some time later.

[tolitius]

* only build takes opts map and does something to it. destroy does not do anything with the map yet.

[dhruvbhatia]

Awesome - this looks a lot cleaner than my solution (I shall close that PR now).
Thanks for the update!

[tolitius]

sure.
thanks for the PR and for raising the issue though, since it would not happen without them :)