I have a macOS application that is integrated with Crashlytics. If I run it as an agent, everything seems to work fine. But when I run it as a daemon, the crashs and errors don't show up on the web panel.
I'm thinking the problem might be that crashlytics uses a framework that is not daemon-safe. Apple documentation regarding the subject says:
If your daemon uses frameworks that aren't daemon-safe, you can run into a variety of problems.
Is this really the issue? Is there a workaround so I can get it to work?
Former maintainer for the Crashlytics SDK on Apple platforms here. However, I haven't been with the organization for a while, so my information could be out of date. You should definitely reach out to them for assistance. However, I'll still give this a shot.
A number of others have asked for this kind of functionality in the past, and from what I know, have successfully integrated Crashlytics into non-UI processes. There are some things to watch out for, though. I'm also aware of the daemon-safe issue, and that could be a problem. However, I'm unsure of how it might manifest itself.
When you say agent vs daemon, are you talking about per-process vs per-user launchd jobs, or something else? One thing I can be fairly certain of, is Crashlytics does not support multiple processes with the same bundle id running simultaneously. If there can be multiple copies of your process running at the same time, you cannot make this work. Even if it seems like it does work sometimes, it will not work reliably, at best, can could lead to serious issues at worst (potentially crashes).
One thing that is absolutely essential for correct operation is a main runloop. Crashlytics will definitely not work correctly without one.
Crashlytics also requires an Info.plist. This is actually possible to add to standalone binaries, but often trips people up. I'm guessing you figured this one out.
On macOS, Crashlytics integrates a bit with AppKit, to improve exception reporting. If I recall right, it's possible to just skip this integration completely, as outlined in the docs.
Another thing that Crashlytics relies on is a standard user file system home directory. There must be a ~\Library directory present with the standard internal structure. This one might be problematic for launchd daemons, since they run as root.
Keeping those things in mind, I'm pretty sure it's possible to make this work. There could be some things I'm not remembering, as it's been a while. However, one thing I definitely do know is this is a bit of a gray area. It works, but wasn't an explicit design goal. It might now be unsupported. You should definitely check in with them about this before shipping something.