CF Docker CustomTags

tslow, I don't think this is an issue about use of the CF Docker image.

Are you saying you have a working CF instance (non-docker) where you place jars in the CF custom tags, and somehow they "just work"? you can call them with cfobject or createobject, etc? That would be a surprise, as the customtags folder has no inherent connection with CF's support of Java objects/jars.

Instead, one who wanted use a jar could do any of a few things, such as add the jar (or the jar's folder) to the classpath (in the CF Admin "java and jvm" page), or they could point to it using the app-specific class-loading feature introduced in CF10. There are also some implicit libraries inside CF where classes can be loaded from.

I wonder if your issue may be that on your "working system", someone DID add the path to that customtags location into the classpath field of the CF admin, If so, that's why it would work on that sytem but not in Docker. You'd need to add that into the Docker implementation, either manually (in the admin) or via the Admin API (which can be called implicitly during container startup if placed in a template in a particular folder, as you may have seen in the CF docs on the CF Docker images.) 

Finally, in case someone there (you or a colleague) may "swear" that they did "something" regarding custom tags and java libraries, note also that CF has long supported CFX custom tags, where you a) register the class/jar in the CF Admin special page for CFX's, and then b) you'd call them in your code as a CFML tag with a cfx_ prefix. For more, see https://helpx.adobe.com/coldfusion/developing-applications/building-blocks-of-coldfusion-applications/building-custom-cfxapi-tags/writing-a-java-cfx-tag.html. But you don't mention using such cfx's, so I don't think that's your issue (but it could be).

If what I share doesn't get you going, tell us the exact error you are getting, and what kind of CFML tag or function is failing. When it comes to working with Docker images (at all, let alone CF), it can be more challenging, finding the diagnostics needed to understand how to solve problems. But it sounds like you have a handle on that.

Finally, it is certainly is a smaller pool of people you can turn to who are using CF Docker images at all (still not quite taking hold in the hearts and minds of the CF community, for a variety or reasons). And then the number within that group using "additional jars" (with respect to calling java objects from CFML) would certainly be a very small number. I'll admit, I haven't even had occasion to try that (calling a Java object from CFML, in a jar I've placed within CF), but I've done that with normal CF instances for years, and worked with the CF Docker images for over a year, so if anyone can help you resolve things, I hope I can. 🙂