Your CF engine (Lucee, Adobe, etc) or Java app may have application logs of its own and their locations will vary based on what you have running. In any case, they will most likely be located under the server home directory.
CF App server logs
You can find out where your server home is by running:
server info property=serverHomeDirectory
You can also get the full path to your servlet's "out" log with this command:
server info property=consolelogPath
This log file is the equivalent of your catalina.out file on a typical Lucee/Tomcat install or the equivalent of your coldfusion-out.log file on a typical ColdFusion install.
The Servlet's "out" log can be tailed with this command:
server log --follow
server log myServerName --follow
Your console "out" log will auto-rotate every 10MB to keep it from getting too big. Don't use the --debug or --trace flag on a production server or you'll get a lot of logging information! Without those flags, the "out" log doesn't log anything for each request. With debug enabled, you'll get basic information for each request that comes in as well as whether a rewrite rule fired, and with trace, you'll get a ton of information about every request as well as every local path resolution by the path resource manager.
Lucee Server's Log Files
There are many log files for Lucee. For the guide below, I'm assuming you haven't set a custom serverConfigDir or webConfigDir for your servers. If you have, adjust the paths for the server and web context to be whatever it is you've configured. Here are the three locations you'll find log file and is pretty much the same for Lucee 4 and Lucee 5.
Lucee's server context log files - The server context is located under the server home which you can find with the command server info property=serverHomeDirectory. Open that directory and then navigate to WEB-INF/lucee-server/context/logs/.
Lucee's web context log files - The web context is also located under the server home. Open that directory and then navigate to WEB-INF/lucee-web/logs/.
So, to give real examples-- a Lucee server I just looked at on my machine has the three folders of log files I just covered above in these locations:
Since Adobe doesn't have the separation of server and web contexts, it only has two log locations which are as follows on all versions.
ColdFusion server log files - The remaining log files are located under the server home which you can find with the command server info property=serverHomeDirectory. Open that directory and then navigate to WEB-INF\cfusion\logs/.
So, to give real examples-- a ColdFusion server I just looked at on my machine has the two folders of log files I just covered above in these locations:
CommandBox servers use a powerful Java-based web server which we've tested to have throughput just as good as Apache or IIS. You can enable "access" logs which output one line for each HTTP request (even for static assets like JS or image files) in the same "common" format that Apache web server uses.
server set web.accessLogEnable=true
View the location of this log or tail the log contents like so:
server info property=accessLogPath
server log --follow --access
server log myServername --follow --access
Your access log will be auto-rotated every day.
Rewrite Log
CommandBox servers use the java-based Tuckey rewrite engine for easy URL rewriting. There's a lot of good debugging information available to help figure out why your rewrites aren't working. You can enable a separate rewrite log to view this information. Keep in mind this can generate a lot of logging output.
server set web.rewrites.logEnable=true
View the location of this log or tail the log contents like so:
server info property=rewritesLogPath
server log --follow --rewrites
server log myServername --follow --rewrites
Your rewrites log will be auto-rotated every 10MB. The amount of information that appears in the rewrites log will be affected by the --debug and --trace flags when you start the server.
Request Dumping
There is a feature you can use to dump all the header details for an HTTP request and response in the form of an Undertow handler called dump-request(). Just include the following server rule in your server.json
{"web" : {"rules": ["dump-request()" ] }}
To fire only for certain requests, you can pair the handler with any predicate you wish: