Vert.x based application crashes on docker container

Judging by FileResolver.java, vert.x tries to create a ".vertx" directory in the current working directory by default. You have configured a user called "daemon", are you sure that this user has write access to the working dir in the docker image? If not, change the permissions as outlined in docker-image-author-guidance, or revert to using the root user.

This directory is used to serve files contained in jar files (for example web assets packaged in a fat jar). If you are not using this feature, you can disable the creation of this directory by setting the vertx.disableFileCPResolving system property to true. You can also change the location using the vertx.cacheDirBase system property.

Reference: https://groups.google.com/forum/#!topic/vertx/7cBbKrjYfeI

This exception is caused when Vert.x tries to create .vertx (cache dir) so that it can copy and read a file from the classpath or file that's on the classpath. It's possible, the $user doesn't have permission to create the cache directory.

The reason behind cache dir is simple: reading a file from a jar or from an input stream is blocking. So to avoid to pay the price every time, Vert.x copies the file to its cache directory and reads it from there every subsequent read. This behavior can be configured.

vertx run my.Verticle -Dvertx.cacheDirBase=/tmp/vertx-cache
# or
java -jar my-fat.jar -Dvertx.cacheDirBase=/tmp/vertx-cache

Otherwise, you can completely avoid this behavior, launch your application with -Dvertx.disableFileCaching=true. With this setting, Vert.x still uses the cache, but always refresh the version stored in the cache with the original source. So if you edit a file served from the classpath and refresh your browser, Vert.x reads it from the classpath, copies it to the cache directory and serves it from there. Do not use this setting in production, it can kill your performances.

link to documentation