Binaries & libraries

Using strace

This guide describes how to debug an application on Vorteil that may be behaving unexpectedly. Undesirable behaviour can be the result of incorrect/missing shared object libraries. While tools such as the Vorteil CLI provide an easy method of gathering shared objects ($ vorteil projects import-shared-objects ...), some shared dependencies only become apparent during runtime (for example, DNS resolution via libresolv.so).

In these situations, it can be useful to use the strace tool for debugging purposes. To enable strace, adjust the [[program]] block that defines your application:

[[program]]
  binary = "/app"
  args = "-arg1 -arg2"
  strace = true

Shared objects in non-standard locations

The import-shared-objects command takes most of the effort out of finding and importing any shared objects that a Vorteil project depends on, but it’s not bulletproof. Despite running vorteil projects import-shared-objectsr’, it is possible that an app will be unable to locate all of the shared objects it requires even if they do exist inside the project directory. Luckily, this is usually quite a simple issue to resolve.

If an app is unable to locate certain shared objects, the following output (for example) might be observed:

Failed to open dedicated.so (dedicated.so: cannot open shared object file: No such file or directory)

The first step is to confirm that the missing shared object is located within the project directory.

$ cd $PROJECT_DIR
$ find ./ | grep dedicated.so
./csgo-ds/bin/dedicated.so

Running a find operation shows that the missing shared object is located within the csgo-ds/bin directory inside of the project. Simply take this path and add the LD_LIBRARY_PATH environment variable to the affected [[program]] within the project .vcfg file:

[[program]]
  binary = "/path/to/my/binary"
  args   = "args go here"
  env    = ["LD_LIBRARY_PATH=/csgo-ds/bin"]

Note: Additional fields can be added to the LD_LIBRARY_PATH environment variable using : as a delimiter. For example: LD_LIBRARY_PATH=/csgo-ds/bin:/test/bin

Run the app again an observe the results. It may be necessary to repeat this process a number of times before all dependencies have been properly located.