There are different ways to get more insight on what’s going wrong with your tasks in case of errors. Generally, those errors come from the fact the running environment may be different from your task development environment (OS configuration, software set,…).
Every time an administrator submit a new job and receives result on the frontend, a Debug information is made available in the sidebar. Those information contain all the submission metadata (input, result, feedback,…) as well as the grading container standard output and standard error output.
Please note that every manipulation done with those streams will not be visible anymore in those information. Redirected output won’t be shown. This is important as spawning processes in non-shell oriented languages will not redirect the spawned process standard output on the grading container standard output.
Debugging tasks is made more easy using SSH debug feature. This aims at providing the same user experience as local development. To make this feature work remotely (regarding the INGInious Docker agent), please make sure you’ve correctly set up the debug hosts and ports (see Configuration reference if needed).
Every administrator is able from the frontend to launch a debugging job. This is done by clicking on the >_ (left-chevron, underscore) button next to the Submit button. According to your configuration, either a SSH command-line with auto-generated password will be given you (you will, in this case, need an SSH client installed), or an embedded SSH console will pop up as the feedback position.