Revision 6 as of 2006-10-23 09:58:27

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Apport - Automatic crash reports

What is this all about?

Debugging program crashes without any automated tools has pretty time consuming and hard for both developers and users. Many program crashes remain unreported or unfixed because:

  • Many crashes are not easily reproducible.
  • End users do not know how to prepare a report that is really useful for developers, like building a package with debug symbols, operating gdb, etc.

  • A considerable part of bug triage is spent with collecting relevant information about the crash itself, package versions, hardware architecture, operating system version, etc.
  • There is no easy frontend which allow users to submit detailed problem reports.
  • Existing solutions like bug-buddy or krash are specific to a particular desktop environment, are nontrivial to adapt to the needs of a distribution developer, and do not work for crashes of background servers (like a database or an email server).

Apport is a system which

  • intercepts crashes right when they happen the first time,
  • gathers potentially useful information about the crash and the OS environment,
  • and presents an UI that informs about the crash and instructs the user how to proceed.

We hope that this will lead to a much better level of quality assurance in the future.

How does it look like for users?

The user side of apport is designed to be extremely simple and as unannoying as possible.

If any process in the system dies due to a signal that is commonly refered to as 'crash' (segmentation violation, bus error, floating point exception, etc.), the apport backend is automatically invoked. It produces an initial crash report in a file in /var/crash (the file name is composed from the name of the crashed executable and the user id). If the crashed process belongs to the user who is currently logged in, apport informs the user about the crash and offers to report the problem:

  • attachment:apport-gtk-desktopfile.png

If an user process crashes while the user is not currently logged in, update-notifier will present a notification when the user starts a desktop session the next time:

  • attachment:apport-async-crash.png

Clicking on the bomb icon will cause the same frontend to appear.

There currently is no automatic way to submit a crash report to the distribution developers (see "Future plans" below). For now, if the user chooses "Report bug", apport-gtk opens the packages' bug tracking page in the web browser and asks the user to create a bug and attach the apport report:

  • attachment:apport-gtk-report.png

Experienced can also take a look into the report content:

  • attachment:apport-gtk-report-details.png

I'm a developer. How to I use these crash reports?

Report format

apport uses the standard Debian control syntax for reports, i. e. keeps everything in a flat file that looks like this:

DistroRelease: Ubuntu 6.10
ExecutablePath: /usr/bin/gcalctool
Package: gcalctool 5.8.24-0ubuntu2
ProcCmdline: gcalctool
 #0  0x00002ae577bb37bf in poll () from /lib/
 No symbol table info available.
 #1  0x00002ae57786991e in g_main_context_check () from /usr/lib64/
 No symbol table info available.
CoreDump: base64

Only a tiny subset of the available fields are shown here. Apport reports include a core dump in a compressed and uuencoded format, which is useful for post-mortem debugging and post-mortem generation of a symbolic stack trace.


There are several tools available for working with a crash report:

  • apport-unpack: Unpack a report into single files (one per attribute). This is most useful for extracting the core dump. Please see the manpage for further details.

  • apport-retrace: Regenerate stack traces of a report. If you supply the -d option, this tool will automatically download available debug symbol packages and use them to generate a symbolic stack trace. The manpage explains the functionality and all available options in detail.

  • python-problem-report: This package ships a Python module problem_report which provides general dictionary access to a crash report and loading/saving methods (not specific to apport reports).

  • python-apport-utils: This package ships a Python module apport_utils which encapsulates core functionality of apport and is specific to crash reports. You can use it to implement your own frontends as well as creating custom crash reports (Ubuntu's graphical installer "ubiquity" uses this).

How does it work internally?

kernel patch, crashdump-helper, report, update-notifier, inotify, apport-gtk

Future plans

Use the source, Luke!