Features/RetraceServer

Retrace Server

Summary

Retrace server allows ABRT users to get better backtraces from their crashes by retracing coredumps remotely, on a server owned by Fedora Project.

Owner

• Name: Michal Toman

• Email: mtoman@redhat.com

Co-workers

• The ABRT team
• E-mail: crash-catcher@lists.fedoraproject.org
• Name: Karel Klic
• Name: Jiri Moskovcak

Current Status

• Targeted release: Fedora 15
• Last updated: 2011-02-21
• Percentage of completion: 95%

Detailed description

When ABRT generates a backtrace from a coredump, it needs debuginfo data to be available for the binary and all libraries involved in the crash. Debuginfo packages require a lot of storage space, and sometimes they are not available at all -- a package update causes the removal of older updates of the same package and their debuginfo.

Another problem is that GDB (which generates the backtrace from the coredump) needs data from the binary and libraries that were involved in the crash. If a user updated some relevant package between observing the crash and reporting it, he might be unable to generate a good quality backtrace because of the updates. This happens often, because Fedora is updated frequently.

Retrace server is one possibility to solve these issues. ABRT offers user to upload her coredump to a remote server, then the retracing step happens there. The server creates an environment identical to what was on the user's computer at the time of the crash, by installing all the required packages and their debuginfo. The retrace server is able to do that because it keeps all the older packages from updates, and relevant part of updates-testing locally on the server.

After creating the backtrace, only the submitter is allowed to download/view it.

Benefit to Fedora

Users:

1. Less disk space and processing time needed to use ABRT to report crashes.
2. Possibility to report older crashes.
3. Lower chance of failure, less time spent on crashes which cannot be retraced because debuginfo is no longer available.

Developers:

1. Higher quality of ABRT reports.
2. Possibility to quickly get a backtrace from any/random Fedora coredump.

Scope

ABRT is extended to support Retrace Server.

Retrace server is installed on https://retrace01.fedoraproject.org.

The server implementation consists of three parts:

• HTTP Interface: Receives the archive with a coredump from user, unpacks all files, puts new task into the queue.
• Analyzer: Takes a task from queue, creates a virtual root with all required packages and debuginfos installed and runs GDB to create the backtrace.
• Repository Synchronizer: Downloads packages to a local repository containing all versions of all packages (no removal of older updates).

How To Test

CLI retrace client can be built from ABRT Git repository. CLI is integrated into latest ABRT GUI (analyze_RetraceServer).

Usage

$ abrt-retrace-client
Usage: abrt-retrace-client <operation> [options]
Operations: create/status/backtrace/log/batch

    -v, --verbose         Be verbose
    -s, --syslog          log to syslog
    -k, --insecure        allow insecure connection to retrace server
    --url URL             retrace server URL
    --headers             (debug) show received HTTP headers

For create and batch operations
    -d, --dir DIR         read data from ABRT crash dump directory
    -c, --core COREDUMP   read data from coredump (not yet implemented)
    --no-unlink           (debug) do not delete temporary archive created from dump dir in /tmp

For status, backtrace, and log operations
    -t, --task ID         id of your task on server
    -p, --password PWD    password of your task on server

Create a new retrace job:

$ abrt-retrace-client create -d ~/.abrt/spool/ccpp-whatever
Task ID: 123456789
Task Password: qwerty123456

Ask for status:

$ abrt-retrace-client status -t 123456789 -p qwerty123456
PENDING / FINISHED_SUCCESS / FINISHED_FAILURE

Ask for log:

$ abrt-retrace-client log -t 123456789 -p qwerty123456
log (text/plain)

Ask for backtrace:

$ abrt-retrace-client backtrace -t 123456789 -p qwerty123456
backtrace (text/plain)

Batch processing (all-in-one):

$ abrt-retrace-client batch -d ~/.abrt/spool/ccpp-whatever
[create]
[status] PENDING
[status] PENDING
[status] PENDING
[status] FINISHED_SUCCESS
[backtrace]

The retrace server at retrace01.fedoraproject.org (used by default) is configured to handle crashes for the following releases:

• Fedora 14 i686
• Fedora 14 x86_64
• Fedora 15 i686
• Fedora 15 x86_64

There is no trusted HTTPS certificate on retrace01.fedoraproject.org yet. You need to use -k option.

User Experience

ABRT reporting wizard offers a possibility to use retrace server instead of local retracing to generate a backtrace. Local retracing is still the default action.

Dependencies

• new version of ABRT, supporting the retrace server option
• a server with the retrace server application up and running

Server code dependencies:

• mock
• xz
• elfutils
• createrepo
• mod_ssl
• mod_wsgi
• python-webob

Contingency Plan

Hide the possibility of using the retrace server from users in ABRT's graphical user interface.

Documentation

• Design document
• Retrace server wiki page on ABRT wiki

Release Notes

ABRT, a crash reporting tool in Fedora, now allows to prepare a part of crash processing remotely, on a server owned by Fedora Project. Remote coredump retracing leads to better quality of reports. Retrace server can generate good backtraces with much higher success rate than local retracing.

Comments and Discussion

• See Talk:Features/RetraceServer