Examples

Automatic crash reporting through e-mails

This example deals with configuration of libreport for sending full crash reports including backtrace via an e-mail service from an autonomous system. We usually encounter such systems in automatic testing environments. Let’s configure ABRT to send notification e-mails to devel@lists.project.org.

libreport’s default configuration already supports sending of notification e-mails to root user on a local system. This functionality is stored in /etc/libreport/events.d/mailx_event.conf file that contains the following definition of notify and notify-dup events:

EVENT=notify
    # do not rely on the default config nor on the config file
    Mailx_Subject="[abrt] a crash has been detected" \
    Mailx_EmailFrom="ABRT Daemon <DoNotReply>" \
    Mailx_EmailTo="root@localhost" \
    reporter-mailx --notify-only

EVENT=notify-dup
    # do not rely on the default config nor on the config file
    Mailx_Subject="[abrt] a crash has been detected again" \
    Mailx_EmailFrom="ABRT Daemon <DoNotReply>" \
    Mailx_EmailTo="root@localhost" \
    reporter-mailx --notify-only

Note

The subject, sender and recipient are passed through the environment variables because reporter-mailx does not support these options in its command line arguments and putting it to its configuration file would break the general reporting workflow.

Detected problem types can be divided into two groups based on availability of backtrace at the time of detection. The first group consists of Python, Kernel oops, Ruby and Java problem types where backtrace is available at the time of detection. The second group consists of CCpp (process crashes, C/Cpp) where backtrace must be extracted from a dump file.

The default configuration of notify event is almost usable for the problem types having backtrace available at the time of detection. We can reuse the default configuration with some tweaks. We need to update recipient’s address and remove --notify-only string from reporter-mailx‘s command line arguments as it forces reporters-mailx to compose the message from a minimal subset of problem data in order to not waste too much disk space on a local system where all the excluded data are easily accessible anyway. We also need to configure libreport to not use it for CCpp problems because we will provide its own event definition.

The default notify-dup event is almost usable for all problem types because it is run for consecutive occurrences of a single problem (notify event is run for the first occurrence and should create all the required data). We only need to update recipient’s address because --notify-only argument make sense for notify-dup event.

Since we are going to use repoter-mailx in several places and we do not want to repeat ourself, we first move the static e-mail preferences (sender and recipient) to /etc/libreport/plugins/mailx.conf:

EmailFrom="ABRT Daemon <DoNotReply>"
EmailTo="devel@lists.project.org"

And the updated default configuration lines follow:

EVENT=notify analyzer!=CCpp
    # full notify e-mail
    Mailx_Subject="[abrt] a crash has been detected" \
    reporter-mailx

EVENT=notify-dup
    # full notify-dup e-mail
    Mailx_Subject="[abrt] a crash has been detected again" \
    reporter-mailx --notify-only

"analyzer!=CCpp" tells libreport to run the lines above only if contents of analyzer file does not equal to "CCpp" string.

We are done with the default configuration and now we are going to define notify event for CCpp. To be able to generate full GDB backtrace, we need all relevant debug data. On Fedora like systems, ABRT can provide the required debug data by extracting build ids from coredump file and unpacking rpm packages providing paths made from the extracted build ids.

CCpp notify event lines follow:

EVENT=notify analyzer=CCpp
    # CCpp notify event sending e-mail with full gdb backtrace
    # extract build ids from coredump file and save them in 'build_ids' file
    abrt-action-analyze-core --core=coredump -o build_ids >>event_log 2>&1 &&
    # download and unpack rpm package for each id in 'build_ids' file
    abrt-action-install-debuginfo -y >>event_log 2>&1 &&
    # call gdb to generate backtrace with local variables, call arguments
    # disassembly, etc. and save it in 'backtrace' file
    abrt-action-generate-backtrace >>event_log 2>&1 &&
    # generate 'duphash', 'crash_function' and 'backtrace_rating'
    abrt-action-analyze-backtrace >>event_log 2>&1
    #
    # send e-mail
    Mailx_Subject="[abrt] a crash has been detected" \
    reporter-mailx

Along with other problem data, the notification e-mail will also contain event_log (useful for ABRT debugging), backtrace_rating (backtrace quality measure value based on ration of resolved and unresolved frames) and duphash which ABRT uses to identify a crash across all supported bug-tracking systems and all machines (e.g. ABRT puts "abrt_hash:$(cat duphash)" string to Whiteboard field of Bugzilla bug reports.)

Tip 1:

You can add reporter-bugzilla -h $(cat duphash) >>bugzilla_bug_id command to include existing Bugzilla bug report IDs for the currently processed crash. This works on Fedora only.

Tip 2:

You can make e-mail’s subject more informative. The following script is not bullet proof but produces really nice e-mail subject for C/Cpp problems:

Mailx_Subject="[abrt] $(cat package || cat executable): $(cat crash_function && echo "():") $(cat reason || (cat executable && echo " crashed"))"

Getting core files from systemd-coredumctl

By default, ABRT detects crashes of native programs (C, C++) by its core dump helper which is registered in /proc/sys/kernel/core_pattern. Unfortunately, there can be only one core pattern helper at the time so the ABRT core dump helper cannot coexists with systemd-coredumctl.

However, the ABRT core dumper helper can be turned off and the ABRT systemd-coredumpctl watcher can be used to make ABRT notified of crashes of native programs.

Everything you need to do is to disable abrt-ccpp.service which replaces the core_pattern configured via sysctl with the ABRT core pattern helper. If the service is running the core_pattern should start with |/usr/libexec/abrt-hook-ccpp.

systemctl stop abrt-ccpp.service
systemctl disable abrt-ccpp.service

Once you stop and disable the abrt-ccpp.service the core_pattern help should start with |/usr/lib/systemd/systemd-coredump. If it does not, please check if the file /usr/lib/sysctl.d/50-coredump.conf exist and ensure that there is no other file containing kernel.core_pattern= (sysctl.d(5)).

The last two things you need to do is to enable and start abrt-journal-core.service.

systemctl enable abrt-journal-core.service
systemctl start abrt-journal-core.service

The current version of abrt-journal-core.service needs to make copies of data that ABRT needs to be able to open a report in a bug tracking tool and leaves the systemd-coredumpctl data untouched. That means that you cannot use the ABRT journal core service to clean systemd-coredumpctl and you will end up having two copies of core files, one in systemd-coredumpctl‘s storage and one in a sub-directory of /var/spool/abrt/.

Collecting extra log files for crashes of a particular package

ABRT tries to provide maintainers with as much information as possible. Good source of problem details can be log files. Hence, upon detection of a crashed process, ABRT goes through the system logs and copy lines looking related to the crashed process to a file called var_log_messages in the problem directory. The file can be found attached to bug reports opened by ABRT/libreport.

However, application may not opt in for logging to system logs for various reasons. In such case, ABRT can be configured to copy log files to problem data directory and libreport will automatically attach them to bug reports.

Let’s assume we have a package called foo and we want to copy log files that are created in user’s /var/run/ directory. The application runs several concurrent processes and each of the processes writes debug messages to its own log file denoted by process’ PID.

To get these log files, we need to create a new libreport EVENT configuration file and instruct ABRT to run it after a crash of foo’s executable appears. By default, ABRT runs post-create, notify, and notify-dup EVENTs upon new problem detection. We cannot use post-create because at that time package of crashed executable might not be known. notify-dup is not suitable because the event is executed for re-appearing problems, hence, the log files should be already captured. Therefore we must define new notify EVENT.

EVENT=notify pkg_name=foo
    # Copy log files of crashed process to foo.log
    cp /var/run/$(cat uid)/foo.$(cat pid).log foo.log

The pkg_name=foo string tells ABRT to run the lines above for problems in any of executable shipped by the foo package. You can add as many such conditions as you need. The lines below the first line are interpreted by /bin/sh and current working directory contains all problem data captured by ABRT.

The code must be placed in a file in the /etc/libreport/events.d/ directory. Packages often follow the ${package name}_event.conf rule for these files.

Ignore particular binaries on hook level in older version of ABRT

Ignoring crashes of specific binaries on hook level was introduced in RHEL 7.3 in ABRT version 2.1.11-36, in RHEL 6.8 in version 2.0.8-37, and in Fedora in ABRT version 2.8.1. Option IgnoredPaths in conf file /etc/abrt/plugins/CCpp.conf.

Is it possible to ignore crashes on hook level even in older version of ABRT?

Yes, it is. You can write your own core_pattern script (man core(5)) which filters/ignores binaries and works as a wrapper for abrt-hook-ccpp which cannot do the filtering.

Example how to do this:

Create the core_pattern script (for instance /etc/my_abrt_ccpp_hook.sh) with following content:

#!/bin/bash

# kernel.core_pattern = |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t %e
#                                                    $1 $2 $3 $4 $5 $6 $7
# You want to filter %e - executable filename (without path prefix), so parameter $7

# Is it the particular binary you want to ignore?
if [[ $7 == "EXECUTABLE_YOU_WANT_TO_IGNORE" ]]
then
    # Do what you want
else
    # In other cases use ABRT's hook in standard way
    cat /dev/stdin |/usr/libexec/abrt-hook-ccpp $1 $2 $3 $4 $5 $6 $7
fi

Set the new kernel.core_pattern (basically, change /usr/libexec/abrt-hook-ccpp to /etc/my_abrt_ccpp_hook.sh):

# sudo sysctl kernel.core_pattern
kernel.core_pattern = |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t %e
# sudo sysctl kernel.core_pattern="|/etc/my_abrt_ccpp_hook.sh  %s %c %p %u %g %t %e"
kernel.core_pattern = |/etc/my_abrt_ccpp_hook.sh %s %c %p %u %g %t %e