Log collection in Khaleesi

Collecting and saving the logs after a job run from the affected machines is an important step. Khaleesi has a playbook dedicated for this process.

To collect the logs from the machines, run the khaleesi/playbooks/collect_logs.yml playbook right after the job run with the same settings and host file. The localhost and the machine called host0 is excluded from the log collection. They are usually long running machines (the slave and if it exists, a virtual host) that have a large amount and mostly irrelevant logs.

What files are gathered?

Quite a few diagnostic commands are run on the machines (found in the playbook) and then a set of log files collected. If some specific setting used require specific logs to be collected, it’s practical to add these files to that specific settings yaml:

        - /var/foo/*.log
        - /var/bar/engine.log
        - /opt/baz/*.xml

If any file is missing it won’t cause the log collection to fail.

Methods of gathering logs

By default the logs are stored on the machine running ansible in khaleesi/collected_files, each machine’s log in a different tar.gz file.

This behavior can be changed by the --logs=gzip option, which will result in individually gzipping the files instead.

Uploading the logs

When using the gzip method, it’s possible to upload the logs on an artifact server. Ideally the logs are then exposed on a HTTP server for online browsing.

To set up a new site, add a new option to khaleesi/settings/logs/gzip/site, then use the --logs-site option when running ksgen.

An example site definition looks like:

    rsync_logs: true
    rsync_path: myuser@example.com:/opt/artifacts
    artifact_url: http://example.com/artifacts

The rsync_path should be something that rsync understands as a destination, and the artifact_url will be used to generate the link to the logs. This method assumes the job runs on a Jenkins server, so the $BUILD_TAG variable should be set in the environment.

After the upload, the logs are deleted from the local machine and a link file is created as khaleesi/collected_files/full_logs.html. This file should be added as an artifact to the Jenkins job definition and can be used as a one click redirect to the job specific artifacts.

Setting up an artifact storage

The machine running the job should be able to upload the logs without a password to the artifact server. When using Apache to expose the logs for browsing, the following httpd settings will allow transparent browsing of the gzipped files:

Alias /artifacts /opt/artifacts

<Directory /opt/artifacts>
    Options +Indexes
    RewriteCond   %{HTTP:Accept-Encoding} gzip
    RewriteCond   %{LA-U:REQUEST_FILENAME}.gz -f
    RewriteRule   ^(.+)$ $1.gz [L]
    <FilesMatch ".*\.gz$">
        ForceType text/plain
        AddDefaultCharset UTF-8
        AddEncoding x-gzip gz

It’s recommended to put these settings to a separate file in the /etc/httpd/conf.d directory.

Pruning old logs

The artifact directory could grow too big over time, thus it’s useful to set up a cron job for deleting obsolete logs.

On the artifact server, add a line to /etc/crontab similar to this:

0 0 * * * rhos-ci find /opt/artifacts -maxdepth 1 -type d -ctime +14 -exec rm -rf {} +;

This will delete any artifact directory in /opt/artifacts that is older than 14 days. It’s useful to match the Jenkins artifact retention time with the time specified here to avoid broken links in Jenkins.

Use in Jenkins job definitions

To use the advanced gzip+upload method, modify your jobs the following way:

Add --logs=gzip --logs-site=mysite to the ksgen invocation of your builder, for example:

ksgen --config-dir settings generate \
    --provisioner=manual \
    --logs=gzip \
    --logs-site=downstream \

Add **/full_logs.html to the list of artifacts:

- publisher:
    name: default-publishers
        - archive:
            artifacts: '**/collect_logs.txt, **/cleanup.txt, **/nosetests.xml, **/ksgen_settings.yml, **/full_logs.html'

After regnerating the jobs, the logs should start appearing on the artifact server.

It’s practical to match the Jenkins artifact retention time with the artifact server retention time to avoid broken links in Jenkins:

- defaults:
    name: job-defaults
        daysToKeep: 14
        artifactDaysToKeep: 14