Chapter 13. Logging and Monitoring

Most services use the convention of writing their log files to subdirectories of the /var/log directory, as listed in Table 13.1, “OpenStack log locations”.

OpenStack services use the standard logging levels, at increasing severity: DEBUG, INFO, AUDIT, WARNING, ERROR, CRITICAL, and TRACE. That is, messages only appear in the logs if they are more "severe" than the particular log level, with DEBUG allowing all log statements through. For example, TRACE is logged only if the software has a stack trace, while INFO is logged for every message including those that are only for information.

To disable DEBUG-level logging, edit /etc/nova/nova.conf as follows:

1	<a id="d6e5807" class="indexterm">debug=false</a>

Keystone is handled a little differently. To modify the logging level, edit the /etc/keystone/logging.conf file and look at the logger_root and handler_file sections.

Logging for horizon is configured in /etc/openstack_dashboard/local_settings.py. Because horizon is a Django web application, it follows the Django Logging framework conventions.

The first step in finding the source of an error is typically to search for a CRITICAL, TRACE, or ERROR message in the log starting at the bottom of the log file.

Here is an example of a CRITICAL log message, with the corresponding TRACE (Python traceback) immediately following:

2013-02-25 21:05:51 17409 CRITICAL cinder [-] Bad or unexpected response from the storage volume backend API: volume group
 cinder-volumes doesn't exist
2013-02-25 21:05:51 17409 TRACE cinder Traceback (most recent call last):
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/bin/cinder-volume", line 48, in <module>
2013-02-25 21:05:51 17409 TRACE cinder service.wait()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/service.py", line 422, in wait
2013-02-25 21:05:51 17409 TRACE cinder _launcher.wait()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/service.py", line 127, in wait
2013-02-25 21:05:51 17409 TRACE cinder service.wait()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 166, in wait
2013-02-25 21:05:51 17409 TRACE cinder return self._exit_event.wait()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/eventlet/event.py", line 116, in wait
2013-02-25 21:05:51 17409 TRACE cinder return hubs.get_hub().switch()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 177, in switch
2013-02-25 21:05:51 17409 TRACE cinder return self.greenlet.switch()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 192, in main
2013-02-25 21:05:51 17409 TRACE cinder result = function(*args, **kwargs)
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/service.py", line 88, in run_server
2013-02-25 21:05:51 17409 TRACE cinder server.start()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/service.py", line 159, in start
2013-02-25 21:05:51 17409 TRACE cinder self.manager.init_host()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/volume/manager.py", line 95,
 in init_host
2013-02-25 21:05:51 17409 TRACE cinder self.driver.check_for_setup_error()
2013-02-25 21:05:51 17409 TRACE cinder File "/usr/lib/python2.7/dist-packages/cinder/volume/driver.py", line 116,
 in check_for_setup_error
2013-02-25 21:05:51 17409 TRACE cinder raise exception.VolumeBackendAPIException(data=exception_message)
2013-02-25 21:05:51 17409 TRACE cinder VolumeBackendAPIException: Bad or unexpected response from the storage volume
 backend API: volume group cinder-volumes doesn't exist
2013-02-25 21:05:51 17409 TRACE cinder

In this example, cinder-volumes failed to start and has provided a stack trace, since its volume backend has been unable to set up the storage volume—probably because the LVM volume that is expected from the configuration does not exist.

Here is an example error log:

2013-02-25 20:26:33 6619 ERROR nova.openstack.common.rpc.common [-] AMQP server on localhost:5672 is unreachable:
 [Errno 111] ECONNREFUSED. Trying again in 23 seconds.

In this error, a nova service has failed to connect to the RabbitMQ server because it got a connection refused error.

When an instance fails to behave properly, you will often have to trace activity associated with that instance across the log files of various nova-* services and across both the cloud controller and compute nodes.

The typical way is to trace the UUID associated with an instance across the service logs.

Consider the following example:

$ nova list
+--------------------------------+--------+--------+--------------------------+
| ID                             | Name   | Status | Networks                 |
+--------------------------------+--------+--------+--------------------------+
| fafed8-4a46-413b-b113-f1959ffe | cirros | ACTIVE | novanetwork=192.168.100.3|
+--------------------------------------+--------+--------+--------------------+

Here, the ID associated with the instance is faf7ded8-4a46-413b-b113-f19590746ffe. If you search for this string on the cloud controller in the /var/log/nova-*.log files, it appears in nova-api.log and nova-scheduler.log. If you search for this on the compute nodes in /var/log/nova-*.log, it appears in nova-network.log and nova-compute.log. If no ERROR or CRITICAL messages appear, the most recent log entry that reports this may provide a hint about what has gone wrong.

If there is not enough information in the existing logs, you may need to add your own custom logging statements to the nova-* services.

The source files are located in /usr/lib/python2.7/dist-packages/nova.

To add logging statements, the following line should be near the top of the file. For most files, these should already be there:

1 2	<a id="d6e5861" class="indexterm">from nova.openstack.common import log as logging LOG = logging.getLogger(__name__)</a>

To add a DEBUG logging statement, you would do:

1	<a id="d6e5861" class="indexterm">LOG.debug("This is a custom debugging statement")</a>

You may notice that all the existing logging messages are preceded by an underscore and surrounded by parentheses, for example:

1	<a id="d6e5861" class="indexterm">LOG.debug(_("Logging statement appears here"))</a>

This formatting is used to support translation of logging messages into different languages using the gettext internationalization library. You don't need to do this for your own custom log messages. However, if you want to contribute the code back to the OpenStack project that includes logging statements, you must surround your log messages with underscores and parentheses.

Aside from connection failures, RabbitMQ log files are generally not useful for debugging OpenStack related issues. Instead, we recommend you use the RabbitMQ web management interface. Enable it on your cloud controller:

# /usr/lib/rabbitmq/bin/rabbitmq-plugins enable rabbitmq_management

# service rabbitmq-server restart

The RabbitMQ web management interface is accessible on your cloud controller at http://localhost:55672.

	Note
	Ubuntu 12.04 installs RabbitMQ version 2.7.1, which uses port 55672. RabbitMQ versions 3.0 and above use port 15672 instead. You can check which version of RabbitMQ you have running on your local Ubuntu machine by doing: $ dpkg -s rabbitmq-server | grep "Version:" Version: 2.7.1-0ubuntu4

An alternative to enabling the RabbitMQ web management interface is to use the rabbitmqctl commands. For example, rabbitmqctl list_queues| grep cinder displays any messages left in the queue. If there are messages, it's a possible sign that cinder services didn't connect properly to rabbitmq and might have to be restarted.

Items to monitor for RabbitMQ include the number of items in each of the queues and the processing time statistics for the server.

Because your cloud is most likely composed of many servers, you must check logs on each of those servers to properly piece an event together. A better solution is to send the logs of all servers to a central location so that they can all be accessed from the same area.

Ubuntu uses rsyslog as the default logging service. Since it is natively able to send logs to a remote location, you don't have to install anything extra to enable this feature, just modify the configuration file. In doing this, consider running your logging over a management network or using an encrypted VPN to avoid interception.

 rsyslog Client Configuration

To begin, configure all OpenStack components to log to syslog in addition to their standard log file location. Also configure each component to log to a different syslog facility. This makes it easier to split the logs into individual components on the central server:

nova.conf:

1 2	<a id="d6e5907" class="indexterm">use_syslog=True syslog_log_facility=LOG_LOCAL0</a>

glance-api.conf and glance-registry.conf:

1 2	<a id="d6e5907" class="indexterm">use_syslog=True syslog_log_facility=LOG_LOCAL1</a>

cinder.conf:

1 2	<a id="d6e5907" class="indexterm">use_syslog=True syslog_log_facility=LOG_LOCAL2</a>

keystone.conf:

1 2	<a id="d6e5907" class="indexterm">use_syslog=True syslog_log_facility=LOG_LOCAL3</a>

By default, Object Storage logs to syslog.

Next, create /etc/rsyslog.d/client.conf with the following line:

1	<a id="d6e5907" class="indexterm">*.* @192.168.1.10</a>

This instructs rsyslog to send all logs to the IP listed. In this example, the IP points to the cloud controller.

 rsyslog Server Configuration

Designate a server as the central logging server. The best practice is to choose a server that is solely dedicated to this purpose. Create a file called /etc/rsyslog.d/server.conf with the following contents:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

# Enable UDP $ModLoad imudp # Listen on 192.168.1.10 only $UDPServerAddress 192.168.1.10 # Port 514 $UDPServerRun 514 # Create logging templates for nova $template NovaFile,"/var/log/rsyslog/%HOSTNAME%/nova.log" $template NovaAll,"/var/log/rsyslog/nova.log" # Log everything else to syslog.log $template DynFile,"/var/log/rsyslog/%HOSTNAME%/syslog.log" *.* ?DynFile # Log various openstack components to their own individual file local0.* ?NovaFile local0.* ?NovaAll & ~

This example configuration handles the nova service only. It first configures rsyslog to act as a server that runs on port 514. Next, it creates a series of logging templates. Logging templates control where received logs are stored. Using the last example, a nova log from c01.example.com goes to the following locations:

• /var/log/rsyslog/c01.example.com/nova.log

• /var/log/rsyslog/nova.log

This is useful, as logs from c02.example.com go to:

• /var/log/rsyslog/c02.example.com/nova.log

• /var/log/rsyslog/nova.log

You have an individual log file for each compute node as well as an aggregated log that contains nova logs from all nodes.

StackTach is a tool created by Rackspace to collect and report the notifications sent by nova. Notifications are essentially the same as logs but can be much more detailed. A good overview of notifications can be found at System Usage Data.

To enable nova to send notifications, add the following to nova.conf:

1 2	<a id="d6e5956" class="indexterm">notification_topics=monitor notification_driver=nova.openstack.common.notifier.rabbit_notifier</a>

Once nova is sending notifications, install and configure StackTach. Since StackTach is relatively new and constantly changing, installation instructions would quickly become outdated. Please refer to the StackTach GitHub repo for instructions as well as a demo video.

There are two types of monitoring: watching for problems and watching usage trends. The former ensures that all services are up and running, creating a functional cloud. The latter involves monitoring resource usage over time in order to make informed decisions about potential bottlenecks and upgrades.

# ps aux | grep nova-api
nova 12786 0.0 0.0 37952 1312 ? Ss Feb11 0:00 su -s /bin/sh -c exec nova-api
--config-file=/etc/nova/nova.conf nova
nova 12787 0.0 0.1 135764 57400 ? S Feb11 0:01 /usr/bin/python
 /usr/bin/nova-api --config-file=/etc/nova/nova.conf
nova 12792 0.0 0.0 96052 22856 ? S Feb11 0:01 /usr/bin/python
/usr/bin/nova-api --config-file=/etc/nova/nova.conf
nova 12793 0.0 0.3 290688 115516 ? S Feb11 1:23 /usr/bin/python
/usr/bin/nova-api --config-file=/etc/nova/nova.conf
nova 12794 0.0 0.2 248636 77068 ? S Feb11 0:04 /usr/bin/python
/usr/bin/nova-api --config-file=/etc/nova/nova.conf
root 24121 0.0 0.0 11688 912 pts/5 S+ 13:07 0:00 grep nova-api

define service {
    host_name c01.example.com
    check_command check_nrpe_1arg!check_nova-compute
    use generic-service
    notification_period 24x7
    contact_groups sysadmins
    service_description nova-compute
}

\command[check_nova-compute]=/usr/lib/nagios/plugins/check_procs -c 1: \
-a nova-compute

define service {
    host_name c01.example.com
    check_command check_nrpe!check_all_disks!20% 10%
    use generic-service
    contact_groups sysadmins
    service_description Disk
}

command[check_all_disks]=/usr/lib/nagios/plugins/check_disk -w $ARG1$ -c \
$ARG2$ -e

 OpenStack-Specific Resources

Resources such as memory, disk, and CPU are generic resources that all servers (even non-OpenStack servers) have and are important to the overall health of the server. When dealing with OpenStack specifically, these resources are important for a second reason: ensuring that enough are available to launch instances. There are a few ways you can see OpenStack resource usage. The first is through the nova command:

# nova usage-list

This command displays a list of how many instances a tenant has running and some light usage statistics about the combined instances. This command is useful for a quick overview of your cloud, but it doesn't really get into a lot of details.

Next, the nova database contains three tables that store usage information.

The nova.quotas and nova.quota_usages tables store quota information. If a tenant's quota is different from the default quota settings, its quota is stored in the nova.quotas table. For example:

mysql> select project_id, resource, hard_limit from quotas;
+----------------------------------+-----------------------------+------------+
| project_id                       | resource                    | hard_limit |
+----------------------------------+-----------------------------+------------+
| 628df59f091142399e0689a2696f5baa | metadata_items              | 128        |
| 628df59f091142399e0689a2696f5baa | injected_file_content_bytes | 10240      |
| 628df59f091142399e0689a2696f5baa | injected_files              | 5          |
| 628df59f091142399e0689a2696f5baa | gigabytes                   | 1000       |
| 628df59f091142399e0689a2696f5baa | ram                         | 51200      |
| 628df59f091142399e0689a2696f5baa | floating_ips                | 10         |
| 628df59f091142399e0689a2696f5baa | instances                   | 10         |
| 628df59f091142399e0689a2696f5baa | volumes                     | 10         |
| 628df59f091142399e0689a2696f5baa | cores                       | 20         |
+----------------------------------+-----------------------------+------------+

The nova.quota_usages table keeps track of how many resources the tenant currently has in use:

mysql> select project_id, resource, in_use from quota_usages where project_id like '628%';
+----------------------------------+--------------+--------+
| project_id                       | resource     | in_use |
+----------------------------------+--------------+--------+
| 628df59f091142399e0689a2696f5baa | instances    | 1      |
| 628df59f091142399e0689a2696f5baa | ram          | 512    |
| 628df59f091142399e0689a2696f5baa | cores        | 1      |
| 628df59f091142399e0689a2696f5baa | floating_ips | 1      |
| 628df59f091142399e0689a2696f5baa | volumes      | 2      |
| 628df59f091142399e0689a2696f5baa | gigabytes    | 12     |
| 628df59f091142399e0689a2696f5baa | images       | 1      |
+----------------------------------+--------------+--------+

By comparing a tenant's hard limit with their current resource usage, you can see their usage percentage. For example, if this tenant is using 1 floating IP out of 10, then they are using 10 percent of their floating IP quota. Rather than doing the calculation manually, you can use SQL or the scripting language of your choice and create a formatted report:

+----------------------------------+------------+-------------+---------------+
| some_tenant                                                                 |
+-----------------------------------+------------+------------+---------------+
| Resource                          | Used       | Limit      |               |
+-----------------------------------+------------+------------+---------------+
| cores                             | 1          | 20         |           5 % |
| floating_ips                      | 1          | 10         |          10 % |
| gigabytes                         | 12         | 1000       |           1 % |
| images                            | 1          | 4          |          25 % |
| injected_file_content_bytes       | 0          | 10240      |           0 % |
| injected_file_path_bytes          | 0          | 255        |           0 % |
| injected_files                    | 0          | 5          |           0 % |
| instances                         | 1          | 10         |          10 % |
| key_pairs                         | 0          | 100        |           0 % |
| metadata_items                    | 0          | 128        |           0 % |
| ram                               | 512        | 51200      |           1 % |
| reservation_expire                | 0          | 86400      |           0 % |
| security_group_rules              | 0          | 20         |           0 % |
| security_groups                   | 0          | 10         |           0 % |
| volumes                           | 2          | 10         |          20 % |
+-----------------------------------+------------+------------+---------------+

The preceding information was generated by using a custom script that can be found on GitHub.

	Note
	This script is specific to a certain OpenStack installation and must be modified to fit your environment. However, the logic should easily be transferable.

 Intelligent Alerting

Intelligent alerting can be thought of as a form of continuous integration for operations. For example, you can easily check to see whether the Image Service is up and running by ensuring that the glance-api and glance-registry processes are running or by seeing whether glace-api is responding on port 9292.

But how can you tell whether images are being successfully uploaded to the Image Service? Maybe the disk that Image Service is storing the images on is full or the S3 backend is down. You could naturally check this by doing a quick image upload:

1 2 3 4 5 6 7 8 9 10 11 12

<a id="d6e6093" class="indexterm">#!/bin/bash # # assumes that reasonable credentials have been stored at # /root/auth . /root/openrc wget https://launchpad.net/cirros/trunk/0.3.0/+download/ \ cirros-0.3.0-x86_64-disk.img glance image-create --name='cirros image' --is-public=true --container-format=bare --disk-format=qcow2 < cirros-0.3.0-x8 6_64-disk.img</a>

By taking this script and rolling it into an alert for your monitoring system (such as Nagios), you now have an automated way of ensuring that image uploads to the Image Catalog are working.

	Note
	You must remove the image after each test. Even better, test whether you can successfully delete an image from the Image Service.

Intelligent alerting takes considerably more time to plan and implement than the other alerts described in this chapter. A good outline to implement intelligent alerting is:

• Review common actions in your cloud.

• Create ways to automatically test these actions.

• Roll these tests into an alerting system.

Some other examples for Intelligent Alerting include:

• Can instances launch and be destroyed?

• Can users be created?

• Can objects be stored and deleted?

• Can volumes be created and destroyed?

# grep INFO /var/log/nova/nova-api.log | wc

# grep " 200 " /var/log/nova/nova-api.log | wc

For stable operations, you want to detect failure promptly and determine causes efficiently. With a distributed system, it's even more important to track the right items to meet a service-level target. Learning where these logs are located in the file system or API gives you an advantage. This chapter also showed how to read, interpret, and manipulate information from OpenStack services so that you can monitor effectively.