# Logging

## Logging module

Logging behavior can be changed by creating a configuration file. To specify the configuration file, add this line to the `/etc/nova/nova.conf` file:

    log_config_append=/etc/nova/logging.conf

To change the logging level, add `DEBUG`, `INFO`, `WARNING`, or `ERROR` as a parameter.

The logging configuration file is an INI-style configuration file, which must contain a section called `logger_nova`. This controls the behavior of the logging facility in the `nova-*` services. For example:

    [logger_nova]
    level = INFO
    handlers = stderr
    qualname = nova

This example sets the debugging level to `INFO` (which is less verbose than the default `DEBUG` setting).

For more about the logging configuration syntax, including the `handlers` and `qualname` variables, see the Python documentation on logging configuration files.

For an example of the `logging.conf` file with various defined handlers, see the Example Configuration File for nova.

## Syslog

OpenStack Compute services can send logging information to syslog. This is useful if you want to use rsyslog to forward logs to a remote machine. Separately configure the Compute service (nova), the Identity service (keystone), the Image service (glance), and, if you are using it, the Block Storage service (cinder) to send log messages to syslog. Open these configuration files:

- `/etc/nova/nova.conf`

- `/etc/keystone/keystone.conf`

- `/etc/glance/glance-api.conf`

- `/etc/glance/glance-registry.conf`

- `/etc/cinder/cinder.conf`

In each configuration file, add these lines:

    debug = False
    use_syslog = True
    syslog_log_facility = LOG_LOCAL0

In addition to enabling syslog, these settings also turn off debugging output from the log.

Note

Although this example uses the same local facility for each service (`LOG_LOCAL0`, which corresponds to syslog facility `LOCAL0`), we recommend that you configure a separate local facility for each service, as this provides better isolation and more flexibility. For example, you can capture logging information at different severity levels for different services. syslog allows you to define up to eight local facilities, `LOCAL0, LOCAL1, ..., LOCAL7`. For more information, see the syslog documentation.

## Rsyslog

rsyslog is useful for setting up a centralized log server across multiple machines. This section briefly describe the configuration to set up an rsyslog server. A full treatment of rsyslog is beyond the scope of this book. This section assumes rsyslog has already been installed on your hosts (it is installed by default on most Linux distributions).

This example provides a minimal configuration for `/etc/rsyslog.conf` on the log server host, which receives the log files

    # provides TCP syslog reception
    $ModLoad imtcp
    $InputTCPServerRun 1024

Add a filter rule to `/etc/rsyslog.conf` which looks for a host name. This example uses COMPUTE_01 as the compute host name:

    :hostname, isequal, "COMPUTE_01" /mnt/rsyslog/logs/compute-01.log

On each compute host, create a file named `/etc/rsyslog.d/60-nova.conf`, with the following content:

    # prevent debug from dnsmasq with the daemon.none parameter
    *.*;auth,authpriv.none,daemon.none,local0.none -/var/log/syslog
    # Specify a log level of ERROR
    local0.error    @@172.20.1.43:1024

Once you have created the file, restart the `rsyslog` service. Error-level log messages on the compute hosts should now be sent to the log server.

## Serial console

The serial console provides a way to examine kernel output and other system messages during troubleshooting if the instance lacks network connectivity.

Read-only access from server serial console is possible using the `os-GetSerialOutput` server action. Most cloud images enable this feature by default. For more information, see Common errors and fixes for Compute.

OpenStack Juno and later supports read-write access using the serial console using the `os-GetSerialConsole` server action. This feature also requires a websocket client to access the serial console.

Configuring read-write serial console access

1. On a compute node, edit the `/etc/nova/nova.conf` file:

   In the `[serial_console]` section, enable the serial console:

       [serial_console]
       # ...
       enabled = true

2. In the `[serial_console]` section, configure the serial console proxy similar to graphical console proxies:

       [serial_console]
       # ...
       base_url = ws://controller:6083/
       listen = 0.0.0.0
       proxyclient_address = MANAGEMENT_INTERFACE_IP_ADDRESS

   The `base_url` option specifies the base URL that clients receive from the API upon requesting a serial console. Typically, this refers to the host name of the controller node.

   The `listen` option specifies the network interface nova-compute should listen on for virtual console connections. Typically, 0.0.0.0 will enable listening on all interfaces.

   The `proxyclient_address` option specifies which network interface the proxy should connect to. Typically, this refers to the IP address of the management interface.

   When you enable read-write serial console access, Compute will add serial console information to the Libvirt XML file for the instance. For example:

       <console type='tcp'>
         <source mode='bind' host='127.0.0.1' service='10000'/>
         <protocol type='raw'/>
         <target type='serial' port='0'/>
         <alias name='serial0'/>
       </console>

Accessing the serial console on an instance

1. Use the nova get-serial-console command to retrieve the websocket URL for the serial console on the instance:

       $ nova get-serial-console INSTANCE_NAME

   Or use the openstack console url show command.

       $ openstack console url show --serial INSTANCE_NAME

   Type | Url
   serial | ws://127.0.0.1:6083/?token=18510769-71ad-4e5a-8348-4218b5613b3d

   Alternatively, use the API directly:

       $ curl -i 'http://<controller>:8774/v2.1/<tenant_uuid>/servers/<instance_uuid>/action' \
         -X POST \
         -H "Accept: application/json" \
         -H "Content-Type: application/json" \
         -H "X-Auth-Project-Id: <project_id>" \
         -H "X-Auth-Token: <auth_token>" \
         -d '{"os-getSerialConsole": {"type": "serial"}}'

2. Use Python websocket with the URL to generate `.send`, `.recv`, and `.fileno` methods for serial console access. For example:

       import websocket
       ws = websocket.create_connection(
           'ws://127.0.0.1:6083/?token=18510769-71ad-4e5a-8348-4218b5613b3d',
           subprotocols=['binary', 'base64'])

Alternatively, use a Python websocket client.

Note

When you enable the serial console, typical instance logging using the nova console-log command is disabled. Kernel output and other system messages will not be visible unless you are actively viewing the serial console.

this page last updated: 2026-04-14 07:16:25

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