openstack-ansible/doc/source/install-guide/ops-troubleshooting.rst

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Troubleshooting

Container networking issues

All LXC containers on the host have two virtual Ethernet interfaces:

• eth0 in the container connects to lxcbr0 on the host
• eth1 in the container connects to br-mgmt on the host

Note

Some containers, such as cinder, glance, neutron_agents, and swift_proxy, have more than two interfaces to support their functions.

Predictable interface naming

On the host, all virtual Ethernet devices are named based on their container as well as the name of the interface inside the container:

${CONTAINER_UNIQUE_ID}_${NETWORK_DEVICE_NAME}

As an example, an all-in-one (AIO) build might provide a utility container called aio1_utility_container-d13b7132. That container will have two network interfaces: d13b7132_eth0 and d13b7132_eth1.

Another option would be to use the LXC tools to retrieve information about the utility container:

# lxc-info -n aio1_utility_container-d13b7132

Name:           aio1_utility_container-d13b7132
State:          RUNNING
PID:            8245
IP:             10.0.3.201
IP:             172.29.237.204
CPU use:        79.18 seconds
BlkIO use:      678.26 MiB
Memory use:     613.33 MiB
KMem use:       0 bytes
Link:           d13b7132_eth0
 TX bytes:      743.48 KiB
 RX bytes:      88.78 MiB
 Total bytes:   89.51 MiB
Link:           d13b7132_eth1
 TX bytes:      412.42 KiB
 RX bytes:      17.32 MiB
 Total bytes:   17.73 MiB

The Link: lines will show the network interfaces that are attached to the utility container.

Reviewing container networking traffic

To dump traffic on the br-mgmt bridge, use tcpdump to see all communications between the various containers. To narrow the focus, run tcpdump only on the desired network interface of the containers.

Cached Ansible facts issues

At the beginning of a playbook run, information about each host, such as its Linux distribution, kernel version, and network interfaces, is gathered. To improve performance, particularly in larger deployments, these facts can be cached.

OpenStack-Ansible enables fact caching by default. The facts are cached in JSON files within /etc/openstack_deploy/ansible_facts.

Fact caching can be disabled by commenting out the fact_caching parameter in playbooks/ansible.cfg. Refer to the Ansible documentation on fact caching for more details.

Forcing regeneration of cached facts

If a host's kernel is upgraded or additional network interfaces or bridges are created on the host, its cached facts may be incorrect. This can lead to unexpected errors while running playbooks, and require that the cached facts be regenerated.

Run the following command to remove all currently cached facts for all hosts:

# rm /etc/openstack_deploy/ansible_facts/*

New facts will be gathered and cached during the next playbook run.

To clear facts for a single host, find its file within /etc/openstack_deploy/ansible_facts/ and remove it. Each host has a JSON file that is named after its hostname. The facts for that host will be regenerated on the next playbook run.

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