Troubleshooting¶

Host kernel upgrade from version 3.13¶

Ubuntu kernel packages newer than version 3.13 contain a change in module naming from nf_conntrack to br_netfilter. After upgrading the kernel, re-run the openstack-hosts-setup.yml playbook against those hosts. See OSA bug 157996 for more information.

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 is gathered. Examples of the information gathered are:

Linux distribution
Kernel version
Network interfaces

To improve performance, particularly in large deployments, you can cache host facts and information.

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¶

Cached facts may be incorrect if the host receives a kernel upgrade or new network interfaces. Newly created bridges also disrupt cache facts.

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.