Operator Maintenance Guide

This document is intended for operators. For a developer guide see the Developer / Operator Quick Start Guide in this documentation repository. For an end-user guide, please see the Basic Load Balancing Cookbook in this documentation repository.

Monitoring

Monitoring Load Balancer Amphora

Octavia will monitor the load balancing amphorae itself and initiate failovers and/or replacements if they malfunction. Therefore, most installations won’t need to monitor the amphorae running the load balancer.

Octavia will log each failover to the corresponding health manager logs. It is advisable to use log analytics to monitor failover trends to notice problems in the OpenStack installation early. We have seen neutron (network) connectivity issues, Denial of Service attacks, and nova (compute) malfunctions lead to a higher than normal failover rate. Alternatively, the monitoring of the other services showed problems as well, so depending on your overall monitoring strategy this might be optional.

If additional monitoring is necessary, review the corresponding calls on the amphora agent REST interface (see Octavia HAProxy Amphora API)

Monitoring Pool Members

Octavia will use the health information from the underlying load balancing application to determine the health of members. This information will be streamed to the Octavia database and made available via the status tree or other API methods. For critical applications we recommend to poll this information in regular intervals.

Monitoring Load Balancers

For critical applications, we recommend to monitor the access to the application with a tool which polls the application from various points on the Internet and measures response times. Alerts should be triggered when response times become too high.

An additional check might be to monitor the provisioning status of a load balancer (see Load Balance Status Codes) and alert depending on the application if the provisioning status is not ACTIVE. For some applications other states might not lead to alerts: For instance if an application is making regular changes to the pool several PENDING stages should not alert as well.

In most cases, when a load balancer is in states other than ACTIVE it will still be passing traffic, which is why the response time check mentioned above is recommended. However, even if the load balancer is still functioning, it is advisable to investigate and potentially recreate it if it is stuck in a non-ACTIVE state.

A load balancer in a PENDING provisioning status is immutable, it cannot be updated or deleted by another process, this PENDING status acts as a lock on the resource. If a database outage occurs while a load balancer is deleted, created or updated, the Octavia control plane will try to remove the PENDING status and set it to ERROR during a long period of time (around 2h45min with the default settings), to prevent the resource from remaining immutable.

Monitoring load balancer functionality

For production sites we recommend to use outside monitoring services. They will use servers distributed around the globe to not only monitor if the site is up but also parts of the system outside the visibility of Octavia like routers, network connectivity, etc.

Monitoring Octavia Control Plane

To monitor the Octavia control plane we recommend process monitoring of the main Octavia processes:

  • octavia-api

  • octavia-worker

  • octavia-health-manager

  • octavia-housekeeping

The Monasca project has a plugin for such monitoring (see Monasca Octavia plugin). Please refer to this project for further information.

Octavia’s control plane components are shared nothing and can be scaled linearly. For high availability of the control plane we recommend to run at least one set of components in each availability zone. Furthermore, the octavia-api endpoint could be behind a load balancer or other HA technology. That said, if one or more components fail the system will still be available (though potentially degraded). For instance if you have installed one set of components in three availability zones even if you lose a whole zone Octavia will still be responsive and available - only if you lose the Octavia control plane in all three zones will the service be unavailable. Please note this only addresses control plane availability; the availability of the load balancing function depends highly on the chosen topology and the anti-affinity settings. See our forthcoming HA guide for more details.

Additionally, we recommend to monitor the Octavia API endpoint(s). There currently is no special url to use so just polling the root URL in regular intervals is sufficient.

There is a host of information in the log files which can be used for log analytics. A few examples of what could be monitored are:

  • Amphora Build Rate - to determine load of the system

  • Amphora Build Time - to determine how long it takes to build an amphora

  • Failures/Errors - to be notified of system problems early

Rotating the Amphora Images

Octavia will start load balancers with a pre-built image which contain the amphora agent, a load balancing application, and are seeded with cryptographic certificates through the config drive at start up.

Rotating the image means making a load balancer amphora running with an old image failover to an amphora with a new image. This should be without any measurable interruption in the load balancing functionality when using ACTIVE/STANDBY topology. Standalone load balancers might experience a short outage.

Here are some reasons you might need to rotate the amphora image:

  • There has been a (security) update to the underlying operating system

  • You want to deploy a new version of the amphora agent or haproxy

  • The cryptographic certificates and/or keys on the amphora have been compromised.

  • Though not related to rotating images, this procedure might be invoked if you are switching to a different flavor for the underlying virtual machine.

Preparing a New Amphora Image

To prepare a new amphora image you will need to use diskimage-create.sh as described in the README in the diskimage-create directory.

For instance, in the octavia/diskimage-create directory, run:

./diskimage-create.sh

Once you have created a new image you will need to upload it into glance. The following shows how to do this if you have set the image tag in the Octavia configuration file. Make sure to use a user with the same tenant as the Octavia service account:

openstack image create --file amphora-x64-haproxy.qcow2 \
--disk-format qcow2 --tag <amphora-image-tag> --private \
--container-format bare /var/lib/octavia/amphora-x64-haproxy.qcow2

If you didn’t configure image tags and instead configured an image id, you will need to update the Octavia configuration file with the new id and restart the Octavia services (except octavia-api).

Rotating spare Amphorae

Warning

Spares pool support is deprecated as of the Victoria release.

If the spare pool is enabled in Octavia, spare amphorae must be rotated first, so a new load balancer will use the new amphora image from a newly spawned spare amphora.

To rotate spare amphorae, list the IDs of all amphorae in READY status:

openstack loadbalancer amphora list -c id -f value --status READY

Then, for each ID, perform the failover on the amphora:

openstack loadbalancer amphora failover <amphora id>

Spare amphorae now use the new amphora image, and those spare amphorae will be used when creating a new load balancer or when performing a failover of a load balancer.

Generating a List of Load Balancers to Rotate

The easiest way to generate a list, is to just list the IDs of all load balancers:

openstack loadbalancer list -c id -f value

Take note of the IDs.

Rotating a Load Balancer

Octavia has an API call to initiate the failover of a load balancer:

openstack loadbalancer failover <loadbalancer id>

You can observe the failover by querying octavia openstack load balancer show  <loadbalancer id> until the load balancer goes ACTIVE again.

Best Practices/Optimizations

To speed up the failovers, the spare pool can be temporarily increased to accommodate the rapid failover of the amphora. In this case after the new image has been loaded into glance, shut down or initiate a failover of the amphora in the spare pool. They can be found by listing amphorae in READY status:

openstack loadbalancer amphora list --status READY

After you have increased the spare pool size and restarted all Octavia services, failovers will be greatly accelerated. To preserve resources, restore the old settings and restart the Octavia services. Since Octavia won’t terminate superfluous spare amphora on its own, they can be left in the system and will automatically be used up as new load balancers are created and/or load balancers in error state are failed over.

Warning

If you are using the anti-affinity feature please be aware that it is not compatible with spare pools and you are risking both the ACTIVE and BACKUP amphora being scheduled on the same host. It is recommended to not increase the spare pool during fail overs in this case (and not to use the spare pool at all).

Since a failover puts significant load on the OpenStack installation by creating new virtual machines and ports, it should either be done at a very slow pace, during a time with little load, or with the right throttling enabled in Octavia. The throttling will make sure to prioritize failovers higher than other operations and depending on how many failovers are initiated this might crowd out other operations.

Rotating Cryptographic Certificates

Octavia secures the communication between the amphora agent and the control plane with two-way SSL encryption. To accomplish that, several certificates are distributed in the system:

  • Control plane:

    • Amphora certificate authority (CA) certificate: Used to validate amphora certificates if Octavia acts as a Certificate Authority to issue new amphora certificates

    • Client certificate: Used to authenticate with the amphora

  • Amphora:

    • Client CA certificate: Used to validate control plane client certificate

    • Amphora certificate: Presented to control plane processes to prove amphora identity.

The heartbeat UDP packets emitted from the amphora are secured with a symmetric encryption key. This is set by the configuration option heartbeat_key in the health_manager section. We recommend setting it to a random string of a sufficient length.

Rotating Amphora Certificates

For the server part Octavia will act as a certificate authority itself to issue amphora certificates to be used by each amphora. Octavia will also monitor those certificates and refresh them before they expire.

There are three ways to initiate a rotation manually:

  • Change the expiration date of the certificate in the database. Octavia will then rotate the amphora certificates with newly issued ones. This requires the following:

    • Client CA certificate hasn’t expired or the corresponding client certificate on the control plane hasn’t been issued by a different client CA (in case the authority was compromised)

    • The Amphora CA certificate on the control plane didn’t change in any way which jeopardizes validation of the amphora certificate (e.g. the certificate was reissued with a new private/public key)

  • If the amphora CA changed in a way which jeopardizes validation of the amphora certificate an operator can manually upload newly issued amphora certificates by switching off validation of the old amphora certificate. This requires a client certificate which can be validated by the client CA file on the amphora. Refer to Octavia HAProxy Amphora API for more details.

  • If the client certificate on the control plane changed in a way that it can’t be validated by the client certificate authority certificate on the amphora, a failover (see Rotating Amphora Certificates) of all amphorae needs to be initiated. Until the failover is completed the amphorae can’t be controlled by the control plane.

Rotating the Certificate Authority Certificates

If there is a compromise of the certificate authorities’ certificates, or they expired, new ones need to be installed into the system. If Octavia is not acting as the certificate authority only the certificate authority’s cert needs to be changed in the system so amphora can be authenticated again.

  • Issue new certificates (see the script in the bin folder of Octavia if Octavia is acting as the certificate authority) or follow the instructions of the third-party certificate authority. Copy the certificate and the private key (if Octavia acts as a certificate authority) where Octavia can find them.

  • If the previous certificate files haven’t been overridden, adjust the paths to the new certs in the configuration file and restart all Octavia services (except octavia-api).

Review Rotating Amphora Certificates above to determine if and how the amphora certificates needs to be rotated.

Rotating Client Certificates

If the client certificates expired new ones need to be issued and installed on the system:

  • Issue a new client certificate (see the script in the bin folder of Octavia if self signed certificates are used) or use the ones provided to you by your certificate authority.

  • Copy the new cert where Octavia can find it.

  • If the previous certificate files haven’t been overridden, adjust the paths to the new certs in the configuration file. In all cases restart all Octavia services except octavia-api.

If the client CA certificate has been replaced in addition to rotating the client certificate the new client CA certificate needs to be installed in the system. After that initiate a failover of all amphorae to distribute the new client CA cert. Until the failover is completed the amphorae can’t be controlled by the control plane.

Changing The Heartbeat Encryption Key

Special caution needs to be taken to replace the heartbeat encryption key. Once this is changed Octavia can’t read any heartbeats and will assume all amphora are in an error state and initiate an immediate failover.

In preparation, read the chapter on Best Practices/Optimizations in the Failover section. In particular, it is advisable if the throttling enhancement (available in Pike) doesn’t exist to create a sufficient number of spare amphorae to mitigate the stress on the OpenStack installation when Octavia starts to replace all amphora immediately.

Given the risks involved with changing this key it should not be changed during routine maintenance but only when a compromise is strongly suspected.

Note

For future versions of Octavia an “update amphora” API is planned which will allow this key to be changed without failover. At that time there would be a procedure to halt health monitoring while the keys are rotated and then resume health monitoring.

Handling a VM Node Failure

If a node fails which is running amphora, Octavia will automatically failover the amphora to a different node (capacity permitting). In some cases, the node can be recovered (e.g. through a hard reset) and the hypervisor might bring back the amphora vms. In this case, an operator should manually delete all amphora on this specific node since Octavia assumes they have been deleted as part of the failover and will not touch them again.

Note

As a safety measure an operator can, prior to deleting, manually check if the VM is in use. First, use the Amphora API to obtain the current list of amphorae, then match the nova instance ID to the compute_id column in the amphora API response (it is not currently possible to filter amphora by compute_id). If there are any matches where the amphora status is not ‘DELETED’, the amphora is still considered to be in use.

Evacuating a Specific Amphora from a Host

In some cases an amphora needs to be evacuated either because the host is being shutdown for maintenance or as part of a failover. Octavia has a rich amphora API to do that.

First use the amphora API to find the specific amphora. Then, if not already performed, disable scheduling to this host in nova. Lastly, initiate a failover of the specific amphora with the failover command on the amphora API.

Alternatively, a live migration might also work if it happens quick enough for Octavia not to notice a stale amphora (the default configuration is 60s).