services.xml: Vespa Cloud

services.xml is the primary Vespa configuration file. This documents services.xml amendments for Vespa Cloud - see services.xml at docs.vespa.ai for the general reference.

<nodes>

In cloud applications nodes are specified by count and node resources. Example:

<nodes count="4">
    <resources vcpu="2.5" memory="32Gb" disk="1Tb"/>
</nodes>

Subelements: resources

Attributes:

• count: An integer or range. The number of nodes of the cluster.
• exclusive (optional): true or false (default false). If true, the nodes of this cluster will be placed on hosts shared only with other nodes of the same application. This is useful for container clusters in applications storing sensitive data or secrets as it adds another layer of protection against leaking sensitive information between applications sharing host.

In addition there are some attributes for specific cluster types, listed below.

<nodes> for <content>

• groups (optional): Integer or range. Sets the number of groups into which content nodes should be divided. Each group will have an equal share of the nodes and redundancy copies of the corpus, and each query will be routed to just one group. This allows scaling to a higher query load than within a single group.

• group-size (optional): Integer or range where either value can be skipped (replaced by an empty string) to create a one-sided limit. If this is set, the group sizes used will always be within these limits (inclusive).

  If neither groups nor group-size is set, all nodes will always be placed in a single group.

<nodes> for <controllers> <slobroks> and <logservers>

The nodes element nested in these elements allow specifying whether the nodes used should be dedicated to the service or if it should run on existing nodes. Attribute:

• dedicated (optional): true or false (default false). Whether separate nodes should be allocated for this service or not.

<resources>

Contained in the nodes element, specifies each node's resource requirements. Resources is a powerful way to optimize cost and performance. For new launches, allocate enough to reduce risk - then use the performance guides to find the sweet spot to balance cost and free capacity, based on real production load. Migration to new capacity is automated, read more in elastic Vespa.

Subelements: None

See index bootstrap for how to set resources in a step-by-step procedure, estimating settings by feeding smaller subsets. Also note that autoscaling described below is not designed for index bootstrapping, as a bootstrap normally is much quicker than a cluster will autoscale.

Autoscaling ranges

Resources specified as a range will be autoscaled by the system. Ranges are expressed by the syntax [lower-limit, upper-limit]. Both limits are inclusive.

Autoscaling will attempt to keep utilization of all allocated resources close to ideal, and will automatically reconfigure to the cheapest option allowed by the ranges when necessary.

The ideal utilization takes into account that a node may be down or failing, that another region may be down causing doubling of traffic, and that we need headroom for maintenance operations and handling requests with low latency. It acts on what it has observed on your system in the recent past. If you need much more capacity in the near future than you do currently, you may want to set the lower limit to take this into account. Upper limits should be set to the maximum size that makes business sense.

When a new cluster (or application) is deployed it will initially be configured with the minimal resources given by the ranges. When autoscaling is turned on for an existing cluster, it will continue unchanged until autoscaling determines that a change is beneficial.

Examples:

Autoscaling node count:

<nodes count="[4, 8]">
    <resources vcpu="2.5" memory="32Gb" disk="100Gb" disk-speed="any"/>
</nodes>

Autoscaling on all resources:

<nodes count="[4, 8]" groups="[1, 2]">
  <resources vcpu="[2.5, 8]" memory="[32Gb, 150Gb]" disk="[100Gb, 1Tb]"/>
</nodes>

Elements with different meaning on Vespa Cloud

<redundancy>

<redundancy> sets the number of data copies in each group, not in total.

It is usually preferable to set <min-redundancy> instead - especially with autoscaling.

Ignored elements

The admin element is ignored, with one exception: when using metrics - example:

<admin>
    <metrics>
        <consumer id="my-custom-consumer">
            <metric-set id="default" />
            <metric id="vds.idealstate.garbage_collection.documents_removed.count" />
        </consumer>
    </metrics>
</admin>

When migrating from self-hosted to Vespa Cloud, one can safely remove admin, unless one want to configure a metric-set.

Deployment variants

services.xml settings can be made to vary by tags, instance, environment and region, see deployment variants.