97 lines
3.1 KiB
Plaintext
97 lines
3.1 KiB
Plaintext
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---
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layout: docs
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page_title: Scaling Policies
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sidebar_title: Policy
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description: >
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Scaling policies describe the target resource desired state and how to
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perform calculations to ensure the current state reaches the desired.
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---
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# Nomad Autoscaler Scaling Policies
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Nomad Autoscaler scaling policies can be configured via the
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[task group scaling stanza][jobspec_scaling_stanza] or by configuration
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files stored on disk.
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## Top Level Options
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- `enabled` - A boolean flag that allows operators to administratively disable a
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policy from active evaluation.
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- `min` - The minimum running count of the targeted resource. This can be 0 or any
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positive integer.
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- `max` - The maximum running count of the targeted resource. This can be 0 or any
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positive integer.
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## `policy` Options
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- `cooldown` - A time interval after a scaling action during which no additional
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scaling will be performed on the resource. It should be provided as a duration
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(e.g.: "5s", "1m"). If omitted the configuration value
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[policy_default_cooldown][policy_default_cooldown_agent] from the agent will
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be used.
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- `evaluation_interval` - Defines how often the policy is evaluated by the
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Autoscaler. It should be provided as a duration (e.g.: "5s", "1m"). If
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omitted the configuration value [default_evaluation_interval][eval_interval_agent]
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from the agent will be used.
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- `target` - Defines where the autoscaling target is running. Detailed information
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on the configuration options can be found on the [target plugin][target_plugin_docs]
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page.
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- `check` - Specifies one or more checks to be executed when determining if a
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scaling action is required.
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## `check` Options
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- `source` - The APM plugin that should handle the metric query. If omitted,
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this defaults to using the Nomad APM.
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- `query` - The query to run against the specified APM. Currently this query
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should return a single value. Detailed information on the configuration options
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can be found on the [apm plugin][apm_plugin_docs] page.
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- `strategy` - The strategy to use, and it's configuration when calculating the
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desired state based on the current count and the metric returned by the APM.
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Detailed information on the configuration options can be found on the
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[strategy plugin][strategy_plugin_docs] page.
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### Example
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A full example of a policy document that can be written into the Nomad task group
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scaling stanza or via a file within the policy dir can be seen below.
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```hcl
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min = 2
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max = 10
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enabled = true
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policy {
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evaluation_interval = "5s"
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cooldown = "1m"
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target "target" {
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Job = "example"
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Group = "example"
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}
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check "active_connections" {
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source = "prometheus"
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query = "scalar(open_connections_example_cache)"
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strategy "target_value" {
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target = 10
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}
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}
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}
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```
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[policy_default_cooldown_agent]: /docs/autoscaling/agent#default_cooldown
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[eval_interval_agent]: /docs/autoscaling/agent#default_evaluation_interval
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[target_plugin_docs]: /docs/autoscaling/plugins/target
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[strategy_plugin_docs]: /docs/autoscaling/plugins/strategy
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[apm_plugin_docs]: /docs/autoscaling/plugins/apm
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[jobspec_scaling_stanza]: /docs/job-specification/scaling
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