152 lines
4.4 KiB
Plaintext
152 lines
4.4 KiB
Plaintext
---
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layout: docs
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page_title: Strategy
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sidebar_title: Strategy
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description: Strategy plugins compare the current state of the system against the desired state.
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---
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# Strategy Plugins
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Strategy plugins compare the current state of the system against the desired state
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defined by the operator in the scaling policy and generate an action that will
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bring the system closer to the desired state. In practical terms, strategies
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receive the current value and a metric value for a resource and output what the
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new value should be.
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## Target Value Strategy Plugin
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The target value strategy plugin will perform count calculations in order to keep
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the value resulting from the APM query at or around a specified target.
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### Agent Configuration Options
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```hcl
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strategy "target-value" {
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driver = "target-value"
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}
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```
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### Policy Configuration Options
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```hcl
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check {
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...
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strategy "target-value" {
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target = 20
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threshold = 0.0001
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}
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...
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```
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- `target` `(float: <required>)` - Specifies the metric value the Autscaler
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should try to meet.
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- `threshold` `(float: 0.01)` - Specifies how significant a change in the input
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metric should be considered. Small threshold values can lead to output
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fluctuation.
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## Dynamic Application Sizing Average Strategy Plugin
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~> **Enterprise Only!** This functionality only exists in Nomad Autoscaler
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Enterprise. This is not present in the open source version of Nomad Autoscaler.
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The `app-sizing-avg` plugin calculates the average value seen across the dataset.
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The plugin applies an exponential weight decay to data, in order to give
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more significance to recent data over older data.
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This plugin is only recommended for CPU values of workloads with very stable
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resource usage levels, such as batch jobs.
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### Agent Configuration Options
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The `app-sizing-avg` plugin is automatically launched by Nomad Autoscaler
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Enterprise and so the following setup is optional.
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```hcl
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strategy "app-sizing-avg" {
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driver = "app-sizing-avg"
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}
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```
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### Policy Configuration Options
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```hcl
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check "avg" {
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strategy "app-sizing-avg" {}
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}
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```
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## Dynamic Application Sizing Max Strategy Plugin
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~> **Enterprise Only!** This functionality only exists in Nomad Autoscaler
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Enterprise. This is not present in the open source version of Nomad Autoscaler.
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The `app-sizing-max` plugin calculates the maximum value seen for the target
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resource within the available dataset. This plugin is ideally suited for memory
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resources since workloads don’t release their memory too often and
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underprovisioning could cause OOM errors.
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### Agent Configuration Options
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The `app-sizing-max` plugin is automatically launched by Nomad Autoscaler
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Enterprise and so the following setup is optional.
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```hcl
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strategy "app-sizing-max" {
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driver = "app-sizing-max"
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}
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```
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### Policy Configuration Options
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```hcl
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check "max" {
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strategy "app-sizing-max" {}
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}
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```
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## Dynamic Application Sizing Percentile Strategy Plugin
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~> **Enterprise Only!** This functionality only exists in Nomad Autoscaler
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Enterprise. This is not present in the open source version of Nomad Autoscaler.
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The `app-sizing-percentile` plugin calculates its result based on a desired
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percentile value from the dataset.
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The plugin applies an exponential weight decay to data, in order to give
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more significance to recent data over older data. It also adjusts its calculation
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based on the amount of resources used per unit of time. This load-adjusted
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calculation results in values that are more likely to actually meet the usage
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needs of the workload when compared to the traditional time-based percentile
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calculation.
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This Dynamic Application Sizing plugin is the most versatile, since the percentile
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level can be fine-tuned as needed. If your workload can withstand occasional OOM
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errors gracefully, using a 98th percentile for memory instead of app-sizing-max
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could result in smaller recommendations and subsequently more resource availability
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for other tasks. A 95th to 90th percentile for CPU could have the same effect.
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### Agent Configuration Options
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The `app-sizing-percentile` plugin is automatically launched by Nomad Autoscaler
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Enterprise and so the following setup is optional.
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```hcl
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strategy "target-value" {
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driver = "target-value"
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}
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```
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### Policy Configuration Options
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```hcl
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check "p95" {
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strategy "app-sizing-percentile" {
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percentile = "95"
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}
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}
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```
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- `percentile` `(int: 99)` - Specifies the percentile value to use when performing
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the strategy calculation.
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