Load Scheduling for PostgreSQL

Introduction

This policy detects traffic overloads and cascading failure build-up on PostgreSQL by checking the real-time percentage of PostgreSQL connections against the maximum number of connections.

It also uses the CPU utilization ratio of the PostgreSQL pod to confirm traffic overloads and cascading failure build-up. The CPU utilization ratio is the percentage of CPU used by the PostgreSQL pod divided by the total CPU available to the pod.

All the PostgreSQL related metrics are collected by the PostgreSQL OpenTelemetry Collector so if the system under observation requires using different metrics for the overload confirmation, the list of available metrics can be used to configure the policy.

A gradient controller calculates a proportional response to limit accepted concurrency. The concurrency is reduced by a multiplicative factor when the service is overloaded, and increased by an additive factor while the service is no longer overloaded.

info

Please see reference for the AdaptiveLoadScheduler component that is used within this blueprint.

Configuration

Blueprint name: load-scheduling/postgresql

Parameters

policy

Parameter	policy.components
Description	List of additional circuit components.
Type	Array of Object (aperture.spec.v1.Component)
Default Value	Expand []

Parameter	policy.policy_name
Description	Name of the policy.
Type	string
Default Value	__REQUIRED_FIELD__

Parameter	policy.resources
Description	Additional resources.
Type	Object (aperture.spec.v1.Resources)
Default Value	Expand flow_control: classifiers: []

Parameter	policy.evaluation_interval
Description	The interval between successive evaluations of the Circuit.
Type	string
Default Value	10s

Parameter	policy.promql_query
Description	PromQL query to detect PostgreSQL overload.
Type	string
Default Value	(sum(postgresql_backends) / sum(postgresql_connection_max)) * 100

Parameter	policy.setpoint
Description	Setpoint.
Type	Number (double)
Default Value	__REQUIRED_FIELD__

Parameter	policy.postgresql
Description	Configuration for PostgreSQL OpenTelemetry receiver. Refer https://docs.fluxninja.com/integrations/metrics/postgresql for more information.
Type	Object (postgresql)
Default Value	Expand agent_group: default endpoint: __REQUIRED_FIELD__ password: __REQUIRED_FIELD__ username: __REQUIRED_FIELD__

policy.service_protection_core

Parameter	policy.service_protection_core.adaptive_load_scheduler
Description	Parameters for Adaptive Load Scheduler.
Type	Object (aperture.spec.v1.AdaptiveLoadSchedulerParameters)
Default Value	Expand alerter: alert_name: Load Throttling Event gradient: max_gradient: 1 min_gradient: 0.1 slope: -1 load_multiplier_linear_increment: 0.025 load_scheduler: selectors: - control_point: __REQUIRED_FIELD__ service: __REQUIRED_FIELD__ max_load_multiplier: 2

Parameter	policy.service_protection_core.dry_run
Description	Default configuration for setting dry run mode on Load Scheduler. In dry run mode, the Load Scheduler acts as a passthrough and does not throttle flows. This config can be updated at runtime without restarting the policy.
Type	Boolean
Default Value	false

Parameter	policy.service_protection_core.kubelet_overload_confirmations
Description	Overload confirmation signals from kubelet.
Type	Object (kubelet_overload_confirmations)
Default Value	Expand {}

Parameter	policy.service_protection_core.overload_confirmations
Description	List of overload confirmation criteria. Load scheduler can throttle flows when all of the specified overload confirmation criteria are met.
Type	Array of Object (overload_confirmation)
Default Value	Expand []

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dashboard

Parameter	dashboard.extra_filters
Description	Additional filters to pass to each query to Grafana datasource.
Type	Object (map[string]string)
Default Value	Expand {}

Parameter	dashboard.refresh_interval
Description	Refresh interval for dashboard panels.
Type	string
Default Value	15s

Parameter	dashboard.time_from
Description	From time of dashboard.
Type	string
Default Value	now-15m

Parameter	dashboard.time_to
Description	To time of dashboard.
Type	string
Default Value	now

Parameter	dashboard.title
Description	Name of the main dashboard.
Type	string
Default Value	Aperture Service Protection for PostgreSQL

dashboard.datasource

Parameter	dashboard.datasource.filter_regex
Description	Datasource filter regex.
Type	string
Default Value

Parameter	dashboard.datasource.name
Description	Datasource name.
Type	string
Default Value	$datasource

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Schemas

driver_criteria

Parameter	enabled
Description	Enables the driver.
Type	Boolean
Default Value	__REQUIRED_FIELD__

Parameter	threshold
Description	Threshold for the driver.
Type	Number (double)
Default Value	__REQUIRED_FIELD__

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overload_confirmation_driver

Parameter	pod_cpu
Description	The driver for using CPU usage as overload confirmation.
Type	Object (driver_criteria)
Default Value	Expand {}

Parameter	pod_memory
Description	The driver for using CPU usage as overload confirmation.
Type	Object (driver_criteria)
Default Value	Expand {}

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kubelet_overload_confirmations

Parameter	criteria
Description	Criteria for overload confirmation.
Type	Object (overload_confirmation_driver)
Default Value	__REQUIRED_FIELD__

Parameter	infra_context
Description	Kubernetes selector for scraping metrics.
Type	Object (aperture.spec.v1.KubernetesObjectSelector)
Default Value	__REQUIRED_FIELD__

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overload_confirmation

Parameter	operator
Description	The operator for the overload confirmation criteria. oneof: `gt | lt | gte | lte | eq | neq`
Type	string
Default Value

Parameter	query_string
Description	The Prometheus query to be run. Must return a scalar or a vector with a single element.
Type	string
Default Value

Parameter	threshold
Description	The threshold for the overload confirmation criteria.
Type	Number (double)
Default Value

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postgresql

Parameter	agent_group
Description	Name of the Aperture Agent group.
Type	string
Default Value	default

Parameter	collection_interval
Description	This receiver collects metrics on an interval.
Type	string
Default Value

Parameter	database
Description	The list of databases for which the receiver will attempt to collect statistics.
Type	Array of string
Default Value

Parameter	endpoint
Description	Endpoint of the PostgreSQL.
Type	string
Default Value	__REQUIRED_FIELD__

Parameter	initial_delay
Description	Defines how long this receiver waits before starting.
Type	string
Default Value

Parameter	password
Description	Password of the PostgreSQL.
Type	string
Default Value	__REQUIRED_FIELD__

Parameter	transport
Description	The transport protocol being used to connect to postgresql. Available options are tcp and unix.
Type	string
Default Value

Parameter	username
Description	Username of the PostgreSQL.
Type	string
Default Value	__REQUIRED_FIELD__

tls

Parameter	ca_file
Description	A set of certificate authorities used to validate the database server SSL certificate.
Type	string
Default Value

Parameter	cert_file
Description	A cerficate used for client authentication, if necessary.
Type	string
Default Value

Parameter	insecure
Description	Whether to enable client transport security for the postgresql connection.
Type	Boolean
Default Value

Parameter	insecure_skip_verify
Description	Whether to validate server name and certificate if client transport security is enabled.
Type	Boolean
Default Value

Parameter	key_file
Description	An SSL key used for client authentication, if necessary.
Type	string
Default Value

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Dynamic Configuration

note

The following configuration parameters can be dynamically configured at runtime, without reloading the policy.

Parameters

Parameter	dry_run
Description	Dynamic configuration for setting dry run mode at runtime without restarting this policy. In dry run mode the scheduler acts as pass through to all flow and does not queue flows. It is useful for observing the behavior of load scheduler without disrupting any real traffic.
Type	Boolean
Default Value	__REQUIRED_FIELD__

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