Scaling policy
When creating an instance group, you can choose how to increase and decrease the number of instances in the group.
The policy is defined in the scale_policy key in the YAML file.
fixed_scalekey
The fixed_scale key defines a group of fixed-size instances. The size of the group is defined in the size key. You can create a group with the required number of instances within the available quotas and limits.
Here is how a YAML file entry may look like:
...
scale_policy:
fixed_scale:
size: 3
...
Where:
| Key | Value |
|---|---|
fixed_scale |
Fixed-size instance group |
size* |
Number of instances in the group. Valid values range from 0 to 100. |
* Required field.
auto_scalekey
The auto_scale key defines an automatically scalable instance group. The initial size of the group is defined in the initial_size key. You can create a group with the required number of instances within the available quotas and limits.
The VM instance group will be scaled based on specified metrics: CPU utilization (the cpu_utilization_rule key) and/or metrics from Yandex Monitoring. If multiple metrics are specified in the file, the largest estimated VM instance group size is used.
Here is how a YAML file entry may look like:
scale_policy:
auto_scale:
auto_scale_type: REGIONAL
initial_size: 5
max_size: 15
min_zone_size: 3
measurement_duration: 30s
warmup_duration: 60s
stabilization_duration: 120s
cpu_utilization_rule:
utilization_target: 75
custom_rules:
- rule_type: WORKLOAD
metric_type: GAUGE
metric_name: queue.messages.stored_count
labels:
queue: dj6000000002********
target: 5
Where:
| Key | Value |
|---|---|
auto_scale |
Automatically scaled instance group |
auto_scale_type |
Type of automatic scaling. The possible values are:
ZONAL. |
initial_size* |
Initial number of instances in the group. Valid values range from 0 to 100. |
max_size |
Maximum number of instances in the group. Valid values range from 0 to 100. |
min_zone_size |
Minimum number of instances in one availability zone. Valid values range from 0 to 100. |
measurement_duration |
Utilization measurement period: The value of each metric is computed as the average of all measurements taken during the period in question. If this value exceeds the target value of the metric for scaling, Instance Groups will increase the number of VM instances in the group. The valid values are within 60 and 600 seconds. The default value is 60 seconds. |
warmup_duration |
Instance warmup period. This is a period of time following startup during which the traffic is routed to the VM, while the values of metrics from this VM are not used to scale the group. The average values of the group metrics are used instead. The valid values range between 0 and 600 seconds. The default value is 0 seconds. |
stabilization_duration |
Stabilization period. After the number of VM instances increases, the group size does not decrease until the stabilization period ends, even if the average value of the metric for scaling drops below the target level. The valid values range between 60 and 1800 seconds. |
cpu_utilization_rule |
Sets the target CPU utilization to run scaling based on the average CPU utilization in the instance group. |
utilization_target |
Target CPU utilization to support by Instance Groups. If the average CPU utilization is below the target value, Instance Groups will reduce the number of instances until it reaches min_zone_size in each availability zone.If the average CPU utilization is higher than the target value, Instance Groups will create instances until max_size is reached.Valid values range from 10 to 100. |
custom_rules |
List of metrics from Yandex Monitoring for automatic scaling. It can include up to three metrics. |
rule_type |
Metric rule type:
|
metric_type |
Type of metric:
|
metric_name |
Name of the metric in Monitoring. |
labels |
Metrics labels from Monitoring. |
target |
Target metric value by which Instance Groups calculates the number of required VM instances. For more information, see Monitoring metrics. |
* Required field.
test_auto_scalekey
The test_auto_scale key defines a fixed-size instance group with auto scaling testing enabled. The Monitoring tab charts display the recommended increase or decrease in the number of instances depending on the value of the selected metric, while the actual number of instances always remains equal to the value specified in the size key. You can create a group with the required number of instances within the available quotas and limits.
scale_policy:
fixed_scale:
size: 5
test_auto_scale:
initial_size: 5
max_size: 15
min_zone_size: 3
measurement_duration: 30s
warmup_duration: 60s
stabilization_duration: 120s
cpu_utilization_rule:
utilization_target: 75
For test_auto_scale, use the same keys as for auto_scale.