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[Improvement] state/elasticsearch: add option to spread nodes in 3-AZs #524

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[Improvement] state/elasticsearch: add option to spread nodes in 3-AZs #524

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40 changes: 30 additions & 10 deletions state/elasticsearch.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ Metadata:
- ElasticsearchVersion
- EBSEnabled
- EBSVolumeSize
- AvailabilityZones
- ClusterInstanceCount
- ClusterInstanceType
- DedicatedMasterCount
Expand Down Expand Up @@ -78,8 +79,13 @@ Parameters:
Type: String
Default: '5.5'
AllowedValues: ['7.7', '7.4', '7.1', '6.8', '6.7', '6.5', '6.4', '6.3', '6.2', '6.0', '5.6', '5.5'] # aws es list-elasticsearch-versions --query "ElasticsearchVersions[]"
AvailabilityZones:
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What's the benefit of using a String instead of a Number type?

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I can find the configuration value faster in the list of parameters, because it looks differently visually. I do not know anymore why I choose a string instead of a number, because the change was made months ago. It could be that I wanted to create a similarity to the 2azs and 3azs vpc templates.

Description: 'Number of Availability Zones nodes are spread across.'
Type: String
Default: '2-AZ'
AllowedValues: ['1-AZ', '2-AZ', '3-AZ']
ClusterInstanceCount:
Description: 'The number of data nodes (instances) to use in the Amazon ES domain.'
Description: 'The number of data nodes (instances) to use in the Amazon ES domain. If the defaul value of 1 is used, then automatically 1 node per Availability Zones is used. Therefore if 3-AZ is selected the value 1 and 3 produces the same result and 2 is not supported.'
Type: Number
Default: 1
ClusterInstanceType:
Expand All @@ -103,10 +109,12 @@ Conditions:
HasZone: !Not [!Equals [!Ref ParentZoneStack, '']]
HasSSHBastionSecurityGroup: !Not [!Equals [!Ref ParentSSHBastionStack, '']]
HasAlertTopic: !Not [!Equals [!Ref ParentAlertStack, '']]
HasSingleClusterInstance: !Equals [!Ref ClusterInstanceCount, '1']
HasDedicatedMasterNodes: !Not [!Equals [!Ref DedicatedMasterCount, 0]]
HasEBSEnabled: !Equals [!Ref EBSEnabled, 'true']
HasAlertTopicAndNotSingleClusterInstance: !And [!Condition HasAlertTopic, !Not [!Condition HasSingleClusterInstance]]
HasZoneAwareness: !Not [!Equals [!Ref AvailabilityZones, '1-AZ']]
HasAlertTopicAndZoneAwareness: !And [!Condition HasAlertTopic, !Condition HasZoneAwareness]
Has3AvailabilityZones: !Equals [!Ref AvailabilityZones, '3-AZ']
HasCustomClusterInstanceCount: !Not [!Equals [!Ref ClusterInstanceCount, 1]]
Resources:
RecordSet:
Condition: HasZone
Expand Down Expand Up @@ -163,25 +171,37 @@ Resources:
DedicatedMasterCount: !If [HasDedicatedMasterNodes, !Ref DedicatedMasterCount, !Ref 'AWS::NoValue']
DedicatedMasterEnabled: !If [HasDedicatedMasterNodes, true, false]
DedicatedMasterType: !If [HasDedicatedMasterNodes, !Ref DedicatedMasterType, !Ref 'AWS::NoValue']
InstanceCount: !Ref ClusterInstanceCount
InstanceCount: !If
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Why did you decide to do it like that? Why not just use the InstanceCount in any case? Wouldn't that be less complex?

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I always try to automatically set the correct values for dependent values and the count of instances must be at least the number of availability zones. I contemplated setting the default value to 0 and only then use the number of availability zones as instance count. But I was not sure if this will cause an issue if someone updates the template and is not aware, that the default value has changed.

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I think we should add one parameter AvailabilityZoneCount that can be either 2 or 3.

If InstanceCount = 1: we ignore AvailabilityZoneCount and use subnet A.
If InstanceCount > 1 && AvailabilityZoneCount = 2: we use subnet A, and B.
If InstanceCount > 1 && AvailabilityZoneCount = 3: we use subnetA, B, and C.

Would that make sense?

- HasCustomClusterInstanceCount
- !Ref ClusterInstanceCount
- !Select ['0', {'Fn::Split': ['-', !Ref AvailabilityZones]}]
InstanceType: !Ref ClusterInstanceType
ZoneAwarenessEnabled: !If [HasSingleClusterInstance, false, true]
ZoneAwarenessEnabled: !If [HasZoneAwareness, true, false]
ZoneAwarenessConfig: !If
- HasZoneAwareness
- AvailabilityZoneCount: !Select ['0', {'Fn::Split': ['-', !Ref AvailabilityZones]}]
- !Ref 'AWS::NoValue'
ElasticsearchVersion: !Ref ElasticsearchVersion
EncryptionAtRestOptions: !If [HasKmsKey, {Enabled: true, KmsKeyId: {'Fn::ImportValue': !Sub '${ParentKmsKeyStack}-KeyId'}}, !Ref 'AWS::NoValue']
SnapshotOptions:
AutomatedSnapshotStartHour: 10
VPCOptions:
SecurityGroupIds:
- !Ref SecurityGroup
SubnetIds: !If
- HasSingleClusterInstance
- - {'Fn::ImportValue': !Sub '${ParentVPCStack}-SubnetAPrivate'}
- - {'Fn::ImportValue': !Sub '${ParentVPCStack}-SubnetAPrivate'}
SubnetIds:
- {'Fn::ImportValue': !Sub '${ParentVPCStack}-SubnetAPrivate'}
- !If
- HasZoneAwareness
- {'Fn::ImportValue': !Sub '${ParentVPCStack}-SubnetBPrivate'}
- !Ref 'AWS::NoValue'
- !If
- Has3AvailabilityZones
- {'Fn::ImportValue': !Sub '${ParentVPCStack}-SubnetCPrivate'}
- !Ref 'AWS::NoValue'
UpdatePolicy:
EnableVersionUpgrade: true
ClusterStatusYellowAlarm:
Condition: HasAlertTopicAndNotSingleClusterInstance
Condition: HasAlertTopicAndZoneAwareness
Type: 'AWS::CloudWatch::Alarm'
Properties:
AlarmActions:
Expand Down