In the current implementation, ACM supports multi-participant with same supported element Type but different participantId, so they need different properties file.
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Participant replicas can be a kubernetes StatefulSets that consume two different properties file with unique UUIDs and unique consumer groups.
The StatefulSet uses the SPRING_CONFIG_NAME environment variable pointing to the spring application properties file unique to each of the participant replica.
Each of the properties file with the names pod-0.yaml, pod-1.yaml is mounted to the volumes. And the SPRING_CONFIG_NAME variable can be set to /path/to/$HOSTNAME.yaml to use the corresponding
properties file.
By this approach the participant can have multiple replicas with different UUIDs and kafka consumer groups to work with a shared data.
env:
- name: HOSTNAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: SPRING_CONFIG_NAME
value: /path/to/${HOSTNAME}.yaml
For example considering the http participant replica, ${HOSTNAME} will be "policy-http-ppnt-0" and "policy-http-ppnt-1" and their
corresponding properties files with the names "http-ppnt-0.yaml" and "http-ppnt-1.yaml" is volume mounted.
Note: In a scenario of two participants in replicas (we are calling "policy-http-ppnt-0" and "policy-http-ppnt-1"), ACM-Runtime will assignee randomly any composition definition in prime time to specific participant based of supported element definition type. So we could have a scenario where a composition definition "composition 1.0.0" is assigned to policy-http-ppnt-0 and the instance too; the new composition "composition 1.0.1" is assigned to policy-http-ppnt-1. In that scenario the migration of an instance from "composition 1.0.0" to "composition 1.0.1" wouldn't work, because policy-http-ppnt-0 do not have "composition 1.0.1" assigned.
Issues:
- At migrate time - In that scenario the migration of an instance from "composition 1.0.0" to "composition 1.0.1" wouldn't work, because policy-http-ppnt-0 do not have "composition 1.0.1" assigned. This is a critical issue.
Solution 3: Replicas and Database support - no cache
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- Arbitrary number of participants possible
- DB migrator upgrades older versions
- Restart scenario not applicable anymore. Could be removed.
- Approval not an issue - postgres already used by acm.
- DB will be created automatically - as are required tables.
Older participant versions support (Regression)
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