B PodDisruptionBudget Configuration
PodDisruptionBudget (PDB) is a Kubernetes resource that allows to achieve high availability of scalable application services when the cluster administrators perform voluntary disruptions to manage the cluster nodes. PDB restricts the number of pods that are down simultaneously from voluntary disruptions. Defining PDB is helpful to keep the services running undisrupted when a pod is deleted accidentally or deliberately. PDB can be defined for high available and scalable Policy services such as SM Service, AM Service, User service, app-info, perf-info, etc.
It allows safe eviction of pods when a Kubernetes node is drained to perform
maintenance on the node. It uses the default value of the
maxUnavailable parameter specified in the Helm chart to determine
the maximum number of pods that are unavailable during a voluntary disruption. For
example, if maxUnavailable is 50%, the evictions are allowed until not
more than 50% of the desired replicas are unhealthy.
Note:
The performance and capacity of the Policy system may vary based on the Call model, Feature/Interface configuration, underlying CNE and hardware environment, including but not limited to the complexity of deployed policies, policy table size , object expression and custom json usage in policy design.The following Policy services support PDB:
Table B-1 Default PodDisruptionBudget for Policy microservices
| Microservice | PDB Default Value (maxUnavailable) |
|---|---|
alternate_route |
1 |
am-service |
20% |
app-info |
20% |
audit-service |
NA |
binding service |
20% |
bulwark |
0 |
cm-service |
20% |
config-server |
20% |
diam-connector |
20% |
diam-gateway |
20% |
ingress_gateway |
1 |
egress_gateway |
1 |
ldap-gateway |
20% |
notifier service |
20% |
nrf-client-discovery |
25% |
nrf-client-management |
NA |
nwdaf-agent |
20% |
pcrf-core |
20% |
perf-info |
20% |
policyds |
20% |
pre |
20% |
pre-test |
-- |
queryservice |
20% |
sm-service |
20% |
soap connector |
20% |
udr connector |
20% |
ue-service |
20% |
user-service |
20% |
usage-mon |
20% |
chf-connector |
20% |