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Highly Available Aidbox

Run parallel Aidbox replicas supported from 2208 version

Concept

To provide increased High availability, the approach is to run two or more application instances. All incoming traffic is balanced between all running Aidbox instances. In case of failure of one of the instances, the network layer stops receiving incoming traffic to failed instance and distributes it to other available instances. The task of the orchestration system is to detect failure of one of the instances and restart it.

Configuration

Let's take the Kubernetes example of a high availability Aidbox configuration (this example can also be applied to Multibox)
apiVersion: apps/v1
kind: Deployment
metadata:
name: aidbox
namespace: production
spec:
replicas: 2
selector:
matchLabels:
service: aidbox
template:
metadata:
labels:
service: aidbox
spec:
topologySpreadConstraints:
- maxSkew: 1
topologyKey: topology.kubernetes.io/zone
whenUnsatisfiable: ScheduleAnyway
labelSelector:
matchLabels:
service: aidbox
containers:
- name: main
image: healthsamurai/aidboxone:latest
imagePullPolicy: Always
ports:
- containerPort: 8080
protocol: TCP
envFrom:
- configMapRef:
name: aidbox
- secretRef:
name: aidbox
livenessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 20
timeoutSeconds: 5
periodSeconds: 5
successThreshold: 1
failureThreshold: 4
readinessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 20
timeoutSeconds: 5
periodSeconds: 5
successThreshold: 1
failureThreshold: 2

Replicas

First of all you should specify how many replicas you need
...
spec:
replicas: 2
...

Readiness probe

Readiness probe - indicates that applications running and ready to receive traffic.
readinessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 20
timeoutSeconds: 5
periodSeconds: 5
successThreshold: 1
failureThreshold: 2

Liveness probe

Liveness probe - indicates whether the container is running. If the liveness probe fails, the kubelet kills the container, and the container is subjected to its restart policy.
livenessProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 20
timeoutSeconds: 5
periodSeconds: 5
successThreshold: 1
failureThreshold: 4

Startup probe

Startup probe - provide a way to defer the execution of liveness and readiness probes until a container indicates it’s able to handle them. Kubernetes won’t direct the other probe types to a container if it has a startup probe that hasn’t yet succeeded..
startupProbe:
httpGet:
path: /health
port: 8080
scheme: HTTP
initialDelaySeconds: 20
timeoutSeconds: 5
periodSeconds: 5
successThreshold: 1
failureThreshold: 4
​

Pod topology

To improve fault tolerance in case of failure of one or more availability zones, you must specify — Pod Topology Spread Constraints​
topologySpreadConstraints:
- maxSkew: 1
topologyKey: topology.kubernetes.io/zone
whenUnsatisfiable: ScheduleAnyway
labelSelector:
matchLabels:
service: aidbox