Feature(strategy): support mysql read_write_splitting

[xuanyuan300]

Read-write-splitting is an important part of pisa-proxy traffic management, which can be improve query performance and reduce server load in practical scenarios.

The following is internal design diagram:

RuleMatch is used to match SQL statements by rules. Currently, only support regex and in the future, rego will be supported.
TargetGroup is the backend target group after successful matching, and the target group corresponds to the role attribute, the role need to be defined in annotations field of DatabaseEndpoint crd.
LoadBalance is used to select an instance in the target group by the LoadBalance algorithm.
TargetInstace is executes the instance of the SQL statement.

An complete config of TrafficStrategy as follows:

apiVersion: core.database-mesh.io/v1alpha1
kind: TrafficStrategy
metadata:
  name: test 
  namespace: default 
spec:
  selector:
    matchLabels:
      source: test
  loadBalance:
    readWriteSplitting:
      static:  
        defaultTarget: read // or read_write
        rules:
          - name: read-rule
            type: regex
            regex: ".*"
            target: read // read_write
            algorithmName: random // lb algorithm
          - name: write-rule
            type: regex
            regex: ".*"
            target: read_write
            algorithmName: roundrobin

An complete config of DatabaseEndpoint as follows:

apiVersion: core.database-mesh.io/v1alpha1
kind: DatabaseEndpoint
metadata:
  annotations:
    database-mesh.io/role: read // or read_write
    database-mesh.io/weight: 1
  labels:
    source: test 
  name: mysql 
  namespace: default 
spec:
  database:
    MySQL:
      db: test 
      host: mysql.default 
      password: root 
      port: 3306
      user: root

Development Task

pisa-proxy

• Add config for read_write_splitting.
• Add RuleMatch engine.
• Update build_loadbalance logic for RuleMatch engine.
• Implement RuleMatch engine for mysql server runtime.
• Implement new LoadBalancer to FSM.
• Add unit test.

pisa-controller

• Add config for read_write_splitting.
• Update DatabaseEndpoint crd for role.

integration test

• pisa-proxy and pisa-controller integration test.

[mlycore]

The TODOs need to be updated