Motivation

MySQL Router exposes monitoring data via REST endpoints.

The metadata-cache component of the router takes care of:

• querying the data from the metadata servers
• communicating with the routing component for
  • liveness of group replication backends
  • liveness of network connections
• maintains a cache of the metadata that is refreshed on trigger or TTL

User Stories

1. As a tester I want to wait until metadata component has fetched data before sending traffic to the routing component to avoid false-positive test-results.
2. As a devop I want to be able to configure a liveness test in the load-balancer to send only traffic to the router when it has valid metadata of the cluster.

Goal

Add REST endpoints for the metadata-cache that expose

• current known cluster nodes and their state
• success and failure counters
• time of last fetch
• current configuration

Function Requirements

FR1

HTTP GET request to <base>/metadata/{metadaName}/status MUST return the cache status as JSON object

FR2

HTTP GET request to <base>/metadata/{metadataName}/config MUST return the configuration of the metadata cache

FR3

HTTP GET request to <base>/metadata/ MUST return the list of configurated metadata caches.

Implementation

• add a new plugin rest_metadata_cache
  • depends on metadata_cache component running
  • depends on rest_api component running (WL#8965)

Configuration Options

• require_realm, required, string, name of an authentication realm

rest_metadata_cache

metadata-list

URL

<base>/metadata/

Methods

GET

• object
  • items: array of objects
  • name: string, name of metadata instance

cache-config

URL

<base>/metadata/{metadataName}/config

Methods

GET

• object
  • timeRefreshInMs number, ttl
  • clusterName: string, optional, name of the Replication Group
  • groupReplicationId: string, optional
  • nodes: array of object:
  • hostname: string
  • port: integer

cache-status

URL

<base>/metadata/{metadataName}/status

Methods

GET

• object
  • refreshSucceeded: number (positive, integer)
  • refreshFailed: number (positive, integer)
  • timeLastRefreshSucceeded: string (date-time)
  • timeLastRefreshFailed: string (date-time)
  • lastRefreshHostname: string
  • lastRefreshPort: integer