@setu-ts/service-discovery-plugin — locate and select service instances

Add it: setu add service-discovery adds it and prints the registration for setu.config.ts. It provides CAPABILITIES.SERVICE_DISCOVERY (IServiceDiscovery).

Configure a static service pool

import { ServiceDiscoveryPlugin } from '@setu-ts/service-discovery-plugin';

export const discovery = ServiceDiscoveryPlugin({
  provider: 'static',
  services: {
    billing: [{ host: '10.0.0.1', port: 8080 }, { host: '10.0.0.2', port: 8080 }],
  },
});

Resolve an upstream URL from a route

import { CAPABILITIES } from '@setu-ts/common';
import type { IRouterApi, IServiceDiscovery } from '@setu-ts/common';

export function registerBillingRoutes(router: IRouterApi): void {
  router.get('/billing-location', {
    handler: async (ctx) => {
      const discovery = ctx.services.get<IServiceDiscovery>(CAPABILITIES.SERVICE_DISCOVERY);
      const url = await discovery.resolveUrl('billing', '/invoices');
      return url === null
        ? ctx.response.status(503).json({ error: 'No billing instance' })
        : ctx.response.json({ url });
    },
  });
}

Behaviour the types do not show

• resolveUrl and pick return null for an empty pool. resolve lists all known instances, including ejected ones; pick filters ejected instances, falling back to the full pool if needed.
• Selection defaults to round-robin. A per-call strategy overrides the configured default.
• Resolved lists are cached for 30000 ms by default; cacheTtlMs: 0 disables cache reuse. Concurrent cold reads of one service share a backend read.
• Ejection depends on application report(instance, outcome) calls. By default five failures within 30000 ms eject for 30000 ms, subject to a 50% pool cap; success clears the state.
• A watch delivers the full list and refreshes the cache on change. Stop it using the returned unsubscribe function.

Other options

• provider also selects 'consul', 'kubernetes', 'dns' or 'custom' with discovery.
• strategy also accepts 'random' and 'weighted-random'; ejection: false disables ejection.
• selfRegistration is Consul-only; other providers reject it with SelfRegistrationNotSupportedError. DNS requires the runtime DNS surface.