attaché

A hapi.js plugin that registers a Consul service.

Example

const Attache = require('attache');
const Hapi = require('@hapi/hapi');

const server = Hapi.Server();

const provision = async () => {

    await server.register({
        register: require('attache'),
        options: {
            service: {
                name: 'myservice'
            }
        }
    });

    server.route({
        method: 'GET',
        path: '/',
        handler() => {

            return 'Hello World!';
        }
    });

    server.route({
        method: 'GET',
        path: '/_health',
        handler() => {

            return 'OK';
        }
    });

    await server.start();

    console.log('Server started at', server.info.uri);
});

This will register a "myservice" service with Consul.

The service can be discovered using the standard Consul interfaces (eg. DNS or HTTP).

Usage

Install using npm install attache, and register with Hapi using server.register().

Service registration & de-registration

Service registration is performed automatically as part of the server.start() processing.

Service de-registration is performed as part of the server.stop() processing. Once the server has started, it is important that server.stop() is called (and completed) before exiting the process. Otherwise, the service won't be deregistered. Note that server.stop() must also be called when server.start() returns with an error.

If the service is not de-registered, it will linger in the Consul registry. If configured with a health check, it will eventually be marked as unhealthy.

Plugin registration options

All configuration is optional:

• service - Object containing service registration information:
  • name - String with service name, as registered with Consul. Default: "hapi".
  • check - Object describing optional Consul health check:
    • path - String with path to http health check endpoint. Return any 2xx code to indicate "passing", 429 for "warning", and any other response for "failure". If false, disables health check. Default: "/_health".
    • ttl - Number with check interval in ms, or a String. Default: undefined.
    • interval - Number with check interval in ms, or a String. Default: "5s".
    • deregisterAfter - Number with automatic critical service de-registration interval in ms, or a String. Default: "120m".
    • startHealthy - Boolean, when set starts service in "passing" state. Default: true.
• retryStrategy - async function that is passed (consul, err, details) when an automatic registration or de-registration fails. If a Number is returned, it is used as a delay before retrying.
• lowProfile- Boolean that enables a low profile mode, which registers in the background and silences errors.
• consul - Object with consul agent connection information:
  • host - String with agent address. Default: "127.0.0.1".
  • port - Number with agent HTTP(s) port. Default: 8500.
  • secure - Boolean indicating if HTTPS is required. Default: false
  • ca - Array of Strings or Buffers of trusted certificates in PEM format.

If a http health check is configured, you can either point it to an existing path, or preferably create a custom route:

server.route({
    method: 'GET',
    path: '/_health',
    handler() => {

        return 'OK';
    }
});

Note that Consul does not use the returned value but it is recorded as part of the health check, useable for debugging, etc.

For ttl checks, a periodic check-in within the ttl timeout is required. This can be done using the consul object on the server, eg.:

setInterval(() => {

    server.consul.checkin(true);
}

Custom service id options

The service is registered as a unique service instance. The instance has a host unique ids, generated based on the service name, listening port, and process PID. Alternatively, a custom id and/or tags can be specified with the connection plugin option:

Hapi.Server({ plugins: { attache: { id: 'myservice-1', tags: ['hello'] } } });

Consul class interface

Available at server.consul once the plugin has been registered.

`await checkin(isOk, [note])

Reports current status of the consul service when TTL checks are used. If it has not been called successfully within the TTL interval since the last checkin, the health check will fail.

• isOk - true indicates a "passing" state, false a "failing", and anything else is a "warning".
• note - String with optional note that is recorded by consul.

Logging

All internal logging is tagged with attache and performed at the server level. Any de-registration errors are only exposed through this mechanism.