How to enable the Monitor plugin

The Monitor plugin provides insights about a running node, for example:

  • It provides information about blocks and transactions received from the network.

  • It provides information about connected/disconnected/banned peers and includes data about other network activities.

  • The Monitor plugin gives hints for debugging the network, and detecting any network splits or attacks.

The Monitor plugin monitors a node’s activity and stores this data in the plugin’s store. It then exposes the aforementioned data using the endpoints as described in the Retrieving data section. The Monitor plugin also exports this data in the Prometheus format for the Prometheus toolkit (an open-source systems monitoring and alerting toolkit).

On this page, you’ll learn how to perform the following:

  • Register the Monitor plugin to a blockchain client.

  • Configure the Monitor plugin.

  • Retrieve various types of data from the Monitor plugin.

Using this guide, the Monitor plugin can be registered to a Klayr Core node or any Klayr-based blockchain client.

1. Plugin registration

With the latest version of Klayr Core v4 and Klayr SDK v6, the default plugins come pre-installed after a client is installed or initiated respectively.

You can check the package.json file of the blockchain client to ensure the installation has been performed correctly.

hello_client/package.json
"dependencies": {
  //[...]
	"@klayr/framework-monitor-plugin": "0.4.1",
	//[...]
},

Otherwise, you can install the Monitor plugin like this:

npm install --save @klayr/framework-monitor-plugin

There are various ways to enable the Monitor plugin. You can opt for any of the below-mentioned options to register the plugin to the blockchain client.

It is essential to enable the WS API and configure the allowedMethods property before registering the MonitorPlugin. For more information, see the configurations described in the configuration guide.

1.1. Registering via source

For blockchain clients that were initialized with Klayr Commander, it is possible to register the plugin through the plugins.ts file. Open the plugins.ts file, import the Monitor plugin, and register it with the application as shown below:

src/app/plugins.ts
/* eslint-disable @typescript-eslint/no-empty-function */
import { MonitorPlugin } from '@klayr/framework-monitor-plugin';
import { Application } from 'klayr-sdk';

export const registerPlugins = (app: Application): void => {
    app.registerPlugin(new MonitorPlugin ());
};

Save and close the plugins.ts file.

After updating the plugins.ts file, build the blockchain client again:

npm run build

2. Starting the node

Depending on how you chose to register the plugin, start the blockchain client accordingly.

  • Registered via built-in flag

  • Registered via Source

It is also possible to enable the Monitor plugin without updating the plugins.ts file. This can be done simply by adding the --enable-monitor-plugin flag to the start command.

Mainchain

  • Start the blockchain client with designated flags on a mainchain node.

    klayr-core start --network testnet --enable-monitor-plugin
Sidechain

  • Or, start the blockchain client with designated flags on a sidechain node.

    ./bin/run start --config=config/custom_config.json --enable-monitor-plugin
Start the blockchain client with custom_config.json
./bin/run start --config=config/custom_config.json

3. Configuring the Monitor Plugin

The Monitor plugin comes with a set of pre-defined configurations, which can be tweaked as per the node operator’s requirements.

  • Available Configurations

  • Usage

Name Type Description Sample

port

string

Defines the port for a custom express server.

4003

host

string

Defines the host such as a custom express server.

127.0.0.1

whiteList

string

When given a value, only those IPs are allowed to interact with the Monitor plugin.

['127.0.0.1']

cors

string

Defines the CORS properties such as origin and allowed methods which should be handled by the Monitor plugin.

 
"cors": {
    "origin": '*',
    "methods": ['GET', 'POST', 'PUT'],
},

limits

string

Defines various types of limits for example max, delayMs, delayeAfter, windowMs, headersTimeout, and serverSetTimeout for the monitor plugin.

 
"limits": {
    "max": 0,
    "delayMs": 0,
    "delayAfter": 0,
    "windowMs": 60000,
    "headersTimeout": 5000,
    "serverSetTimeout": 20000,
},
config.json
"plugins": {
    "monitor": {
        "port": "9000"
    }
}

4. Retrieving data

The data recorded by the Monitor plugin can be retrieved via RPC endpoints or in Prometheus format, as described in the following sub-sections.

4.1. Via RPC endpoints

The monitor plugin exposes four endpoints that return important data about a node. The following table briefly describes them:

Name Description

monitor_getTransactionStats

Returns the data about the number of times a transaction is received on an average from the network for a given number of connected peers.

monitor_getBlockStats

Returns the data about the number of times a block is received on an average from the network for a given number of connected peers.

monitor_getNetworkStats

Returns the data about the number of connected/disconnected/banned peers, and the number of outgoing/incoming connections with several peers at a certain height.

monitor_getForkStats

Returns the data about the number of fork events and related block headers.

Once the Monitor plugin is enabled on a node, the aforementioned endpoints can be invoked to get the latest status of a node. For more information about each endpoint, see klayr-framework-monitor-plugin/src/endpoint.ts.

4.2. Data in Prometheus format

The data in Prometheus format is exported via the /api/prometheus/metrics handle, and the data received can be visualized by plugging it into tools like Grafana. For more information, see Grafana’s support for Prometheus.

To retrieve data in Prometheus format, you can perform a GET request to the api/prometheus/metrics of the Monitor plugin. By default, the Plugin host address is localhost or 127.0.0.1 and the port is 4003. These parameters can be changed as described in the Configuring the Monitor Plugin section.

CURL request to the Monitor plugin to retrieve data in Prometheus format
curl --location 'http://127.0.0.1:4003/api/prometheus/metrics'
Monitoring data in the Prometheus format
# HELP klayr_avg_times_blocks_received_info Average number of times blocks received
# TYPE klayr_avg_times_blocks_received_info gauge
klayr_avg_times_blocks_received_info 1

# HELP klayr_avg_times_transactions_received_info Average number of times transactions received
# TYPE klayr_avg_times_transactions_received_info gauge
klayr_avg_times_transactions_received_info 0

# HELP klayr_node_height_total Node Height
# TYPE klayr_node_height_total gauge
klayr_node_height_total 17268

# HELP klayr_finalized_height_total Finalized Height
# TYPE klayr_finalized_height_total gauge
klayr_finalized_height_total 17267

# HELP klayr_unconfirmed_transactions_total Unconfirmed transactions
# TYPE klayr_unconfirmed_transactions_total gauge
klayr_unconfirmed_transactions_total 0

# HELP klayr_peers_total Total number of peers
# TYPE klayr_peers_total gauge
klayr_peers_total{state="connected"} 0
klayr_peers_total{state="disconnected"} 0

# HELP klayr_fork_events_total Fork events
# TYPE klayr_fork_events_total gauge
klayr_fork_events_total 0

You can configure Prometheus to automatically invoke the aforementioned endpoint after regular intervals. For more information, see the Configuration section of the Prometheus documentation.

Configuring the Prometheus to automatically invoke the aforementioned endpoint and then plugging such data into visualizing tools such as Grafana, can enable a node operator to stay up to date with the latest status of their node.