Class Prometheus

packages/server/src/metrics/Prometheus.ts:6–180

import { getVersion } from 'flowise-components'

export class Prometheus implements IMetricsProvider {
    private app: express.Application
    private readonly register: Registry
    private counters: Map<string, promClient.Counter<string> | promClient.Gauge<string> | promClient.Histogram<string>>
    private requestCounter: Counter<string>
    private httpRequestDurationMicroseconds: Histogram<string>

    constructor(app: express.Application) {
        this.app = app
        // Clear any existing default registry metrics to avoid conflicts
        promClient.register.clear()
        // Create a separate registry for our metrics
        this.register = new promClient.Registry()
    }

    public getName(): string {
        return 'Prometheus'
    }

    async initializeCounters(): Promise<void> {
        const serviceName: string = process.env.METRICS_SERVICE_NAME || 'FlowiseAI'
        this.register.setDefaultLabels({
            app: serviceName
        })

        // look at the FLOWISE_COUNTER enum in Interface.Metrics.ts and get all values
        // for each counter in the enum, create a new promClient.Counter and add it to the registry
        this.counters = new Map<string, promClient.Counter<string> | promClient.Gauge<string> | promClient.Histogram<string>>()
        const enumEntries = Object.entries(FLOWISE_METRIC_COUNTERS)
        enumEntries.forEach(([name, value]) => {
            // derive proper counter name from the enum value (chatflow_created = Chatflow Created)
            const properCounterName: string = name.replace(/_/g, ' ').replace(/\b\w/g, (l) => l.toUpperCase())
            try {
                this.counters.set(
                    value,
                    new promClient.Counter({
                        name: value,
                        help: `Total number of ${properCounterName}`,
                        labelNames: ['status'],
                        registers: [this.register] // Explicitly set the registry
                    })
                )
            } catch (error) {
                // If metric already exists, get it from the registry instead
                const existingMetrics = this.register.getSingleMetric(value)
                if (existingMetrics) {
                    this.counters.set(value, existingMetrics as promClient.Counter<string>)
                }
            }
        })

        // in addition to the enum counters, add a few more custom counters
        // version, http_request_duration_ms, http_requests_total
        try {
            const versionGaugeCounter = new promClient.Gauge({
                name: 'flowise_version_info',
                help: 'Flowise version info.',
                labelNames: ['version'],