Repository: louislam/uptime-kuma
File: server/prometheus.js (JavaScript)

Code before:
     */
    constructor(monitor, tags) {
        this.monitorLabelValues = {
            monitor_id: monitor.id,
            monitor_name: monitor.name,
            monitor_type: monitor.type,
            monitor_url: monitor.url,
            monitor_hostname: monitor.hostname,
            monitor_port: monitor.port,
            ...this.mapTagsToLabels(tags)
        };
    }

    /**
     * Initialize Prometheus metrics, and add all available tags as possible labels.
     * This should be called once at the start of the application.
     * New tags will NOT be added dynamically, a restart is sadly required to add new tags to the metrics.
     * Existing tags added to monitors will be updated automatically.
     * @returns {Promise<void>}
     */
    static async init() {
        const tags = (await R.findAll("tag")).map((tag) => {
            return Prometheus.sanitizeForPrometheus(tag.name);
        }).filter((tagName) => {
            return tagName !== "";
        });

        const commonLabels = [
            "monitor_id",
            "monitor_name",
            "monitor_type",
            "monitor_url",
            "monitor_hostname",
            "monitor_port",
            ...tags // Add all available tags as possible labels
        ];

        monitorCertDaysRemaining = new PrometheusClient.Gauge({
            name: "monitor_cert_days_remaining",
            help: "The number of days remaining until the certificate expires",
            labelNames: commonLabels
        });

        monitorCertIsValid = new PrometheusClient.Gauge({
            name: "monitor_cert_is_valid",
            help: "Is the certificate still valid? (1 = Yes, 0= No)",
            labelNames: commonLabels
        });

        monitorResponseTime = new PrometheusClient.Gauge({
            name: "monitor_response_time",

Review comment (suggestion):
🤔 this does not impose a distinct constraint on the tag names => If I have `foo=bar` and `foo=baz`, foo is now twice in this list.

Will need to test if this causes problems in the prometheus code.

Code after:
     */
    constructor(monitor, tags) {
        this.monitorLabelValues = {
            ...this.mapTagsToLabels(tags),
            monitor_id: monitor.id,
            monitor_name: monitor.name,
            monitor_type: monitor.type,
            monitor_url: monitor.url,
            monitor_hostname: monitor.hostname,
            monitor_port: monitor.port
        };
    }

    /**
     * Initialize Prometheus metrics, and add all available tags as possible labels.
     * This should be called once at the start of the application.
     * New tags will NOT be added dynamically, a restart is sadly required to add new tags to the metrics.
     * Existing tags added to monitors will be updated automatically.
     * @returns {Promise<void>}
     */
    static async init() {
        // Add all available tags as possible labels,
        // and use Set to remove possible duplicates (for when multiple tags contain non-ascii characters, and thus are sanitized to the same label)
        const tags = new Set((await R.findAll("tag")).map((tag) => {
            return Prometheus.sanitizeForPrometheus(tag.name);
        }).filter((tagName) => {
            return tagName !== "";
        }).sort(this.sortTags));

        const commonLabels = [
            ...tags,
            "monitor_id",
            "monitor_name",
            "monitor_type",
            "monitor_url",
            "monitor_hostname",
            "monitor_port",
        ];

        monitorCertDaysRemaining = new PrometheusClient.Gauge({
            name: "monitor_cert_days_remaining",
            help: "The number of days remaining until the certificate expires",
            labelNames: commonLabels
        });

        monitorCertIsValid = new PrometheusClient.Gauge({
            name: "monitor_cert_is_valid",
            help: "Is the certificate still valid? (1 = Yes, 0= No)",
            labelNames: commonLabels
        });