Feature: Prometheus Metric service widget (#4269)

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/utils/config/service-helpers.js

@@ -418,7 +418,7 @@ export function cleanServiceGroups(groups) {
           pointsLimit,
           diskUnits,
 
-          // glances, customapi, iframe
+          // glances, customapi, iframe, prometheusmetric
           refreshInterval,
 
           // hdhomerun
@@ -461,6 +461,9 @@ export function cleanServiceGroups(groups) {
           // opnsense, pfsense
           wan,
 
+          // prometheusmetric
+          metrics,
+
           // proxmox
           node,
 
@@ -646,6 +649,10 @@ export function cleanServiceGroups(groups) {
         if (type === "vikunja") {
           if (enableTaskList !== undefined) cleanedService.widget.enableTaskList = !!enableTaskList;
         }
+        if (type === "prometheusmetric") {
+          if (metrics) cleanedService.widget.metrics = metrics;
+          if (refreshInterval) cleanedService.widget.refreshInterval = refreshInterval;
+        }
       }
 
       return cleanedService;

src/widgets/components.js

@@ -95,6 +95,7 @@ const components = {
   plex: dynamic(() => import("./plex/component")),
   portainer: dynamic(() => import("./portainer/component")),
   prometheus: dynamic(() => import("./prometheus/component")),
+  prometheusmetric: dynamic(() => import("./prometheusmetric/component")),
   prowlarr: dynamic(() => import("./prowlarr/component")),
   proxmox: dynamic(() => import("./proxmox/component")),
   pterodactyl: dynamic(() => import("./pterodactyl/component")),

src/widgets/prometheusmetric/component.jsx

@@ -0,0 +1,115 @@
+import { useTranslation } from "next-i18next";
+
+import Container from "components/services/widget/container";
+import Block from "components/services/widget/block";
+import useWidgetAPI from "utils/proxy/use-widget-api";
+
+function formatValue(t, metric, rawValue) {
+  if (!rawValue) return "-";
+
+  let value = rawValue;
+
+  // Scale the value. Accepts either a number to multiply by or a string
+  // like "12/345".
+  const scale = metric?.format?.scale;
+  if (typeof scale === "number") {
+    value *= scale;
+  } else if (typeof scale === "string" && scale.includes("/")) {
+    const parts = scale.split("/");
+    const numerator = parts[0] ? parseFloat(parts[0]) : 1;
+    const denominator = parts[1] ? parseFloat(parts[1]) : 1;
+    value = (value * numerator) / denominator;
+  } else {
+    value = parseFloat(value);
+  }
+
+  // Format the value using a known type and optional options.
+  switch (metric?.format?.type) {
+    case "text":
+      break;
+    default:
+      value = t(`common.${metric.format.type}`, { value, ...metric.format?.options });
+  }
+
+  // Apply fixed prefix.
+  const prefix = metric?.format?.prefix;
+  if (prefix) {
+    value = `${prefix}${value}`;
+  }
+
+  // Apply fixed suffix.
+  const suffix = metric?.format?.suffix;
+  if (suffix) {
+    value = `${value}${suffix}`;
+  }
+
+  return value;
+}
+
+export default function Component({ service }) {
+  const { t } = useTranslation();
+
+  const { widget } = service;
+
+  const { metrics = [], refreshInterval = 10000 } = widget;
+
+  let prometheusmetricError;
+
+  const prometheusmetricData = new Map(
+    metrics.slice(0, 4).map((metric) => {
+      // disable the rule that hooks should not be called from a callback,
+      // because we don't need a strong guarantee of hook execution order here.
+      // eslint-disable-next-line react-hooks/rules-of-hooks
+      const { data: resultData, error: resultError } = useWidgetAPI(widget, "query", {
+        query: metric.query,
+        refreshInterval: Math.max(1000, metric.refreshInterval ?? refreshInterval),
+      });
+      if (resultError) {
+        prometheusmetricError = resultError;
+      }
+      return [metric.key ?? metric.label, resultData];
+    }),
+  );
+
+  if (prometheusmetricError) {
+    return <Container service={service} error={prometheusmetricError} />;
+  }
+
+  if (!prometheusmetricData) {
+    return (
+      <Container service={service}>
+        {metrics.slice(0, 4).map((item) => (
+          <Block label={item.label} key={item.label} />
+        ))}
+      </Container>
+    );
+  }
+
+  function getResultValue(data) {
+    // Fetches the first metric result from the Prometheus query result data.
+    // The first element in the result value is the timestamp which is ignored here.
+    const resultType = data?.data?.resultType;
+    const result = data?.data?.result;
+
+    switch (resultType) {
+      case "vector":
+        return result?.[0]?.value?.[1];
+      case "scalar":
+        return result?.[1];
+      default:
+        return "";
+    }
+  }
+
+  return (
+    <Container service={service}>
+      {metrics.map((metric) => (
+        <Block
+          label={metric.label}
+          key={metric.key ?? metric.label}
+          value={formatValue(t, metric, getResultValue(prometheusmetricData.get(metric.key ?? metric.label)))}
+        />
+      ))}
+    </Container>
+  );
+}

src/widgets/prometheusmetric/widget.js

@@ -0,0 +1,16 @@
+import genericProxyHandler from "utils/proxy/handlers/generic";
+
+const widget = {
+  api: "{url}/api/v1/{endpoint}",
+  proxyHandler: genericProxyHandler,
+
+  mappings: {
+    query: {
+      method: "GET",
+      endpoint: "query",
+      params: ["query"],
+    },
+  },
+};
+
+export default widget;

src/widgets/widgets.js

@@ -87,6 +87,7 @@ import plantit from "./plantit/widget";
 import plex from "./plex/widget";
 import portainer from "./portainer/widget";
 import prometheus from "./prometheus/widget";
+import prometheusmetric from "./prometheusmetric/widget";
 import prowlarr from "./prowlarr/widget";
 import proxmox from "./proxmox/widget";
 import pterodactyl from "./pterodactyl/widget";
@@ -218,6 +219,7 @@ const widgets = {
   plex,
   portainer,
   prometheus,
+  prometheusmetric,
   prowlarr,
   proxmox,
   pterodactyl,