add metrics endpoint to api

packages/server/src/api/controllers/public/metrics.ts

@@ -0,0 +1,122 @@
+import { App, BBContext } from "@budibase/types"
+import { db as dbCore, context } from "@budibase/backend-core"
+import os from "os"
+
+export async function fetch(ctx: BBContext) {
+  const allDatabases = await dbCore.getAllDbs()
+  const devAppIDs = await dbCore.getDevAppIDs({ idsOnly: true })
+  const prodAppIDs = await dbCore.getProdAppIDs({ idsOnly: true })
+  const allAppIds = await dbCore.getAllApps({ idsOnly: true })
+
+  var outputString = ""
+
+  const freeMem = os.freemem()
+  const totalMem = os.totalmem()
+  const usedMem = totalMem - freeMem
+  const uptime = os.uptime()
+
+  // **** budibase_os_uptime ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_uptime",
+    "Time in seconds that the host operating system has been up",
+    "counter",
+    uptime
+  )
+
+  // **** budibase_os_free_mem ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_free_mem",
+    "Bytes of memory free for usage on the host operating system",
+    "gauge",
+    freeMem
+  )
+
+  // **** budibase_os_total_mem ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_total_mem",
+    "Total bytes of memory on the host operating system",
+    "gauge",
+    totalMem
+  )
+
+  // **** budibase_os_used_mem ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_used_mem",
+    "Total bytes of memory in use on the host operating system",
+    "gauge",
+    usedMem
+  )
+
+  // **** budibase_os_load1 ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_load1",
+    "Host operating system load average",
+    "gauge",
+    os.loadavg()[0]
+  )
+
+  // **** budibase_os_load5 ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_load5",
+    "Host operating system load average",
+    "gauge",
+    os.loadavg()[1]
+  )
+  // **** budibase_os_load15 ****
+  outputString += convertToOpenMetrics(
+    "budibase_os_load15",
+    "Host operating system load average",
+    "gauge",
+    os.loadavg()[2]
+  )
+
+  // **** budibase_tenant_app_count ****
+  outputString += convertToOpenMetrics(
+    "budibase_tenant_app_count",
+    "The number of apps created by a user",
+    "gauge",
+    allAppIds.length
+  )
+
+  // **** budibase_tenant_production_app_count ****
+  outputString += convertToOpenMetrics(
+    "budibase_tenant_production_app_count",
+    "The number of apps a user has published",
+    "gauge",
+    prodAppIDs.length
+  )
+
+  // **** budibase_tenant_dev_app_count ****
+  outputString += convertToOpenMetrics(
+    "budibase_tenant_dev_app_count",
+    "The number of apps a user has unpublished in development",
+    "gauge",
+    devAppIDs.length
+  )
+
+  // **** budibase_tenant_db_count ****
+  outputString += convertToOpenMetrics(
+    "budibase_tenant_db_count",
+    "The number of couchdb databases including global tables such as _users",
+    "gauge",
+    allDatabases.length
+  )
+
+  ctx.body = outputString
+}
+
+export function convertToOpenMetrics(
+  metricName: string,
+  metricHelp: string,
+  metricType: string,
+  metricValue: number
+) {
+  return `
+    # HELP ${metricName} ${metricHelp}.
+    # TYPE ${metricName} ${metricType}
+    ${metricName} ${metricValue}`
+}
+
+export default {
+  fetch,
+}

packages/server/src/api/routes/public/index.ts

@@ -1,4 +1,5 @@
 import appEndpoints from "./applications"
+import metricEndpoints from "./metrics"
 import queryEndpoints from "./queries"
 import tableEndpoints from "./tables"
 import rowEndpoints from "./rows"
@@ -120,6 +121,7 @@ function applyRoutes(
 }
 
 applyRoutes(appEndpoints, PermissionType.APP, "appId")
+applyRoutes(metricEndpoints, PermissionType.APP, "appId")
 applyRoutes(tableEndpoints, PermissionType.TABLE, "tableId")
 applyRoutes(userEndpoints, PermissionType.USER, "userId")
 applyRoutes(queryEndpoints, PermissionType.QUERY, "queryId")

packages/server/src/api/routes/public/metrics.ts

@@ -0,0 +1,28 @@
+import controller from "../../controllers/public/metrics"
+import Endpoint from "./utils/Endpoint"
+
+const read = []
+
+/**
+ * @openapi
+ * /metrics:
+ *   get:
+ *     operationId: getById
+ *     summary: Retrieve Budibase tenant metrics
+ *     description: Output metrics in openMetrics format compatible with Prometheus
+ *     tags:
+ *       - metrics
+ *     responses:
+ *       200:
+ *         description: Returns tenant metrics.
+ *         content:
+ *           text/plain:
+ *             schema:
+ *               $ref: '#/components/schemas/tableOutput'
+ *             examples:
+ *               table:
+ *                 $ref: '#/components/examples/table'
+ */
+read.push(new Endpoint("get", "/metrics", controller.fetch))
+
+export default { read }