Azure Monitor

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{
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  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
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  "contentVersion": "1.0.0.0",
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  "parameters": {
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    "launchDarklyClientSideId": {
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      "type": "string",
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      "metadata": {
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        "description": "Your LaunchDarkly environment client-side ID"
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      }
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    },
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    "location": {
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      "type": "string",
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      "defaultValue": "[resourceGroup().location]",
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      "metadata": {
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        "description": "Azure region for all resources"
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      }
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    }
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  },
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  "variables": {
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    "suffix": "[uniqueString(resourceGroup().id)]",
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    "eventHubNamespaceName": "[format('ld-obs-{0}', variables('suffix'))]",
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    "eventHubName": "launchdarkly-diagnostics",
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    "storageAccountName": "[format('ldobs{0}', variables('suffix'))]",
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    "functionAppName": "[format('ld-obs-func-{0}', variables('suffix'))]",
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    "hostingPlanName": "[format('ld-obs-plan-{0}', variables('suffix'))]"
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  },
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  "resources": [
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    {
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      "type": "Microsoft.EventHub/namespaces",
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      "apiVersion": "2022-10-01-preview",
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      "name": "[variables('eventHubNamespaceName')]",
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      "location": "[parameters('location')]",
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      "sku": {
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        "name": "Standard",
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        "tier": "Standard",
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        "capacity": 1
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      }
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    },
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    {
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      "type": "Microsoft.EventHub/namespaces/eventhubs",
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      "apiVersion": "2022-10-01-preview",
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      "name": "[format('{0}/{1}', variables('eventHubNamespaceName'), variables('eventHubName'))]",
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      "dependsOn": ["[resourceId('Microsoft.EventHub/namespaces', variables('eventHubNamespaceName'))]"],
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      "properties": {
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        "messageRetentionInDays": 1,
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        "partitionCount": 2
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      }
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    },
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    {
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      "type": "Microsoft.Storage/storageAccounts",
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      "apiVersion": "2023-01-01",
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      "name": "[variables('storageAccountName')]",
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      "location": "[parameters('location')]",
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      "sku": {
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        "name": "Standard_LRS"
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      },
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      "kind": "StorageV2"
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    },
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    {
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      "type": "Microsoft.Web/serverfarms",
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      "apiVersion": "2023-01-01",
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      "name": "[variables('hostingPlanName')]",
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      "location": "[parameters('location')]",
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      "sku": {
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        "name": "Y1",
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        "tier": "Dynamic"
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      },
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      "properties": {}
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    },
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    {
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      "type": "Microsoft.Web/sites",
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      "apiVersion": "2023-01-01",
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      "name": "[variables('functionAppName')]",
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      "location": "[parameters('location')]",
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      "kind": "functionapp",
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      "dependsOn": [
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        "[resourceId('Microsoft.Web/serverfarms', variables('hostingPlanName'))]",
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        "[resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName'))]",
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        "[resourceId('Microsoft.EventHub/namespaces', variables('eventHubNamespaceName'))]"
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      ],
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      "properties": {
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        "serverFarmId": "[resourceId('Microsoft.Web/serverfarms', variables('hostingPlanName'))]",
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        "siteConfig": {
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          "appSettings": [
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            {
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              "name": "AzureWebJobsStorage",
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              "value": "[format('DefaultEndpointsProtocol=https;AccountName={0};EndpointSuffix={1};AccountKey={2}', variables('storageAccountName'), environment().suffixes.storage, listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2023-01-01').keys[0].value)]"
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            },
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            {
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              "name": "WEBSITE_CONTENTAZUREFILECONNECTIONSTRING",
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              "value": "[format('DefaultEndpointsProtocol=https;AccountName={0};EndpointSuffix={1};AccountKey={2}', variables('storageAccountName'), environment().suffixes.storage, listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2023-01-01').keys[0].value)]"
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            },
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            {
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              "name": "WEBSITE_CONTENTSHARE",
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              "value": "[toLower(variables('functionAppName'))]"
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            },
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            {
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              "name": "FUNCTIONS_EXTENSION_VERSION",
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              "value": "~4"
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            },
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            {
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              "name": "FUNCTIONS_WORKER_RUNTIME",
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              "value": "node"
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            },
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            {
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              "name": "WEBSITE_NODE_DEFAULT_VERSION",
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              "value": "~22"
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            },
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            {
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              "name": "EventHubConnection",
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              "value": "[listKeys(resourceId('Microsoft.EventHub/namespaces/authorizationRules', variables('eventHubNamespaceName'), 'RootManageSharedAccessKey'), '2022-10-01-preview').primaryConnectionString]"
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            },
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            {
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              "name": "LAUNCHDARKLY_CLIENT_SIDE_ID",
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              "value": "[parameters('launchDarklyClientSideId')]"
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            },
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            {
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              "name": "LAUNCHDARKLY_SERVICE",
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              "value": "azure"
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            }
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          ]
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        }
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      }
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    },
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    {
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      "type": "Microsoft.Web/sites/functions",
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      "apiVersion": "2023-01-01",
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      "name": "[format('{0}/ForwardToLaunchDarkly', variables('functionAppName'))]",
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      "dependsOn": [
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        "[resourceId('Microsoft.Web/sites', variables('functionAppName'))]"
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      ],
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      "properties": {
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        "config": {
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          "bindings": [
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            {
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              "type": "eventHubTrigger",
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              "name": "eventHubMessages",
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              "direction": "in",
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              "eventHubName": "[variables('eventHubName')]",
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              "connection": "EventHubConnection",
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              "cardinality": "many",
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              "consumerGroup": "$Default"
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            }
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          ]
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        },
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        "files": {
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          "index.js": "const https = require('https')\n\nconst PROJECT_ID = process.env.LAUNCHDARKLY_CLIENT_SIDE_ID\nconst SERVICE = process.env.LAUNCHDARKLY_SERVICE || 'azure'\nconst OTEL_HOSTNAME = 'otel.observability.app.launchdarkly.com'\nconst MAX_RETRIES = 6\nconst RETRY_INTERVAL = 1000\n\nconst SEVERITY_MAP = {\n  verbose: 'TRACE', debug: 'DEBUG', informational: 'INFO',\n  info: 'INFO', warning: 'WARN', warn: 'WARN',\n  error: 'ERROR', critical: 'FATAL',\n}\n\nfunction sendWithRetries(context, path, payload) {\n  const options = {\n    hostname: OTEL_HOSTNAME,\n    path,\n    method: 'POST',\n    headers: {\n      'Content-Type': 'application/json',\n      'x-launchdarkly-project': PROJECT_ID,\n    },\n  }\n  let numRetries = MAX_RETRIES\n  let retryInterval = RETRY_INTERVAL\n  return new Promise((resolve, reject) => {\n    const sendRequest = () => {\n      const retryRequest = errMsg => {\n        if (numRetries === 0) return reject(errMsg)\n        context.log.warn(`Request failed: ${errMsg}. Retrying ${numRetries} more times`)\n        numRetries--\n        retryInterval *= 2\n        setTimeout(sendRequest, retryInterval)\n      }\n      const req = https\n        .request(options, resp => {\n          if (resp.statusCode >= 200 && resp.statusCode <= 299) {\n            resolve(true)\n          } else if (resp.statusCode >= 400 && resp.statusCode <= 499) {\n            reject(`HTTP ${resp.statusCode}`)\n          } else {\n            retryRequest(`HTTP ${resp.statusCode}`)\n          }\n        })\n        .on('error', error => retryRequest(error.message))\n        .on('timeout', () => {\n          req.destroy()\n          retryRequest('request timed out')\n        })\n      req.write(JSON.stringify(payload))\n      req.end()\n    }\n    sendRequest()\n  })\n}\n\nconst toNanos = ts => String(new Date(ts).getTime() * 1000000)\nconst toAttr = (k, v) => ({ key: k, value: { stringValue: String(v) } })\n\nfunction parseRecords(eventHubMessages) {\n  const logs = []\n  const metrics = []\n  for (const message of eventHubMessages) {\n    const items = message.records || [message]\n    for (const item of items) {\n      const timestamp = new Date(item.time || item.timeStamp || Date.now()).toISOString()\n\n      if (item.metricName) {\n        const dimensions = (item.dimensions || []).reduce((acc, d) => {\n          acc[`azure.dimension.${d.name}`] = d.value\n          return acc\n        }, {})\n        metrics.push({\n          name: `azure.${item.metricName}`,\n          timestamp,\n          count: item.count ?? 1,\n          sum: item.total ?? item.average ?? 0,\n          min: item.minimum,\n          max: item.maximum,\n          attributes: {\n            'azure.resource.id': item.resourceId,\n            'azure.namespace': item.namespace,\n            'azure.timeGrain': item.timeGrain,\n            ...dimensions,\n          },\n        })\n      } else {\n        const level = (item.level || item.resultType || 'info').toLowerCase()\n        let props = {}\n        if (item.properties) {\n          try {\n            props = typeof item.properties === 'string'\n              ? JSON.parse(item.properties) : item.properties\n          } catch (_) { /* ignore parse errors */ }\n        }\n        let message = item.resultDescription || item.operationName\n        if (!message && props.CsMethod) {\n          message = `${props.CsMethod} ${props.CsUriStem || '/'} ${props.ScStatus || ''} ${props.TimeTaken != null ? props.TimeTaken + 'ms' : ''}`.trim()\n        }\n        if (!message) message = JSON.stringify(item)\n        const attrs = {\n          'azure.resourceId': item.resourceId,\n          'azure.category': item.category,\n          'azure.operationName': item.operationName,\n        }\n        for (const [k, v] of Object.entries(props)) {\n          if (v != null && v !== '') attrs[`azure.properties.${k}`] = String(v)\n        }\n        logs.push({\n          message,\n          timestamp,\n          severityText: SEVERITY_MAP[level] || 'INFO',\n          attributes: attrs,\n        })\n      }\n    }\n  }\n  return { logs, metrics }\n}\n\nfunction buildOtlpLogs(logs) {\n  return {\n    resourceLogs: [{\n      resource: {\n        attributes: [\n          toAttr('service.name', SERVICE),\n          toAttr('highlight.project_id', PROJECT_ID),\n        ],\n      },\n      scopeLogs: [{\n        scope: { name: 'azure-monitor-forwarder', version: '1.0.0' },\n        logRecords: logs.map(l => ({\n          timeUnixNano: toNanos(l.timestamp),\n          body: { stringValue: l.message },\n          severityText: l.severityText,\n          attributes: Object.entries(l.attributes)\n            .filter(([, v]) => v != null)\n            .map(([k, v]) => toAttr(k, v)),\n        })),\n      }],\n    }],\n  }\n}\n\nfunction buildOtlpMetrics(metrics) {\n  return {\n    resourceMetrics: [{\n      resource: {\n        attributes: [\n          toAttr('service.name', SERVICE),\n          toAttr('highlight.project_id', PROJECT_ID),\n        ],\n      },\n      scopeMetrics: [{\n        scope: { name: 'azure-monitor-forwarder', version: '1.0.0' },\n        metrics: metrics.map(m => {\n          const dp = {\n            timeUnixNano: toNanos(m.timestamp),\n            count: m.count,\n            sum: m.sum,\n            explicitBounds: [],\n            bucketCounts: [m.count],\n            attributes: Object.entries(m.attributes)\n              .filter(([, v]) => v != null)\n              .map(([k, v]) => toAttr(k, v)),\n          }\n          if (m.min != null) dp.min = m.min\n          if (m.max != null) dp.max = m.max\n          return {\n            name: m.name,\n            histogram: {\n              aggregationTemporality: 1,\n              dataPoints: [dp],\n            },\n          }\n        }),\n      }],\n    }],\n  }\n}\n\nmodule.exports = async function (context, eventHubMessages) {\n  if (!PROJECT_ID) {\n    context.log.error('LAUNCHDARKLY_CLIENT_SIDE_ID is not configured.')\n    return\n  }\n\n  const { logs, metrics } = parseRecords(eventHubMessages)\n  const promises = []\n\n  if (logs.length > 0) {\n    promises.push(\n      sendWithRetries(context, '/v1/logs', buildOtlpLogs(logs))\n        .catch(e => context.log.error(e))\n    )\n  }\n\n  if (metrics.length > 0) {\n    promises.push(\n      sendWithRetries(context, '/v1/metrics', buildOtlpMetrics(metrics))\n        .catch(e => context.log.error(e))\n    )\n  }\n\n  const results = await Promise.all(promises)\n  if (!results.every(v => v === true)) {\n    context.log.error('Failed to send some records')\n  }\n}"
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        }
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      }
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    }
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  ],
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  "outputs": {
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    "functionAppName": {
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      "type": "string",
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      "value": "[variables('functionAppName')]"
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    },
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    "eventHubNamespaceName": {
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      "type": "string",
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      "value": "[variables('eventHubNamespaceName')]"
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    },
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    "eventHubName": {
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      "type": "string",
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      "value": "[variables('eventHubName')]"
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    }
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  }
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}

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const https = require('https')
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const PROJECT_ID = process.env.LAUNCHDARKLY_CLIENT_SIDE_ID
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const SERVICE = process.env.LAUNCHDARKLY_SERVICE || 'azure'
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const OTEL_HOSTNAME = 'otel.observability.app.launchdarkly.com'
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const MAX_RETRIES = 6
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const RETRY_INTERVAL = 1000
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const SEVERITY_MAP = {
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  verbose: 'TRACE', debug: 'DEBUG', informational: 'INFO',
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  info: 'INFO', warning: 'WARN', warn: 'WARN',
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  error: 'ERROR', critical: 'FATAL',
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}
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function sendWithRetries(context, path, payload) {
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  const options = {
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    hostname: OTEL_HOSTNAME,
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    path,
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    method: 'POST',
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    headers: {
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      'Content-Type': 'application/json',
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      'x-launchdarkly-project': PROJECT_ID,
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    },
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  }
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  let numRetries = MAX_RETRIES
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  let retryInterval = RETRY_INTERVAL
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  return new Promise((resolve, reject) => {
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    const sendRequest = () => {
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      const retryRequest = errMsg => {
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        if (numRetries === 0) return reject(errMsg)
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        context.log.warn(`Request failed: ${errMsg}. Retrying ${numRetries} more times`)
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        numRetries--
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        retryInterval *= 2
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        setTimeout(sendRequest, retryInterval)
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      }
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      const req = https
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        .request(options, resp => {
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          if (resp.statusCode >= 200 && resp.statusCode <= 299) {
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            resolve(true)
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          } else if (resp.statusCode >= 400 && resp.statusCode <= 499) {
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            reject(`HTTP ${resp.statusCode}`)
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          } else {
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            retryRequest(`HTTP ${resp.statusCode}`)
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          }
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        })
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        .on('error', error => retryRequest(error.message))
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        .on('timeout', () => {
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          req.destroy()
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          retryRequest('request timed out')
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        })
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      req.write(JSON.stringify(payload))
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      req.end()
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    }
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    sendRequest()
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  })
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}
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const toNanos = ts => String(new Date(ts).getTime() * 1000000)
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const toAttr = (k, v) => ({ key: k, value: { stringValue: String(v) } })
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function parseRecords(eventHubMessages) {
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  const logs = []
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  const metrics = []
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  for (const message of eventHubMessages) {
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    const items = message.records || [message]
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    for (const item of items) {
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      const timestamp = new Date(item.time || item.timeStamp || Date.now()).toISOString()
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      if (item.metricName) {
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        const dimensions = (item.dimensions || []).reduce((acc, d) => {
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          acc[`azure.dimension.${d.name}`] = d.value
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          return acc
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        }, {})
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        metrics.push({
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          name: `azure.${item.metricName}`,
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          timestamp,
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          count: item.count ?? 1,
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          sum: item.total ?? item.average ?? 0,
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          min: item.minimum,
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          max: item.maximum,
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          attributes: {
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            'azure.resource.id': item.resourceId,
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            'azure.namespace': item.namespace,
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            'azure.timeGrain': item.timeGrain,
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            ...dimensions,
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          },
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        })
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      } else {
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        const level = (item.level || item.resultType || 'info').toLowerCase()
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        let props = {}
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        if (item.properties) {
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          try {
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            props = typeof item.properties === 'string'
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              ? JSON.parse(item.properties) : item.properties
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          } catch (_) { /* ignore parse errors */ }
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        }
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        let message = item.resultDescription || item.operationName
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        if (!message && props.CsMethod) {
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          message = `${props.CsMethod} ${props.CsUriStem || '/'} ${props.ScStatus || ''} ${props.TimeTaken != null ? props.TimeTaken + 'ms' : ''}`.trim()
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        }
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        if (!message) message = JSON.stringify(item)
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        const attrs = {
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          'azure.resourceId': item.resourceId,
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          'azure.category': item.category,
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          'azure.operationName': item.operationName,
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        }
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        for (const [k, v] of Object.entries(props)) {
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          if (v != null && v !== '') attrs[`azure.properties.${k}`] = String(v)
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        }
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        logs.push({
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          message,
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          timestamp,
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          severityText: SEVERITY_MAP[level] || 'INFO',
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          attributes: attrs,
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        })
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      }
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    }
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  }
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  return { logs, metrics }
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}
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function buildOtlpLogs(logs) {
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  return {
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    resourceLogs: [{
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      resource: {
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        attributes: [
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          toAttr('service.name', SERVICE),
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          toAttr('highlight.project_id', PROJECT_ID),
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        ],
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      },
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      scopeLogs: [{
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        scope: { name: 'azure-monitor-forwarder', version: '1.0.0' },
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        logRecords: logs.map(l => ({
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          timeUnixNano: toNanos(l.timestamp),
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          body: { stringValue: l.message },
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          severityText: l.severityText,
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          attributes: Object.entries(l.attributes)
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            .filter(([, v]) => v != null)
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            .map(([k, v]) => toAttr(k, v)),
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        })),
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      }],
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    }],
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  }
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}
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function buildOtlpMetrics(metrics) {
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  return {
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    resourceMetrics: [{
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      resource: {
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        attributes: [
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          toAttr('service.name', SERVICE),
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          toAttr('highlight.project_id', PROJECT_ID),
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        ],
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      },
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      scopeMetrics: [{
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        scope: { name: 'azure-monitor-forwarder', version: '1.0.0' },
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        metrics: metrics.map(m => {
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          const dp = {
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            timeUnixNano: toNanos(m.timestamp),
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            count: m.count,
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            sum: m.sum,
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            explicitBounds: [],
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            bucketCounts: [m.count],
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            attributes: Object.entries(m.attributes)
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              .filter(([, v]) => v != null)
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              .map(([k, v]) => toAttr(k, v)),
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          }
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          if (m.min != null) dp.min = m.min
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          if (m.max != null) dp.max = m.max
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          return {
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            name: m.name,
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            histogram: {
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              aggregationTemporality: 1,
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              dataPoints: [dp],
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            },
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          }
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        }),
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      }],
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    }],
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  }
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}
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module.exports = async function (context, eventHubMessages) {
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  if (!PROJECT_ID) {
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    context.log.error('LAUNCHDARKLY_CLIENT_SIDE_ID is not configured.')
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    return
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  }
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  const { logs, metrics } = parseRecords(eventHubMessages)
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  const promises = []
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  if (logs.length > 0) {
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    promises.push(
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      sendWithRetries(context, '/v1/logs', buildOtlpLogs(logs))
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        .catch(e => context.log.error(e))
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    )
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  }
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  if (metrics.length > 0) {
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    promises.push(
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      sendWithRetries(context, '/v1/metrics', buildOtlpMetrics(metrics))
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        .catch(e => context.log.error(e))
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    )
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  }
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  const results = await Promise.all(promises)
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  if (!results.every(v => v === true)) {
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    context.log.error('Failed to send some records')
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  }
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}