Monitor App Check request metrics for Cloud Functions
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After you add the App Check SDK to your app, but before you enable
App Check enforcement, you should make sure that doing so won't disrupt your
existing legitimate users.
For Cloud Functions, you can get App Check metrics by examining your
functions' logs. Every invocation of a callable function emits a structured log
entry like the following example:
{"severity":"INFO",// INFO, WARNING, or ERROR"logging.googleapis.com/labels":{"firebase-log-type":"callable-request-verification"},"jsonPayload":{"message":"Callable header verifications passed.","verifications":{// ..."app":"MISSING",// VALID, INVALID, or MISSING}}}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-22 UTC."],[],[],null,["After you add the App Check SDK to your app, but before you enable\nApp Check enforcement, you should make sure that doing so won't disrupt your\nexisting legitimate users.\n\nFor Cloud Functions, you can get App Check metrics by examining your\nfunctions' logs. Every invocation of a callable function emits a structured log\nentry like the following example: \n\n {\n \"severity\": \"INFO\", // INFO, WARNING, or ERROR\n \"logging.googleapis.com/labels\": {\"firebase-log-type\": \"callable-request-verification\"},\n \"jsonPayload\": {\n \"message\": \"Callable header verifications passed.\",\n \"verifications\": {\n // ...\n \"app\": \"MISSING\", // VALID, INVALID, or MISSING\n }\n }\n }\n\nYou can analyze these metrics in the Google Cloud console by [creating a\nlogs-based counter metric](https://cloud.google.com/logging/docs/logs-based-metrics/counter-metrics)\nwith the following metric filter: \n\n```\nresource.type=\"cloud_function\"\nresource.labels.function_name=\"YOUR_CLOUD_FUNCTION\"\nresource.labels.region=\"us-central1\"\nlabels.firebase-log-type=\"callable-request-verification\"\n```\n\n[Label the metric](https://cloud.google.com/logging/docs/logs-based-metrics/labels#create-label)\nusing the field `jsonPayload.verifications.appCheck`.\n\nNext steps\n\nWhen you understand how App Check will affect your users and you're ready to\nproceed, you can [enable App Check enforcement](/docs/app-check/cloud-functions)\nfor Cloud Functions."]]