What do these Firebase Google Cloud Function `DEBUG` severity logs mean?

Question

I have been using Logs Explorer to inspect my Firebase Google Cloud Function.

The cloud function works as expected, so I was surprised to find various DEBUG severity logs in Logs Explorer.

Also when looking at those logs there isn't any clear information for the cause or problem.

So why am I seeing these DEBUG severity logs and what do they mean?

Here is a screenshot of the DEBUG logs in Logs Explorer:

And here are the payloads of each DEBUG log:

DEBUG log 1:

{
  "textPayload": "Function execution started",
  "insertId": "000000-8ce5e770-7b77-4a3b-b117-d1da870c625c",
  "resource": {
    "type": "cloud_function",
    "labels": {
      "project_id": "agentcake-app-75f12",
      "region": "us-central1",
      "function_name": "getZohoDeskTicketsLoggedInUser"
    }
  },
  "timestamp": "2022-04-01T07:22:43.908875861Z",
  "severity": "DEBUG",
  "labels": {
    "execution_id": "algpjnkt4jk5"
  },
  "logName": "projects/agentcake-app-75f12/logs/cloudfunctions.googleapis.com%2Fcloud-functions",
  "trace": "projects/agentcake-app-75f12/traces/499b082c83a571995237fe47e65243d1",
  "receiveTimestamp": "2022-04-01T07:22:54.727147697Z"
}

DEBUG log 2:

{
  "textPayload": "Function execution took 39 ms, finished with status code: 204",
  "insertId": "000000-8f0e70dd-10c4-4d0a-a319-f73ce04f4f33",
  "resource": {
    "type": "cloud_function",
    "labels": {
      "project_id": "agentcake-app-75f12",
      "function_name": "getZohoDeskTicketsLoggedInUser",
      "region": "us-central1"
    }
  },
  "timestamp": "2022-04-01T07:22:43.947441971Z",
  "severity": "DEBUG",
  "labels": {
    "execution_id": "algpjnkt4jk5"
  },
  "logName": "projects/agentcake-app-75f12/logs/cloudfunctions.googleapis.com%2Fcloud-functions",
  "trace": "projects/agentcake-app-75f12/traces/499b082c83a571995237fe47e65243d1",
  "receiveTimestamp": "2022-04-01T07:22:54.727147697Z"
}

DEBUG log 3:

{
  "textPayload": "Function execution started",
  "insertId": "000000-1252ca30-6f7a-477f-9845-ed1c06ad9d25",
  "resource": {
    "type": "cloud_function",
    "labels": {
      "region": "us-central1",
      "function_name": "getZohoDeskTicketsLoggedInUser",
      "project_id": "agentcake-app-75f12"
    }
  },
  "timestamp": "2022-04-01T07:22:44.313316115Z",
  "severity": "DEBUG",
  "labels": {
    "execution_id": "algpnb41b69d"
  },
  "logName": "projects/agentcake-app-75f12/logs/cloudfunctions.googleapis.com%2Fcloud-functions",
  "trace": "projects/agentcake-app-75f12/traces/a78c37916b173ecac071ee290da7d968",
  "receiveTimestamp": "2022-04-01T07:22:54.727147697Z"
}

DEBUG log 4:

{
  "textPayload": "Function execution took 3141 ms, finished with status code: 200",
  "insertId": "000000-da00728a-e2f2-45f3-a4f2-3b17a4c2ada8",
  "resource": {
    "type": "cloud_function",
    "labels": {
      "region": "us-central1",
      "function_name": "getZohoDeskTicketsLoggedInUser",
      "project_id": "agentcake-app-75f12"
    }
  },
  "timestamp": "2022-04-01T07:22:47.454109349Z",
  "severity": "DEBUG",
  "labels": {
    "execution_id": "algpnb41b69d"
  },
  "logName": "projects/agentcake-app-75f12/logs/cloudfunctions.googleapis.com%2Fcloud-functions",
  "trace": "projects/agentcake-app-75f12/traces/a78c37916b173ecac071ee290da7d968",
  "receiveTimestamp": "2022-04-01T07:22:54.727147697Z"
}

Answer 1

From the documentation,

Internal system messages have the DEBUG log level.

Answer 2

As mentioned in this document, the DEBUG log levels in the Cloud Functions log are just the internal system messages i.e. when your execution started, the status of the function execution, the time taken for function execution etc it is recorded as DEBUG log level. So even if your Cloud Functions does not have any error and works fine, it will have the DEBUG logs.