Log 'jsonPayload' in Firebase Cloud Functions - firebase

Question

TL;DR;
Does anyone know if it's possible to use console.log in a Firebase/Google Cloud Function to log entries to Stack Driver using the jsonPayload property so my logs are searchable (currently anything I pass to console.log gets stringified into textPayload).
I have a multi-module project with some code running on Firebase Cloud Functions, and some running in other environments like Google Compute Engine. Simplifying things a little, I essentially have a 'core' module, and then I deploy the 'cloud-functions' module to Cloud Functions, 'backend-service' to GCE, which all depend on 'core' etc.
I'm using bunyan for logging throughout my 'core' module, and when deployed to GCE the logger is configured using '#google-cloud/logging-bunyan' so my logs go to Stack Driver.
Aside: Using this configuration in Google Cloud Functions is causing issues with Error: Endpoint read failed which I think is due to functions not going cold and trying to reuse dead connections, but I'm not 100% sure what the real cause is.
So now I'm trying to log using console.log(arg) where arg is an object, not a string. I want this object to appear in Stack Driver under the jsonPayload but it's being stringified and put into the textPayload field.

Answer 1

It took me awhile, but I finally came across this example in firebase functions samples repository. In the end I settled on something a bit like this:
const Logging = require('#google-cloud/logging');
const logging = new Logging();
const log = logging.log('my-func-logger');
const logMetadata = {
resource: {
type: 'cloud_function',
labels: {
function_name: process.env.FUNCTION_NAME ,
project: process.env.GCLOUD_PROJECT,
region: process.env.FUNCTION_REGION
},
},
};
const logData = { id: 1, score: 100 };
const entry = log.entry(logMetaData, logData);
log.write(entry)
You can add a string severity property value to logMetaData (e.g. "INFO" or "ERROR"). Here is the list of possible values.
Update for available node 10 env vars. These seem to do the trick:
labels: {
function_name: process.env.FUNCTION_TARGET,
project: process.env.GCP_PROJECT,
region: JSON.parse(process.env.FIREBASE_CONFIG).locationId
}
UPDATE: Looks like for Node 10 runtimes they want you to set env values explicitly during deploy. I guess there has been a grace period in place because my deployed functions are still working.

Answer 2

I ran into the same problem, and as stated by comments on #wtk's answer, I would like to add replicating all of the default cloud function logging behavior I could find in the snippet below, including execution_id.
At least for using Cloud Functions with the HTTP Trigger option the following produced correct logs for me. I have not tested for Firebase Cloud Functions
// global
const { Logging } = require("#google-cloud/logging");
const logging = new Logging();
const Log = logging.log("cloudfunctions.googleapis.com%2Fcloud-functions");
const LogMetadata = {
severity: "INFO",
type: "cloud_function",
labels: {
function_name: process.env.FUNCTION_NAME,
project: process.env.GCLOUD_PROJECT,
region: process.env.FUNCTION_REGION
}
};
// per request
const data = { foo: "bar" };
const traceId = req.get("x-cloud-trace-context").split("/")[0];
const metadata = {
...LogMetadata,
severity: 'INFO',
trace: `projects/${process.env.GCLOUD_PROJECT}/traces/${traceId}`,
labels: {
execution_id: req.get("function-execution-id")
}
};
Log.write(Log.entry(metadata, data));

Answer 3

The github link in #wtk's answer should be updated to:
https://github.com/firebase/functions-samples/blob/2f678fb933e416fed9be93e290ae79f5ea463a2b/stripe/functions/index.js#L103
As it refers to the repository as of when the question was answered, and has the following function in it:
// To keep on top of errors, we should raise a verbose error report with Stackdriver rather
// than simply relying on console.error. This will calculate users affected + send you email
// alerts, if you've opted into receiving them.
// [START reporterror]
function reportError(err, context = {}) {
// This is the name of the StackDriver log stream that will receive the log
// entry. This name can be any valid log stream name, but must contain "err"
// in order for the error to be picked up by StackDriver Error Reporting.
const logName = 'errors';
const log = logging.log(logName);
// https://cloud.google.com/logging/docs/api/ref_v2beta1/rest/v2beta1/MonitoredResource
const metadata = {
resource: {
type: 'cloud_function',
labels: {function_name: process.env.FUNCTION_NAME},
},
};
// https://cloud.google.com/error-reporting/reference/rest/v1beta1/ErrorEvent
const errorEvent = {
message: err.stack,
serviceContext: {
service: process.env.FUNCTION_NAME,
resourceType: 'cloud_function',
},
context: context,
};
// Write the error log entry
return new Promise((resolve, reject) => {
log.write(log.entry(metadata, errorEvent), (error) => {
if (error) {
return reject(error);
}
resolve();
});
});
}
// [END reporterror]