Bug: Log Level SILENT must be set before instantiation

[zirkelc]

Expected Behaviour

I expected the log level to be a toggle that is being evaluated at the time a message is being printed. That means if I set process.env.LOG_LEVEL="SILENT", the message should not be printed and if I reset the log level the message should be printed.

const logger = new Logger({ serviceName: "serverlessAirline" });
logger.info("INFO"); // should log 

process.env.LOG_LEVEL = "SILENT";
logger.info("SILENT"); // should not log

Current Behaviour

The log level is evaluated at the time of instantiation. That means changing the log level after the logger was created, has no effect and will still print messages.

This prints:

const logger = new Logger({ serviceName: "serverlessAirline" });
logger.info("INFO"); // prints

process.env.LOG_LEVEL = "SILENT";
logger.info("SILENT"); //  prints

And this doesn't print:

process.env.LOG_LEVEL = "SILENT";
const logger = new Logger({ serviceName: "serverlessAirline" });
logger.info("INFO"); // doesn't print
logger.info("SILENT"); // doesn't print

Code snippet

See sandbox: https://codesandbox.io/s/muddy-bush-j54nwp?file=/src/index.ts

Steps to Reproduce

See sandbox: https://codesandbox.io/s/muddy-bush-j54nwp?file=/src/index.ts

Possible Solution

The process.env.LOG_LEVEL variable should always be checked when a message is being printed. If the process.env.LOG_LEVEL differs from the constructor logLevel, the environment variable should have priority.

Alternatively, the if the constructor was was called without logLevel, then the log level from process.env.LOG_LEVEL, should always have priority.

Powertools for AWS Lambda (TypeScript) version

1.7

AWS Lambda function runtime

18.x

Packaging format used

npm

Execution logs

No response

[boring-cyborg]

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[dreamorosi]

Hi @zirkelc thank you for taking the time to open the issue.

The behavior you describe is intended.

You have multiple ways of setting the e log level, both when instantiating the Logger and at runtime.

One of them is via environment variables, which together with the logLevel parameter passed to the constructor, is always evaluated upon instance creation and stored in the class.

If you want to change the log level after that, aka at runtime, then you can do so using the setLogLevel() method. When you change the log level using the method, all logs emitted after that should comply with that level. The feature was released/added in the last release (1.9.0)

[zirkelc]

Hi @dreamorosi thanks for the quick response!

I understand, I thought changing the environment variable LOG_LEVEL should have the same effect as changing the log level via the class method setLogLevel().

In some case I don't have access to the logger instance, because the logger is nested in other functions which I don't have access to. In these cases it would be good to have a flag to temporarily switch the log level.

A similar discussion happened a few months ago: #1198
I think evaluating the LOG_LEVEL variable at log-time would allow to turn off the logs during tests without having the need to silence the test framework completely, like it is currently needed for Jest with --silent.

[dreamorosi]

I'm not sure I'm following, if you don't have access to the logger then how are you logging?

Regarding to that discussion, we decided to support local development via another environment variable called POWERTOOLS_DEV.

Overall I don't think evaluating the log level every time we need to print a log is a good idea for performance, and generally speaking I don't consider environment variables something that should change at runtime in most cases.

I think it'd help if you could share a few more details on the use case and what you're trying to do, maybe I can help find an alternative.

[zirkelc]

I meant that the logger instance is created inside functions that are called, but those functions do not export the logger instance itself.

Nonetheless, I thought it might be a bug that changing LOG_LEVEL has no effect, but if it is intended that way, it is fine. Thanks for the clarification!

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