Logging server messages (Realtime Servers) - Amazon GameLift
Logging messages in your server scriptAccessing server logsAdjusting the logging level

Logging server messages (Realtime Servers)

You can capture custom server messages from your Realtime Servers in log files. To learn about logging for custom servers, see Logging server messages (custom servers).

There are different types of messages that you can ouptput to your log files (see Logging messages in your server script). In addition to your custom messages, your Realtime Servers output system messages using the same message types and write to the same log files. You can adjust the logging level for your fleet to reduce the amount of logging messages that your servers generate (see Adjusting the logging level).

Important

There is a limit on the size of a log file per game session (see Amazon GameLift endpoints and quotas in the AWS General Reference). When a game session ends, Amazon GameLift uploads the server logs to Amazon Simple Storage Service (Amazon S3). Amazon GameLift will not upload logs that exceed the limit. Logs can grow very quickly and exceed the size limit. You should monitor your logs and limit the log output to necessary messages only.

Logging messages in your server script

You can output custom messages in the script for your Realtime Servers. Use the following steps to send server messages to a log file:

  1. Create a varaible to hold the reference to the logger object.

    var logger;

  2. In the init() function, get the logger from the session object and assign it to your logger variable.

    function init(rtSession) {
    session = rtSession;
    logger = session.getLogger();
}

  3. Call the appropriate function on the logger to output a message.

    Debug messages

    logger.debug("This is my debug message...");

    Informational messages

    logger.info("This is my info message...");

    Warning messages

    logger.warn("This is my warn message...");

    Error messages

    logger.error("This is my error message...");

    Fatal error messages

    logger.fatal("This is my fatal error message...");

    Customer experience fatal error messages

    logger.cxfatal("This is my customer experience fatal error message...");

For an example of the logging statements in a script, see Realtime Servers script example.

The output in the log files indicates the type of message (DEBUG, INFO, WARN, ERROR, FATAL, CXFATAL), as shown in the following lines from an example log:

09 Sep 2021 11:46:32,970 [INFO] (gamelift.js) 215: Calling GameLiftServerAPI.InitSDK...
09 Sep 2021 11:46:32,993 [INFO] (gamelift.js) 220: GameLiftServerAPI.InitSDK succeeded
09 Sep 2021 11:46:32,993 [INFO] (gamelift.js) 223: Waiting for Realtime server to start...
09 Sep 2021 11:46:33,15 [WARN] (index.js) 204: Connection is INSECURE. Messages will be sent/received as plaintext.

Accessing server logs

When a game session ends, Amazon GameLift automatically stores the logs in Amazon S3 and retains them for 14 days. You can use the GetGameSessionLogUrl API call to get the location of the logs for a game session. Use URL returned by the API call to download the logs.

Adjusting the logging level

Logs can grow very quickly and exceed the size limit. You should monitor your logs and limit the log output to necessary messages only. For Realtime Servers, you can adjust the logging level by providing a parameter in your fleet's runtime configuration in the form loggingLevel:LOGGING_LEVEL, where LOGGING_LEVEL is one of the following values:

  1. debug

  2. info (default)

  3. warn

  4. error

  5. fatal

  6. cxfatal

This list is ordered from least severe (debug) to most severe (cxfatal). You set a single loggingLevel and the server will only log messages at that severity level or a higher severity level. For example, setting loggingLevel:error will make all of the servers in your fleet only write error, fatal, and cxfatal messages to the log.

You can set the logging level for your fleet when you create it or after it is running. Changing your fleet's logging level after it is running will only affect logs for game sessions created after the update. Logs for any existing game sessions won't be affected. If you don't set a logging level when you create your fleet, your servers will set the logging level to info by default. Refer to the following sections for instructions to set the logging level.

Setting the logging level when creating a Realtime Servers fleet (Console)

Follow the instructions at Create a Amazon GameLift managed fleet to create your fleet, with the following addition:

  • In the Server process allocation substep of the Process management step, provide the logging level key-value pair (such as loggingLevel:error) as a value for Launch parameters. Use a non-alphanumeric character (except comma) to separate the logging level from any additional parameters (for example, loggingLevel:error +map Winter444).

Setting the logging level when creating a Realtime Servers fleet (AWS CLI)

Follow the instructions at Create a Amazon GameLift managed fleet to create your fleet, with the following addition:

  • In the argument to the --runtime-configuration parameter for create-fleet, provide the logging level key-value pair (such as loggingLevel:error) as a value for Parameters. Use a non-alphanumeric character (except comma) to separate the logging level from any additional parameters. See the following example:

--runtime-configuration "GameSessionActivationTimeoutSeconds=60,
                    MaxConcurrentGameSessionActivations=2,
                    ServerProcesses=[{LaunchPath=/local/game/myRealtimeLaunchScript.js,
                                    Parameters=loggingLevel:error +map Winter444,
                                    ConcurrentExecutions=10}]"
Setting the logging level for a running Realtime Servers fleet (Console)

Follow the instructions at Update a fleet configuration to update your fleet using the Amazon GameLift Console, with the following addition:

  • On the Edit fleet page, under Server process allocation, provide the logging level key-value pair (such as loggingLevel:error) as a value for Launch parameters. Use a non-alphanumeric character (except comma) to separate the logging level from any additional parameters (for example, loggingLevel:error +map Winter444).

Setting the logging level for a running Realtime Servers fleet (AWS CLI)

Follow the instructions at Update a fleet configuration to update your fleet using the AWS CLI, with the following addition:

  • In the argument to the --runtime-configuration parameter for update-runtime-configuration, provide the logging level key-value pair (such as loggingLevel:error) as a value for Parameters. Use a non-alphanumeric character (except comma) to separate the logging level from any additional parameters. See the following example:

--runtime-configuration "GameSessionActivationTimeoutSeconds=60,
                    MaxConcurrentGameSessionActivations=2,
                    ServerProcesses=[{LaunchPath=/local/game/myRealtimeLaunchScript.js,
                                    Parameters=loggingLevel:error +map Winter444,
                                    ConcurrentExecutions=10}]"