log4js-node/docs/crlfFilter.md

CRLF Filter

This is not strictly an appender - it wraps around another appender and to prevent log forging by replacing starting the line with a > prefix after line-breaks.

Configuration

• type - "crlfFilter"
• appender - string | Array<String> - the name of the appender to filter. (exists for backward compatibility)
• appenders - string | Array<String> - the names of the appenders to filter.

Example

log4js.configure({
  appenders: {
    everything: { type: "file", filename: "all-the-logs.log" },
    crlfFilter: {
      type: "crlfFilter",
      appenders: ["everything"],
    },
  },
  categories: {
    default: { appenders: ["crlfFilter"], level: "debug" },
  },
});

const logger = log4js.getLogger();
logger.info(
  "Some debug messages\n[2023-01-17T11:58:38.150] [INFO] default - Log forging"
);

[2023-01-17T11:58:38.150] [INFO] default - Some debug messages
> [2023-01-17T11:58:38.150] [INFO] default - Log forging