Source Location & Timestamps

Logly captures source file location and timestamps by default. You can customize or disable both.

Source Location

How It Works

When you call a log method, Logly inspects the call stack to capture:

• File: Absolute path to the source file
• Line: Line number in the source file
• Function: Function name where the call was made
• Module: Filename without extension

Enable/Disable Source Capture

Source capture is enabled by default (capture=True):

from logly import logger

# Source info captured (default)
logger.info("Has file/line/function info")

# Disable source capture
logger.opt(capture=False).info("No source info captured")

Source Location in Format Strings

Use these tokens to include source info in output:

from logly import logger

logger.add(
    "app.log",
    format="{time:YYYY-MM-DD HH:mm:ss} | {level:<8} | {file}:{line} {function} | {message}",
)

logger.info("Hello")
# Output: 2026-06-22 14:30:45 | INFO     | app.py:42 main | Hello

Available Source Tokens

Token	Description	Example
{file}	Full source file path	/home/user/app.py
{filename}	Just the filename	app.py
{line}	Line number	42
{function}	Function name	main
{module}	Module name (no extension)	app
{file_line}	Combined file:line	/home/user/app.py:42
{function_location}	function (file:line)	main (app.py:42)

Source with Depth

For decorators or wrappers, use depth to skip stack frames:

from logly import logger

def log_wrapper(func):
    def wrapper(*args, **kwargs):
        # depth=1 skips the wrapper, points to the caller
        logger.opt(depth=1).info(f"Calling {func.__name__}")
        return func(*args, **kwargs)
    return wrapper

@log_wrapper
def my_function():
    pass

my_function()
# Source points to my_function, not log_wrapper

Source Context (Rust Feature)

The Rust source crate can read surrounding lines from source files:

// Rust API (internal)
let context = source_context(&file_path, line_number, 2); // 2 lines before/after
// Returns formatted output like:
//    40 |     fn main() {
//    41 |         let x = 42;
//  >> 42 |         println!("{x}");
//    43 |     }

Timestamps

Default Format

The default timestamp format is %Y-%m-%d %H:%M:%S (local timezone):

from logly import logger

logger.info("Current time")
# Output: 2026-06-22 14:30:45 | INFO | Current time

Custom Timestamp Formats

Use {time:FORMAT} in your format string:

from logly import logger

# Date only
logger.add("app.log", format="{time:YYYY-MM-DD} | {message}")

# Time only
logger.add("app.log", format="{time:HH:mm:ss} | {message}")

# With milliseconds
logger.add("app.log", format="{time:HH:mm:ss.SSS} | {message}")

# Custom date format
logger.add("app.log", format="{time:DD/MM/YYYY HH:mm} | {message}")

# ISO format
logger.add("app.log", format="{time:YYYY-MM-DDTHH:mm:ss} | {message}")

Time Format Tokens

Logly supports both Loguru-style and strftime tokens:

Loguru Token	strftime Equivalent	Example
YYYY	%Y	2026
YY	%y	26
MMMM	%B	June
MMM	%b	Jun
MM	%m	06
DD	%d	21
dddd	%A	Monday
ddd	%a	Mon
HH	%H	14 (24h)
hh	%I	02 (12h)
mm	%M	30
ss	%S	45
SSS	%.3f	123 (ms)
A	%p	AM

Disable Timestamps

Remove the {time} token from your format string:

from logly import logger

# No timestamp
logger.add("app.log", format="{level:<8} | {message}")

# Minimal
logger.add("app.log", format="{message}")

Timestamp in JSON Output

When serialize=True, timestamps are ISO 8601:

from logly import logger

logger.add("app.json", serialize=True)
logger.info("JSON log")

Output:

{"time": "2026-06-22T14:30:45.123000+00:00", "level": "INFO", "message": "JSON log", ...}

Elapsed Time

Track time since logger creation with {elapsed}:

from logly import logger
import time

logger.add("app.log", format="{elapsed} | {level:<8} | {message}")

time.sleep(1)
logger.info("After 1 second")
# Output: 1.000 | INFO | After 1 second

Combined Example

from logly import logger

logger.remove()

# Detailed format with source and timestamp
logger.add(
    "app.log",
    format="{time:YYYY-MM-DD HH:mm:ss.SSS} | {level:<8} | {file}:{line} {function} | {message}",
    rotation="daily",
    retention="30 days",
)

# Minimal console format
logger.add(
    "stderr",
    format="{time:HH:mm:ss} | {level:<8} | {message}",
    colorize=True,
)

logger.info("Application started")
# Console: 14:30:45 | INFO     | Application started
# File:    2026-06-22 14:30:45.123 | INFO     | app.py:42 main | Application started