Logger Component¶
The logger component automatically logs all log messages through the
serial port and through MQTT topics (if there is an MQTT client in the
configuration). By default, all logs with a severity DEBUG
or higher will be shown.
Increasing the log level severity (to e.g INFO
or WARNING
) can help with the performance of the application and memory size.
# Example configuration entry
logger:
level: DEBUG
Configuration variables:¶
baud_rate (Optional, int): The baud rate to use for the serial UART port. Defaults to
115200
. Set to0
to disable logging via UART.level (Optional, string): The global log level. Any log message with a lower severity will not be shown. Defaults to
DEBUG
.logs (Optional, mapping): Manually set the log level for a specific component or tag. See Manual Log Levels for more information.
id (Optional, ID): Manually specify the ID used for code generation.
Advanced settings:
tx_buffer_size (Optional, int): The size of the buffer used for log messages. Decrease this if you’re having memory problems. Defaults to
512
.hardware_uart (Optional, string): The Hardware UART to use for logging. Defaults to
UART0
.esp8266_store_log_strings_in_flash (Optional, boolean): If set to false, disables storing log strings in the flash section of the device (uses more memory). Defaults to true.
on_message (Optional, Automation): An action to be performed when a message is to be logged. The variables
int level
,const char* tag
andconst char* message
are available for lambda processing.deassert_rts_dtr (Optional, boolean): Deasserts RTS/DTR when opening log over UART. This is useful if RTS/DTR signals are directly connected to the reset pin or strapping pins. Note: Deassert typically means high on TTL level since RTS/DTR are usually low active signals. Defaults to
false
.
Hardware UARTs¶
The logger component makes use of platform-specific hardware UARTs for serial logging.
By default, the logger will occupy UART0
. The ESP32 has three hardware UARTs, all of
which can be used for both transmit and receive. The ESP8266 only has two hardware UARTs,
one of which is transmit-only. The ESP8266 UART0
can also be ‘swapped’ to TX/RX on the
CTS/RTS pins, if you need to use GPIO1 and GPIO3 for something else. Note that the common
NodeMCU boards have their USB-UART Adapters fixed to the default GPIOs used by UART0
,
so if you use anything else you will not get log messages over the on-board USB.
Possible Hardware UART configurations:
UART0
- TX: GPIO1, RX: GPIO3UART0_SWAP
- TX: GPIO15, RX: GPIO13 (Only on ESP8266)UART1
- TX: GPIO2, RX: None (Only on ESP8266)UART1
- TX: GPIO9, RX: GPIO10 (Only on ESP32)UART2
- TX: GPIO16, RX: GPIO17 (Only on ESP32 but not ESP32S2, ESP32S3 or ESP32C3)USB_CDC
- uses the USB CDC driver (Only on ESP32S2 and ESP32S3)USB_SERIAL_JTAG
- uses the USB Serial/JTAG driver (Only on ESP32S3 and ESP32C3)
Log Levels¶
Possible log levels are (sorted by severity):
NONE
No messages are logged.
ERROR
With this log level, only errors are logged. Errors are issues that prevent the ESP from working correctly. Color: red
WARN
With this log level, warnings and errors are logged. Warnings are issues like invalid readings from sensors that ESPHome can recover from. Color: yellow
INFO
With this log level, everything up to info messages are logged; so errors, warnings and info. Color: green
DEBUG
(Default)
Everything up to this log level is logged. Debug messages include the current readings from a sensor and status messages. Color: cyan
VERBOSE
Like debug, but a few more messages that are usually deemed to be spam are also included. Color: grey
VERY_VERBOSE
All internal messages are logged. Including all the data flowing through data buses like I²C, SPI or UART. Warning: May cause the device to slow down and have trouble staying connecting due to amount of generated messages. Color: white
Manual Tag-Specific Log Levels¶
If some component is spamming the logs and you want to manually set the log level for it, first identify the tag of the log messages in question and then disable them in your configuration.
Suppose we want to have verbose log messages globally, but the MQTT
client spams too much. In the following example, we’d first see that the
tag of the MQTT client is mqtt.client
(before the first colon) and
the tag for MQTT components is mqtt.component
.

Next, we can manually set the log levels in the configuration like this:
logger:
level: VERBOSE
logs:
mqtt.component: DEBUG
mqtt.client: ERROR
Please note that the global log level determines what log messages are
saved in the binary. So for example an INFO
global log message will
purge all DEBUG
log statements from the binary in order to conserve
space. This however means that you cannot set tag-specific log levels
that have a lower severity than the global log level.
logger.log
Action¶
Print a formatted message to the logs.
In the format
option, you can use printf
-style formatting (see Formatted Text).
on_...:
then:
- logger.log: "Hello World"
# Formatted:
- logger.log:
format: "The temperature sensor reports value %.1f and humidity %.1f"
args: [ 'id(temperature_sensor).state', 'id(humidity_sensor).state' ]
Configuration options:
format (Required, string): The format for the message in printf-style.
args (Optional, list of lambda): The optional arguments for the format message.
level (Optional, string): The log level to print the message with. Defaults to
DEBUG
.tag (Optional, string): The tag (seen in front of the message in the logs) to print the message with. Defaults to
main
.
Logger Automation¶
on_message
¶
This automation will be triggered when a new message is added to the log.
In lambdas you can get the message, log level and tag from the trigger
using message
(const char *
), level
(int
) and tag
(const char *
).
logger:
# ...
on_message:
level: ERROR
then:
- mqtt.publish:
topic: some/topic
payload: !lambda |-
return "Triggered on_message with level " + to_string(level) + ", tag " + tag + " and message " + message;
Note
Logging will not work in the on_message
trigger. You can’t use the logger.log action
and the ESP_LOGx
logging macros in this automation.