Configure logging
editConfigure logging
editThe Kibana logging system has three main components: loggers, appenders and layouts. These components allow us to log messages according to message type and level, to control how these messages are formatted and where the final logs will be displayed or stored.
Loggers, Appenders and Layouts
editLoggers define what logging settings should be applied to a particular logger.
Appenders define where log messages are displayed (eg. stdout or console) and stored (eg. file on the disk).
Layouts define how log messages are formatted and what type of information they include.
Log level
editCurrently we support the following log levels: all, fatal, error, warn, info, debug, trace, off.
Levels are ordered, so all > fatal > error > warn > info > debug > trace > off.
A log record will be logged by the logger if its level is higher than or equal to the level of its logger. Otherwise, the log record is ignored.
The all and off levels can only be used in configuration and are handy shortcuts that allow you to log every log record or disable logging entirely for a specific logger. These levels can also be specified using cli arguments.
Layouts
editEvery appender should know exactly how to format log messages before they are written to the console or file on the disk.
This behavior is controlled by the layouts and configured through appender.layout
configuration property for every
custom appender. Currently we don’t define any default layout for the
custom appenders, so one should always make the choice explicitly.
There are two types of layout supported at the moment: pattern
and json
.
Pattern layout
editWith pattern
layout it’s possible to define a string pattern with special placeholders %conversion_pattern
that will be replaced with data from the actual log message. By default the following pattern is used: [%date][%level][%logger] %message
.
The pattern
layout uses a sub-set of log4j 2 pattern syntax and doesn’t implement all log4j 2
capabilities.
The conversions that are provided out of the box are:
level
Outputs the level of the logging event.
Example of %level
output: TRACE
, DEBUG
, INFO
.
logger
Outputs the name of the logger that published the logging event.
Example of %logger
output: server
, server.http
, server.http.kibana
.
message Outputs the application supplied message associated with the logging event.
meta
Outputs the entries of meta
object data in json format, if one is present in the event.
Example of %meta
output:
// Meta{from: 'v7', to: 'v8'} '{"from":"v7","to":"v8"}' // Meta empty object '{}' // no Meta provided ''
date
Outputs the date of the logging event. The date conversion specifier may be followed by a set of braces containing a name of predefined date format and canonical timezone name.
Timezone name is expected to be one from TZ database name.
Timezone defaults to the host timezone when not explicitly specified.
Example of %date
output:
Conversion pattern | Example |
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pid Outputs the process ID.
The pattern layout also offers a highlight
option that allows you to highlight
some parts of the log message with different colors. Highlighting is quite handy if log messages are forwarded
to a terminal with color support.
JSON layout
editWith json
layout log messages will be formatted as JSON strings in ECS format that includes a timestamp, log level, logger, message text and any other metadata that may be associated with the log message itself.
Logger hierarchy
editEvery logger has a unique name that follows a hierarchical naming rule. The logger is considered to be an
ancestor of another logger if its name followed by a .
is a prefix of the descendant logger. For example, a logger
named a.b
is an ancestor of logger a.b.c
. All top-level loggers are descendants of a special root
logger at the top of the logger hierarchy. The root
logger always exists, is fully configured and logs to info
level by default. The root
logger must also be configured if any other logging configuration is specified in your kibana.yml
.
You can configure log level and appenders for a specific logger. If a logger only has a log level configured, then the appenders configuration applied to the logger is inherited from the ancestor logger, up to the root
logger.
In the current implementation we don’t support so called appender additivity when log messages are forwarded to every distinct appender within the
ancestor chain including root
. That means that log messages are only forwarded to appenders that are configured for a particular logger. If a logger doesn’t have any appenders configured, the configuration of that particular logger will be inherited from its closest ancestor.
Dedicated loggers
editRoot
The root
logger has a dedicated configuration node since this logger is special and should always exist. By default root
is configured with info
level and default
appender that is also always available. This is the configuration that all custom loggers will use unless they’re re-configured explicitly.
For example to see all log messages that fall back on the root
logger configuration, just add one line to the configuration:
logging.root.level: all
Or disable logging entirely with off
:
logging.root.level: off
Metrics Logs
The metrics.ops
logger is configured with debug
level and will automatically output sample system and process information at a regular interval.
The metrics that are logged are a subset of the data collected and are formatted in the log message as follows:
Ops formatted log property | Location in metrics service | Log units |
---|---|---|
memory |
process.memory.heap.used_in_bytes |
depends on the value, typically MB or GB |
uptime |
process.uptime_in_millis |
HH:mm:ss |
load |
os.load |
[ "load for the last 1 min" "load for the last 5 min" "load for the last 15 min"] |
delay |
process.event_loop_delay |
ms |
The log interval is the same as the interval at which system and process information is refreshed and is configurable under ops.interval
:
ops.interval: 5000
The minimum interval is 100ms and defaults to 5000ms.
The http.server.response
logger is configured with debug
level and will automatically output
data about http requests and responses occurring on the Kibana server.
The message contains some high-level information, and the corresponding log meta contains the following:
Meta property | Description | Format |
---|---|---|
client.ip |
IP address of the requesting client |
ip |
http.request.method |
http verb for the request (uppercase) |
string |
http.request.mime_type |
(optional) mime as specified in the headers |
string |
http.request.referrer |
(optional) referrer |
string |
http.request.headers |
request headers |
object |
http.response.body.bytes |
(optional) Calculated response payload size in bytes |
number |
http.response.status_code |
status code returned |
number |
http.response.headers |
response headers |
object |
http.response.responseTime |
(optional) Calculated response time in ms |
number |
url.path |
request path |
string |
url.query |
(optional) request query string |
string |
user_agent.original |
raw user-agent string provided in request headers |
string |
Appenders
editRolling File Appender
editSimilar to Log4j’s RollingFileAppender
, this appender will log into a file, and rotate it following a rolling
strategy when the configured policy triggers.
Triggering Policies
editThe triggering policy determines when a rollover should occur.
There are currently two policies supported: size-limit
and time-interval
.
This policy will rotate the file when it reaches a predetermined size.
logging: appenders: rolling-file: type: rolling-file fileName: /var/logs/kibana.log policy: type: size-limit size: 50mb strategy: //... layout: type: pattern
The options are:
-
size
The maximum size the log file should reach before a rollover should be performed. The default value is 100mb
Time-interval triggering policy
This policy will rotate the file every given interval of time.
logging: appenders: rolling-file: type: rolling-file fileName: /var/logs/kibana.log policy: type: time-interval interval: 10s modulate: true strategy: //... layout: type: pattern
The options are:
-
interval
How often a rollover should occur. The default value is 24h
-
modulate
Whether the interval should be adjusted to cause the next rollover to occur on the interval boundary.
For example, if modulate is true and the interval is 4h
, if the current hour is 3 am then the first rollover will occur at 4 am
and then next ones will occur at 8 am, noon, 4pm, etc. The default value is true
.
Rolling strategies
editThe rolling strategy determines how the rollover should occur: both the naming of the rolled files, and their retention policy.
There is currently one strategy supported: numeric
.
Numeric rolling strategy
This strategy will suffix the file with a given pattern when rolling, and will retains a fixed amount of rolled files.
logging: appenders: rolling-file: type: rolling-file fileName: /var/logs/kibana.log policy: // ... strategy: type: numeric pattern: '-%i' max: 2 layout: type: pattern
For example, with this configuration:
- During the first rollover kibana.log is renamed to kibana-1.log. A new kibana.log file is created and starts being written to.
- During the second rollover kibana-1.log is renamed to kibana-2.log and kibana.log is renamed to kibana-1.log. A new kibana.log file is created and starts being written to.
- During the third and subsequent rollovers, kibana-2.log is deleted, kibana-1.log is renamed to kibana-2.log and kibana.log is renamed to kibana-1.log. A new kibana.log file is created and starts being written to.
The options are:
-
pattern
The suffix to append to the file path when rolling. Must include %i
, as this is the value
that will be converted to the file index.
For example, with fileName: /var/logs/kibana.log
and pattern: '-%i'
, the rolling files created
will be /var/logs/kibana-1.log
, /var/logs/kibana-2.log
, and so on. The default value is -%i
-
max
The maximum number of files to keep. Once this number is reached, oldest files will be deleted. The default value is 7
Rewrite appender
editThis appender is currently considered experimental and is not intended for public consumption. The API is subject to change at any time.
Similar to log4j’s RewriteAppender
, this appender serves as a sort of middleware,
modifying the provided log events before passing them along to another
appender.
logging: appenders: my-rewrite-appender: type: rewrite appenders: [console, file] # name of "destination" appender(s) policy: # ...
The most common use case for the RewriteAppender
is when you want to
filter or censor sensitive data that may be contained in a log entry.
In fact, with a default configuration, Kibana will automatically redact
any authorization
, cookie
, or set-cookie
headers when logging http
requests & responses.
To configure additional rewrite rules, you’ll need to specify a RewritePolicy
.
Rewrite policies
editRewrite policies exist to indicate which parts of a log record can be modified within the rewrite appender.
Meta
The meta
rewrite policy can read and modify any data contained in the
LogMeta
before passing it along to a destination appender.
Meta policies must specify one of three modes, which indicate which action
to perform on the configured properties:
- update
updates an existing property at the provided path
.
- remove
removes an existing property at the provided path
.
The properties
are listed as a path
and value
pair, where path
is
the dot-delimited path to the target property in the LogMeta
object, and
value
is the value to add or update in that target property. When using
the remove
mode, a value
is not necessary.
Here’s an example of how you would replace any cookie
header values with [REDACTED]
:
logging: appenders: my-rewrite-appender: type: rewrite appenders: [console] policy: type: meta # indicates that we want to rewrite the LogMeta mode: update # will update an existing property only properties: - path: "http.request.headers.cookie" # path to property value: "[REDACTED]" # value to replace at path
Rewrite appenders can even be passed to other rewrite appenders to apply multiple filter policies/modes, as long as it doesn’t create a circular reference. Each rewrite appender is applied sequentially (one after the other).
logging: appenders: remove-request-headers: type: rewrite appenders: [censor-response-headers] # redirect to the next rewrite appender policy: type: meta mode: remove properties: - path: "http.request.headers" # remove all request headers censor-response-headers: type: rewrite appenders: [console] # output to console policy: type: meta mode: update properties: - path: "http.response.headers.set-cookie" value: "[REDACTED]"
Complete Example For Rewrite Appender
editlogging: appenders: custom_console: type: console layout: type: pattern highlight: true pattern: "[%date][%level][%logger] %message %meta" file: type: file fileName: ./kibana.log layout: type: json censor: type: rewrite appenders: [custom_console, file] policy: type: meta mode: update properties: - path: "http.request.headers.cookie" value: "[REDACTED]" loggers: - name: http.server.response appenders: [censor] # pass these logs to our rewrite appender level: debug