Configuring logging

Learn how to configure Logging

Keycloak uses the JBoss Logging framework. The following is a high-level overview for the available log handlers:

  • root

    • console (default)

    • file

    • GELF

Logging configuration

Logging is done on a per-category basis in Keycloak. You can configure logging for the root log level or for more specific categories such as org.hibernate or org.keycloak. This guide describes how to configure logging.

Log levels

The following table defines the available log levels.

Level

Description

FATAL

Critical failures with complete inability to serve any kind of request.

ERROR

A significant error or problem leading to the inability to process requests.

WARN

A non-critical error or problem that might not require immediate correction.

INFO

Keycloak lifecycle events or important information. Low frequency.

DEBUG

More detailed information for debugging purposes, such as database logs. Higher frequency.

TRACE

Most detailed debugging information. Very high frequency.

ALL

Special level for all log messages.

OFF

Special level to turn logging off entirely (not recommended).

Configuring the root log level

When no log level configuration exists for a more specific category logger, the enclosing category is used instead. When there is no enclosing category, the root logger level is used.

To set the root log level, enter the following command:

bin/kc.[sh|bat] start --log-level=<root-level>

Use these guidelines for this command:

  • For <root-level>, supply a level defined in the preceding table.

  • The log level is case-insensitive. For example, you could either use DEBUG or debug.

  • If you were to accidentally set the log level twice, the last occurrence in the list becomes the log level. For example, if you included the syntax --log-level=info,…​,DEBUG,…​, the root logger would be DEBUG.

Configuring category-specific log levels

You can set different log levels for specific areas in Keycloak. Use this command to provide a comma-separated list of categories for which you want a different log level:

bin/kc.[sh|bat] start --log-level=<root-level>,<org.category1>:<org.category1-level>

A configuration that applies to a category also applies to its sub-categories unless you include a more specific matching sub-category.

Example
bin/kc.[sh|bat] start --log-level=INFO,org.hibernate:debug,org.hibernate.hql.internal.ast:info

This example sets the following log levels:

  • Root log level for all loggers is set to INFO.

  • The hibernate log level in general is set to debug.

  • To keep SQL abstract syntax trees from creating verbose log output, the specific subcategory org.hibernate.hql.internal.ast is set to info. As a result, the SQL abstract syntax trees are omitted instead of appearing at the debug level.

Enabling log handlers

To enable log handlers, enter the following command:

bin/kc.[sh|bat] start --log=<handler1>,<handler2>

The available handlers are console, file and gelf. The more specific handler configuration mentioned below will only take effect when the handler is added to this comma-separated list.

Console log handler

The console log handler is enabled by default, providing unstructured log messages for the console.

Configuring the console log format

Keycloak uses a pattern-based logging formatter that generates human-readable text logs by default.

The logging format template for these lines can be applied at the root level. The default format template is:

  • %d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c] (%t) %s%e%n

The format string supports the symbols in the following table:

Symbol

Summary

Description

%%

%

Renders a simple % character.

%c

Category

Renders the log category name.

%d{xxx}

Date

Renders a date with the given date format string.String syntax defined by java.text.SimpleDateFormat

%e

Exception

Renders a thrown exception.

%h

Hostname

Renders the simple host name.

%H

Qualified host name

Renders the fully qualified hostname, which may be the same as the simple host name, depending on the OS configuration.

%i

Process ID

Renders the current process PID.

%m

Full Message

Renders the log message and an exception, if thrown.

%n

Newline

Renders the platform-specific line separator string.

%N

Process name

Renders the name of the current process.

%p

Level

Renders the log level of the message.

%r

Relative time

Render the time in milliseconds since the start of the application log.

%s

Simple message

Renders only the log message without exception trace.

%t

Thread name

Renders the thread name.

%t{id}

Thread ID

Render the thread ID.

%z{<zone name>}

Timezone

Set the time zone of log output to <zone name>.

%L

Line number

Render the line number of the log message.

Setting the logging format

To set the logging format for a logged line, perform these steps:

  1. Build your desired format template using the preceding table.

  2. Enter the following command:

    bin/kc.[sh|bat] start --log-format="'<format>'"

Note that you need to escape characters when invoking commands containing special shell characters such as ; using the CLI. Therefore, consider setting it in the configuration file instead.

Example: Abbreviate the fully qualified category name
bin/kc.[sh|bat] start --log-console-format="'%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c{3.}] (%t) %s%e%n'"

This example abbreviates the category name to three characters by setting [%c{3.}] in the template instead of the default [%c].

Configuring JSON or plain console logging

By default, the console log handler logs plain unstructured data to the console. To use structured JSON log output instead, enter the following command:

bin/kc.[sh|bat] start --log-console-output=json
Example Log Message
{"timestamp":"2022-02-25T10:31:32.452+01:00","sequence":8442,"loggerClassName":"org.jboss.logging.Logger","loggerName":"io.quarkus","level":"INFO","message":"Keycloak 18.0.0-SNAPSHOT on JVM (powered by Quarkus 2.7.2.Final) started in 3.253s. Listening on: http://0.0.0.0:8080","threadName":"main","threadId":1,"mdc":{},"ndc":"","hostName":"host-name","processName":"QuarkusEntryPoint","processId":36946}

When using JSON output, colors are disabled and the format settings set by --log-console-format will not apply.

To use unstructured logging, enter the following command:

bin/kc.[sh|bat] start --log-console-output=default
Example Log Message:
2022-03-02 10:36:50,603 INFO  [io.quarkus] (main) Keycloak 18.0.0-SNAPSHOT on JVM (powered by Quarkus 2.7.2.Final) started in 3.615s. Listening on: http://0.0.0.0:8080

Colors

Colored console log output for unstructured logs is disabled by default. Colors may improve readability, but they can cause problems when shipping logs to external log aggregation systems. To enable or disable color-coded console log output, enter following command:

bin/kc.[sh|bat] start --log-console-color=<false|true>

File logging

As an alternative to logging to the console, you can use unstructured logging to a file.

Enable file logging

Logging to a file is disabled by default. To enable it, enter the following command:

bin/kc.[sh|bat] start --log=console,file

A log file named keycloak.log is created inside the data/log directory of your Keycloak installation.

Configuring the location and name of the log file

To change where the log file is created and the file name, perform these steps:

  1. Create a writable directory to store the log file.

    If the directory is not writable, Keycloak will start correctly, but it will issue an error and no log file will be created.

  2. Enter this command:

    bin/kc.[sh|bat] start --log=console,file --log-file=<path-to>/<your-file.log>

Configuring the file handler format

To configure a different logging format for the file log handler, enter the following command:

bin/kc.[sh|bat] start --log-file-format=<pattern>

Please see the Configuring the console log format section in this guide for more information and a table of the available pattern configuration.

Centralized logging using GELF

Keycloak can send logs to a centralized log management system such as the following:

  • Graylog

  • Logstash, inside the Elasticsearch, Logstash, Kibana (ELK) logging stack

  • Fluentd, inside the Elasticsearch, Fluentd, Kibana (EFK) logging stack

Keycloak uses the Quarkus Logging GELF extension to support these environments.

Enabling the GELF handler

To enable logging using GELF, add it to the list of activated log handlers.

Example:
bin/kc.[sh|bat] start --log=console,gelf

Configuring the GELF handler

To configure the Host and Port of your centralized logging system, enter the following command and substitute the values with your specific values: .Host and port of the GELF server:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-host=myhost --log-gelf-port=12345

When the GELF handler is enabled, the host is using localhost as host value and UDP for communication. To use TCP instead of UDP, prefix the host value with tcp:. The Default port is 12201.

Include or exclude Stacktraces

Keycloak includes the complete Stacktrace inside the StackTrace field. To exclude this field, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-include-stack-trace=false
Configure the timestamp format

You can change the format of the timestamp field. For example, you can include the date and time down to seconds by entering the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-timestamp-format="'yyyy-MM-dd HH:mm:ss'"

Alternatively, you could use the config file to avoid escaping:

log-gelf-timestamp-format=yyyy-MM-dd HH:mm:ss

The default timestamp format is yyyy-MM-dd HH:mm:ss,SSS. You can use the available SimpleDateFormat patterns to define an appropriate timestamp.

Configure the facility

The facility field is an indicator of the process or program that is the source of log messages. The default value is keycloak. To set this field to your preferred identifier, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-facility=MyKeycloak

To use the CLI to configure Keycloak and use whitespaces for facility, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-facility="'my keycloak'"

Alternatively, you could use the config file to avoid escaping:

log-gelf-facility=my keycloak
Configure the default message size

To change the default message size of 8kb (8192 bytes) of GELF log messages for Keycloak, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-max-message-size=16384

The maximum size of one GELF log message is set in Bytes. The preceding example increases the size to 16kb. When messages exceed the maximum size, GELF submits the message in multiple chunks.

Configure sending of message parameters

Keycloak includes message parameters of the occurred log event. These fields appear in the output as MessageParam0, MessageParam1, and so on, depending on the parameter length. To switch off this behavior, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-include-message-parameters=false
Configure sending of source code location

Keycloak includes the SourceClassName, SourceMethodName and SourceSimpleClassName fields in the GELF log messages. These fields provide detail on the location of an exception that occurred. To stop sending these fields, enter the following command:

bin/kc.[sh|bat] start --log=console,gelf --log-gelf-include-location=false

Example: Send logs to Graylog

The following example shows how to send Keycloak logs to the Graylog centralized logging stack. This example assumes you have a container tool such as docker installed to start the compose.yml.

Starting the Graylog stack

The composed stack consists of:

  • Graylog

  • ElasticSearch

  • MongoDB

version: '3.8'

services:
  elasticsearch:
    image: docker.io/elastic/elasticsearch:7.10.2
    ports:
      - "9200:9200"
    environment:
      ES_JAVA_OPTS: "-Xms512m -Xmx512m"
      discovery.type: "single-node"
    networks:
      - graylog

  mongo:
    image: mongo:4.4
    networks:
      - graylog

  graylog:
    image: graylog/graylog:4.3.3
    ports:
      - "9000:9000"
      - "12201:12201/udp"
      - "1514:1514"
    environment:
      GRAYLOG_HTTP_EXTERNAL_URI: "http://127.0.0.1:9000/"
      # CHANGE ME (must be at least 16 characters)!
      GRAYLOG_PASSWORD_SECRET: "forpasswordencryption"
      # Password: admin
      GRAYLOG_ROOT_PASSWORD_SHA2: "8c6976e5b5410415bde908bd4dee15dfb167a9c873fc4bb8a81f6f2ab448a918"
    networks:
      - graylog
    depends_on:
      - elasticsearch
      - mongo

networks:
  graylog:
    driver: bridge

Copy and save the example locally into a compose.yml file and enter this command:

docker compose up -d

After a few seconds, the Stack is ready to serve requests.

Creating a Graylog UDP Input

Once the stack is running, you need to create a UDP Input Graylog listens to. You can create it from the Graylog web UI (System → Input → Select GELF UDP) available at http://localhost:9000 or using the API:

This curl example creates a new GELF UDP Input using the API and the default Graylog login credentials (admin/admin).

curl -H "Content-Type: application/json" -H "Authorization: Basic YWRtaW46YWRtaW4=" -H "X-Requested-By: curl" -X POST -v -d \
'{"title":"udp input","configuration":{"recv_buffer_size":262144,"bind_address":"0.0.0.0","port":12201,"decompress_size_limit":8388608},"type":"org.graylog2.inputs.gelf.udp.GELFUDPInput","global":true}' \
http://localhost:9000/api/system/inputs

If the stack is still in the bootstrap phase, you receive a response containing * Empty reply from server. A successful response includes HTTP/1.1 201 Created to indicate that the UDP input is created.

Configure Keycloak to send logs using GELF

Keycloak needs to be configured to send logs using GELF. The appropriate configuration can be seen in the following keycloak.conf example. The example includes the log-gelf-host and log-gelf-port values. These are optional values that are included for illustration purposes; default values exist.

Keycloak GELF Configuration
log=console,gelf
log-gelf-host=localhost
log-gelf-port=12201

Graylog: See the results

  1. Open your web browser, go to http://localhost:9000.

  2. Log in to the Graylog web UI using the administrator credentials (admin/admin).

  3. Go to Streams, All Messages.

  4. Start updating the stream by pressing the Play button in the upper right corner.

  5. Start Keycloak using start or start-dev and your GELF config.

After a few seconds, Keycloak messages appear in the Graylog dashboard.

Example Setup using the ELK Stack

The following example shows how to send Keycloak logs to the ELK centralized logging stack. It assumes you have a container tool such as docker installed to start the compose.yml.

Enable the logstash GELF plugin and create a pipeline

Logstash uses an input plugin that understands and parses the GELF format. To activate this plugin when you are starting the ELK stack later on, create a directory pipelines and a file gelf.conf located in this directory. Then create an empty compose.yml in the parent directory.

File Structure:
/ELK
  - compose.yml
  - pipelines/
    - gelf.conf

Add the following contents to pipelines/gelf.conf and save it:

input {
  gelf {
    port => 12201
  }
}
output {
  stdout {}
  elasticsearch {
    hosts => ["http://elasticsearch:9200"]
  }
}

This file activates and configures the logstash GELF plugin and points it to the right elasticsearch instance.

Starting the ELK stack

The composed stack consists of:

  • ElasticSearch

  • Logstash

  • Kibana

Copy the following content to your compose.yml file:

# Launch Elasticsearch
version: '3.8'

services:
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch-oss:6.8.2
    ports:
      - "9200:9200"
      - "9300:9300"
    environment:
      ES_JAVA_OPTS: "-Xms512m -Xmx512m"
    networks:
      - elk

  logstash:
    image: docker.elastic.co/logstash/logstash-oss:6.8.2
    volumes:
      - source: ./pipelines #the source dir gelf.conf resides
        target: /usr/share/logstash/pipeline
        type: bind
    ports:
      - "12201:12201/udp"
      - "5000:5000"
      - "9600:9600"
    networks:
      - elk
    depends_on:
      - elasticsearch

  kibana:
    image: docker.elastic.co/kibana/kibana-oss:6.8.2
    ports:
      - "5601:5601"
    networks:
      - elk
    depends_on:
      - elasticsearch

networks:
  elk:
    driver: bridge

Start the stack by entering the following command:

docker compose up -d

After a few seconds the Stack should be ready to serve requests.

Configuring Keycloak to send logs using GELF

Keycloak needs to be configured to send logs using GELF. The appropriate configuration can be seen in the following keycloak.conf example. This example includes the log-gelf-host and log-gelf-port values. These are optional values, which are included for illustration purposes; default values exist.

Keycloak Gelf Configuration
log=console,gelf
log-gelf-host=localhost
log-gelf-port=12201

With this configuration applied, start keycloak using start-dev or start.

Kibana: See the results

Open http://localhost:5601 to reach the Kibana dashboard. The exact configuration of a good monitoring dashboard is out of scope for this guide. To find out if logs sent by Keycloak are delivered to Kibana, open the Dev Tools and execute the default match_all query. The logs should appear in the result field.

Configure a different log level for the GELF logger

To keep log storage costs and verbosity low, it is often wanted to only store a subset of the verbose application logs inside a centralized log management system. To configure Keycloak to use a different log level for the logs you want to ingest, use the following configuration:

log=console,gelf
log-gelf-level=<desired-log-level>
...
Example

To only see occurred log levels of warn and above in your centralized logging stack, but still see INFO level logs on the applications console logs, use the following configuration:

log=console,gelf
log-level=INFO
log-gelf-level=warn
...

Looking at your ingested logs, you will see only messages of level warn or above will appear.

Keep in mind that --log-level is setting the leading log level, so for example when you invoke the following command:

bin/kc.[sh|bat] start --log=console,gelf, log-level=error, log-gelf-level=info

nothing below the error level will be sent to your logging stack. That means that even GELF in this example will receive only error level log messages.

Configure additional key values

Currently, the Keycloak configuration does not support partly dynamic configuration keys, as they are used in quarkus properties. For example, they are used when defining quarkus.log.handler.gelf.additional-field.<my-name>.value.

To add user-defined fields, you can provide these fields through a quarkus.properties file. Refer to the Configuring Keycloak guide and the Using unsupported server options section.

Relevant options

Type Default

log-console-color

Enable or disable colors when logging to console.

CLI: --log-console-color

Env: KC_LOG_CONSOLE_COLOR

true, false

false

log-console-format

The format of unstructured console log entries.

If the format has spaces in it, escape the value using "<format>".

CLI: --log-console-format

Env: KC_LOG_CONSOLE_FORMAT

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c] (%t) %s%e%n

log-console-output

Set the log output to JSON or default (plain) unstructured logging.

CLI: --log-console-output

Env: KC_LOG_CONSOLE_OUTPUT

default, json

default

log-file

Set the log file path and filename.

CLI: --log-file

Env: KC_LOG_FILE

data/log/keycloak.log

log-file-format

Set a format specific to file log entries.

CLI: --log-file-format

Env: KC_LOG_FILE_FORMAT

%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p [%c] (%t) %s%e%n

log-file-output

Set the log output to JSON or default (plain) unstructured logging.

CLI: --log-file-output

Env: KC_LOG_FILE_OUTPUT

default, json

default

log-gelf-facility

The facility (name of the process) that sends the message.

CLI: --log-gelf-facility

Env: KC_LOG_GELF_FACILITY

keycloak

log-gelf-host

Hostname of the Logstash or Graylog Host.

By default UDP is used, prefix the host with 'tcp:' to switch to TCP. Example: 'tcp:localhost'

CLI: --log-gelf-host

Env: KC_LOG_GELF_HOST

localhost

log-gelf-include-location

Include source code location.

CLI: --log-gelf-include-location

Env: KC_LOG_GELF_INCLUDE_LOCATION

true, false

true

log-gelf-include-message-parameters

Include message parameters from the log event.

CLI: --log-gelf-include-message-parameters

Env: KC_LOG_GELF_INCLUDE_MESSAGE_PARAMETERS

true, false

true

log-gelf-include-stack-trace

If set to true, occuring stack traces are included in the 'StackTrace' field in the GELF output.

CLI: --log-gelf-include-stack-trace

Env: KC_LOG_GELF_INCLUDE_STACK_TRACE

true, false

true

log-gelf-level

The log level specifying which message levels will be logged by the GELF logger.

Message levels lower than this value will be discarded.

CLI: --log-gelf-level

Env: KC_LOG_GELF_LEVEL

INFO

log-gelf-max-message-size

Maximum message size (in bytes).

If the message size is exceeded, GELF will submit the message in multiple chunks.

CLI: --log-gelf-max-message-size

Env: KC_LOG_GELF_MAX_MESSAGE_SIZE

8192

log-gelf-port

The port the Logstash or Graylog Host is called on.

CLI: --log-gelf-port

Env: KC_LOG_GELF_PORT

12201

log-gelf-timestamp-format

Set the format for the GELF timestamp field.

Uses Java SimpleDateFormat pattern.

CLI: --log-gelf-timestamp-format

Env: KC_LOG_GELF_TIMESTAMP_FORMAT

yyyy-MM-dd HH:mm:ss,SSS

log-level

The log level of the root category or a comma-separated list of individual categories and their levels.

For the root category, you don’t need to specify a category.

CLI: --log-level

Env: KC_LOG_LEVEL

info

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