Configuring Logging in API Manager

Logging is one of the most important aspects of a production-grade server. A properly configured logging system is vital for identifying errors, security threats, and usage patterns.

WSO2 API Manager uses various types of logs to track real time internal and external activities. Separate log files are created for each of those log types in the <API-M_HOME>/repository/logs directory. The following sections illustrate the types of logs that are supported by API-M and also as to how you should configure the logs.

Carbon Logs

WSO2 API Manager is shipped with log4j2 logging capabilities, which generate logs for administrative and server-side activities. By default, the Carbon Logs are persisted in the wso2carbon.log file, which is located in the <API-M_HOME>/repository/logs directory. You can configure the details that are captured in this log file by configuring the <API-M_HOME>/repository/conf/log4j2.properties.

Java

In addition to the logs from libraries that use Log4j, all logs from libraries such as, Tomcat and Hazelcast, which use Java logging framework are also visible in the same log files. Therefore, when Java logging is enabled in Carbon, only the Log4j appenders will write to the log files. If the Java Logging Handlers have logs, these logs will be delegated to the log events of the corresponding Log4j appenders. A Pub/Sub registry pattern implementation has been used in the latter mentioned scenario to plug the handlers and appenders.

Configuring Carbon Logs

The following are the default configurations for the Carbon Logs and the default values can be changed by manually updating the log4j2.properties file.

appender.CARBON_LOGFILE.type = RollingFile
appender.CARBON_LOGFILE.name = CARBON_LOGFILE
appender.CARBON_LOGFILE.fileName = ${sys:carbon.home}/repository/logs/wso2carbon.log
appender.CARBON_LOGFILE.filePattern = ${sys:carbon.home}/repository/logs/wso2carbon-%d{MM-dd-yyyy}.log
appender.CARBON_LOGFILE.layout.type = PatternLayout
appender.CARBON_LOGFILE.layout.pattern = TID: [%tenantId] [%appName] [%d] %5p {%c} - %m%ex%n
appender.CARBON_LOGFILE.policies.type = Policies
appender.CARBON_LOGFILE.policies.time.type = TimeBasedTriggeringPolicy
appender.CARBON_LOGFILE.policies.time.interval = 1
appender.CARBON_LOGFILE.policies.time.modulate = true
appender.CARBON_LOGFILE.policies.size.type = SizeBasedTriggeringPolicy
appender.CARBON_LOGFILE.policies.size.size=10MB
appender.CARBON_LOGFILE.strategy.type = DefaultRolloverStrategy
appender.CARBON_LOGFILE.strategy.max = 20
appender.CARBON_LOGFILE.filter.threshold.type = ThresholdFilter
appender.CARBON_LOGFILE.filter.threshold.level = DEBUG

appenders = CARBON_LOGFILE, CARBON_CONSOLE, AUDIT_LOGFILE, ATOMIKOS_LOGFILE, CARBON_TRACE_LOGFILE, CARBON_MEMORY, 
DELETE_EVENT_LOGFILE, TRANSACTION_LOGFILE

For information on managing the log growth of the Carbon Logs, see the Managing log growth guide.

Enabling logs for a tenant

You can write logs of tenants to a different log file by adding the following configurations in the log4j2.properties file.

appenders=CARBON_CONSOLE, CARBON_LOGFILE, ...., TENANT_LOGFILE

rootLogger.appenderRef.TENANT_LOGFILE.ref = TENANT_LOGFILE

# Creates tenant-wise log files
appender.TENANT_LOGFILE.type = Routing
appender.TENANT_LOGFILE.name = TENANT_LOGFILE
appender.TENANT_LOGFILE.routes.type = Routes
appender.TENANT_LOGFILE.routes.pattern = $${TenantLookup:tenantId}
appender.TENANT_LOGFILE.routes.route1.type = Route
appender.TENANT_LOGFILE.routes.route1.rolling.type = RollingFile
appender.TENANT_LOGFILE.routes.route1.rolling.name = Routing-${TenantLookup:tenantId}
appender.TENANT_LOGFILE.routes.route1.rolling.fileName = ${sys:carbon.home}/repository/logs/wso2-tenant-${TenantLookup:tenantId}.log
appender.TENANT_LOGFILE.routes.route1.rolling.filePattern = ${sys:carbon.home}/repository/logs/wso2-tenant-${TenantLookup:tenantId}-%d{MM-dd-yyyy}.log
appender.TENANT_LOGFILE.routes.route1.rolling.layout.type = PatternLayout
appender.TENANT_LOGFILE.routes.route1.rolling.layout.pattern = %d %p %C{1.} [%t] %m%n
appender.TENANT_LOGFILE.routes.route1.rolling.policy.type = SizeBasedTriggeringPolicy
appender.TENANT_LOGFILE.routes.route1.rolling.policy.size = 500MB

The log files will be created in the <API-M_HOME>/repository/logs directory with the name wso2-tenant-<tenantDomain>.log file.

Enabling logs for a component

Follow the instructions below to enable logs for a given service component that is available in WSO2 API Manager.

  1. Open the <API-M_HOME>/repository/conf/log4j2.properties file.
  2. Add a new logger specifying the component name that you need to enable logs and the log level as shown below.

    logger.<Logger_Name>.name = <Component_name>
    logger.<Logger_Name>.level = <Log_level>
    logger.org-wso2-carbon-user-core.name = org.wso2.carbon.user.core
    logger.org-wso2-carbon-user-core.level = DEBUG
  3. Append the newly added logger name to loggers configuration which is a comma separated list of all active loggers.

    loggers = <Logger_Name>, trace-messages, org-apache-coyote,com-hazelcast
    loggers = org-wso2-carbon-user-core, trace-messages, org-apache-coyote,com-hazelcast

Setting the log levels

The log level can be set specifically for each appender in the log4j2.properties file by setting the threshold value. If a log level is not specifically given for an appender as explained below, the root log level (INFO) will apply to all appenders by default.

For example, shown below is how the log level is set to DEBUG for the CARBON_LOGFILE appender:

appender.CARBON_LOGFILE.filter.threshold.level = DEBUG

The following are the log levels that you can configure:

Level Description
OFF The highest possible log level. This is intended for disabling logging.
FATAL Indicates server errors that cause premature termination. These logs are expected to be immediately visible on the command line that you used for starting the server.
ERROR Indicates other runtime errors or unexpected conditions. These logs are expected to be immediately visible on the command line that you used for starting the server.
WARN Indicates the use of deprecated APIs, poor use of API, possible errors, and other runtime situations that are undesirable or unexpected but not necessarily wrong. These logs are expected to be immediately visible on the command line that you used for starting the server.
INFO Indicates important runtime events, such as server startup/shutdown. These logs are expected to be immediately visible on the command line that you used for starting the server. It is recommended to keep these logs to a minimum.
DEBUG Provides detailed information on the flow through the system. This information is expected to be written to logs only. Generally, most lines logged by your application should be written as DEBUG logs.
TRACE Provides additional details on the behavior of events and services. This information is expected to be written to logs only.

Gateway Wire Logs

You can configure the Gateway Wire Logs to monitor the HTTP message flow through the API Gateway. Wire Logs allow you to track the request headers, request payloads, response headers, response payloads, etc. of incoming and outgoing HTTP traffic.

Warning

Note that Wire Logs should be enabled for troubleshooting purposes only. It is not recommended to run production systems with Wire Logs enabled.

In order to read the Wire Logs, you must first identify the message direction.

DEBUG - wire >> Represents the message coming into the API Gateway from the wire.
DEBUG - wire << Represents the message that goes to the wire from the API Gateway.

In a single roundtrip of an API request/response, you can observe the following message flows via the Wire log.

  • Incoming request to API Gateway from API client (>>).
  • Outgoing request from API Gateway to actual backend (<<).
  • Incoming response from actual backend to API Gateway (>>).
  • Outgoing response from API Gateway to API client (<<).

The following is a sample Gateway Wire Log for an API request.

[2019-12-12 17:30:08,091] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "GET /helloWorld/1.0.0 HTTP/1.1[\r][\n]"
[2019-12-12 17:30:08,093] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "Host: localhost:8243[\r][\n]"
[2019-12-12 17:30:08,094] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "User-Agent: curl/7.54.0[\r][\n]"
[2019-12-12 17:30:08,095] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "accept: */*[\r][\n]"
[2019-12-12 17:30:08,096] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "Authorization: Bearer 07f6b26d-0f8d-312a-8d38-797e054566cd[\r][\n]"
[2019-12-12 17:30:08,097] DEBUG - wire HTTPS-Listener I/O dispatcher-5 >> "[\r][\n]"
[2019-12-12 17:30:08,105] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "GET /v2/5df22aa131000084009a30a9 HTTP/1.1[\r][\n]"
[2019-12-12 17:30:08,106] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "accept: */*[\r][\n]"
[2019-12-12 17:30:08,107] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "Host: www.mocky.io[\r][\n]"
[2019-12-12 17:30:08,108] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "Connection: Keep-Alive[\r][\n]"
[2019-12-12 17:30:08,109] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "User-Agent: Synapse-PT-HttpComponents-NIO[\r][\n]"
[2019-12-12 17:30:08,110] DEBUG - wire HTTP-Sender I/O dispatcher-1 << "[\r][\n]"
[2019-12-12 17:30:08,266] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "HTTP/1.1 200 OK[\r][\n]"
[2019-12-12 17:30:08,268] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Server: Cowboy[\r][\n]"
[2019-12-12 17:30:08,269] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Connection: keep-alive[\r][\n]"
[2019-12-12 17:30:08,271] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Date: Thu, 12 Dec 2019 12:00:08 GMT[\r][\n]"
[2019-12-12 17:30:08,272] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Content-Type: application/json[\r][\n]"
[2019-12-12 17:30:08,273] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Content-Length: 20[\r][\n]"
[2019-12-12 17:30:08,274] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "Via: 1.1 vegur[\r][\n]"
[2019-12-12 17:30:08,275] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "[\r][\n]"
[2019-12-12 17:30:08,276] DEBUG - wire HTTP-Sender I/O dispatcher-1 >> "{ "hello": "world" }"
[2019-12-12 17:30:08,282] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "HTTP/1.1 200 OK[\r][\n]"
[2019-12-12 17:30:08,283] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Access-Control-Expose-Headers: [\r][\n]"
[2019-12-12 17:30:08,284] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Access-Control-Allow-Origin: *[\r][\n]"
[2019-12-12 17:30:08,285] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Access-Control-Allow-Methods: GET[\r][\n]"
[2019-12-12 17:30:08,286] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Access-Control-Allow-Headers: authorization,Access-Control-Allow-Origin,Content-Type,SOAPAction,Authorization[\r][\n]"
[2019-12-12 17:30:08,287] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Content-Type: application/json[\r][\n]"
[2019-12-12 17:30:08,287] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Via: 1.1 vegur[\r][\n]"
[2019-12-12 17:30:08,288] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Date: Thu, 12 Dec 2019 12:00:08 GMT[\r][\n]"
[2019-12-12 17:30:08,289] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "Transfer-Encoding: chunked[\r][\n]"
[2019-12-12 17:30:08,290] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "[\r][\n]"
[2019-12-12 17:30:08,290] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "14[\r][\n]"
[2019-12-12 17:30:08,291] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "{ "hello": "world" }[\r][\n]"
[2019-12-12 17:30:08,292] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "0[\r][\n]"
[2019-12-12 17:30:08,293] DEBUG - wire HTTPS-Listener I/O dispatcher-5 << "[\r][\n]"

Enabling the Gateway Wire Logs

  1. Open the <API-M_HOME>/repository/conf/log4j2.properties file.
  2. Locate the synapse-wire logger, which is already defined in the default log4j2.properties file.

    logger.synapse-wire.name = org.apache.synapse.transport.http.wire logger.synapse-wire.level = DEBUG

    You can use the synapse-headers logger to log the request and response headers only.

    logger.synapse-headers.name = org.apache.synapse.transport.http.headers
    logger.synapse-headers.level = DEBUG
  3. Append the synapse-wire logger name to the loggers configuration which is a comma separated list of all the active loggers.

    loggers = synapse-wire, trace-messages, org-apache-coyote,com-hazelcast

    If you want to activate the Wire Logs only for message headers, you can activate synapse-headers logger.

    loggers = synapse-headers, trace-messages, org-apache-coyote,com-hazelcast
  4. Observe the logs for incoming and outgoing traffic in the <API-M_HOME>/repository/logs/wso2carbon.log file.

HTTP Access Logs

HTTP requests/responses are logged in Access Logs to monitor the activities related to an application's usage. For instructions on how to configure and use the HTTP Access Logs in WSO2 API Manager, see Monitoring the HTTP Access Logs.

Audit Logs

Audit Logs are used for tracking the sequence of actions that affect a particular task carried out on the server. For instructions on how to configure and use Audit Logs in WSO2 API Manager, see Monitoring Audit Logs.

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