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Official R1 documentation snapshot in https://onap.readthedocs.io/en/latest/submodules/logging-analytics.git/docs/
THIS IS A DRAFT WIP for R2 - ONAP Beijing Release
This document specifies logging conventions to be followed by ONAP component applications.
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Java is assumed, but conventions may also be implemented by non-Java components.
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Log4j 2.X is somewhat less common than Logback, but equivalent. It is generally configured by an XML document named log4j.xml. See Configuration.
Log4j 1.X
AvoidStrongly discouraged from Beijing onwards, since 1.X is EOL, and since it does not support escaping, so its output may not be machine-readable. See https://logging.apache.org/log4j/1.2/.
This affects existing OpenDaylight-based components like SDNC and APPC, since ODL releases prior to Carbon bundle bundled Log4j 1.X, and make it difficult to replace. The Common Controller SDK Project project targets ODL Carbon, so the problem should resolve in timeremaining instances of Log4j 1.X should disappear by the time of the Beijing release.
What to Log
The purpose of logging is to capture diagnostic information.
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A Mapped Diagnostic Context (MDC) allows an arbitrary string-valued attribute to be attached to a Java thread. The MDC's value is then emitted with each log message logged by that thread. The set of MDCs associated with a log message is serialized as unordered name-value pairs (see Text Output).
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EELF doesn't directly support MDCs, but SLF4J will receive any MDC that is set its default provider (where com.att.eelf.configuration.SLF4jWrapper is the configured EELF provider)normally logs via SLF4J, and SLF4J will receive any MDC that is set:
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import java.util.UUID; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.slf4j.MDC; import com.att.eelf.configuration.EELFLogger; import com.att.eelf.configuration.EELFManager; // ... final EELFLogger logger = EELFManager.getInstance().getLogger(this.getClass()); MDC.put("SomeUUID", UUID.randomUUID().toString()); try { logger.info("This message will have a UUID-valued 'SomeUUID' MDC attached."); // ... } finally { MDC.clear(); } |
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- It's only a few calls.
- It can be largely abstracted in the case of EELF logging.
TODO: code.
MDCs - the Rest
Other MDCs are logged in a wide range of contexts.
Certain MDCs and their semantics may be specific to EELF log types.
TODO: cross-reference EELF output to v1 doc.
MDC - PartnerName
This field should contain the name of the client application user agent or user invoking the API.
This is often used for heuristic analysis to identify invocations between ONAP individual ONAP components. Its value has never been clearly stipulated, so a common problem has been a lack of consistency.
There is no clear consensus, but:
- Use the short name of your component, e.g. xyzdriver.
- Values should be human-readable.
- Values should be fine-grained enough to disambiguate subcomponents where it's likely to matter. This is subjective.
- Be consistent: your component should ALWAYS report same value.
Real-life examples include MSO, bpmnclient, BPELClient, (all of which are reported by SO), openECOMP (SDNC), vid (VID!) etc. (See the problem?)
Usage overlaps with InvocationID, which doesn't mean PartnerName gets retired, but which might mean it serves a more descriptive purpose. (Since it hasn't proven to be a great way of generating a call graph).
MDC - ServiceName
For EELF Audit log records that capture API requests, this field contains the name of the API invoked at the component creating the record (e.g., Layer3ServiceActivateRequest).
For EELF Audit log records that capture processing as a result of receipt of a message, this field should contain the name of the module that processes the message.
Usage is the same for indexable logs.
MDCs - the Rest
Other MDCs are logged in a wide range of contexts.
Certain MDCs and their semantics may be specific to EELF log types.
TODO: cross-reference EELF output to v1 doc.
ID | MDC | Description | Required | EELF Audit | EELF Metric | EELF Error | EELF Debug | ||||||||||||||||
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RequestID | See above. | Y | |||||||||||||||||||||
InvocationID | See above. | Y | |||||||||||||||||||||
ServiceName | See above. | Y | |||||||||||||||||||||
PartnerName | See above. | Y | |||||||||||||||||||||
1 | BeginTimestamp | Date-time that processing activities being logged begins. The value should be represented in UTC and formatted per ISO 8601, such as “2015-06-03T13:21:58+00:00”. The time should be shown with the maximum resolution available to the logging component (e.g., milliseconds, microseconds) by including the appropriate number of decimal digits. For example, when millisecond precision is available, the date-time value would be presented as, as “2015-06-03T13:21:58.340+00:00”. | Y | ||||||||||||||||||||
2 | EndTimestamp | Date-time that processing for the request or event being logged ends. Formatting rules are the same as for the BeginTimestamp field above. In the case of a request that merely logs an event and has not subsequent processing, the EndTimestamp value may equal the BeginTimestamp value. | Y | ||||||||||||||||||||
3 | ElapsedTime | This field contains the elapsed time to complete processing of an API call or transaction request (e.g., processing of a message that was received). This value should be the difference between. EndTimestamp and BeginTimestamp fields and must be expressed in milliseconds. | Y | ||||||||||||||||||||
4 | ServiceInstanceID | This field is optional and should only be included if the information is readily available to the logging component. | |||||||||||||||||||||
ID | MDC | Description | Required | EELF Audit | EELF Metric | EELF Error | EELF Debug | ||||||||||||||||
1 | BeginTimestamp | Date-time that processing activities being logged begins. The value should be represented in UTC and formatted per ISO 8601, such as “2015-06-03T13:21:58+00:00”. The time should be shown with the maximum resolution available to the logging component (e.g., milliseconds, microseconds) by including the appropriate number of decimal digits. For example, when millisecond precision is available, the date-time value would be presented as, as “2015-06-03T13:21:58.340+00:00”. | Y | 2 | EndTimestamp | Date-time that processing for the request or event being logged ends. Formatting rules are the same as for the BeginTimestamp field above. In the case of a request that merely logs an event and has not subsequent processing, the EndTimestamp value may equal the BeginTimestamp value. | Y | 3 | ElapsedTime | This field contains the elapsed time to complete processing of an API call or transaction request (e.g., processing of a message that was received). This value should be the difference between. EndTimestamp and BeginTimestamp fields and must be expressed in milliseconds. | Y | 4 | ServiceInstanceID | This field is optional and should only be included if the information is readily available to the logging component. Transaction requests that create or operate on a particular instance of a service/resource can
NOTE: AAI won’t have a serviceInstanceUUID for every service instance. For example, no serviceInstanceUUID is available when the request is coming from an application that may import inventory data. | 5 | VirtualServerName | Physical/virtual server name. Optional: empty if determined that its value can be added by the agent that collects the log files collecting. | ). In other words:
NOTE: AAI won’t have a serviceInstanceUUID for every service instance. For example, no serviceInstanceUUID is available when the request is coming from an application that may import inventory data. | |||||
5 | VirtualServerName | Physical/virtual server name. Optional: empty if determined that its value can be added by the agent that collects the log files collecting. | |||||||||||||||||||||
6 | 6 | ServiceName | For Audit log records that capture API requests, this field contains the name of the API invoked at the component creating the record (e.g., Layer3ServiceActivateRequest). For Audit log records that capture processing as a result of receipt of a message, this field should contain the name of the module that processes the message. | Y | 7 | PartnerName | This field contains the name of the client application user agent or user invoking the API if known. | Y | 8 | StatusCode | This field indicates the high level status of the request. It must have the value COMPLETE when the request is successful and ERROR when there is a failure. | Y | |||||||||||
97 | ResponseCode | This field contains application-specific error codes. For consistency, common error categorizations should be used. | |||||||||||||||||||||
108 | ResponseDescription | This field contains a human readable description of the ResponseCode. | 1111 | ||||||||||||||||||||
9 | InstanceUUID | If known, this field contains a universally unique identifier used to differentiate between multiple instances of the same (named) log writing service/application. Its value is set at instance creation time (and read by it, e.g., at start/initialization time from the environment). This value should be picked up by the component instance from its configuration file and subsequently used to enable differentiation of log records created by multiple, locally load balanced ONAP component or subcomponent instances that are otherwise identically configured. | |||||||||||||||||||||
1210 | Severity | Optional: 0, 1, 2, 3 see Nagios monitoring/alerting for specifics/details. | |||||||||||||||||||||
1311 | TargetEntity | It contains the name of the ONAP component or sub-component, or external entity, at which the operation activities captured in this metrics log record is invoked. | Y | ||||||||||||||||||||
1412 | TargetServiceName | It contains the name of the API or operation activities invoked at the TargetEntity. | Y | ||||||||||||||||||||
1513 | Server | This field contains the Virtual Machine (VM) Fully Qualified Domain Name (FQDN) if the server is virtualized. Otherwise, it contains the host name of the logging component. | Y | ||||||||||||||||||||
1614 | ServerIPAddress | This field contains the logging component host server’s IP address if known (e.g. Jetty container’s listening IP address). Otherwise it is empty. | |||||||||||||||||||||
1715 | ServerFQDN | Unclear, but possibly duplicating one or both of Server and ServerIPAddress. | |||||||||||||||||||||
1816 | ClientIPAddress | This field contains the requesting remote client application’s IP address if known. Otherwise this field can be empty. | |||||||||||||||||||||
1917 | ProcessKey | This field can be used to capture the flow of a transaction through the system by indicating the components and operations involved in processing. If present, it can be denoted by a comma separated list of components and applications. | |||||||||||||||||||||
2018 | RemoteHost | Unknown. | |||||||||||||||||||||
2119 | AlertSeverity | Unknown. | |||||||||||||||||||||
2220 | TargetVirtualEntity | Unknown | |||||||||||||||||||||
2321 | ClassName | Defunct. Doesn't require an MDC. | |||||||||||||||||||||
2422 | ThreadID | Defunct. Doesn't require an MDC. | |||||||||||||||||||||
2523 | CustomField1 | (Defunct now that MDCs are serialized as NVPs.) | |||||||||||||||||||||
2624 | CustomField2 | (Defunct now that MDCs are serialized as NVPs.) | |||||||||||||||||||||
2725 | CustomField3 | (Defunct now that MDCs are serialized as NVPs.) | |||||||||||||||||||||
2826 | CustomField4 | (Defunct now that MDCs are serialized as NVPs.) |
Examples
SDC-BE
20170907: audit.log
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//TODOfinal EELFLogger logger = EELFManager.getAuditLogger(); logger.auditEvent("Entering."); |
SLF4J:
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public static final Marker ENTRY = MarkerFactory.getMarker("ENTRY"); // ... final Logger logger = LoggerFactory.getLogger(this.getClass()); logger.debug(ENTRY, "Entering."); |
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final EELFLogger logger = EELFManager.getMetricsLogger(); logger.metricsEvent("Exiting.");//TODO |
SLF4J:
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public static final Marker EXIT = MarkerFactory.getMarker("EXIT"); // ... final Logger logger = LoggerFactory.getLogger(this.getClass()); logger.debug(EXIT, "Exiting."); |
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public static final Marker INVOKE = MarkerFactory.getMarker("INVOKE"); // ... // Generate and report invocation ID. final String invocationID = UUID.randomUUID().toString(); MDC.put(MDC_INVOCATION_ID, invocationID); try { logger.debug(INVOKE_SYNCHRONOUS, "Invoking synchronously ... "); } finally { MDC.remove(MDC_INVOCATION_ID); } // Pass invocationID as HTTP X-InvocationID header. callDownstreamSystem(invocationID, ... ); |
TODO: EELF examples of INVOCATION_ID reporting, without changing published APIs.
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public static final Marker INVOKE_SYNCHRONOUS; static { INVOKE_SYNCHRONOUS = MarkerFactory.getMarker("INVOKE"); INVOKE_SYNCHRONOUS.add(MarkerFactory.getMarker("SYNCHRONOUS")); } // ... // Generate and report invocation ID. final String invocationID = UUID.randomUUID().toString(); MDC.put(MDC_INVOCATION_ID, invocationID); try { logger.debug(INVOKE_SYNCHRONOUS, "Invoking synchronously ... "); } finally { MDC.remove(MDC_INVOCATION_ID); } // Pass invocationID as HTTP X-InvocationID header. callDownstreamSystem(invocationID, ... ); |
TODO: EELF example of SYNCHRONOUS reporting, without changing published APIs.
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Logfiles should default to beneath /var/log, and beneath /var/log, and beneath /var/log/ONAP in the case of core ONAP components:
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/var/log/ONAP/<component>[/<subcomponent>]/*.log |
For the duration of Beijing, logs will be written to a separate directory, /var/log/ONAP in the case of core ONAP components_EELF:
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/var/log/ONAP_EELF/<component>[/<subcomponent>]/*.log |
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/etc/onapONAP/<component>[/<subcomponent>]/<provider>.xml |
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Audit log records are intended to capture the high level view of activity within an ONAP component. Specifically, an API request handled by an ONAP component is reflected in a single Audit log record that captures the time the request was received, the time that processing was completed, as well as other information about the API request (e.g., API name, on whose behalf it was invoked, etc).
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Metrics Log
A metric metrics log is required for EELF-enabled components, and provides a more detailed view into the processing of a transaction within an application. It captures the beginning and ending of activities needed to complete it. These can include calls to or interactions with other ONAP or non-ONAP entities.
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- Field separator reverted to pipe.
- Dual appenders in Logback and Log4j reference configurations:
- Indexable, for shipping and indexing.
- EELF, for backward compatibility.
- Minor changes to path conventions.
- XML output deprecated (required only for Log4j1.2, which is also expected to go).
- Improved documentation of semantics and usage (including initialization and propagation via ThreadLocal and HTTP headers) for existing MDCs and attributes.
- Add MDCs/Markers + usage for invocation IDs, allowing call graphs to be built without reliance on heuristics.
- Revisiting persistence (a clear requirement) and rollover settings, based on feedback from operations.
- More discussion of How to Log. (Where previously guidelines were largely concerned with architecture and mechanics).
- Locking in other changes proposed in R1, including MDC serialization, escaping, etc. These can be treated as accepted. (Note that they only affect indexable output).
In addition, we expect to provide (as a Beijing deliverable) a minimal, synthetic component as an example of best-practices, and this will provide all code examples for this guide. (Does that mean the example will log via EELF, or will we end up with two variants?)