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Use a spring based Aspect library that emits Markers automatically around function calls and retrofit your code to log via Luke's SLF4J for internal log messages.
Logging Library Location and Use
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- By selection of a logging provider such as Logback or Log4j, typically via the classpath.
- By way of a provider configuration document, typically logback.xml or log4j.xml. See 71831691Providers.
SLF4J
SLF4J is a logging facade, and a humble masterpiece. It combines what's common to all major, modern Java logging providers into a single interface. This decouples the caller from the provider, and encourages the use of what's universal, familiar and proven.
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Logback is the most commonly used provider. It is generally configured by an XML document named logback.xml. See 71831691 Configuration.
See HELM template https://git.onap.org/logging-analytics/tree/reference/provider/helm/logback
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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 71831691 Configuration.
Log4j 1.X
Strongly 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/.
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This is the most important item of information in most log messages. See 71831691 General guidelines.
Internationalization
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if (logger.isDebugEnabled()) { logger.debug("But this WILL hurt: " + costlyToSerialize); } |
Parameterized logging is preferable.
Context
MDCs
A Mapped Diagnostic Context (MDC) allows an arbitrary string-valued attribute to be attached to a Java thread via a ThreadLocal variable. The MDC's value is then emitted with each message logged by that thread. The set of MDCs associated with a log message is serialized as unordered name-value pairs (see 71831691 Text Output).
A good discussion of MDCs can be found at https://logback.qos.ch/manual/mdc.html.
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Pipe Order | Name | Type | Group | Description | Applicable (per log file) | Marker Associations | Moved MDC to standard attribute | Removed (was in older spec) | Required? Y/N/C (C= context dependent) N = not required L=Library provided | Derived | Historical | Acumos ref | Use Cases | Code References |
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1 | LogTimestamp | log system | use %d field - see %d{"yyyy-MM-dd'T'HH:mm:ss.SSSXXX",UTC} | L | ||||||||||
2 | EntryTimestamp | MDC | if part of an ENTRY marker log | C | ||||||||||
3 | InvokeTimestamp | MDC | if part of an INVOKE marker log | C | ||||||||||
4 | RequestID | MDC | UUID to track the processing of each client request across all the ONAP components involved in its processing | Y | In general | |||||||||
5 | InvocationID | MDC | UUID correlates log entries relating to a single invocation of a single component | Y | ||||||||||
6 | InstanceID | MDC | UUID to differentiate between multiple instances of the same (named) log writing service/application | Y | was InstanceUUID | |||||||||
7 | ServiceInstanceID | MDC | C | |||||||||||
8 | thread | log system | use %thread field | L | ||||||||||
9 | ServiceName | The service inside the partner doing the call - includes API name | Y | |||||||||||
10 | PartnerName | The identification of the entity that made the request being served. For a serving API that is authenticating the request, this should be the authenticated username or equivalent (e.g. an attuid or a mechid) unauthenticated = The part of the URI specifying the agent that the caller used to make the call to the component that is logging the message. authenticated = userid
| Y | user | ||||||||||
11 | StatusCode | This field indicates the high level status of the request - one of (COMPLETE, ERROR, INPROGRESS) | Y | 20180807: expand from 2 fields to add "INPROGRESS" addresses Chris Lott question on https://wiki.acumos.org/display/OAM/Log+Standards | ||||||||||
12 | ResponseCode | This field contains application-specific error codes. | Y | |||||||||||
13 | ResponseDesc | This field contains a human readable description of the ResponseCode | Y | |||||||||||
14 | level | %level | L | |||||||||||
15 | Severity | Logging level by default aligned with the reported log level - one of INFO/TRACE/DEBUG/WARN/ERROR/FATAL | Y | level (but numbers) | ||||||||||
16 | ServerIPAddress | C | ||||||||||||
17 | ElapsedTime | C | ||||||||||||
18 | ServerFQDN | The VM FQDN if the server is virtualized. Otherwise the host name of the logging component. | Y | |||||||||||
19 | ClientIPAddress | This field contains the requesting remote client application’s IP address if known. Otherwise empty. | Y | |||||||||||
20 | VirtualServerName | C | ||||||||||||
21 | ContextName | C | ||||||||||||
22 | TargetEntity | 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. | C | |||||||||||
23 | TargetServiceName | The name of the API or operation activities invoked (name on the remote/target application) at the TargetEntity. | C | |||||||||||
24 | TargetElement | VNF/PNF context dependent - on CRUD operations of VNF/PNFs The IDs that need to be covered with the above Attributes are
| C | |||||||||||
25 | User | MDC | User - used for %X{user} | C | ||||||||||
26 | p_logger | log system | The name of the class doing the logging (in my case the ApplicationController – close to the targetservicename but at the class granular level - this field is %logger | L | ||||||||||
27 | p_mdc | log system | allows forward compatability with ELK indexers that read all MDCs in a single field - while maintaining separate MDCs above. The key/value pairs all in one pipe field (will have some duplications currently with MDC’s that are in their own pipe – but allows us to expand the MDC list – replaces customvalue1-3 older fields - this field is %mdc | L | ||||||||||
28 | p_message | log system | The marker labels INVOKE, ENTRY, EXIT – and later will also include DEBUG, AUDIT, METRICS, ERROR when we go to 1 log file - this field is %marker | L | ||||||||||
29 | p_marker | log system | The marker labels INVOKE, ENTRY, EXIT – and later will also include DEBUG, AUDIT, METRICS, ERROR when we go to 1 log file - this field is %marker | L |
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%replace(%replace(%mdc){'\t','\\\\t'}){'\n','\\\\n'} |
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This is often referred to by other names, including "Transaction ID", and one of several (pre-standardization) REST header names including X-TransactionID, X-ECOMP-TransactionID, X-ECOMP-RequestID and X-ONAP-RequestID.
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Used as valuable URI - to annnote invoke marker
Review in terms of 71831691 Marker-INVOKE - possiblly add INVOKE-return - to filter reporting
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Note there are 3 tabs (see p_mak in logback.xml) delimiting the MARKERS (ENTRY and EXIT) at the end of each line
<property name="p_mak" value="%replace(%replace(%marker){'\t', '\\\\t'}){'\n','\\\\n'}"/>
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2018-07-05T20:21:34.794Z http-nio-8080-exec-2 INFO org.onap.demo.logging.ApplicationService InstanceID=ede7dd52-91e8-45ce-9406-fbafd17a7d4c, RequestID=f9d8bb0f-4b4b-4700-9853-d3b79d861c5b, ServiceName=/logging-demo/rest/health/health, InvocationID=8f4c1f1d-5b32-4981-b658-e5992f28e6c8, InvokeTimestamp=2018-07-05T20:21:26.617Z, PartnerName=, ClientIPAddress=0:0:0:0:0:0:0:1, ServerFQDN=localhost ENTRY 2018-07-05T20:22:09.268Z http-nio-8080-exec-2 INFO org.onap.demo.logging.ApplicationService ResponseCode=, InstanceID=ede7dd52-91e8-45ce-9406-fbafd17a7d4c, RequestID=f9d8bb0f-4b4b-4700-9853-d3b79d861c5b, ServiceName=/logging-demo/rest/health/health, ResponseDescription=, InvocationID=8f4c1f1d-5b32-4981-b658-e5992f28e6c8, Severity=, InvokeTimestamp=2018-07-05T20:21:26.617Z, PartnerName=, ClientIPAddress=0:0:0:0:0:0:0:1, ServerFQDN=localhost, StatusCode= EXIT |
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- Choose a Logging provider and/or EELF. Decisions, decisions.
- Create a configuration file based on an existing archetype. See 71831691Configuration.
- Read your configuration file when your components initialize logging.
- Write logs to a standard location so that they can be shipped by Filebeat for indexing. See 71831691Output Location.
- Report transaction state:
- Retrieve, default and propagate RequestID. See 71831691 MDC - RequestID.
- At each invocation of one ONAP component by another:
- Initialize and propagate InvocationID. See 71831691 MDC - Invocation ID.
- Report INVOKE and SYNCHRONOUS markers in caller.
- Report ENTRY and EXIT markers in recipient.
- Write useful logs!
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