Configuration-based Java Trace SDK
TABLE OF CONTENTS
The configuration-based Java Trace SDK enables a declarative specification of spans, and tags they should carry, and creating them by executing certain methods of your application.
The expressiveness is comparable to that of the
SpanSupport.annotate() facilities of the
programmatic Java Trace SDK.
Before you implement custom tracing, please read the tracing best practices.
The configuration-based SDK is brittle against changes in your application. You may rename a class or a method, and all of a sudden the configuration does no longer match, and you lose your tracing data. Whenever possible, we advise to use the Java Trace SDK, which is far more resilient against code changes and has more features to help you accomplish your goals.
The configuration is specified in the
NOTE: Changes to the configuration of the configuration-based Java Trace SDK are automatically picked up by the Instana agent. Already instrumented applications need to be restarted to use the changed configuration.
NOTE: The configuration based Java Trace SDK is available in the Java Trace Sensor version
1.2.351 or above.
The following listing describes the general format of the configuration:
# Java Tracing com.instana.plugin.javatrace: instrumentation: sdk: targets: - match: type: 'interface'|'class'|'baseclass' name: '<type-name>' method: '<method-name>' [argumentTypes: - '<argument-type-index0>' - '<argument-type-indexn>'] [returnType: '<return-type-name>'] span: name: '<span-name>' [type: '<span-type>'] [stackDepth: <depth>] [tags: - kind: 'argument' name: 'name' index: 0 - kind: 'return' name: 'name' - kind: 'constant' name: 'name' value: 'constant-value']
Multiple targets can be defined within the
targets key, each of which specifies one span to be created.
match object of one
target specifies the method to apply the instrumentation to.
span object specifies how to build the span, including its name (which is used for example in Unbounded Analytics for the
call.name filter) and which tags should be set.
NOTE: Instrumenting interfaces or base classes may be very resource intensive, especially in applications using a lot of classes, and should be avoided if possible.
This object describes the code point at which an instrumentation should take place:
type: Type of the code to instrument; supported values:
class, match a concrete class
interface, match all classes implementing the interface
baseclass, match all classes extending the base class
name: Fully qualified name of the class, interface or base class to match
For nested classes, the notation
method: Name of the method of the given class, interface or base class of which an invocation should be recorded
argumentTypes: List of fully qualified argument types of the method to match (optional)
- If missing, arguments are not matched, and the instrumentation will be applied to all method in case of overloading
- If present, all arguments have to match the given types in order, otherwise the method will not match
returnType: Fully qualified returned type of the method to match (optional)
- If missing, return type is not considered
- If present, return type has to match the given type, otherwise the method will not match
This object describes properties of the span that will be created if the method described in
match is invoked:
name: Span name
type: Span type (optional); supported values:
ENTRY, used to indicate "incoming" calls from external systems
INTERMEDIATE, used to capture internal calls to "interesting" methods (default)
EXIT, used to indicate "outgoing" calls to external systems
stackDepth: Number of stack frames to capture of the method invocation (optional); default is
tags: List of tags/annotations to capture and how to obtain their values (optional); supported values:
constant, capture a constant value
name: Name of the tag to create
value: Constant value of the tag to create
return, capture the return value of the method invocation
name: Name of the tag to create; value will be the value of the returned object
argument, capture a specific argument value of the method invocation
name: Name of the tag to create
index: 0-based index of the argument to capture as value of the tag
NOTE: If the captured value is
Optional.empty the defined tag will not be added. Spans with missing tags can be looked up in Unbounded Analytics using the
is not present operator in conjunction with the
Throwable propagates outside of an instrumented method, the span will be automatically marked as erroneous, and the value of
Throwable#getMessage() will be set as the error message, which you can search in Unbounded Analytics via the
The following snippet shows an example configuration of how an application handling batch jobs could be traced:
com.instana.plugin.javatrace: instrumentation: sdk: targets: - match: type: class name: com.instana.java.sdk.BatchApplication method: processBatch span: name: Job type: ENTRY stackDepth: 2 tags: - kind: constant name: endpoint value: BatchJob - kind: argument name: batch.job index: 0 - match: type: class name: com.instana.java.sdk.BatchApplication method: updateDatabase span: name: DatabaseCall type: EXIT stackDepth: 2 tags: - kind: constant name: db.connection_string value: jdbc:mysql://127.0.0.1:3306/jobs - kind: argument name: db.statement index: 0
First the method
processBatch in class
com.instana.java.sdk.BatchApplication is instrumented to create entry spans with name
endpoint with the constant value
BatchJob, and the annotation
batch.job with the first argument as its value.
Furthermore, outgoing DB calls during the batch processing, that is invocations of method
updateDatabase in the same class,
will create exit spans with name
DatabaseCall and the annotation
db.connection_string with the constant value
jdbc:mysql://127.0.0.1:3306/jobs and annotation
db.statement with the first argument of the method invocation.
Processing a new batch with
processBatch will start a new trace and subsequent DB updates with
updateDatabase will be listed
as child spans within it. All Instana features, like Unbounded Analytics, can be used identically to traces created with
The following restrictions apply to the configuration-based Java Trace SDK:
- Instrumenting constructors is not supported.
- Starting a span in one method and closing it in another is not supported; that is, the configuration-based SDK has no equivalent for the
- Capturing all arguments or the return value without explicitly creating a
tagis not supported.
- Specifying placeholders in the argument list for unimportant arguments or "all the rest" is not supported; the arguments-based match is executed in a strict fashion.
- Specifying name patterns for classes or methods is not supported.
- Restoring a trace context before creating a span is not supported; that is, the configuration-based SDK does not have a capability equivalent to