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API reference

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API reference

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Although most usage is covered automatically, Elastic APM also has a public API that allows custom usage.

Agent life cycle

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Controlling when the agent starts and stops.

ElasticAPM.start

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To create and start an ElasticAPM agent use ElasticAPM.start:

ElasticAPM.start(server_url: 'http://localhost:8200')
  • config: An optional hash or ElasticAPM::Config instance with configuration options. See Configuration.

If you are using Ruby on Rails this is done automatically for you. If you choose not to require the elastic_apm gem and instead want to start the agent and hook into Rails manually, see hooking into Rails explicitly. If you’re not using Rails, see Getting started with Rack.

ElasticAPM.stop

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Stop the currently running agent. Use this inside at_exit in your Rack app to gracefully shut down.

ElasticAPM.running?

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Returns whether the ElasticAPM Agent is currently running.

ElasticAPM.agent

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Returns the currently running agent or nil.

Instrumentation

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ElasticAPM.current_transaction

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Returns the current ElasticAPM::Transaction or nil.

ElasticAPM.start_transaction

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Start a transaction eg. an incoming web request or a background job.

# call with block
ElasticAPM.start_transaction('Name')
do_work # ...
ElasticAPM.end_transaction('result')

Arguments:

  • name: A name for your transaction. Transactions are grouped by name. Required.
  • type: A type for your transaction eg. db.postgresql.sql.
  • context:: An optional Context used to enrich the transaction with information about the current request.
  • trace_context:: An optional TraceContext object for Distributed Tracing.

Returns the transaction.

ElasticAPM.end_transaction

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Ends the currently running transaction.

Arguments:

  • result: A String result of the transaction, eg. 'success'.

ElasticAPM.with_transaction

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Wrap a block in a Transaction, starting and ending around the block

ElasticAPM.with_transaction 'Do things' do |transaction|
  do_work # ...

  transaction.result = 'success'
end

Arguments:

  • name: A name for your transaction. Transactions are grouped by name. Required.
  • type: A type for your transaction eg. db.postgresql.sql.
  • context:: An optional Context used to enrich the transaction with information about the current request.
  • trace_context:: An optional TraceContext object for Distributed Tracing.
  • &block: A block to wrap. Optionally yields the transaction.

Returns the return value of the given block.

ElasticAPM.start_span

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Start a new span.

ElasticAPM.with_transaction 'Do things' do
  ElasticAPM.start_span 'Do one of the things'
  Database.query # ...
  ElasticAPM.end_span
end

Arguments:

  • name: A name for your span. Required.
  • type: The type of span eg. db.
  • subtype: The subtype of span eg. postgresql.
  • action: The action type of span eg. connect or query.
  • context: An instance of Span::Context.
  • include_stacktrace: Whether or not to collect a Stacktrace.
  • &block: An optional block to wrap with the span. The block is passed the span as an optional argument.

Returns the created span.

ElasticAPM.end_span

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Ends the currently running span.

ElasticAPM.with_span

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Wraps a block in a Span.

Arguments:

  • name: A name for your span. Required.
  • type: The type of span eg. db.
  • subtype: The subtype of span eg. postgresql.
  • action: The action type of span eg. connect or query.
  • context: An instance of Span::Context.
  • include_stacktrace: Whether or not to collect a Stacktrace.
  • &block: An optional block to wrap with the span. The block is passed the span as an optional argument.

Returns the return value of the given block.

ElasticAPM.build_context

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Build a new Context from a Rack env.

A context provides information about the current request, response, user and more.

Arguments:

  • rack_env: An instance of Rack::Env
  • for_type: Symbol representing type of event, eg. :transaction or error

Returns the built context.

Manually hooking into Rails

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Start the agent and hook into Rails explicitly. This is useful if you skip requiring the gem and using the Railtie.

ElasticAPM::Rails.start(server_url: 'http://localhost:8200')

Errors

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ElasticAPM.report

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Send an Exception to Elastic APM.

If reported inside a transaction, the context from that will be added.

begin
  do_a_thing_and_fail
rescue Exception => e
  ElasticAPM.report(e)
end

Arguments:

  • exception: An instance of Exception. Required.
  • handled: Whether the error was handled eg. wasn’t rescued and was represented to the user. Default: true.

Returns [String] ID of the generated [ElasticAPM::Error] object.

ElasticAPM.report_message

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Send a custom message to Elastic APM.

If reported inside a transaction, the context from that will be added.

ElasticAPM.report_message('This should probably never happen?!')

Arguments:

  • message: A custom error string. Required.

Returns [String] ID of the generated [ElasticAPM::Error] object.

Context

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ElasticAPM.set_tag

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Add a tag to the current transaction. Tags are basic key-value pairs that are indexed in your Elasticsearch database and therefore searchable. The value will always be converted to a String.

Before using custom tags, ensure you understand the different types of metadata that are available.

before_action do
  ElasticAPM.set_tag(:company_id, current_user.company.id)
end

Arguments:

  • key: A string key. Note that ., * or " will be converted to _.
  • value: A string value.

Returns the set value.

Be aware that tags are indexed in Elasticsearch. Using too many unique keys will result in Mapping explosion.

This method has been deprecated in favor of set_label, which does not convert values to Strings.

ElasticAPM.set_label

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Add a label to the current transaction. Labels are basic key-value pairs that are indexed in your Elasticsearch database and therefore searchable. The value can be a string, nil, numeric or boolean.

Before using custom labels, ensure you understand the different types of metadata that are available.

before_action do
  ElasticAPM.set_label(:company_id, current_user.company.id)
end

Arguments:

  • key: A string key. Note that ., * or " will be converted to _.
  • value: A value.

Returns the set value.

Be aware that labels are indexed in Elasticsearch. Using too many unique keys will result in Mapping explosion.

ElasticAPM.set_custom_context

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Add custom context to the current transaction. Use this to further specify a context that will help you track or diagnose what’s going on inside your app.

Before using custom context, ensure you understand the different types of metadata that are available.

If called several times during a transaction the custom context will be destructively merged with merge!.

before_action do
  ElasticAPM.set_custom_context(company: current_user.company.to_h)
end

Arguments:

  • context: A hash of JSON-compatible key-values. Can be nested.

Returns current custom context.

ElasticAPM.set_user

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Add the current user to the current transaction’s context.

Arguments:

  • user: An object representing the user

Returns the given user

Data

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ElasticAPM.add_filter

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Provide a filter to transform payloads before sending.

Arguments:

  • key: A unique key identifying the filter
  • callable: An object or proc (responds to .call(payload))

Return the altered payload.

If nil is returned all subsequent filters will be skipped and the post request cancelled.

Example:

ElasticAPM.add_filter(:filter_pings) do |payload|
  payload[:transactions]&.reject! do |t|
    t[:name] == 'PingsController#index'
  end
  payload
end

Transaction

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ElasticAPM.transaction returns a Transaction (if the agent is running).

Properties

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  • name: String
  • type: String
  • result: String
  • trace_id: String (readonly)

#sampled?

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Whether the transaction is sampled eg. it includes stacktraces for its spans.

#ensure_parent_id

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If the transaction does not have a parent-ID yet, calling this method generates a new ID, sets it as the parent-ID of this transaction, and returns it as a String.

This enables the correlation of the spans the JavaScript Real User Monitoring (RUM) agent creates for the initial page load with the transaction of the backend service.

If your service generates the HTML page dynamically, initializing the JavaScript RUM agent with the value of this method allows analyzing the time spent in the browser vs in the backend services.

To enable the JavaScript RUM agent, initilialize the RUM agent with the Ruby agent’a current transaction:

<script src="elastic-apm-js-base/dist/bundles/elastic-apm-js-base.umd.min.js"></script>
<script>
  var elasticApm = initApm({
    serviceName: '',
    serverUrl: 'http://localhost:8200',
    pageLoadTraceId: "<%= ElasticAPM.current_transaction&.trace_id %>",
    pageLoadSpanId: "<%= ElasticAPM.current_transaction&.ensure_parent_id %>",
    pageLoadSampled: <%= ElasticAPM.current_transaction&.sampled? %>
  })
</script>

See the JavaScript RUM agent documentation for more information.

Span

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Properties

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  • name: String
  • type: String
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