End User Monitoring Server · inspectIT Ocelot Documentation

This server provides Enduser Monitoring data by using the OpenCensus toolkit.

Metrics

The Ocelot EUM server offers a backend for Javascript monitoring with Boomerang. Boomerang is a Javascript metrics agent, which is able to capture arbitrary customizable metrics.

For testing purposes, you can inject the following snipped in your webpage. This snippet loads the boomerang version shipped with the Ocelot server and sends all measured metrics back to it:

 <script src="http://[inspectit-eum-server-url]/boomerang/boomerang.js"></script>
 <script src="http://[inspectit-eum-server-url]/boomerang/plugins/rt.js"></script>
 <!-- any other plugins you want to include -->
 <script>
   BOOMR.init({
     beacon_url: "http://[inspectit-eum-server-url]:8080/beacon/"
   });
 </script>

All boomerang-specific scripts are exposed by the eum server under http://{eum-server}/boomerang/**.

You can access the boomerang main script under: http://[inspectit-eum-server-url]/boomerang/boomerang.js. All boomerang plugins can be downloaded under http://[inspectit-eum-server-url]/boomerang/plugins/{plugin_name}.js. The list of available plugins can be found here.

Note that this approach is not recommended for production use as the scripts are not minified and are loaded synchronously.

Boomerang recommends that you use a minified JS containing all your plugins. In addition you should use asynchronous injection as described in the Boomerang documentation.

If enabled, the server exposes the metrics by using the Prometheus exporter. A tutorial on how to install Prometheus can be found here.

Server Setup

Before starting the server, please build the server by cloning the repository and executing the following command or download the latest release.

$ ./gradlew build

Start the server with the following command:

$ java -jar inspectit-ocelot-eum-{version}.jar

By default, the server is starting with the port 8080. You can simply configure the port by using the Java property -Dserver.port=[port]:

$ java -Dserver.port=[port] -jar inspectit-ocelot-eum-0.0.1-SNAPSHOT.jar

Our server is delivered with a default configuration supporting the metrics t_page, t_done, rt.tstart, rt.nstart and rt.end of the Boomerang plugin RT. In order to provide a custom configuration, please set the Java property -Dspring.config.location=file:[path-to-config]:

$ java -Dserver.port=[port] -Dspring.config.location=file:[path-to-config] -jar inspectit-ocelot-eum-0.0.1-SNAPSHOT.jar

Configuration

The configuration file defines the mapping between the concrete Boomerang metric and a OpenCensus metric, as the following sample configuration file shows:

inspectit-eum-server:
  definitions:
     page_ready_time:
      measure-type: LONG
      value-expression: "{t_page}"
      unit: ms
      views:
        '[page_ready_time/SUM]': {aggregation: SUM}
        '[page_ready_time/COUNT]': {aggregation: COUNT}

    load_time:
      measure-type: LONG
      value-expression: "{t_done}"
      beacon-requirements:
        - field: rt.quit
          requirement: NOT_EXISTS
      unit: ms
      views:
        '[load_time/SUM]': {aggregation: SUM}
        '[load_time/COUNT]': {aggregation: COUNT}

    calc_load_time:
      measure-type: LONG
      value-expression: "{rt.end} - {rt.tstart}"
      beacon-requirements:
        - field: rt.quit
          requirement: NOT_EXISTS
      unit: ms
      views:
        '[calc_load_time/SUM]': {aggregation: SUM}
        '[calc_load_time/COUNT]': {aggregation: COUNT}

    start_timestamp:
      measure-type: LONG
      value-expression: "{rt.tstart}"
      unit: ms

    navigation_start_timestamp:
      measure-type: LONG
      value-expression: "{rt.nstart}"
      unit: ms

    end_timestamp:
      measure-type: LONG
      value-expression: "{rt.end}"
      unit: ms
      views:
        end_timestamp:
          aggregation: LAST_VALUE
          tags: {APPLICATION: true}

  tags:
    extra:
      APPLICATION: my-application
    
    beacon:
      URL: u
      OS: ua.plt
    
    define-as-global:
      - URL
      - OS
      - COUNTRY_CODE
    
    custom-ip-mapping:
      department-1:
        - 10.10.0.0/16
        - 11.11.0.3
      department-2:
        - 14.14.0.0/16
        - 14.15.0.1
  exporters:
    metrics:
      prometheus:
        enabled: true
        host: localhost
        port: 8888

Metrics Definition

A metric is defined the same way as in the inspectIT Ocelot Java agent. Please see the section Metrics / Custom Metrics for detailed information.

In contrast to the agent's metric definition, the EUM server's metric definition contains additional fields. These additional fields are the following:

Attributes	Note
`value-expression`	An expression used to calculate the measure's value from a beacon.
`beacon-requirements`	Requirements which have to be fulfilled by Beacons. Beacons which do not match all requirements will be ignored by this metric definition.

Value Expressions

The value-expression field can be used to specify a field which value is used for the specified metrics. In order to reference a field, the following pattern is used: {FIELD_KEY}. For example, a valid expression, used to extract the value of a field t_load, would be {t_load}.

Note that a beacon has to contain all fields referenced by the expression in order to be evaluated and recorded.

Value expressions also support operations for basic arithmetic operations. Thus, to calculate a difference of two beacon fields, the following expression can be used:

  ...
    my-metric:
      ...
      value-expression: "{field.a} - {field.b}"
      ...

Value expression are supporting the following operations:

addition
subtraction
multiplication
division
unary plus/minus
parentheses

Using the operations above, complex calculations can be done, for example:

  ...
    my-metric:
      ...
      value-expression: "- {field.c} * ({field.a} - {field.b}) / {field.a}"
      ...

Beacon Requirements

The beacon-requirements field can be used to specify requirements which have to be fulfilled by the beacons in order to be evaluated by a certain metric. If any requirement does not fit a beacon, the beacon is ignored by the metric.

Beacon requirements consist of two attributes field and requirement. field specified the beacon's field which is validated using the requirement type specified in NOT_EXISTS.

  ...
    my-metric:
      ...
      beacon-requirements:
        - field: rt.quit
          requirement: NOT_EXISTS

The following requirement types are currently be supported:

Type	Note
`EXISTS`	The targeted field must exist.
`NOT_EXISTS`	The targeted field must not exist.

Tags Definition

We distinguish between to different types of tags:

Attributes	Note
`extra`	Extra tags define tags, which are manually set in the configuration and can be considered as constants.
`beacon`	Beacon tags define tags, whose value is resolved by an incoming beacon entry.

For example, the following configuration specifies the two tags APP and URL. The tag APP will always be resolved to the value my-application, where the tag URL will be resolved to the value of the field u of a received beacon.

inspectit-eum-server:
  tags:
    extra:
      APP: my-application
    beacon:
      URL: u

Additional Tags

The EUM server provides a set of additional tags which can be used like all other tags. Currently, the following tags exist:

Tag	Description
`COUNTRY_CODE`	Contains the geolocation of the beacon's origin. It is resolved by using the client IP and the GeoLite2 database. If the IP cannot be resolved, the tag value will be empty.
`U_NO_QUERY`	The Boomerang u property but without query parameters. Check out Boomerang.
`PGU_NO_QUERY`	The Boomerang pgu property but without query parameters. Check out Boomerang.

Custom COUNTRY_CODE Mapping

Besides using the internal GeoLite2 database, it is possible to define custom IP mappings. The property custom-ip-mapping holds a map of possible tag values, which are mapped to certain IPs or CIDRs. The tag values are published with the tag COUNTRY_CODE and have a higher priority than the results of the GeoLite2 database. If the IP cannot be resolved with the custom mapping, the mapping of the GeoLite2 database will be used.

inspectit-eum-server:
  tags:
    custom-ip-mapping:
      department-1:
        - 10.10.0.0/16
        - 11.11.0.3
      department-2:
        - 14.14.0.0/16
        - 14.15.0.1

Global Tags

Tags will not be attached to metrics unless a metric explicitly defines to use a certain tag.

In order to simplify the configuration, it is possible to define tags which are always attached to metrics, even a metric does not explicitly specifies it. This can be achieved by adding a tag's name to the define-as-global property. Each tag which is listed under this property will be added to each registered metric.

For example, the following configuration causes that each metric will be enriched by a tag called COUNTRY_CODE.

inspectit-eum-server:
  tags:
    define-as-global:
      - COUNTRY_CODE

Exporters

By now, the prometheus exporter is available. If enabled is set to true, the exporter is exposes the metrics under the following HTTP endpoint: http://[host]:[port]/metrics

Self-Monitoring

For the purpose of self-monitoring, the EUM server offers a set of metrics that reflect its state. These metrics are exposed using its Prometheus endpoint which also is used for the EUM beacon data. Currently, the following self monitoring metrics are available.

Metric name	Description
`beacons_received`	Counts the number of received beacons