= Vert.x Micrometer Metrics

This project is an implementation of the Vert.x Metrics Service Provider Interface (SPI).
It uses link:http://micrometer.io/[Micrometer] for managing metrics and reporting to several backends.

== Features

* Vert.x core tools monitoring: TCP/HTTP client and servers, {@link io.vertx.core.datagram.DatagramSocket}
, {@link io.vertx.core.eventbus.EventBus} and pools
* User defined metrics through Micrometer
* Reporting to any backend supported by Micrometer
* Built-in options for https://www.influxdata.com/[InfluxDB], https://prometheus.io/[Prometheus] and JMX reporting.

== InfluxDB

=== Prerequisites

Follow the https://docs.influxdata.com/influxdb/latest/introduction/getting_started/[instructions to get InfluxDb up and running].

=== Getting started

The modules _vertx-micrometer-metrics_ and _micrometer-registry-influx_ must be present in the classpath.

Maven users should add this to their project POM file:

[source,xml,subs="+attributes"]
----
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-micrometer-metrics</artifactId>
  <version>${maven.version}</version>
</dependency>
<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-influx</artifactId>
  <version>${micrometer.version}</version>
</dependency>
----

And Gradle users, to their build file:

[source,groovy,subs="+attributes"]
----
compile 'io.vertx:vertx-micrometer-metrics:${maven.version}'
compile 'io.micrometer:micrometer-registry-influx:${micrometer.version}'
----

=== Configuration examples

Vert.x does not enable SPI implementations by default. You must enable metric collection in the Vert.x options.

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupMinimalInfluxDB()}
----

==== Using a specific URI and database name

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupInfluxDBWithUriAndDatabase()}
----

==== With authentication

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupInfluxDBWithAuthentication()}
----

== Prometheus

=== Prerequisites

Follow the https://prometheus.io/docs/prometheus/latest/getting_started/[instructions to get Prometheus up and running].

=== Getting started

The modules _vertx-micrometer-metrics_ and _micrometer-registry-prometheus_ must be present in the classpath.
You may also probably need _vertx-web_, to expose the metrics.

Maven users should add this to their project POM file:

[source,xml,subs="+attributes"]
----
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-micrometer-metrics</artifactId>
  <version>${maven.version}</version>
</dependency>
<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-prometheus</artifactId>
  <version>${micrometer.version}</version>
</dependency>
----

And Gradle users, to their build file:

[source,groovy,subs="+attributes"]
----
compile 'io.vertx:vertx-micrometer-metrics:${maven.version}'
compile 'io.micrometer:micrometer-registry-prometheus:${micrometer.version}'
----

=== Configuration examples

Vert.x does not enable SPI implementations by default. You must enable metric collection in the Vert.x options

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupMinimalPrometheus()}
----

==== Using an embedded HTTP server with custom endpoint

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupPrometheusEmbeddedServer()}
----

If the embedded server endpoint is not specified, it defaults to _/metrics_.

==== Binding metrics to an existing Vert.x Web router

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupPrometheusBoundRouter()}
----

== JMX

=== Getting started

The modules _vertx-micrometer-metrics_ and _micrometer-registry-jmx_ must be present in the classpath.

Maven users should add this to their project POM file:

[source,xml,subs="+attributes"]
----
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-micrometer-metrics</artifactId>
  <version>${maven.version}</version>
</dependency>
<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-jmx</artifactId>
  <version>${micrometer.version}</version>
</dependency>
----

And Gradle users, to their build file:

[source,groovy,subs="+attributes"]
----
compile 'io.vertx:vertx-micrometer-metrics:${maven.version}'
compile 'io.micrometer:micrometer-registry-jmx:${micrometer.version}'
----

=== Configuration examples

Vert.x does not enable SPI implementations by default. You must enable metric collection in the Vert.x options

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupMinimalJMX()}
----

==== With step and domain

In Micrometer, `step` refers to the reporting period, in seconds. `domain` is the JMX domain under which
MBeans are registered.

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupJMXWithStepAndDomain()}
----

== Other backends or combinations

Even if not all backends supported by Micrometer are implemented in Vert.x options, it is still possible
to create any Micrometer registry and pass it to Vert.x.

The list of available backends includes Graphite, Ganglia, Atlas, link:http://micrometer.io/docs[etc].
It also enables the link:http://micrometer.io/docs/concepts#_composite_registries[Micrometer Composite Registry]
in order to report the same metrics to multiple backends.

In this example, metrics are reported both for JMX and Graphite:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupWithCompositeRegistry()}
----

== Advanced usage

Please refer to {@link io.vertx.micrometer.MicrometerMetricsOptions} for an exhaustive list of options.

=== Averages and quantiles in Prometheus

By default, when using the Prometheus registry, histogram-kind metrics will not contain averages or quantile stats.

Averages don't come out of the box but they are typically link:https://prometheus.io/docs/practices/histograms/#count-and-sum-of-observations[computed at query time],
with `promql`. Example, for HTTP client response time average during the last 5 minutes:

[source]
----
  rate(vertx_http_client_response_time_seconds_sum[5m])
/
  rate(vertx_http_client_response_time_seconds_count[5m])
----

To compute quantiles, there are two options available. The first is to activate quantile stats globally
and make them usable for Prometheus function `histogram_quantile`:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#enableQuantiles()}
----

And then, for example the `promql` query for the HTTP client response time, 99th percentile over the last 5 minutes:
[source]
----
  histogram_quantile(0.99, sum(rate(vertx_http_client_response_time_seconds_bucket[5m])) by (le))
----

The advantage of this option is that it can be leveraged in `promql`, aggregable across dimensions.
The downside is that it creates a lot of timeseries for stats under the hood.

The second option is to create limited stats, non-aggregable across dimensions.
It requires to access directly the Micrometer / Prometheus registry:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#enableLimitedQuantiles()}
----

See also, more on histograms and percentiles:

* from link:https://micrometer.io/docs/concepts#_histograms_and_percentiles[Micrometer doc]
* from link:https://prometheus.io/docs/prometheus/latest/querying/functions/#histogram_quantile[Prometheus doc]

Furthermore, you can check some link:https://github.com/vert-x3/vertx-examples/tree/master/micrometer-metrics-examples[full working examples].
They come along with few instructions to setup with Prometheus and view dashboards in Grafana.

=== Disable some metric domains

Restricting the Vert.x modules being monitored can be done using
{@link io.vertx.micrometer.MicrometerMetricsOptions#disabledMetricsCategories}.

For a full list of domains, see {@link io.vertx.micrometer.MetricsDomain}

=== User-defined metrics

The Micrometer registries are accessible, in order to create new metrics or fetch the existing ones.
By default, an unique registry is used and will be shared across the Vert.x instances of the JVM:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#accessDefaultRegistry()}
----

It is also possible to have separate registries per Vertx instance, by giving a registry name in metrics options.
Then it can be retrieved specifically:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupAndAccessCustomRegistry()}
----

As an example, here is a custom timer that will track the execution time of a piece of code that is regularly called:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#customTimerExample()}
----

For more examples, documentation about the Micrometer registry and how to create metrics, check
link:http://micrometer.io/docs/concepts#_registry[Micrometer doc].

=== Reusing an existing registry

It is possible to reuse an existing Micrometer registry (or `CollectorRegistry` from the Prometheus Java client),
and inject it into the Vert.x metrics options:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#useExistingRegistry()}
----

=== JVM or other instrumentations

Since plain access to Micrometer registries is provided, it is possible to leverage the Micrometer API.
For instance, to instrument the JVM:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#instrumentJVM()}
----

_From link:http://micrometer.io/docs/ref/jvm[Micrometer documentation]._

=== Metric names

Each metric that Vert.x provides can be renamed through the metrics options, using
{@link io.vertx.micrometer.MetricsNaming} and {@link io.vertx.micrometer.MicrometerMetricsOptions#setMetricsNaming}.
The default metric names were changed in Vert.x 4 to better align with backend conventions, but it is
still possible to retrieve the names used in Vert.x 3.x for compatibility:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#useV3CompatNames()}
----

=== Labels and matchers

Vert.x Micrometer Metrics defines a set of labels (aka tags or fields) that are used to provide dimensionality
to a metric. For instance, metrics related to event bus messages have an _address_ label, which allows then to query
timeseries for a specific event bus address, or compare timeseries per address, or perform any kind of aggregation
that the query API allows.

While setting up metrics options, you can specify which labels you want to enable or not:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupWithLabelsEnabled()}
----

The full list of labels is detailed here: {@link io.vertx.micrometer.Label}.

WARNING: Enabling labels may result in a high cardinality in values, which can cause troubles on the metrics backend and affect performances.
So it must be used with care.
In general, it is fine to enable labels when the set of possible values is bounded.

For that reason, labels enabled by default are restricted to the ones with known bounded values.

It is possible to interact with labels further than just enabling/disabling. There are two ways for that:

==== Using Matchers

{@link io.vertx.micrometer.Match}  objects can be used to filter or rename some label value
by matching it with either an exact string or a regular expression (the former being more efficient).

Here is an example to restrict HTTP server metrics to those with label _local=localhost:8080_ only:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#setupWithMatcherForFiltering()}
----

When an _alias_ is specified in the Match, it will be used to rename value instead of filtering.

Matchers are especially useful to control labelling through configuration as they are set via
{@link io.vertx.micrometer.MicrometerMetricsOptions}.

==== Using Micrometer's MeterFilter

Micrometer's link:http://micrometer.io/docs/concepts#_meter_filters[MeterFilter API] can be accessed directly in order to define rules on labels.
Compared to Matchers, it offers more features in manipulating the labels, but cannot be defined from configuration.
So both have their advantages.

Here is an example to replace the actual `path` label of HTTP requests with a generic form using regex:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#useMicrometerFilters()}
----

NOTE: Matchers use MeterFilters under the hood.

=== Custom tags provider

You can define a function that generates additional tags (or labels) for HTTP server or client metrics.
Such function takes an {@link io.vertx.core.spi.observability.HttpRequest} object as a parameter, and returns
an Iterable of {@link io.micrometer.core.instrument.Tag}.

As an example, here is how to map the _x-user_ header to a custom label _user_ in both server and client metrics:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#useCustomTagsProvider()}
----

=== Snapshots

A {@link io.vertx.micrometer.MetricsService} can be created out of a {@link io.vertx.core.metrics.Measured} object
in order to take a snapshot of its related metrics and measurements.
The snapshot is returned as a {@link io.vertx.core.json.JsonObject}.

A well known _Measured_ object is simply {@link io.vertx.core.Vertx}:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#createFullSnapshot()}
----

Other components, such as an {@link io.vertx.core.eventbus.EventBus} or a {@link io.vertx.core.http.HttpServer} are
measurable:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#createPartialSnapshot()}
----

Finally it is possible to filter the returned metrics from their base names:

[source,$lang]
----
{@link examples.MicrometerMetricsExamples#createSnapshotFromPrefix()}
----

== Vert.x core tools metrics

This section lists all the metrics generated by monitoring the Vert.x core tools.

NOTE: The metric backends may have different conventions or rules for naming metrics.
The names described below are the default ones used in Vert.x 4, using underscore separators.
The actual names may vary depending on the metrics backend.

=== Net Client

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_net_client_bytes_read`
|`local`, `remote`
|Counter
|Number of bytes received from the remote host.

|`vertx_net_client_bytes_written`
|`local`, `remote`
|Counter
|Number of bytes sent to the remote host.

|`vertx_net_client_active_connections`
|`local`, `remote`
|Gauge
|Number of connections to the remote host currently opened.

|`vertx_net_client_errors`
|`local`, `remote`, `class`
|Counter
|Number of errors.

|===

=== HTTP Client

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_http_client_bytes_read`
|`local`, `remote`
|Counter
|Number of bytes received from the remote host.

|`vertx_http_client_bytes_written`
|`local`, `remote`
|Counter
|Number of bytes sent to the remote host.

|`vertx_http_client_active_connections`
|`local`, `remote`
|Gauge
|Number of connections to the remote host currently opened.

|`vertx_http_client_errors`
|`local`, `remote`, `class`
|Counter
|Number of errors.

|`vertx_http_client_queue_time_seconds`
|`local`, `remote`
|Timer
|Time spent in queue before being processed, in seconds.

|`vertx_http_client_queue_pending`
|`local`, `remote`
|Gauge
|Number of pending elements in queue.

|`vertx_http_client_active_requests`
|`local`, `remote`, `path`, `method`
|Gauge
|Number of requests being processed, waiting for a response.

|`vertx_http_client_requests_total`
|`local`, `remote`, `path`, `method`
|Counter
|Number of requests sent.

|`vertx_http_client_request_bytes`
|`local`, `remote`, `path`, `method`
|Summary
|Size in bytes of the requests.

|`vertx_http_client_response_time_seconds`
|`local`, `remote`, `path`, `method`, `code`
|Timer
|Response time in seconds.

|`vertx_http_client_responses_total`
|`local`, `remote`, `path`, `method`, `code`
|Counter
|Number of received responses.

|`vertx_http_client_response_bytes`
|`local`, `remote`, `path`, `method`, `code`
|Summary
|Size in bytes of the responses.

|`vertx_http_client_active_ws_connections`
|`local`, `remote`
|Gauge
|Number of websockets currently opened.

|===

=== Net Server

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_net_server_bytes_read`
|`local`, `remote`
|Counter
|Number of bytes received by the Net Server.

|`vertx_net_server_bytes_written`
|`local`, `remote`
|Counter
|Number of bytes sent by the Net Server.

|`vertx_net_server_active_connections`
|`local`, `remote`
|Gauge
|Number of opened connections to the Net Server.

|`vertx_net_server_errors`
|`local`, `remote`, `class`
|Counter
|Number of errors.

|===

=== HTTP Server

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_http_server_bytes_read`
|`local`, `remote`
|Counter
|Number of bytes received by the HTTP Server.

|`vertx_http_server_bytes_written`
|`local`, `remote`
|Counter
|Number of bytes sent by the HTTP Server.

|`vertx_http_server_active_connections`
|`local`, `remote`
|Gauge
|Number of opened connections to the HTTP Server.

|`vertx_http_server_errors`
|`local`, `remote`, `class`
|Counter
|Number of errors.

|`vertx_http_server_active_requests`
|`local`, `remote`, `path`, `method`
|Gauge
|Number of requests being processed.

|`vertx_http_server_requests_total`
|`local`, `remote`, `path`, `method`, `code`, `route`
|Counter
|Number of processed requests.

|`vertx_http_server_request_resets_total`
|`local`, `remote`, `path`, `method`
|Counter
|Number of request resets.

|`vertx_http_server_request_bytes`
|`local`, `remote`, `path`, `method`
|Summary
|Size in bytes of the requests.

|`vertx_http_server_response_time_seconds`
|`local`, `remote`, `path`, `method`, `code`, `route`
|Timer
|Request processing time in seconds.

|`vertx_http_server_response_bytes`
|`local`, `remote`, `path`, `method`, `code`, `route`
|Summary
|Size in bytes of the responses.

|`vertx_http_client_active_ws_connections`
|`local`, `remote`
|Gauge
|Number of websockets currently opened.

|===

=== Datagram socket

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_datagram_bytes_read`
|`local`
|Summary
|Total number of bytes received on the `<host>:<port>` listening address.

|`vertx_datagram_bytes_written`
|(none)
|Summary
|Total number of bytes sent to the remote host.

|`vertx_datagram_errors`
|`class`
|Counter
|Total number of errors.

|===

=== Event Bus

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_eventbus_bytes_read`
|`address`
|Summary
|Total number of bytes received while reading messages from event bus cluster peers.

|`vertx_eventbus_bytes_written`
|`address`
|Summary
|Total number of bytes sent while sending messages to event bus cluster peers.

|`vertx_eventbus_handlers`
|`address`
|Gauge
|Number of event bus handlers in use.

|`vertx_eventbus_pending`
|`address`,`side` (local/remote)
|Gauge
|Number of messages not processed yet. One message published will count for `N` pending if `N` handlers
are registered to the corresponding address.

|`vertx_eventbus_processed`
|`address`,`side` (local/remote)
|Counter
|Number of processed messages.

|`vertx_eventbus_published`
|`address`,`side` (local/remote)
|Counter
|Number of messages published (publish / subscribe).

|`vertx_eventbus_discarded`
|`address`,`side` (local/remote)
|Counter
|Number of discarded messages (e.g. still pending messages while handler is unregistered, or overflowing messages).

|`vertx_eventbus_sent`
|`address`,`side` (local/remote)
|Counter
|Number of messages sent (point-to-point).

|`vertx_eventbus_received`
|`address`,`side` (local/remote)
|Counter
|Number of messages received.

|`vertx_eventbus_delivered`
|`address`,`side` (local/remote)
|Counter
|Number of messages delivered to handlers.

|`vertx_eventbus_reply_failures`
|`address`,`failure`
|Counter
|Number of message reply failures.

|===

== Vert.x pool metrics

This section lists all the metrics generated by monitoring Vert.x pools.

There are two types currently supported:

* _worker_ (see {@link io.vertx.core.WorkerExecutor})
* _datasource_ (created with Vert.x JDBC client)

NOTE: Vert.x creates two worker pools upfront, _worker-thread_ and _internal-blocking_.

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_pool_queue_time_seconds`
|`pool_type`,`pool_name`
|Timer
|Time spent in queue before being processed, in seconds.

|`vertx_pool_queue_pending`
|`pool_type`,`pool_name`
|Gauge
|Number of pending elements in queue.

|`vertx_pool_usage`
|`pool_type`,`pool_name`
|Timer
|Time using a resource (i.e. processing time for worker pools).

|`vertx_pool_in_use`
|`pool_type`,`pool_name`
|Gauge
|Number of resources used.

|`vertx_pool_completed`
|`pool_type`,`pool_name`
|Counter
|Number of elements done with the resource (i.e. total number of tasks executed for worker pools).

|`vertx_pool_ratio`
|`pool_type`,`pool_name`
|Gauge
|Pool usage ratio, only present if maximum pool size could be determined.

|===

== Other clients

Vert.x clients, other than the core HTTP / Net clients, may implement a standard set of client metrics. This is the case, for instance, of the SQL client.

Such client metrics are named after a "client type" identifier, displayed as `$TYPE` in the table below.
For instance, `vertx_$TYPE_queue_pending` is `vertx_sql_queue_pending` for the SQL client.

The meaning of the `namespace` label is left to the discretion of the client implementation.

[cols="35,20,10,35", options="header"]
|===
|Metric name
|Labels
|Type
|Description

|`vertx_$TYPE_queue_pending`
|`remote`, `namespace`
|Gauge
|Number of pending elements in queue.

|`vertx_$TYPE_queue_time_seconds`
|`remote`, `namespace`
|Timer
|Time spent in queue before being processed, in seconds.

|`vertx_$TYPE_processing_pending`
|`remote`, `namespace`
|Gauge
|Number of elements being processed.

|`vertx_$TYPE_processing_time_seconds`
|`remote`, `namespace`
|Timer
|Processing time, from request start to response end, in seconds.

|`vertx_$TYPE_resets_total`
|`remote`, `namespace`
|Counter
|Total number of resets.

|===
