# Python Agent how to track various counters/values evolution over time?

**URL:** <https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176>\
**Category:** APM\
**Tags:** python\
**Created:** [November 24, 2019, 11:13am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176 "2019-11-24T11:13:17Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![AlexRa](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@AlexRa](https://discuss.elastic.co/u/AlexRa)\
**Post date:** [November 24, 2019, 11:13am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/1 "2019-11-24T11:13:17Z")

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I'm really new to APM & Kibana, but ok with Python & ElasticSearch, so forgive me my question seems stupid. Before I had Graphite and it was quite easy to do custom tracking.

I'm looking to track 3 simple custom metrics and their evolution over time.

1. Counter and it's value. For example **queue\_size: 23** and send it by any of the workers. What happens when different workers send different values? (because of the time, the value might increase/decrease rapidly).  
I do have 20 names of queues to track. Should I put all under a service\_name or should I use labels?  
Before I used:  
self.\_graphite.gauge("service.queuesize", 3322)  
No idea what to have here:  
....

2. Time spent within a method. I saw here it's possible to have a context manager.  
Before I had:  
with self.\_graphite.timer("service.action")  
Will become  
with elasticapm.capture\_span('service.action')

3. Number of requests. (only count no other tracking)  
Before I had  
self.\_graphite.incr("service.incoming\_requests")  
Is this correct?  
client.begin\_transaction('processors')  
client.end\_transaction('processors')  
...

THanks a lot!

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<div class="post-metadata">

**Author:** ![axw](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/axw/32/28197_2.png) [@axw](https://discuss.elastic.co/u/axw)\
**Post date:** [November 25, 2019, 1:41am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/2 "2019-11-25T01:41:05Z")

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Hi @AlexRa, welcome to the forum!

> Counter and it's value. For example **queue\_size: 23** and send it by any of the workers

How are you tracking the queue size? Is this something periodic, i.e. every 30 seconds the worker will query and report the queue size? Or are the changes associated with each request?

Custom periodic metrics aren't currently supported by the Python agent, but may be in the future. If it's a number that you can attach to a transaction, then you could label the transaction with the value: [API reference | APM Python Agent Reference [6.x] | Elastic](https://www.elastic.co/guide/en/apm/agent/python/current/api.html#api-label)

For what it's worth, I'd use a separate "queue\_name" label so you can perform aggregations over it like "top 5 queues by size".

> Time spent within a method. I saw here it's possible to have a context manager.

That's right, assuming that a transaction is in progress (i.e. `begin_transaction` was called) within the active context.

Note that [capture\_span](https://www.elastic.co/guide/en/apm/agent/python/current/api.html#api-capture-span) takes a `name`, `type`, and optionally `subtype` and `action`. For example, database queries have the type `db`, a subytpe like `mysql` or `postgresql`, and action `query`. You may want to do something similar if you have multiple span types, so you can more easily search and aggregate them.

> Number of requests. (only count no other tracking)

Yes, [begin\_transaction](https://www.elastic.co/guide/en/apm/agent/python/current/api.html#client-api-begin-transaction) and [end\_transaction](https://www.elastic.co/guide/en/apm/agent/python/current/api.html#client-api-end-transaction) are the right calls to make for this. You'll be able to query the request rate and latency distribution as a result.

How do the requests come in? If it's a Django or Flask-based application, then bear in mind that the agent comes with support for those out of the box, and you don't need to be calling the begin/end\_transaction methods yourself.

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<div class="post-metadata">

**Author:** ![AlexRa](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@AlexRa](https://discuss.elastic.co/u/AlexRa)\
**Post date:** [November 25, 2019, 9:41pm UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/3 "2019-11-25T21:41:08Z")

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thanks for taking time to reply.  
While the most important thing now is to have support for custom metrics, or at least find a solution to get it done for now.

Some more documentation would be great, as it's quite limited to only a few common use cases. For now I can't really see the benefit for switching to it, after spending like 1 week trying to figure out things on my own.

Even the python agent has lots of issues.

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<div class="post-metadata">

**Author:** ![axw](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/axw/32/28197_2.png) [@axw](https://discuss.elastic.co/u/axw)\
**Post date:** [November 26, 2019, 3:02am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/4 "2019-11-26T03:02:52Z")

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> [@](#):
>
> While the most important thing now is to have support for custom metrics, or at least find a solution to get it done for now.

There is an undocumented API which you can use to report your own custom metrics, but please understand that this is unsupported at the moment, and its API may change. It would be useful for us to know your thoughts on making this an officially supported API - whether it does what you need already, or what's missing.

The `elasticapm.Client` has a `_metrics` attribute, holding a metrics registry. It is possible to register a subclass of [MetricsSet](https://github.com/elastic/apm-agent-python/blob/9aaeee86efd2b57e6ea8bd67def77536eff03b90/elasticapm/metrics/base_metrics.py#L112) by calling `client._metrics.register(class_path)`.

So for example if you have a package called "custom\_metrics", then you create a subclass of `MetricsSet` in that package called `Set`, and then call `client._metrics.register("custom_metrics.Set")` to register it. `Set` should have a `before_collect` method which will be periodically invoked in order to create/update metrics.

`$PYTHONPATH/custom_metrics.py:`

```
from elasticapm.metrics.base_metrics import MetricsSet

class Set(MetricsSet):
    def __init__ (self, registry):
        super(Set, self). __init__ (registry)

    def before_collect(self):
        self.gauge("queue_size", queue_name="queue0").val = 123
        self.gauge("queue_size", queue_name="queue1").val = 456

```

> [@](#):
>
> Some more documentation would be great, as it's quite limited to only a few common use cases. For now I can't really see the benefit for switching to it, after spending like 1 week trying to figure out things on my own.
> 
> Even the python agent has lots of issues.

If you can provide any more details on which use cases are missing from the docs, and which issues you're referring to, that would be helpful.

For the docs, I suppose extending the [Instrumenting custom code](https://www.elastic.co/guide/en/apm/agent/python/current/instrumenting-custom-code.html) docs with examples of starting/ending transactions might help?

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<div class="post-metadata">

**Author:** ![beniwohli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/beniwohli/32/21256_2.png) [@beniwohli](https://discuss.elastic.co/u/beniwohli)\
**Post date:** [November 26, 2019, 10:05am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/5 "2019-11-26T10:05:13Z")

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There's also a setting that can be used to register metrics sets: [https://github.com/elastic/apm-agent-python/blob/bca5828503bd42825bb9d8e338e3f9a990d27bfd/elasticapm/conf/ **init**.py#L285-L291](https://github.com/elastic/apm-agent-python/blob/bca5828503bd42825bb9d8e338e3f9a990d27bfd/elasticapm/conf/ __init__.py#L285-L291).

We haven't documented this on purpose, as the API isn't stable yet and may change without warning in upcoming releases.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [December 17, 2019, 6:05am UTC](https://discuss.elastic.co/t/python-agent-how-to-track-various-counters-values-evolution-over-time/209176/6 "2019-12-17T06:05:13Z")

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