+1. It seems to me that underlying metric ids are something we just
want to hide as an implementation detail. Querying for a "family name"
and narrowing by other tags gives you a useful set of TS.
On 2/17/2017 2:44 AM, Joel Takvorian wrote:
For the curly braces in Grafana, I'm going to investigate.
For your second point, I'm trying to put me in the shoes of an ops: if
I want to create a dashboard that shows a labelled metric (in term of
prometheus label), I'd like to see all its avatars in the same chart
to be able to compare them, see in what they converge or in what they
diverge. And maybe compare them in all pods of a given container name.
That would be queries with tags:
Query tags:
- container_name: something
- family_name (or "metric_base_name", or whatever name we give to that
tag): what_i_ate
I can't be 100% sure that it's going to be used, as people do what
they want in Grafana. But it seems interesting to me. The question is:
what's the cost of adding a tag? I believe metric tags are relatively
cheap in term of storage. So, having both "metric_name"
(what_i_ate{food=Banana}) and "family_name" (what_i_ate) would solve
all our issues, no?
On Thu, Feb 16, 2017 at 6:23 PM, John Mazzitelli <mazz(a)redhat.com
<mailto:mazz@redhat.com>> wrote:
I need to resurrect this thread now that some others have had
experience with what we have - specifically, what Thomas reported
in this issue:
https://github.com/hawkular/hawkular-openshift-agent/issues/126
<
https://github.com/hawkular/hawkular-openshift-agent/issues/126>
It has to do with Prometheus metrics and how HOSA names and tags
them in H-Metrics.
Just some quick background first:
Prometheus metrics have two parts - a "family name" (like
"http_response_count") and labels (like "method"). This means
you
can have N metrics in Prometheus with the same metric family name
but each with different label values (like
"http_response_count{method=GET}" and
"http_response_count{method=POST}". Each unique combination of
family name plus label values represent a different set of time
series data (so http_response_count{method=GET} is one set of time
series data and http_response_count{method=POST} is another set of
time series data).
H-Metrics doesn't really have this concept of metric family.
H-Metrics has metric definitions each with unique names (or
"metric IDs") and a set of tags (h-metrics uses the name "tags"
rather than "labels"). In H-Metrics, you cannot have N metrics
with the same name (ID). You must have unique IDs to represent
different sets of time series data.
OK, with that quick intro, two things:
=====
1) Metrics coming from Prometheus by default will be stored in
H-Metrics with metric IDs like:
metric_family_name{label_name1=value1,label_name2=value2}
Basically, HOSA stores the H-Metric ID so it looks identical to
the metric data coming from Prometheus endpoints (name with labels
comma-separated and enclosed within curly braces).
But Grafana might have issues with the curly braces. However, the
original opinion when this was first implemented in HOSA was that
just using underscores in H-Metrics IDs, for example:
metric_family_name_label_name1_value1_label_name2_value2
will make querying from H-Metrics more difficult (it all looks
like one big name and it is hard to distinguish the labels in the
name).
QUESTION #1a: Does Grafana really have an issue with displaying
metrics whose names have curly braces - {} - and commas in them?
QUESTION #1b: If so, what should the default metric ID look like
when we have Prometheus labels like this, if not by using curly
braces and commas?
=====
2) These Prometheus metrics don't look right in the current
OpenShift UI. If we have two Prometheus metrics stored in
H-Metrics with the IDs:
what_i_ate{food=Banana}
what_i_ate{food=Apple}
what you see in the OpenShift UI console is two metric graphs each
with the same metric name "what_i_ate" - you don't know which ones
they are.
Why? Application metrics like these are now shown in the OpenShift
UI and it works fine even for Prometheus metrics UNLESS the
Prometheus metrics had labels (like the example above with
Prometheus labels food=Apple or food=Banana). This is because when
we tag these metrics in H-Metrics, one tag we add to the metric
definition is "metric_name" and for Prometheus the value of this
tag is the METRIC FAMILY name. This is what Joel was asking for
(see the last messages in this thread). But the OS UI console uses
this metric_name tag for the label of the graph (the full, real ID
of the metric is ugly to make sure its unique within the cluster -
e.g.
"pod/3e4553ew-34553d-345433-123a/custom/what_i_ate{food=Banana}" -
so we don't really want to show that to a user).
QUESTION #2a: Should I switch back and make metric_name be the
last part of the actual metric ID (not Prometheus family name)
like "what_i_ate{food=Banana}" so the OS UI console works? Or do
we fix the OS UI console to parse the full metric ID and only show
the last part (after the "/custom/" part) thus leaving
"metric_name" tag in H-Metrics be the Prometheus metric family
name and make querying easier (a-la Joel's suggestion).
QUESTION #2b: Is having metric family name a useful thing to have
as a H-Metric tag in the first place? If so, I will have to get
HOSA to create a new tag "base_metric_name" if "metric_name" is
to
be fixed to get the OS UI to work. But does having the Prometheus
metric family name even a useful thing? Joel seemed to think so; I
would like to make sure it is a useful thing before I go and
implement this change.
----- Forwarded Message -----
From: "John Mazzitelli" <mazz(a)redhat.com
<mailto:mazz@redhat.com>>
To: "Discussions around Hawkular development"
<hawkular-dev(a)lists.jboss.org <mailto:hawkular-dev@lists.jboss.org>>
Sent: Wednesday, February 1, 2017 11:47:18 AM
Subject: Re: [Hawkular-dev] HOSA and conversion from prometheus to
hawkular metrics
https://github.com/hawkular/hawkular-openshift-agent/blob/master/deploy/o...
<
https://github.com/hawkular/hawkular-openshift-agent/blob/master/deploy/o...
:D
That's already there - the ${METRIC:name} resolves to the name of
the metric (not the new ID) and our default config puts that tag
on every metric.
----- Original Message -----
>
> +1, if that is not being done I think it would good. Actually,
it's probably
> a good "best practice" as it make it easier to slice and dice
the data.
>
> On 2/1/2017 10:35 AM, Joel Takvorian wrote:
>
>
>
> +1
>
> Conversion based on labels seems more sane.
>
> I wonder if a new tag that recalls the prometheus metric name
would be
> useful; ex. "baseName=jvm_memory_pool_bytes_committed", to
retrieve all
> metrics of that family. Just an idea.
>
> On Wed, Feb 1, 2017 at 4:25 PM, John Mazzitelli <
mazz(a)redhat.com <mailto:mazz@redhat.com> > wrote:
>
>
> > Are you also tagging the Prometheus metrics with the labels?
>
> Yes, that is what was originally being done, and that is still
in there.
>
> ----- Original Message -----
> >
> > Mazz, this makes sense to me. Our decision to use unique ids
(well +type)
> > is
> > going to lead to this sort of thing. The ids are going to
basically be
> > large
> > concatenations of the tags that identify the data. Then,
additionally we're
> > going to have to tag the metrics with the same name/value
pairs that are
> > present in the id. Are you also tagging the Prometheus metrics
with the
> > labels?
> >
> > On 2/1/2017 9:38 AM, John Mazzitelli wrote:
> >
> >
> >
> > The past several days I've been working on an enhancement to
HOSA that came
> > in from the community (in fact, I would consider it a bug).
I'm about ready
> > to merge the PR [1] for this and do a HOSA 1.1.0.Final
release. I wanted to
> > post this to announce it and see if there is any feedback, too.
> >
> > Today, HOSA collects metrics from any Prometheus endpoint
which you declare
> > -
> > example:
> >
> > metrics
> > - name: go_memstats_sys_bytes
> > - name: process_max_fds
> > - name: process_open_fds
> >
> > But if a Prometheus metric has labels, Prometheus itself
considers each
> > metric with a unique combination of labels as an individual
time series
> > metric. This is different than how Hawkular Metric works -
each Hawkular
> > Metric metric ID (even if its metric definition or its
datapoints have
> > tags)
> > is a single time series metric. We need to account for this
difference. For
> > example, if our agent is configured with:
> >
> > metrics:
> > - name: jvm_memory_pool_bytes_committed
> >
> > And the Prometheus endpoint emits that metric with a label
called "pool"
> > like
> > this:
> >
> > jvm_memory_pool_bytes_committed{pool="Code Cache",} 2.7787264E7
> > jvm_memory_pool_bytes_committed{pool="PS Eden Space",}
2.3068672E7
> >
> > then to Prometheus this is actually 2 time series metrics (the
number of
> > bytes committed per pool type), not 1. Even though the metric
name is the
> > same (what Prometheus calls a "metric family name"), there are
two unique
> > combinations of labels - one with "Code Cache" and one with
"PS Eden Space"
> > - so they are 2 distinct time series metric data.
> >
> > Today, the agent only creates a single Hawkular-Metric in this
case, with
> > each datapoint tagged with those Prometheus labels on the
appropriate data
> > point. But we don't want to aggregate them like that since we
lose the
> > granularity that the Prometheus endpoint gives us (that is,
the number of
> > bytes committed in each pool type). I will say I think we
might be able to
> > get that granularity back through datapoint tag queries in
Hawkular-Metrics
> > but I don't know how well (if at all) that is supported and
how efficient
> > such queries would be even if supported, and how efficient
storage of these
> > metrics would be if we tag every data point with these labels
(not sure if
> > that is the general purpose of tags in H-Metrics). But,
regardless, the
> > fact
> > that these really are different time series metrics should
(IMO) be
> > represented as different time series metrics (via metric
definitions/metric
> > IDs) in Hawkular-Metrics.
> >
> > To support labeled Prometheus endpoint data like this, the
agent needs to
> > split this one named metric into N Hawkular-Metrics metrics
(where N is the
> > number of unique label combinations for that named metric). So
even though
> > the agent is configured with the one metric
> > "jvm_memory_pool_bytes_committed" we need to actually create two
> > Hawkular-Metric metric definitions (with two different and
unique metric
> > IDs
> > obviously).
> >
> > The PR [1] that is ready to go does this. By default it will
create
> > multiple
> > metric definitions/metric IDs in the form
> >
"metric-family-name{labelName1=labelValue1,labelName2=labelValue2,...}"
> > unless you want a different form in which case you can define
an "id" and
> > put in "${labelName}" in the ID you declare (such as
> > "${oneLabelName}_my_own_metric_name_${theOtherLabelName}" or
whatever). But
> > I suspect the default format will be what most people want and
thus nothing
> > needs to be done. In the above example, two metric definitions
with the
> > following IDs are created:
> >
> > 1. jvm_memory_pool_bytes_committed{pool=Code Cache}
> > 2. jvm_memory_pool_bytes_committed{pool=PS Eden Space}
> >
> > --John Mazz
> >
> > [1]
https://github.com/hawkular/hawkular-openshift-agent/pull/117
<
https://github.com/hawkular/hawkular-openshift-agent/pull/117>
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