I cant see how absent() may help me here @juliusv yeah, I tried count_scalar() but I can't use aggregation with it. Has 90% of ice around Antarctica disappeared in less than a decade? I used a Grafana transformation which seems to work. will get matched and propagated to the output. Good to know, thanks for the quick response! See these docs for details on how Prometheus calculates the returned results. source, what your query is, what the query inspector shows, and any other The thing with a metric vector (a metric which has dimensions) is that only the series for it actually get exposed on /metrics which have been explicitly initialized. or something like that. If, on the other hand, we want to visualize the type of data that Prometheus is the least efficient when dealing with, well end up with this instead: Here we have single data points, each for a different property that we measure. The real power of Prometheus comes into the picture when you utilize the alert manager to send notifications when a certain metric breaches a threshold. Why are trials on "Law & Order" in the New York Supreme Court? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Show or hide query result depending on variable value in Grafana, Understanding the CPU Busy Prometheus query, Group Label value prefixes by Delimiter in Prometheus, Why time duration needs double dot for Prometheus but not for Victoria metrics, Using a Grafana Histogram with Prometheus Buckets. This page will guide you through how to install and connect Prometheus and Grafana. If you do that, the line will eventually be redrawn, many times over. If we were to continuously scrape a lot of time series that only exist for a very brief period then we would be slowly accumulating a lot of memSeries in memory until the next garbage collection. Prometheus - exclude 0 values from query result, How Intuit democratizes AI development across teams through reusability. These flags are only exposed for testing and might have a negative impact on other parts of Prometheus server. Prometheus's query language supports basic logical and arithmetic operators. Once TSDB knows if it has to insert new time series or update existing ones it can start the real work. Name the nodes as Kubernetes Master and Kubernetes Worker. The most basic layer of protection that we deploy are scrape limits, which we enforce on all configured scrapes. In order to make this possible, it's necessary to tell Prometheus explicitly to not trying to match any labels by . To learn more, see our tips on writing great answers. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. For that lets follow all the steps in the life of a time series inside Prometheus. With 1,000 random requests we would end up with 1,000 time series in Prometheus. Its not going to get you a quicker or better answer, and some people might I can't work out how to add the alerts to the deployments whilst retaining the deployments for which there were no alerts returned: If I use sum with or, then I get this, depending on the order of the arguments to or: If I reverse the order of the parameters to or, I get what I am after: But I'm stuck now if I want to do something like apply a weight to alerts of a different severity level, e.g. what does the Query Inspector show for the query you have a problem with? In this article, you will learn some useful PromQL queries to monitor the performance of Kubernetes-based systems. prometheus-promql query based on label value, Select largest label value in Prometheus query, Prometheus Query Overall average under a time interval, Prometheus endpoint of all available metrics. rev2023.3.3.43278. Also, providing a reasonable amount of information about where youre starting @rich-youngkin Yes, the general problem is non-existent series. Is a PhD visitor considered as a visiting scholar? If our metric had more labels and all of them were set based on the request payload (HTTP method name, IPs, headers, etc) we could easily end up with millions of time series. PromQL / How to return 0 instead of ' no data' - Medium Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. Subscribe to receive notifications of new posts: Subscription confirmed. an EC2 regions with application servers running docker containers. Querying examples | Prometheus Of course there are many types of queries you can write, and other useful queries are freely available. How to react to a students panic attack in an oral exam? I have just used the JSON file that is available in below website In Prometheus pulling data is done via PromQL queries and in this article we guide the reader through 11 examples that can be used for Kubernetes specifically. Not the answer you're looking for? To learn more, see our tips on writing great answers. 02:00 - create a new chunk for 02:00 - 03:59 time range, 04:00 - create a new chunk for 04:00 - 05:59 time range, 22:00 - create a new chunk for 22:00 - 23:59 time range. We know what a metric, a sample and a time series is. 2023 The Linux Foundation. Both of the representations below are different ways of exporting the same time series: Since everything is a label Prometheus can simply hash all labels using sha256 or any other algorithm to come up with a single ID that is unique for each time series. Have a question about this project? Asking for help, clarification, or responding to other answers. In our example we have two labels, content and temperature, and both of them can have two different values. For that reason we do tolerate some percentage of short lived time series even if they are not a perfect fit for Prometheus and cost us more memory. I believe it's the logic that it's written, but is there any . Samples are stored inside chunks using "varbit" encoding which is a lossless compression scheme optimized for time series data. The actual amount of physical memory needed by Prometheus will usually be higher as a result, since it will include unused (garbage) memory that needs to be freed by Go runtime. Instead we count time series as we append them to TSDB. Select the query and do + 0. Run the following commands in both nodes to configure the Kubernetes repository. The more labels you have, or the longer the names and values are, the more memory it will use. attacks. Since labels are copied around when Prometheus is handling queries this could cause significant memory usage increase. Simple, clear and working - thanks a lot. If both the nodes are running fine, you shouldnt get any result for this query. If we try to visualize how the perfect type of data Prometheus was designed for looks like well end up with this: A few continuous lines describing some observed properties. These queries will give you insights into node health, Pod health, cluster resource utilization, etc. Prometheus provides a functional query language called PromQL (Prometheus Query Language) that lets the user select and aggregate time series data in real time. Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. new career direction, check out our open whether someone is able to help out. How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Does a summoned creature play immediately after being summoned by a ready action? ncdu: What's going on with this second size column? If so it seems like this will skew the results of the query (e.g., quantiles). Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. If we configure a sample_limit of 100 and our metrics response contains 101 samples, then Prometheus wont scrape anything at all. Is there a single-word adjective for "having exceptionally strong moral principles"? Any other chunk holds historical samples and therefore is read-only. I'm displaying Prometheus query on a Grafana table. To better handle problems with cardinality its best if we first get a better understanding of how Prometheus works and how time series consume memory. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 . Then imported a dashboard from 1 Node Exporter for Prometheus Dashboard EN 20201010 | Grafana Labs".Below is my Dashboard which is showing empty results.So kindly check and suggest. Prometheus query check if value exist. count the number of running instances per application like this: This documentation is open-source. If so I'll need to figure out a way to pre-initialize the metric which may be difficult since the label values may not be known a priori. Neither of these solutions seem to retain the other dimensional information, they simply produce a scaler 0. information which you think might be helpful for someone else to understand In general, having more labels on your metrics allows you to gain more insight, and so the more complicated the application you're trying to monitor, the more need for extra labels. PROMQL: how to add values when there is no data returned? Internally time series names are just another label called __name__, so there is no practical distinction between name and labels. That's the query ( Counter metric): sum (increase (check_fail {app="monitor"} [20m])) by (reason) The result is a table of failure reason and its count. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 - 05:59, , 22:00 - 23:59. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Once theyre in TSDB its already too late. Those limits are there to catch accidents and also to make sure that if any application is exporting a high number of time series (more than 200) the team responsible for it knows about it. First is the patch that allows us to enforce a limit on the total number of time series TSDB can store at any time. Of course, this article is not a primer on PromQL; you can browse through the PromQL documentation for more in-depth knowledge. You must define your metrics in your application, with names and labels that will allow you to work with resulting time series easily. Object, url:api/datasources/proxy/2/api/v1/query_range?query=wmi_logical_disk_free_bytes%7Binstance%3D~%22%22%2C%20volume%20!~%22HarddiskVolume.%2B%22%7D&start=1593750660&end=1593761460&step=20&timeout=60s, Powered by Discourse, best viewed with JavaScript enabled, 1 Node Exporter for Prometheus Dashboard EN 20201010 | Grafana Labs, https://grafana.com/grafana/dashboards/2129. type (proc) like this: Assuming this metric contains one time series per running instance, you could This pod wont be able to run because we dont have a node that has the label disktype: ssd. Lets adjust the example code to do this. binary operators to them and elements on both sides with the same label set The problem is that the table is also showing reasons that happened 0 times in the time frame and I don't want to display them. To select all HTTP status codes except 4xx ones, you could run: Return the 5-minute rate of the http_requests_total metric for the past 30 minutes, with a resolution of 1 minute. However, the queries you will see here are a baseline" audit. Being able to answer How do I X? yourself without having to wait for a subject matter expert allows everyone to be more productive and move faster, while also avoiding Prometheus experts from answering the same questions over and over again. A simple request for the count (e.g., rio_dashorigin_memsql_request_fail_duration_millis_count) returns no datapoints).