There's also count_scalar(), Even i am facing the same issue Please help me on this. Explanation: Prometheus uses label matching in expressions. "no data". Each Prometheus is scraping a few hundred different applications, each running on a few hundred servers. 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. Those memSeries objects are storing all the time series information. or something like that. 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. To learn more, see our tips on writing great answers. Why are trials on "Law & Order" in the New York Supreme Court? Asking for help, clarification, or responding to other answers. No error message, it is just not showing the data while using the JSON file from that website. How to follow the signal when reading the schematic? Internet-scale applications efficiently, Hello, I'm new at Grafan and Prometheus. What is the point of Thrower's Bandolier? See this article for details. 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. Now, lets install Kubernetes on the master node using kubeadm. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Thanks for contributing an answer to Stack Overflow! At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. However, the queries you will see here are a baseline" audit. By default Prometheus will create a chunk per each two hours of wall clock. 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. Combined thats a lot of different metrics. Here are two examples of instant vectors: You can also use range vectors to select a particular time range. The below posts may be helpful for you to learn more about Kubernetes and our company. I'd expect to have also: Please use the prometheus-users mailing list for questions. To avoid this its in general best to never accept label values from untrusted sources. You're probably looking for the absent function. By default we allow up to 64 labels on each time series, which is way more than most metrics would use. Which in turn will double the memory usage of our Prometheus server. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? First is the patch that allows us to enforce a limit on the total number of time series TSDB can store at any time. If instead of beverages we tracked the number of HTTP requests to a web server, and we used the request path as one of the label values, then anyone making a huge number of random requests could force our application to create a huge number of time series. I have a query that gets a pipeline builds and its divided by the number of change request open in a 1 month window, which gives a percentage. If we add another label that can also have two values then we can now export up to eight time series (2*2*2). You can run a variety of PromQL queries to pull interesting and actionable metrics from your Kubernetes cluster. whether someone is able to help out. So the maximum number of time series we can end up creating is four (2*2). I'm displaying Prometheus query on a Grafana table. TSDB will try to estimate when a given chunk will reach 120 samples and it will set the maximum allowed time for current Head Chunk accordingly. Has 90% of ice around Antarctica disappeared in less than a decade? Passing sample_limit is the ultimate protection from high cardinality. Doubling the cube, field extensions and minimal polynoms. To make things more complicated you may also hear about samples when reading Prometheus documentation. By clicking Sign up for GitHub, you agree to our terms of service and These will give you an overall idea about a clusters health. This article covered a lot of ground. 2023 The Linux Foundation. This is a deliberate design decision made by Prometheus developers. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. Prometheus metrics can have extra dimensions in form of labels. Cadvisors on every server provide container names. So when TSDB is asked to append a new sample by any scrape, it will first check how many time series are already present. Separate metrics for total and failure will work as expected. The more labels you have, or the longer the names and values are, the more memory it will use. Knowing that it can quickly check if there are any time series already stored inside TSDB that have the same hashed value. Once Prometheus has a list of samples collected from our application it will save it into TSDB - Time Series DataBase - the database in which Prometheus keeps all the time series. are going to make it Or do you have some other label on it, so that the metric still only gets exposed when you record the first failued request it? The difference with standard Prometheus starts when a new sample is about to be appended, but TSDB already stores the maximum number of time series its allowed to have. Our metric will have a single label that stores the request path. what does the Query Inspector show for the query you have a problem with? Arithmetic binary operators The following binary arithmetic operators exist in Prometheus: + (addition) - (subtraction) * (multiplication) / (division) % (modulo) ^ (power/exponentiation) Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Comparing current data with historical data. 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. The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series. A time series is an instance of that metric, with a unique combination of all the dimensions (labels), plus a series of timestamp & value pairs - hence the name time series. There is a single time series for each unique combination of metrics labels. Our HTTP response will now show more entries: As we can see we have an entry for each unique combination of labels. Since the default Prometheus scrape interval is one minute it would take two hours to reach 120 samples. Internally all time series are stored inside a map on a structure called Head. This means that Prometheus must check if theres already a time series with identical name and exact same set of labels present. Has 90% of ice around Antarctica disappeared in less than a decade? Is it possible to create a concave light? ***> wrote: You signed in with another tab or window. If we configure a sample_limit of 100 and our metrics response contains 101 samples, then Prometheus wont scrape anything at all. Are you not exposing the fail metric when there hasn't been a failure yet? You set up a Kubernetes cluster, installed Prometheus on it ,and ran some queries to check the clusters health. It's worth to add that if using Grafana you should set 'Connect null values' proeprty to 'always' in order to get rid of blank spaces in the graph. In order to make this possible, it's necessary to tell Prometheus explicitly to not trying to match any labels by . Of course, this article is not a primer on PromQL; you can browse through the PromQL documentation for more in-depth knowledge. These queries are a good starting point. notification_sender-. PromQL allows you to write queries and fetch information from the metric data collected by Prometheus. I believe it's the logic that it's written, but is there any conditions that can be used if there's no data recieved it returns a 0. what I tried doing is putting a condition or an absent function,but not sure if thats the correct approach. count(ALERTS) or (1-absent(ALERTS)), Alternatively, count(ALERTS) or vector(0). We can use these to add more information to our metrics so that we can better understand whats going on. After sending a request it will parse the response looking for all the samples exposed there. Next, create a Security Group to allow access to the instances. This makes a bit more sense with your explanation. I'm displaying Prometheus query on a Grafana table. Even Prometheus' own client libraries had bugs that could expose you to problems like this. Are there tables of wastage rates for different fruit and veg? Managing the entire lifecycle of a metric from an engineering perspective is a complex process. ncdu: What's going on with this second size column? Minimising the environmental effects of my dyson brain. count(container_last_seen{name="container_that_doesn't_exist"}), What did you see instead? Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. website Instead we count time series as we append them to TSDB. Each chunk represents a series of samples for a specific time range. but it does not fire if both are missing because than count() returns no data the workaround is to additionally check with absent() but it's on the one hand annoying to double-check on each rule and on the other hand count should be able to "count" zero . entire corporate networks, Having better insight into Prometheus internals allows us to maintain a fast and reliable observability platform without too much red tape, and the tooling weve developed around it, some of which is open sourced, helps our engineers avoid most common pitfalls and deploy with confidence. Then you must configure Prometheus scrapes in the correct way and deploy that to the right Prometheus server. We protect It enables us to enforce a hard limit on the number of time series we can scrape from each application instance. So, specifically in response to your question: I am facing the same issue - please explain how you configured your data I've added a data source (prometheus) in Grafana. Today, let's look a bit closer at the two ways of selecting data in PromQL: instant vector selectors and range vector selectors. The idea is that if done as @brian-brazil mentioned, there would always be a fail and success metric, because they are not distinguished by a label, but always are exposed. Is there a solutiuon to add special characters from software and how to do it. In reality though this is as simple as trying to ensure your application doesnt use too many resources, like CPU or memory - you can achieve this by simply allocating less memory and doing fewer computations. Its the chunk responsible for the most recent time range, including the time of our scrape. Is it a bug? it works perfectly if one is missing as count() then returns 1 and the rule fires. privacy statement. How to tell which packages are held back due to phased updates. However when one of the expressions returns no data points found the result of the entire expression is no data points found. - I am using this in windows 10 for testing, which Operating System (and version) are you running it under? your journey to Zero Trust. 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. 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. Youve learned about the main components of Prometheus, and its query language, PromQL. which Operating System (and version) are you running it under? Run the following commands in both nodes to install kubelet, kubeadm, and kubectl. Heres a screenshot that shows exact numbers: Thats an average of around 5 million time series per instance, but in reality we have a mixture of very tiny and very large instances, with the biggest instances storing around 30 million time series each. The next layer of protection is checks that run in CI (Continuous Integration) when someone makes a pull request to add new or modify existing scrape configuration for their application. for the same vector, making it a range vector: Note that an expression resulting in a range vector cannot be graphed directly, I have just used the JSON file that is available in below website All regular expressions in Prometheus use RE2 syntax. *) in region drops below 4. Your needs or your customers' needs will evolve over time and so you cant just draw a line on how many bytes or cpu cycles it can consume. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. What is the point of Thrower's Bandolier? Well occasionally send you account related emails. This is because the Prometheus server itself is responsible for timestamps. Since this happens after writing a block, and writing a block happens in the middle of the chunk window (two hour slices aligned to the wall clock) the only memSeries this would find are the ones that are orphaned - they received samples before, but not anymore. 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.