In addition to that in most cases we dont see all possible label values at the same time, its usually a small subset of all possible combinations. how have you configured the query which is causing problems? Every two hours Prometheus will persist chunks from memory onto the disk. Other Prometheus components include a data model that stores the metrics, client libraries for instrumenting code, and PromQL for querying the metrics. Is it a bug? Perhaps I misunderstood, but it looks like any defined metrics that hasn't yet recorded any values can be used in a larger expression. job and handler labels: Return a whole range of time (in this case 5 minutes up to the query time) Looking to learn more? To do that, run the following command on the master node: Next, create an SSH tunnel between your local workstation and the master node by running the following command on your local machine: If everything is okay at this point, you can access the Prometheus console at http://localhost:9090. are going to make it to your account, What did you do? Thanks, This process helps to reduce disk usage since each block has an index taking a good chunk of disk space. PromQL queries the time series data and returns all elements that match the metric name, along with their values for a particular point in time (when the query runs). What happens when somebody wants to export more time series or use longer labels? Its not going to get you a quicker or better answer, and some people might Why are trials on "Law & Order" in the New York Supreme Court? Chunks that are a few hours old are written to disk and removed from memory. 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. PromQL allows you to write queries and fetch information from the metric data collected by Prometheus. When Prometheus sends an HTTP request to our application it will receive this response: This format and underlying data model are both covered extensively in Prometheus' own documentation. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. whether someone is able to help out. Neither of these solutions seem to retain the other dimensional information, they simply produce a scaler 0. By clicking Sign up for GitHub, you agree to our terms of service and This page will guide you through how to install and connect Prometheus and Grafana. But before that, lets talk about the main components of Prometheus. If so it seems like this will skew the results of the query (e.g., quantiles). ncdu: What's going on with this second size column? 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. 1 Like. To learn more, see our tips on writing great answers. Have a question about this project? The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. These are the sane defaults that 99% of application exporting metrics would never exceed. returns the unused memory in MiB for every instance (on a fictional cluster All they have to do is set it explicitly in their scrape configuration. 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. Once TSDB knows if it has to insert new time series or update existing ones it can start the real work. The simplest construct of a PromQL query is an instant vector selector. Since labels are copied around when Prometheus is handling queries this could cause significant memory usage increase. The downside of all these limits is that breaching any of them will cause an error for the entire scrape. Often it doesnt require any malicious actor to cause cardinality related problems. Visit 1.1.1.1 from any device to get started with These queries are a good starting point. You can verify this by running the kubectl get nodes command on the master node. Managed Service for Prometheus Cloud Monitoring Prometheus # ! These checks are designed to ensure that we have enough capacity on all Prometheus servers to accommodate extra time series, if that change would result in extra time series being collected. Are there tables of wastage rates for different fruit and veg? In this query, you will find nodes that are intermittently switching between Ready" and NotReady" status continuously. 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. The Linux Foundation has registered trademarks and uses trademarks. metric name, as measured over the last 5 minutes: Assuming that the http_requests_total time series all have the labels job Have a question about this project? Our patched logic will then check if the sample were about to append belongs to a time series thats already stored inside TSDB or is it a new time series that needs to be created. Prometheus is an open-source monitoring and alerting software that can collect metrics from different infrastructure and applications. We know what a metric, a sample and a time series is. I made the changes per the recommendation (as I understood it) and defined separate success and fail metrics. Stumbled onto this post for something else unrelated, just was +1-ing this :). 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. scheduler exposing these metrics about the instances it runs): The same expression, but summed by application, could be written like this: If the same fictional cluster scheduler exposed CPU usage metrics like the At this point, both nodes should be ready. Or maybe we want to know if it was a cold drink or a hot one? notification_sender-. the problem you have. Once the last chunk for this time series is written into a block and removed from the memSeries instance we have no chunks left. Any excess samples (after reaching sample_limit) will only be appended if they belong to time series that are already stored inside TSDB. We also limit the length of label names and values to 128 and 512 characters, which again is more than enough for the vast majority of scrapes. what does the Query Inspector show for the query you have a problem with? Find centralized, trusted content and collaborate around the technologies you use most. as text instead of as an image, more people will be able to read it and help. If we configure a sample_limit of 100 and our metrics response contains 101 samples, then Prometheus wont scrape anything at all. You signed in with another tab or window. What this means is that using Prometheus defaults each memSeries should have a single chunk with 120 samples on it for every two hours of data. Prometheus - exclude 0 values from query result, How Intuit democratizes AI development across teams through reusability. This is true both for client libraries and Prometheus server, but its more of an issue for Prometheus itself, since a single Prometheus server usually collects metrics from many applications, while an application only keeps its own metrics. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Simple succinct answer. So I still can't use that metric in calculations ( e.g., success / (success + fail) ) as those calculations will return no datapoints. In both nodes, edit the /etc/hosts file to add the private IP of the nodes. Well occasionally send you account related emails. what error message are you getting to show that theres a problem? Prometheus is an open-source monitoring and alerting software that can collect metrics from different infrastructure and applications. Is it possible to rotate a window 90 degrees if it has the same length and width? I've added a data source (prometheus) in Grafana. accelerate any All regular expressions in Prometheus use RE2 syntax. The number of time series depends purely on the number of labels and the number of all possible values these labels can take. One or more for historical ranges - these chunks are only for reading, Prometheus wont try to append anything here. Returns a list of label values for the label in every metric. The more any application does for you, the more useful it is, the more resources it might need. But the real risk is when you create metrics with label values coming from the outside world. The Prometheus data source plugin provides the following functions you can use in the Query input field. For example, I'm using the metric to record durations for quantile reporting. @zerthimon The following expr works for me 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. The subquery for the deriv function uses the default resolution. source, what your query is, what the query inspector shows, and any other count(ALERTS) or (1-absent(ALERTS)), Alternatively, count(ALERTS) or vector(0). 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. What is the point of Thrower's Bandolier? Both patches give us two levels of protection. I'm still out of ideas here. In our example case its a Counter class object. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Another reason is that trying to stay on top of your usage can be a challenging task. Names and labels tell us what is being observed, while timestamp & value pairs tell us how that observable property changed over time, allowing us to plot graphs using this data. But you cant keep everything in memory forever, even with memory-mapping parts of data. Thirdly Prometheus is written in Golang which is a language with garbage collection. It would be easier if we could do this in the original query though. I used a Grafana transformation which seems to work. In this article, you will learn some useful PromQL queries to monitor the performance of Kubernetes-based systems. Making statements based on opinion; back them up with references or personal experience. To learn more, see our tips on writing great answers. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. This helps Prometheus query data faster since all it needs to do is first locate the memSeries instance with labels matching our query and then find the chunks responsible for time range of the query. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. 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. So perhaps the behavior I'm running into applies to any metric with a label, whereas a metric without any labels would behave as @brian-brazil indicated? The struct definition for memSeries is fairly big, but all we really need to know is that it has a copy of all the time series labels and chunks that hold all the samples (timestamp & value pairs). One of the most important layers of protection is a set of patches we maintain on top of Prometheus. Managing the entire lifecycle of a metric from an engineering perspective is a complex process. First is the patch that allows us to enforce a limit on the total number of time series TSDB can store at any time. @rich-youngkin Yeah, what I originally meant with "exposing" a metric is whether it appears in your /metrics endpoint at all (for a given set of labels). This article covered a lot of ground. The containers are named with a specific pattern: I need an alert when the number of container of the same pattern (eg. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. 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. Thats why what our application exports isnt really metrics or time series - its samples. Simple, clear and working - thanks a lot. Prometheus lets you query data in two different modes: The Console tab allows you to evaluate a query expression at the current time. list, which does not convey images, so screenshots etc. by (geo_region) < bool 4 The main reason why we prefer graceful degradation is that we want our engineers to be able to deploy applications and their metrics with confidence without being subject matter experts in Prometheus. (pseudocode): summary = 0 + sum (warning alerts) + 2*sum (alerts (critical alerts)) This gives the same single value series, or no data if there are no alerts. To this end, I set up the query to instant so that the very last data point is returned but, when the query does not return a value - say because the server is down and/or no scraping took place - the stat panel produces no data. Have you fixed this issue? What this means is that a single metric will create one or more time series. Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. For a list of trademarks of The Linux Foundation, please see our Trademark Usage page. The containers are named with a specific pattern: notification_checker [0-9] notification_sender [0-9] I need an alert when the number of container of the same pattern (eg. Bulk update symbol size units from mm to map units in rule-based symbology. If such a stack trace ended up as a label value it would take a lot more memory than other time series, potentially even megabytes. I'm not sure what you mean by exposing a metric. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. privacy statement. Windows 10, how have you configured the query which is causing problems? This single sample (data point) will create a time series instance that will stay in memory for over two and a half hours using resources, just so that we have a single timestamp & value pair. Well be executing kubectl commands on the master node only. This is one argument for not overusing labels, but often it cannot be avoided. Under which circumstances? Having a working monitoring setup is a critical part of the work we do for our clients. 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. There is no equivalent functionality in a standard build of Prometheus, if any scrape produces some samples they will be appended to time series inside TSDB, creating new time series if needed. Blocks will eventually be compacted, which means that Prometheus will take multiple blocks and merge them together to form a single block that covers a bigger time range. VictoriaMetrics has other advantages compared to Prometheus, ranging from massively parallel operation for scalability, better performance, and better data compression, though what we focus on for this blog post is a rate () function handling. By merging multiple blocks together, big portions of that index can be reused, allowing Prometheus to store more data using the same amount of storage space. Why is there a voltage on my HDMI and coaxial cables? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Since the default Prometheus scrape interval is one minute it would take two hours to reach 120 samples. I'm sure there's a proper way to do this, but in the end, I used label_replace to add an arbitrary key-value label to each sub-query that I wished to add to the original values, and then applied an or to each. Passing sample_limit is the ultimate protection from high cardinality. For that lets follow all the steps in the life of a time series inside Prometheus. Selecting data from Prometheus's TSDB forms the basis of almost any useful PromQL query before . or Internet application, Can airtags be tracked from an iMac desktop, with no iPhone? This is because the Prometheus server itself is responsible for timestamps. Already on GitHub? Please dont post the same question under multiple topics / subjects. 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. 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. While the sample_limit patch stops individual scrapes from using too much Prometheus capacity, which could lead to creating too many time series in total and exhausting total Prometheus capacity (enforced by the first patch), which would in turn affect all other scrapes since some new time series would have to be ignored. Arithmetic binary operators The following binary arithmetic operators exist in Prometheus: + (addition) - (subtraction) * (multiplication) / (division) % (modulo) ^ (power/exponentiation) 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? I was then able to perform a final sum by over the resulting series to reduce the results down to a single result, dropping the ad-hoc labels in the process. With our example metric we know how many mugs were consumed, but what if we also want to know what kind of beverage it was? Now we should pause to make an important distinction between metrics and time series. Where does this (supposedly) Gibson quote come from? 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. A metric is an observable property with some defined dimensions (labels). So, specifically in response to your question: I am facing the same issue - please explain how you configured your data Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. The below posts may be helpful for you to learn more about Kubernetes and our company. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Here are two examples of instant vectors: You can also use range vectors to select a particular time range. Prometheus is a great and reliable tool, but dealing with high cardinality issues, especially in an environment where a lot of different applications are scraped by the same Prometheus server, can be challenging. On Thu, Dec 15, 2016 at 6:24 PM, Lior Goikhburg ***@***. SSH into both servers and run the following commands to install Docker. PROMQL: how to add values when there is no data returned? At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. Separate metrics for total and failure will work as expected. What is the point of Thrower's Bandolier? I believe it's the logic that it's written, but is there any . I don't know how you tried to apply the comparison operators, but if I use this very similar query: I get a result of zero for all jobs that have not restarted over the past day and a non-zero result for jobs that have had instances restart. Will this approach record 0 durations on every success? How to filter prometheus query by label value using greater-than, PromQL - Prometheus - query value as label, Why time duration needs double dot for Prometheus but not for Victoria metrics, How do you get out of a corner when plotting yourself into a corner.

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