I've been using comparison operators in Grafana for a long while. 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. A metric can be anything that you can express as a number, for example: To create metrics inside our application we can use one of many Prometheus client libraries. And then there is Grafana, which comes with a lot of built-in dashboards for Kubernetes monitoring. 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. How to show that an expression of a finite type must be one of the finitely many possible values? Connect and share knowledge within a single location that is structured and easy to search. You signed in with another tab or window. 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. In the screenshot below, you can see that I added two queries, A and B, but only . How can I group labels in a Prometheus query? How to tell which packages are held back due to phased updates. To select all HTTP status codes except 4xx ones, you could run: http_requests_total {status!~"4.."} Subquery Return the 5-minute rate of the http_requests_total metric for the past 30 minutes, with a resolution of 1 minute. Is a PhD visitor considered as a visiting scholar? 1 Like. To get a better understanding of the impact of a short lived time series on memory usage lets take a look at another example. Operating such a large Prometheus deployment doesnt come without challenges. Why is this sentence from The Great Gatsby grammatical? Why are trials on "Law & Order" in the New York Supreme Court? The main motivation seems to be that dealing with partially scraped metrics is difficult and youre better off treating failed scrapes as incidents. About an argument in Famine, Affluence and Morality. With our custom patch we dont care how many samples are in a scrape. 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. First rule will tell Prometheus to calculate per second rate of all requests and sum it across all instances of our server. 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. This thread has been automatically locked since there has not been any recent activity after it was closed. So just calling WithLabelValues() should make a metric appear, but only at its initial value (0 for normal counters and histogram bucket counters, NaN for summary quantiles). For example, if someone wants to modify sample_limit, lets say by changing existing limit of 500 to 2,000, for a scrape with 10 targets, thats an increase of 1,500 per target, with 10 targets thats 10*1,500=15,000 extra time series that might be scraped. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. Labels are stored once per each memSeries instance. 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. Both patches give us two levels of protection. rate (http_requests_total [5m]) [30m:1m] A common pattern is to export software versions as a build_info metric, Prometheus itself does this too: When Prometheus 2.43.0 is released this metric would be exported as: Which means that a time series with version=2.42.0 label would no longer receive any new samples. To get a better idea of this problem lets adjust our example metric to track HTTP requests. Theres no timestamp anywhere actually. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Internally time series names are just another label called __name__, so there is no practical distinction between name and labels. A simple request for the count (e.g., rio_dashorigin_memsql_request_fail_duration_millis_count) returns no datapoints). Use Prometheus to monitor app performance metrics. 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? I'd expect to have also: Please use the prometheus-users mailing list for questions. count(container_last_seen{environment="prod",name="notification_sender.*",roles=".application-server."}) from and what youve done will help people to understand your problem. Our CI would check that all Prometheus servers have spare capacity for at least 15,000 time series before the pull request is allowed to be merged. https://github.com/notifications/unsubscribe-auth/AAg1mPXncyVis81Rx1mIWiXRDe0E1Dpcks5rIXe6gaJpZM4LOTeb. Its least efficient when it scrapes a time series just once and never again - doing so comes with a significant memory usage overhead when compared to the amount of information stored using that memory. Please see data model and exposition format pages for more details. 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. attacks. What is the point of Thrower's Bandolier? following for every instance: we could get the top 3 CPU users grouped by application (app) and process Ive added a data source(prometheus) in Grafana. SSH into both servers and run the following commands to install Docker. what does the Query Inspector show for the query you have a problem with? To get rid of such time series Prometheus will run head garbage collection (remember that Head is the structure holding all memSeries) right after writing a block. (fanout by job name) and instance (fanout by instance of the job), we might Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, How Intuit democratizes AI development across teams through reusability. 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. We know that the more labels on a metric, the more time series it can create. This page will guide you through how to install and connect Prometheus and Grafana. Youll be executing all these queries in the Prometheus expression browser, so lets get started. If the time series doesnt exist yet and our append would create it (a new memSeries instance would be created) then we skip this sample. What am I doing wrong here in the PlotLegends specification? Have you fixed this issue? We can add more metrics if we like and they will all appear in the HTTP response to the metrics endpoint. If we have a scrape with sample_limit set to 200 and the application exposes 201 time series, then all except one final time series will be accepted. At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. Why do many companies reject expired SSL certificates as bugs in bug bounties? I have a data model where some metrics are namespaced by client, environment and deployment name. *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. How do you get out of a corner when plotting yourself into a corner, Partner is not responding when their writing is needed in European project application. 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. The simplest way of doing this is by using functionality provided with client_python itself - see documentation here. If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? This means that looking at how many time series an application could potentially export, and how many it actually exports, gives us two completely different numbers, which makes capacity planning a lot harder. I have just used the JSON file that is available in below website or Internet application, ward off DDoS Are you not exposing the fail metric when there hasn't been a failure yet? positions. We use Prometheus to gain insight into all the different pieces of hardware and software that make up our global network. How To Query Prometheus on Ubuntu 14.04 Part 1 - DigitalOcean Our metrics are exposed as a HTTP response. This works fine when there are data points for all queries in the expression. A time series that was only scraped once is guaranteed to live in Prometheus for one to three hours, depending on the exact time of that scrape. So the maximum number of time series we can end up creating is four (2*2). This process helps to reduce disk usage since each block has an index taking a good chunk of disk space. The number of times some specific event occurred. Use it to get a rough idea of how much memory is used per time series and dont assume its that exact number. This is the standard Prometheus flow for a scrape that has the sample_limit option set: The entire scrape either succeeds or fails. Samples are compressed using encoding that works best if there are continuous updates. 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. If you look at the HTTP response of our example metric youll see that none of the returned entries have timestamps. 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. In the following steps, you will create a two-node Kubernetes cluster (one master and one worker) in AWS. This garbage collection, among other things, will look for any time series without a single chunk and remove it from memory. 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). This is in contrast to a metric without any dimensions, which always gets exposed as exactly one present series and is initialized to 0. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. 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 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 I still can't use that metric in calculations ( e.g., success / (success + fail) ) as those calculations will return no datapoints. However when one of the expressions returns no data points found the result of the entire expression is no data points found. 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. A common class of mistakes is to have an error label on your metrics and pass raw error objects as values. Once configured, your instances should be ready for access. So, specifically in response to your question: I am facing the same issue - please explain how you configured your data Using regular expressions, you could select time series only for jobs whose Simple, clear and working - thanks a lot. Up until now all time series are stored entirely in memory and the more time series you have, the higher Prometheus memory usage youll see. If we let Prometheus consume more memory than it can physically use then it will crash. PromQL tutorial for beginners and humans - Medium This patchset consists of two main elements. Time arrow with "current position" evolving with overlay number. It might seem simple on the surface, after all you just need to stop yourself from creating too many metrics, adding too many labels or setting label values from untrusted sources. Well be executing kubectl commands on the master node only. Theres only one chunk that we can append to, its called the Head Chunk. This is optional, but may be useful if you don't already have an APM, or would like to use our templates and sample queries. This is because the Prometheus server itself is responsible for timestamps. Is there a way to write the query so that a default value can be used if there are no data points - e.g., 0. Under which circumstances? For operations between two instant vectors, the matching behavior can be modified. The below posts may be helpful for you to learn more about Kubernetes and our company. https://grafana.com/grafana/dashboards/2129. Creating new time series on the other hand is a lot more expensive - we need to allocate new memSeries instances with a copy of all labels and keep it in memory for at least an hour. Those memSeries objects are storing all the time series information. Is what you did above (failures.WithLabelValues) an example of "exposing"? The result is a table of failure reason and its count. This makes a bit more sense with your explanation. 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. 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. Returns a list of label values for the label in every metric. Managed Service for Prometheus Cloud Monitoring Prometheus # ! Better Prometheus rate() Function with VictoriaMetrics 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. This helps us avoid a situation where applications are exporting thousands of times series that arent really needed. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? without any dimensional information. For Prometheus to collect this metric we need our application to run an HTTP server and expose our metrics there. Are there tables of wastage rates for different fruit and veg? are going to make it By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Can airtags be tracked from an iMac desktop, with no iPhone? Selecting data from Prometheus's TSDB forms the basis of almost any useful PromQL query before . Please open a new issue for related bugs. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. 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. Having a working monitoring setup is a critical part of the work we do for our clients. Any other chunk holds historical samples and therefore is read-only. Now we should pause to make an important distinction between metrics and time series. PromQL allows querying historical data and combining / comparing it to the current data. Going back to our time series - at this point Prometheus either creates a new memSeries instance or uses already existing memSeries. Before running this query, create a Pod with the following specification: If this query returns a positive value, then the cluster has overcommitted the CPU. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Already on GitHub? Improving your monitoring setup by integrating Cloudflares analytics data into Prometheus and Grafana Pint is a tool we developed to validate our Prometheus alerting rules and ensure they are always working website TSDB used in Prometheus is a special kind of database that was highly optimized for a very specific workload: This means that Prometheus is most efficient when continuously scraping the same time series over and over again. The second patch modifies how Prometheus handles sample_limit - with our patch instead of failing the entire scrape it simply ignores excess time series. Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. For example our errors_total metric, which we used in example before, might not be present at all until we start seeing some errors, and even then it might be just one or two errors that will be recorded. 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. Add field from calculation Binary operation. 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. I am interested in creating a summary of each deployment, where that summary is based on the number of alerts that are present for each deployment. Please dont post the same question under multiple topics / subjects. No, only calling Observe() on a Summary or Histogram metric will add any observations (and only calling Inc() on a counter metric will increment it). count(ALERTS) or (1-absent(ALERTS)), Alternatively, count(ALERTS) or vector(0). If the error message youre getting (in a log file or on screen) can be quoted Its not going to get you a quicker or better answer, and some people might I.e., there's no way to coerce no datapoints to 0 (zero)? 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? On the worker node, run the kubeadm joining command shown in the last step. Managing the entire lifecycle of a metric from an engineering perspective is a complex process. For a list of trademarks of The Linux Foundation, please see our Trademark Usage page. Prometheus provides a functional query language called PromQL (Prometheus Query Language) that lets the user select and aggregate time series data in real time. PromQL allows you to write queries and fetch information from the metric data collected by Prometheus. We will examine their use cases, the reasoning behind them, and some implementation details you should be aware of. metric name, as measured over the last 5 minutes: Assuming that the http_requests_total time series all have the labels job rev2023.3.3.43278. Thanks for contributing an answer to Stack Overflow! 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. The Linux Foundation has registered trademarks and uses trademarks. 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. 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. Internet-scale applications efficiently, Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. 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. by (geo_region) < bool 4 it works perfectly if one is missing as count() then returns 1 and the rule fires. Even i am facing the same issue Please help me on this. 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. 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 . group by returns a value of 1, so we subtract 1 to get 0 for each deployment and I now wish to add to this the number of alerts that are applicable to each deployment. Prometheus does offer some options for dealing with high cardinality problems. Basically our labels hash is used as a primary key inside TSDB. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. What this means is that a single metric will create one or more time series. Chunks will consume more memory as they slowly fill with more samples, after each scrape, and so the memory usage here will follow a cycle - we start with low memory usage when the first sample is appended, then memory usage slowly goes up until a new chunk is created and we start again. 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. Well occasionally send you account related emails. to your account. The only exception are memory-mapped chunks which are offloaded to disk, but will be read into memory if needed by queries. There are a number of options you can set in your scrape configuration block. an EC2 regions with application servers running docker containers. Having good internal documentation that covers all of the basics specific for our environment and most common tasks is very important. This works fine when there are data points for all queries in the expression. Is there a single-word adjective for "having exceptionally strong moral principles"? Making statements based on opinion; back them up with references or personal experience. 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. 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. Prometheus will keep each block on disk for the configured retention period. This is what i can see on Query Inspector. There will be traps and room for mistakes at all stages of this process. Im new at Grafan and Prometheus. job and handler labels: Return a whole range of time (in this case 5 minutes up to the query time) list, which does not convey images, so screenshots etc. We can use these to add more information to our metrics so that we can better understand whats going on. "no data". instance_memory_usage_bytes: This shows the current memory used. Monitoring our monitoring: how we validate our Prometheus alert rules 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? All they have to do is set it explicitly in their scrape configuration. Prometheus allows us to measure health & performance over time and, if theres anything wrong with any service, let our team know before it becomes a problem. Bulk update symbol size units from mm to map units in rule-based symbology. With this simple code Prometheus client library will create a single metric. It enables us to enforce a hard limit on the number of time series we can scrape from each application instance. To your second question regarding whether I have some other label on it, the answer is yes I do. (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. The downside of all these limits is that breaching any of them will cause an error for the entire scrape. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 - 05:59, , 22:00 - 23:59. By clicking Sign up for GitHub, you agree to our terms of service and returns the unused memory in MiB for every instance (on a fictional cluster 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. I've created an expression that is intended to display percent-success for a given metric. To learn more, see our tips on writing great answers. You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. Is a PhD visitor considered as a visiting scholar? Find centralized, trusted content and collaborate around the technologies you use most. Are there tables of wastage rates for different fruit and veg? If we add another label that can also have two values then we can now export up to eight time series (2*2*2). The Head Chunk is never memory-mapped, its always stored in memory. syntax. So lets start by looking at what cardinality means from Prometheus' perspective, when it can be a problem and some of the ways to deal with it. Finally getting back to this. The advantage of doing this is that memory-mapped chunks dont use memory unless TSDB needs to read them. If this query also returns a positive value, then our cluster has overcommitted the memory. In this query, you will find nodes that are intermittently switching between Ready" and NotReady" status continuously. Of course, this article is not a primer on PromQL; you can browse through the PromQL documentation for more in-depth knowledge. By default Prometheus will create a chunk per each two hours of wall clock. Sign in Any excess samples (after reaching sample_limit) will only be appended if they belong to time series that are already stored inside TSDB. whether someone is able to help out. The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series.