syntax. And then there is Grafana, which comes with a lot of built-in dashboards for Kubernetes monitoring. t]. Second rule does the same but only sums time series with status labels equal to "500". Already on GitHub? I'd expect to have also: Please use the prometheus-users mailing list for questions. This makes a bit more sense with your explanation. But I'm stuck now if I want to do something like apply a weight to alerts of a different severity level, e.g. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Having good internal documentation that covers all of the basics specific for our environment and most common tasks is very important. No Data is showing on Grafana Dashboard - Prometheus - Grafana Labs following for every instance: we could get the top 3 CPU users grouped by application (app) and process After a few hours of Prometheus running and scraping metrics we will likely have more than one chunk on our time series: Since all these chunks are stored in memory Prometheus will try to reduce memory usage by writing them to disk and memory-mapping. See this article for details. ward off DDoS Adding labels is very easy and all we need to do is specify their names. Each time series stored inside Prometheus (as a memSeries instance) consists of: The amount of memory needed for labels will depend on the number and length of these. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. but viewed in the tabular ("Console") view of the expression browser. I'm not sure what you mean by exposing a metric. In this blog post well cover some of the issues one might encounter when trying to collect many millions of time series per Prometheus instance. Setting label_limit provides some cardinality protection, but even with just one label name and huge number of values we can see high cardinality. 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. Hmmm, upon further reflection, I'm wondering if this will throw the metrics off. what does the Query Inspector show for the query you have a problem with? count(container_last_seen{name="container_that_doesn't_exist"}), What did you see instead? Is a PhD visitor considered as a visiting scholar? 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. and can help you on That map uses labels hashes as keys and a structure called memSeries as values. However, the queries you will see here are a baseline" audit. The more labels you have, or the longer the names and values are, the more memory it will use. but still preserve the job dimension: If we have two different metrics with the same dimensional labels, we can apply That's the query (Counter metric): sum(increase(check_fail{app="monitor"}[20m])) by (reason). There is a single time series for each unique combination of metrics labels. 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. 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. new career direction, check out our open What sort of strategies would a medieval military use against a fantasy giant? Today, let's look a bit closer at the two ways of selecting data in PromQL: instant vector selectors and range vector selectors. If both the nodes are running fine, you shouldnt get any result for this query. are going to make it Stumbled onto this post for something else unrelated, just was +1-ing this :). One thing you could do though to ensure at least the existence of failure series for the same series which have had successes, you could just reference the failure metric in the same code path without actually incrementing it, like so: That way, the counter for that label value will get created and initialized to 0. help customers build https://github.com/notifications/unsubscribe-auth/AAg1mPXncyVis81Rx1mIWiXRDe0E1Dpcks5rIXe6gaJpZM4LOTeb. Having a working monitoring setup is a critical part of the work we do for our clients. Finally, please remember that some people read these postings as an email This is in contrast to a metric without any dimensions, which always gets exposed as exactly one present series and is initialized to 0. I.e., there's no way to coerce no datapoints to 0 (zero)? Here is the extract of the relevant options from Prometheus documentation: Setting all the label length related limits allows you to avoid a situation where extremely long label names or values end up taking too much memory. For a list of trademarks of The Linux Foundation, please see our Trademark Usage page. 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. AFAIK it's not possible to hide them through Grafana. Once theyre in TSDB its already too late. Operators | Prometheus Asking for help, clarification, or responding to other answers. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. The main motivation seems to be that dealing with partially scraped metrics is difficult and youre better off treating failed scrapes as incidents. 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). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thirdly Prometheus is written in Golang which is a language with garbage collection. 1 Like. Using a query that returns "no data points found" in an expression. Run the following commands on the master node, only copy the kubeconfig and set up Flannel CNI. You can calculate how much memory is needed for your time series by running this query on your Prometheus server: Note that your Prometheus server must be configured to scrape itself for this to work. Now we should pause to make an important distinction between metrics and time series. If we try to append a sample with a timestamp higher than the maximum allowed time for current Head Chunk, then TSDB will create a new Head Chunk and calculate a new maximum time for it based on the rate of appends. Which in turn will double the memory usage of our Prometheus server. 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. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. Cadvisors on every server provide container names. Time arrow with "current position" evolving with overlay number. Once we appended sample_limit number of samples we start to be selective. If this query also returns a positive value, then our cluster has overcommitted the memory. Monitor Confluence with Prometheus and Grafana | Confluence Data Center 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. Cadvisors on every server provide container names. 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. It doesnt get easier than that, until you actually try to do it. Lets adjust the example code to do this. This is because the only way to stop time series from eating memory is to prevent them from being appended to TSDB. feel that its pushy or irritating and therefore ignore it. But you cant keep everything in memory forever, even with memory-mapping parts of data. For example, /api/v1/query?query=http_response_ok [24h]&time=t would return raw samples on the time range (t-24h . https://grafana.com/grafana/dashboards/2129. This process helps to reduce disk usage since each block has an index taking a good chunk of disk space. notification_sender-. will get matched and propagated to the output. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, How Intuit democratizes AI development across teams through reusability. Is what you did above (failures.WithLabelValues) an example of "exposing"? At the same time our patch gives us graceful degradation by capping time series from each scrape to a certain level, rather than failing hard and dropping all time series from affected scrape, which would mean losing all observability of affected applications. This is the standard flow with a scrape that doesnt set any sample_limit: With our patch we tell TSDB that its allowed to store up to N time series in total, from all scrapes, at any time. Managed Service for Prometheus Cloud Monitoring Prometheus # ! If you need to obtain raw samples, then a range query must be sent to /api/v1/query. 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. Once we do that we need to pass label values (in the same order as label names were specified) when incrementing our counter to pass this extra information. Any other chunk holds historical samples and therefore is read-only. 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 this point we should know a few things about Prometheus: With all of that in mind we can now see the problem - a metric with high cardinality, especially one with label values that come from the outside world, can easily create a huge number of time series in a very short time, causing cardinality explosion. entire corporate networks, This means that Prometheus must check if theres already a time series with identical name and exact same set of labels present. You can run a variety of PromQL queries to pull interesting and actionable metrics from your Kubernetes cluster. Secondly this calculation is based on all memory used by Prometheus, not only time series data, so its just an approximation. For operations between two instant vectors, the matching behavior can be modified. We know that the more labels on a metric, the more time series it can create. Lets see what happens if we start our application at 00:25, allow Prometheus to scrape it once while it exports: And then immediately after the first scrape we upgrade our application to a new version: At 00:25 Prometheus will create our memSeries, but we will have to wait until Prometheus writes a block that contains data for 00:00-01:59 and runs garbage collection before that memSeries is removed from memory, which will happen at 03:00. Minimising the environmental effects of my dyson brain. With this simple code Prometheus client library will create a single metric. or something like that. Once the last chunk for this time series is written into a block and removed from the memSeries instance we have no chunks left. At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. Is that correct? Thats why what our application exports isnt really metrics or time series - its samples. Using a query that returns "no data points found" in an - GitHub 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. Is it possible to rotate a window 90 degrees if it has the same length and width? Not the answer you're looking for? I'm displaying Prometheus query on a Grafana table. Short story taking place on a toroidal planet or moon involving flying, How to handle a hobby that makes income in US, Doubling the cube, field extensions and minimal polynoms, Follow Up: struct sockaddr storage initialization by network format-string. To set up Prometheus to monitor app metrics: Download and install Prometheus. an EC2 regions with application servers running docker containers. 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. from and what youve done will help people to understand your problem. Do new devs get fired if they can't solve a certain bug? Often it doesnt require any malicious actor to cause cardinality related problems. binary operators to them and elements on both sides with the same label set Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. Can I tell police to wait and call a lawyer when served with a search warrant? There is a maximum of 120 samples each chunk can hold. If you do that, the line will eventually be redrawn, many times over. In both nodes, edit the /etc/hosts file to add the private IP of the nodes. Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. Run the following commands in both nodes to install kubelet, kubeadm, and kubectl. 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. Examples About an argument in Famine, Affluence and Morality. Finally we maintain a set of internal documentation pages that try to guide engineers through the process of scraping and working with metrics, with a lot of information thats specific to our environment. rev2023.3.3.43278. Time series scraped from applications are kept in memory. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Why do many companies reject expired SSL certificates as bugs in bug bounties? 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. Lets say we have an application which we want to instrument, which means add some observable properties in the form of metrics that Prometheus can read from our application. Name the nodes as Kubernetes Master and Kubernetes Worker. If you're looking for a I then hide the original query. If all the label values are controlled by your application you will be able to count the number of all possible label combinations. How can i turn no data to zero in Loki - Grafana Loki - Grafana Labs To learn more, see our tips on writing great answers. What happens when somebody wants to export more time series or use longer labels? Is it possible to create a concave light? Has 90% of ice around Antarctica disappeared in less than a decade? 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. 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. If we make a single request using the curl command: We should see these time series in our application: But what happens if an evil hacker decides to send a bunch of random requests to our application? Comparing current data with historical data. 2023 The Linux Foundation. Please help improve it by filing issues or pull requests. How can I group labels in a Prometheus query? Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. We covered some of the most basic pitfalls in our previous blog post on Prometheus - Monitoring our monitoring. 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. If the time series already exists inside TSDB then we allow the append to continue. These will give you an overall idea about a clusters health. Here at Labyrinth Labs, we put great emphasis on monitoring. Have a question about this project? 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. A sample is something in between metric and time series - its a time series value for a specific timestamp. Since labels are copied around when Prometheus is handling queries this could cause significant memory usage increase. By default we allow up to 64 labels on each time series, which is way more than most metrics would use. 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. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 - 05:59, , 22:00 - 23:59. without any dimensional information. an EC2 regions with application servers running docker containers. How to show that an expression of a finite type must be one of the finitely many possible values? You must define your metrics in your application, with names and labels that will allow you to work with resulting time series easily. You signed in with another tab or window. Extra metrics exported by Prometheus itself tell us if any scrape is exceeding the limit and if that happens we alert the team responsible for it. What is the point of Thrower's Bandolier? Once configured, your instances should be ready for access. Once you cross the 200 time series mark, you should start thinking about your metrics more. Im new at Grafan and Prometheus. It will record the time it sends HTTP requests and use that later as the timestamp for all collected time series. We use Prometheus to gain insight into all the different pieces of hardware and software that make up our global network. 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. Its not going to get you a quicker or better answer, and some people might If I now tack on a != 0 to the end of it, all zero values are filtered out: Thanks for contributing an answer to Stack Overflow! So the maximum number of time series we can end up creating is four (2*2). bay, Each Prometheus is scraping a few hundred different applications, each running on a few hundred servers. This page will guide you through how to install and connect Prometheus and Grafana. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Labels are stored once per each memSeries instance. We can use these to add more information to our metrics so that we can better understand whats going on. 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. How Cloudflare runs Prometheus at scale All they have to do is set it explicitly in their scrape configuration. As we mentioned before a time series is generated from metrics. You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. 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 Find centralized, trusted content and collaborate around the technologies you use most. Prometheus provides a functional query language called PromQL (Prometheus Query Language) that lets the user select and aggregate time series data in real time. To make things more complicated you may also hear about samples when reading Prometheus documentation. ncdu: What's going on with this second size column? In the following steps, you will create a two-node Kubernetes cluster (one master and one worker) in AWS. gabrigrec September 8, 2021, 8:12am #8. 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. This would happen if any time series was no longer being exposed by any application and therefore there was no scrape that would try to append more samples to it. Returns a list of label names. 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. This thread has been automatically locked since there has not been any recent activity after it was closed. The containers are named with a specific pattern: I need an alert when the number of container of the same pattern (eg. All rights reserved. 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? This would inflate Prometheus memory usage, which can cause Prometheus server to crash, if it uses all available physical memory. prometheus - Promql: Is it possible to get total count in Query_Range This works well if errors that need to be handled are generic, for example Permission Denied: But if the error string contains some task specific information, for example the name of the file that our application didnt have access to, or a TCP connection error, then we might easily end up with high cardinality metrics this way: Once scraped all those time series will stay in memory for a minimum of one hour. I'm displaying Prometheus query on a Grafana table. For Prometheus to collect this metric we need our application to run an HTTP server and expose our metrics there. However when one of the expressions returns no data points found the result of the entire expression is no data points found.In my case there haven't been any failures so rio_dashorigin_serve_manifest_duration_millis_count{Success="Failed"} returns no data points found.Is there a way to write the query so that a . What this means is that a single metric will create one or more time series. I've been using comparison operators in Grafana for a long while. 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. 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. In AWS, create two t2.medium instances running CentOS. 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. Better to simply ask under the single best category you think fits and see to get notified when one of them is not mounted anymore. 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. Also, providing a reasonable amount of information about where youre starting We had a fair share of problems with overloaded Prometheus instances in the past and developed a number of tools that help us deal with them, including custom patches. Now, lets install Kubernetes on the master node using kubeadm. Each chunk represents a series of samples for a specific time range. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. A simple request for the count (e.g., rio_dashorigin_memsql_request_fail_duration_millis_count) returns no datapoints). Are there tables of wastage rates for different fruit and veg? The downside of all these limits is that breaching any of them will cause an error for the entire scrape. I am always registering the metric as defined (in the Go client library) by prometheus.MustRegister(). returns the unused memory in MiB for every instance (on a fictional cluster The result of an expression can either be shown as a graph, viewed as tabular data in Prometheus's expression browser, or consumed by external systems via the HTTP API. Even i am facing the same issue Please help me on this. 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). 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? It would be easier if we could do this in the original query though. This article covered a lot of ground. count(container_last_seen{environment="prod",name="notification_sender.*",roles=".application-server."}) The text was updated successfully, but these errors were encountered: It's recommended not to expose data in this way, partially for this reason. In this query, you will find nodes that are intermittently switching between Ready" and NotReady" status continuously. I have just used the JSON file that is available in below website Or maybe we want to know if it was a cold drink or a hot one? Has 90% of ice around Antarctica disappeared in less than a decade? We protect Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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. 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. Thanks for contributing an answer to Stack Overflow! The simplest way of doing this is by using functionality provided with client_python itself - see documentation here. I've added a data source (prometheus) in Grafana. Our metric will have a single label that stores the request path. 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. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. A metric is an observable property with some defined dimensions (labels). Its the chunk responsible for the most recent time range, including the time of our scrape. Another reason is that trying to stay on top of your usage can be a challenging task. 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. Prometheus query check if value exist. Can airtags be tracked from an iMac desktop, with no iPhone? 11 Queries | Kubernetes Metric Data with PromQL, wide variety of applications, infrastructure, APIs, databases, and other sources. To get a better understanding of the impact of a short lived time series on memory usage lets take a look at another example. If we add another label that can also have two values then we can now export up to eight time series (2*2*2). Any excess samples (after reaching sample_limit) will only be appended if they belong to time series that are already stored inside TSDB. Is a PhD visitor considered as a visiting scholar? 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. count the number of running instances per application like this: This documentation is open-source. Looking at memory usage of such Prometheus server we would see this pattern repeating over time: The important information here is that short lived time series are expensive. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Hello, I'm new at Grafan and Prometheus.