Using regular expressions, you could select time series only for jobs whose But before doing that it needs to first check which of the samples belong to the time series that are already present inside TSDB and which are for completely new time series. Ive deliberately kept the setup simple and accessible from any address for demonstration. Where does this (supposedly) Gibson quote come from? Returns a list of label values for the label in every metric. binary operators to them and elements on both sides with the same label set Although you can tweak some of Prometheus' behavior and tweak it more for use with short lived time series, by passing one of the hidden flags, its generally discouraged to do so. Note that using subqueries unnecessarily is unwise. How to show that an expression of a finite type must be one of the finitely many possible values? 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). The more labels you have, or the longer the names and values are, the more memory it will use. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. Once it has a memSeries instance to work with it will append our sample to the Head Chunk. So I still can't use that metric in calculations ( e.g., success / (success + fail) ) as those calculations will return no datapoints. About an argument in Famine, Affluence and Morality. 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. Thanks, attacks, keep help customers build 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. Prometheus is an open-source monitoring and alerting software that can collect metrics from different infrastructure and applications. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. @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). By default Prometheus will create a chunk per each two hours of wall clock. accelerate any How can I group labels in a Prometheus query? For that lets follow all the steps in the life of a time series inside Prometheus. 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. 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. 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. 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. but viewed in the tabular ("Console") view of the expression browser. 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. The main motivation seems to be that dealing with partially scraped metrics is difficult and youre better off treating failed scrapes as incidents. That map uses labels hashes as keys and a structure called memSeries as values. bay, 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? The containers are named with a specific pattern: I need an alert when the number of container of the same pattern (eg. Connect and share knowledge within a single location that is structured and easy to search. Please see data model and exposition format pages for more details. what does the Query Inspector show for the query you have a problem with? How to tell which packages are held back due to phased updates. Time arrow with "current position" evolving with overlay number. And then there is Grafana, which comes with a lot of built-in dashboards for Kubernetes monitoring. For example, the following query will show the total amount of CPU time spent over the last two minutes: And the query below will show the total number of HTTP requests received in the last five minutes: There are different ways to filter, combine, and manipulate Prometheus data using operators and further processing using built-in functions. Prometheus will keep each block on disk for the configured retention period. You can query Prometheus metrics directly with its own query language: PromQL. What this means is that a single metric will create one or more time series. At this point, both nodes should be ready. Using a query that returns "no data points found" in an expression. Its very easy to keep accumulating time series in Prometheus until you run out of memory. Having good internal documentation that covers all of the basics specific for our environment and most common tasks is very important. A common class of mistakes is to have an error label on your metrics and pass raw error objects as values. There's also count_scalar(), 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 . Explanation: Prometheus uses label matching in expressions. So it seems like I'm back to square one. 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 . @juliusv Thanks for clarifying that. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Simple succinct answer. When Prometheus collects metrics it records the time it started each collection and then it will use it to write timestamp & value pairs for each time series. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. 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. Monitoring Docker container metrics using cAdvisor, Use file-based service discovery to discover scrape targets, Understanding and using the multi-target exporter pattern, Monitoring Linux host metrics with the Node Exporter. 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. If we let Prometheus consume more memory than it can physically use then it will crash. The process of sending HTTP requests from Prometheus to our application is called scraping. to your account. rev2023.3.3.43278. One of the first problems youre likely to hear about when you start running your own Prometheus instances is cardinality, with the most dramatic cases of this problem being referred to as cardinality explosion. All chunks must be aligned to those two hour slots of wall clock time, so if TSDB was building a chunk for 10:00-11:59 and it was already full at 11:30 then it would create an extra chunk for the 11:30-11:59 time range. Is it possible to create a concave light? If the error message youre getting (in a log file or on screen) can be quoted Is it possible to rotate a window 90 degrees if it has the same length and width? If this query also returns a positive value, then our cluster has overcommitted the memory. In the following steps, you will create a two-node Kubernetes cluster (one master and one worker) in AWS. Making statements based on opinion; back them up with references or personal experience. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Prometheus promQL query is not showing 0 when metric data does not exists, PromQL - how to get an interval between result values, PromQL delta for each elment in values array, Trigger alerts according to the environment in alertmanger, Prometheus alertmanager includes resolved alerts in a new alert. If you need to obtain raw samples, then a range query must be sent to /api/v1/query. Not the answer you're looking for? want to sum over the rate of all instances, so we get fewer output time series, Thanks for contributing an answer to Stack Overflow! However, the queries you will see here are a baseline" audit. 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? Looking to learn more? Of course there are many types of queries you can write, and other useful queries are freely available. Other Prometheus components include a data model that stores the metrics, client libraries for instrumenting code, and PromQL for querying the metrics. Why are trials on "Law & Order" in the New York Supreme Court? - grafana-7.1.0-beta2.windows-amd64, how did you install 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. I've created an expression that is intended to display percent-success for a given metric. count(ALERTS) or (1-absent(ALERTS)), Alternatively, count(ALERTS) or vector(0). Instead we count time series as we append them to TSDB. 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. Does a summoned creature play immediately after being summoned by a ready action? Every time we add a new label to our metric we risk multiplying the number of time series that will be exported to Prometheus as the result. to your account, What did you do? 2023 The Linux Foundation. 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. This works fine when there are data points for all queries in the expression. 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. Connect and share knowledge within a single location that is structured and easy to search. 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. Thirdly Prometheus is written in Golang which is a language with garbage collection. 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. This makes a bit more sense with your explanation. 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. This would inflate Prometheus memory usage, which can cause Prometheus server to crash, if it uses all available physical memory. for the same vector, making it a range vector: Note that an expression resulting in a range vector cannot be graphed directly, Are there tables of wastage rates for different fruit and veg? 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. Connect and share knowledge within a single location that is structured and easy to search. (fanout by job name) and instance (fanout by instance of the job), we might These flags are only exposed for testing and might have a negative impact on other parts of Prometheus server. This is one argument for not overusing labels, but often it cannot be avoided. 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. Finally, please remember that some people read these postings as an email You set up a Kubernetes cluster, installed Prometheus on it ,and ran some queries to check the clusters health. Going back to our metric with error labels we could imagine a scenario where some operation returns a huge error message, or even stack trace with hundreds of lines. One of the most important layers of protection is a set of patches we maintain on top of Prometheus. So the maximum number of time series we can end up creating is four (2*2). Play with bool I cant see how absent() may help me here @juliusv yeah, I tried count_scalar() but I can't use aggregation with it. Run the following commands on the master node to set up Prometheus on the Kubernetes cluster: Next, run this command on the master node to check the Pods status: Once all the Pods are up and running, you can access the Prometheus console using kubernetes port forwarding. Why do many companies reject expired SSL certificates as bugs in bug bounties? Each Prometheus is scraping a few hundred different applications, each running on a few hundred servers. It would be easier if we could do this in the original query though. Subscribe to receive notifications of new posts: Subscription confirmed. 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). With our custom patch we dont care how many samples are in a scrape. To learn more about our mission to help build a better Internet, start here. Often it doesnt require any malicious actor to cause cardinality related problems. I used a Grafana transformation which seems to work. our free app that makes your Internet faster and safer. 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 all the label values are controlled by your application you will be able to count the number of all possible label combinations. 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 sort of strategies would a medieval military use against a fantasy giant? With 1,000 random requests we would end up with 1,000 time series in Prometheus. In AWS, create two t2.medium instances running CentOS. privacy statement. Once theyre in TSDB its already too late. 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. Here at Labyrinth Labs, we put great emphasis on monitoring. These queries are a good starting point. (pseudocode): This gives the same single value series, or no data if there are no alerts. There is a maximum of 120 samples each chunk can hold. rev2023.3.3.43278. 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. What does remote read means in Prometheus? 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. This pod wont be able to run because we dont have a node that has the label disktype: ssd. We can use these to add more information to our metrics so that we can better understand whats going on. Better to simply ask under the single best category you think fits and see By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Prometheus lets you query data in two different modes: The Console tab allows you to evaluate a query expression at the current time. By default Prometheus will create a chunk per each two hours of wall clock. This is because the only way to stop time series from eating memory is to prevent them from being appended to TSDB. These are the sane defaults that 99% of application exporting metrics would never exceed. 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. We protect what error message are you getting to show that theres a problem? Samples are stored inside chunks using "varbit" encoding which is a lossless compression scheme optimized for time series data. Windows 10, how have you configured the query which is causing problems? You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. 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. gabrigrec September 8, 2021, 8:12am #8. 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. 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. Find centralized, trusted content and collaborate around the technologies you use most. With any monitoring system its important that youre able to pull out the right data. 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. Hello, I'm new at Grafan and Prometheus. 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. t]. See this article for details. I then hide the original query. Are there tables of wastage rates for different fruit and veg? If you do that, the line will eventually be redrawn, many times over. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. When time series disappear from applications and are no longer scraped they still stay in memory until all chunks are written to disk and garbage collection removes them. https://grafana.com/grafana/dashboards/2129. For example, this expression Managing the entire lifecycle of a metric from an engineering perspective is a complex process. Timestamps here can be explicit or implicit. It doesnt get easier than that, until you actually try to do it. Next you will likely need to create recording and/or alerting rules to make use of your time series. Already on GitHub? If the total number of stored time series is below the configured limit then we append the sample as usual. After running the query, a table will show the current value of each result time series (one table row per output series). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. 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. Even Prometheus' own client libraries had bugs that could expose you to problems like this. Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. Making statements based on opinion; back them up with references or personal experience. You must define your metrics in your application, with names and labels that will allow you to work with resulting time series easily. Adding labels is very easy and all we need to do is specify their names. Visit 1.1.1.1 from any device to get started with Monitor the health of your cluster and troubleshoot issues faster with pre-built dashboards that just work. This is the standard Prometheus flow for a scrape that has the sample_limit option set: The entire scrape either succeeds or fails. This is what i can see on Query Inspector. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. That response will have a list of, When Prometheus collects all the samples from our HTTP response it adds the timestamp of that collection and with all this information together we have a. 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. In order to make this possible, it's necessary to tell Prometheus explicitly to not trying to match any labels by . 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. 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. and can help you on 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. 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. 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. 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. So, specifically in response to your question: I am facing the same issue - please explain how you configured your data as text instead of as an image, more people will be able to read it and help. Making statements based on opinion; back them up with references or personal experience. This is the modified flow with our patch: By running go_memstats_alloc_bytes / prometheus_tsdb_head_series query we know how much memory we need per single time series (on average), we also know how much physical memory we have available for Prometheus on each server, which means that we can easily calculate the rough number of time series we can store inside Prometheus, taking into account the fact the theres garbage collection overhead since Prometheus is written in Go: memory available to Prometheus / bytes per time series = our capacity. 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. But I'm stuck now if I want to do something like apply a weight to alerts of a different severity level, e.g. The way labels are stored internally by Prometheus also matters, but thats something the user has no control over. 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. Im new at Grafan and Prometheus. notification_sender-. This garbage collection, among other things, will look for any time series without a single chunk and remove it from memory. Add field from calculation Binary operation. Has 90% of ice around Antarctica disappeared in less than a decade? 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. I've been using comparison operators in Grafana for a long while. new career direction, check out our open prometheus promql Share Follow edited Nov 12, 2020 at 12:27 Minimising the environmental effects of my dyson brain. I made the changes per the recommendation (as I understood it) and defined separate success and fail metrics. Please dont post the same question under multiple topics / subjects. which version of Grafana are you using? No error message, it is just not showing the data while using the JSON file from that website. from and what youve done will help people to understand your problem. I'm not sure what you mean by exposing a metric.