what does the Query Inspector show for the query you have a problem with? count(container_last_seen{environment="prod",name="notification_sender.*",roles=".application-server."}) Why is this sentence from The Great Gatsby grammatical? Asking for help, clarification, or responding to other answers. how have you configured the query which is causing problems? Even Prometheus' own client libraries had bugs that could expose you to problems like this. 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. Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. information which you think might be helpful for someone else to understand Redoing the align environment with a specific formatting. You can query Prometheus metrics directly with its own query language: PromQL. This is what i can see on Query Inspector. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. Does a summoned creature play immediately after being summoned by a ready action? At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. To your second question regarding whether I have some other label on it, the answer is yes I do. The result is a table of failure reason and its count. We know that time series will stay in memory for a while, even if they were scraped only once. To avoid this its in general best to never accept label values from untrusted sources. Bulk update symbol size units from mm to map units in rule-based symbology. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? syntax. These will give you an overall idea about a clusters health. Of course there are many types of queries you can write, and other useful queries are freely available. If you do that, the line will eventually be redrawn, many times over. One of the most important layers of protection is a set of patches we maintain on top of Prometheus. First rule will tell Prometheus to calculate per second rate of all requests and sum it across all instances of our server. 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. However, the queries you will see here are a baseline" audit. Have you fixed this issue? returns the unused memory in MiB for every instance (on a fictional cluster 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. Instead we count time series as we append them to TSDB. 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. Good to know, thanks for the quick response! Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, How Intuit democratizes AI development across teams through reusability. But the key to tackling high cardinality was better understanding how Prometheus works and what kind of usage patterns will be problematic. privacy statement. 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. And this brings us to the definition of cardinality in the context of metrics. (pseudocode): This gives the same single value series, or no data if there are no alerts. This pod wont be able to run because we dont have a node that has the label disktype: ssd. If the error message youre getting (in a log file or on screen) can be quoted 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. https://github.com/notifications/unsubscribe-auth/AAg1mPXncyVis81Rx1mIWiXRDe0E1Dpcks5rIXe6gaJpZM4LOTeb. Any other chunk holds historical samples and therefore is read-only. 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 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. To get a better idea of this problem lets adjust our example metric to track HTTP requests. 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. Select the query and do + 0. 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. We know that each time series will be kept in memory. Is that correct? If a sample lacks any explicit timestamp then it means that the sample represents the most recent value - its the current value of a given time series, and the timestamp is simply the time you make your observation at. Visit 1.1.1.1 from any device to get started with to get notified when one of them is not mounted anymore. as text instead of as an image, more people will be able to read it and help. Every two hours Prometheus will persist chunks from memory onto the disk. Prometheus and PromQL (Prometheus Query Language) are conceptually very simple, but this means that all the complexity is hidden in the interactions between different elements of the whole metrics pipeline. attacks, keep Run the following command on the master node: Once the command runs successfully, youll see joining instructions to add the worker node to the cluster. Its not difficult to accidentally cause cardinality problems and in the past weve dealt with a fair number of issues relating to it. Are there tables of wastage rates for different fruit and veg? I have a data model where some metrics are namespaced by client, environment and deployment name. The number of times some specific event occurred. 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. Each chunk represents a series of samples for a specific time range. In this query, you will find nodes that are intermittently switching between Ready" and NotReady" status continuously. Returns a list of label values for the label in every metric. If you look at the HTTP response of our example metric youll see that none of the returned entries have timestamps. Run the following commands on the master node, only copy the kubeconfig and set up Flannel CNI. 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. I've created an expression that is intended to display percent-success for a given metric. I have just used the JSON file that is available in below website A time series is an instance of that metric, with a unique combination of all the dimensions (labels), plus a series of timestamp & value pairs - hence the name time series. 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. Finally, please remember that some people read these postings as an email We know that the more labels on a metric, the more time series it can create. These flags are only exposed for testing and might have a negative impact on other parts of Prometheus server. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To select all HTTP status codes except 4xx ones, you could run: Return the 5-minute rate of the http_requests_total metric for the past 30 minutes, with a resolution of 1 minute. Arithmetic binary operators The following binary arithmetic operators exist in Prometheus: + (addition) - (subtraction) * (multiplication) / (division) % (modulo) ^ (power/exponentiation) Where does this (supposedly) Gibson quote come from? count(container_last_seen{name="container_that_doesn't_exist"}), What did you see instead? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? I'm displaying Prometheus query on a Grafana table. What sort of strategies would a medieval military use against a fantasy giant? What video game is Charlie playing in Poker Face S01E07? your journey to Zero Trust. Also the link to the mailing list doesn't work for me. We will also signal back to the scrape logic that some samples were skipped. 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. 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. For operations between two instant vectors, the matching behavior can be modified. t]. 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. or something like that. Thanks for contributing an answer to Stack Overflow! However when one of the expressions returns no data points found the result of the entire expression is no data points found. 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. 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. With any monitoring system its important that youre able to pull out the right data. what error message are you getting to show that theres a problem? 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. SSH into both servers and run the following commands to install Docker. We can use these to add more information to our metrics so that we can better understand whats going on. Do new devs get fired if they can't solve a certain bug? The more labels you have, or the longer the names and values are, the more memory it will use. To learn more about our mission to help build a better Internet, start here. 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. 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? 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. I'm not sure what you mean by exposing a metric. 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. There's also count_scalar(), The Linux Foundation has registered trademarks and uses trademarks. Yeah, absent() is probably the way to go. What this means is that a single metric will create one or more time series. https://grafana.com/grafana/dashboards/2129. Is a PhD visitor considered as a visiting scholar? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. In AWS, create two t2.medium instances running CentOS. With our custom patch we dont care how many samples are in a scrape. 11 Queries | Kubernetes Metric Data with PromQL, wide variety of applications, infrastructure, APIs, databases, and other sources. He has a Bachelor of Technology in Computer Science & Engineering from SRMS. Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. to your account. Why are trials on "Law & Order" in the New York Supreme Court? type (proc) like this: Assuming this metric contains one time series per running instance, you could On Thu, Dec 15, 2016 at 6:24 PM, Lior Goikhburg ***@***. Timestamps here can be explicit or implicit. Im new at Grafan and Prometheus. 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. Here are two examples of instant vectors: You can also use range vectors to select a particular time range. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. Combined thats a lot of different metrics. I'm still out of ideas here. Has 90% of ice around Antarctica disappeared in less than a decade? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Each Prometheus is scraping a few hundred different applications, each running on a few hundred servers. rate (http_requests_total [5m]) [30m:1m] Even i am facing the same issue Please help me on this. Thats why what our application exports isnt really metrics or time series - its samples. 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? @zerthimon The following expr works for me *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. (fanout by job name) and instance (fanout by instance of the job), we might Separate metrics for total and failure will work as expected. By clicking Sign up for GitHub, you agree to our terms of service and prometheus promql Share Follow edited Nov 12, 2020 at 12:27 This is an example of a nested subquery. No error message, it is just not showing the data while using the JSON file from that website. This is one argument for not overusing labels, but often it cannot be avoided. 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. 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 has gained a lot of market traction over the years, and when combined with other open-source tools like Grafana, it provides a robust monitoring solution. Please help improve it by filing issues or pull requests. All they have to do is set it explicitly in their scrape configuration. AFAIK it's not possible to hide them through Grafana. Are you not exposing the fail metric when there hasn't been a failure yet? but still preserve the job dimension: If we have two different metrics with the same dimensional labels, we can apply Run the following commands in both nodes to install kubelet, kubeadm, and kubectl. What happens when somebody wants to export more time series or use longer labels? You can use these queries in the expression browser, Prometheus HTTP API, or visualization tools like Grafana. Is a PhD visitor considered as a visiting scholar? Next, create a Security Group to allow access to the instances. The most basic layer of protection that we deploy are scrape limits, which we enforce on all configured scrapes. Return all time series with the metric http_requests_total: Return all time series with the metric http_requests_total and the given positions. But you cant keep everything in memory forever, even with memory-mapping parts of data. By clicking Post Your Answer, you agree to our terms of service, privacy policy and 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. Then you must configure Prometheus scrapes in the correct way and deploy that to the right Prometheus server. Use it to get a rough idea of how much memory is used per time series and dont assume its that exact number. There are a number of options you can set in your scrape configuration block. - grafana-7.1.0-beta2.windows-amd64, how did you install it? 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. It would be easier if we could do this in the original query though. On the worker node, run the kubeadm joining command shown in the last step. How to react to a students panic attack in an oral exam? Explanation: Prometheus uses label matching in expressions. count(ALERTS) or (1-absent(ALERTS)), Alternatively, count(ALERTS) or vector(0). This garbage collection, among other things, will look for any time series without a single chunk and remove it from memory. an EC2 regions with application servers running docker containers. If so it seems like this will skew the results of the query (e.g., quantiles). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. PromQL allows querying historical data and combining / comparing it to the current data. name match a certain pattern, in this case, all jobs that end with server: All regular expressions in Prometheus use RE2 Cadvisors on every server provide container names. Before running the query, create a Pod with the following specification: Before running the query, create a PersistentVolumeClaim with the following specification: This will get stuck in Pending state as we dont have a storageClass called manual" in our cluster. Finally getting back to this. Internally time series names are just another label called __name__, so there is no practical distinction between name and labels. whether someone is able to help out. 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. Not the answer you're looking for? Will this approach record 0 durations on every success? 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 reason why we still allow appends for some samples even after were above sample_limit is that appending samples to existing time series is cheap, its just adding an extra timestamp & value pair. Prometheus - exclude 0 values from query result, How Intuit democratizes AI development across teams through reusability. 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. 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. 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. All regular expressions in Prometheus use RE2 syntax. @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). See this article for details. Making statements based on opinion; back them up with references or personal experience. Connect and share knowledge within a single location that is structured and easy to search. Any excess samples (after reaching sample_limit) will only be appended if they belong to time series that are already stored inside TSDB. Next you will likely need to create recording and/or alerting rules to make use of your time series. Windows 10, how have you configured the query which is causing problems? entire corporate networks, 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. @juliusv Thanks for clarifying that. Here at Labyrinth Labs, we put great emphasis on monitoring. Theres no timestamp anywhere actually. new career direction, check out our open That map uses labels hashes as keys and a structure called memSeries as values. 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 . How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? In both nodes, edit the /etc/hosts file to add the private IP of the nodes. That's the query (Counter metric): sum(increase(check_fail{app="monitor"}[20m])) by (reason). Can airtags be tracked from an iMac desktop, with no iPhone? 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 Going back to our time series - at this point Prometheus either creates a new memSeries instance or uses already existing memSeries. So when TSDB is asked to append a new sample by any scrape, it will first check how many time series are already present. You set up a Kubernetes cluster, installed Prometheus on it ,and ran some queries to check the clusters health. Often it doesnt require any malicious actor to cause cardinality related problems. These queries are a good starting point. Managed Service for Prometheus https://goo.gle/3ZgeGxv VictoriaMetrics handles rate () function in the common sense way I described earlier! Can airtags be tracked from an iMac desktop, with no iPhone? from and what youve done will help people to understand your problem. list, which does not convey images, so screenshots etc. Inside the Prometheus configuration file we define a scrape config that tells Prometheus where to send the HTTP request, how often and, optionally, to apply extra processing to both requests and responses. Our HTTP response will now show more entries: As we can see we have an entry for each unique combination of labels. Asking for help, clarification, or responding to other answers. This had the effect of merging the series without overwriting any values. This article covered a lot of ground. In the same blog post we also mention one of the tools we use to help our engineers write valid Prometheus alerting rules. I used a Grafana transformation which seems to work. Use Prometheus to monitor app performance metrics. So the maximum number of time series we can end up creating is four (2*2). gabrigrec September 8, 2021, 8:12am #8. 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. These are the sane defaults that 99% of application exporting metrics would never exceed. 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. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. rev2023.3.3.43278. I've added a data source (prometheus) in Grafana. Examples rev2023.3.3.43278. Prometheus's query language supports basic logical and arithmetic operators. 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. The process of sending HTTP requests from Prometheus to our application is called scraping. Our metrics are exposed as a HTTP response. Which in turn will double the memory usage of our Prometheus server. Please dont post the same question under multiple topics / subjects. Looking to learn more? I know prometheus has comparison operators but I wasn't able to apply them. Stumbled onto this post for something else unrelated, just was +1-ing this :). Once it has a memSeries instance to work with it will append our sample to the Head Chunk. Run the following commands in both nodes to disable SELinux and swapping: Also, change SELINUX=enforcing to SELINUX=permissive in the /etc/selinux/config file. The second patch modifies how Prometheus handles sample_limit - with our patch instead of failing the entire scrape it simply ignores excess time series. 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). Simply adding a label with two distinct values to all our metrics might double the number of time series we have to deal with. Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. If the total number of stored time series is below the configured limit then we append the sample as usual. 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. Well occasionally send you account related emails. our free app that makes your Internet faster and safer. 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. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series. source, what your query is, what the query inspector shows, and any other Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? 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). Hmmm, upon further reflection, I'm wondering if this will throw the metrics off. Is what you did above (failures.WithLabelValues) an example of "exposing"? To get a better understanding of the impact of a short lived time series on memory usage lets take a look at another example. 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. 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. 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 for the same vector, making it a range vector: Note that an expression resulting in a range vector cannot be graphed directly, 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. There is a single time series for each unique combination of metrics labels. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. The below posts may be helpful for you to learn more about Kubernetes and our company. (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 Head Chunk is never memory-mapped, its always stored in memory.
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