If so it seems like this will skew the results of the query (e.g., quantiles). When using Prometheus defaults and assuming we have a single chunk for each two hours of wall clock we would see this: Once a chunk is written into a block it is removed from memSeries and thus from memory. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. Better to simply ask under the single best category you think fits and see 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 . Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. At this point, both nodes should be ready. Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. *) in region drops below 4. Once theyre in TSDB its already too late. 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. If both the nodes are running fine, you shouldnt get any result for this query. 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. These queries are a good starting point. PromQL allows querying historical data and combining / comparing it to the current data. You can verify this by running the kubectl get nodes command on the master node. Can airtags be tracked from an iMac desktop, with no iPhone? Having a working monitoring setup is a critical part of the work we do for our clients. I've added a data source (prometheus) in Grafana. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. 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. Why do many companies reject expired SSL certificates as bugs in bug bounties? By clicking Sign up for GitHub, you agree to our terms of service and And then there is Grafana, which comes with a lot of built-in dashboards for Kubernetes monitoring. It doesnt get easier than that, until you actually try to do it. I'm sure there's a proper way to do this, but in the end, I used label_replace to add an arbitrary key-value label to each sub-query that I wished to add to the original values, and then applied an or to each. Have a question about this project? The text was updated successfully, but these errors were encountered: It's recommended not to expose data in this way, partially for this reason. You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. "no data". Our metric will have a single label that stores the request path. This thread has been automatically locked since there has not been any recent activity after it was closed. Those memSeries objects are storing all the time series information. Simply adding a label with two distinct values to all our metrics might double the number of time series we have to deal with. 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. No error message, it is just not showing the data while using the JSON file from that website. 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. If you're looking for a Thanks for contributing an answer to Stack Overflow! Doubling the cube, field extensions and minimal polynoms. If your expression returns anything with labels, it won't match the time series generated by vector(0). This process is also aligned with the wall clock but shifted by one hour. Each time series will cost us resources since it needs to be kept in memory, so the more time series we have, the more resources metrics will consume. 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. The simplest way of doing this is by using functionality provided with client_python itself - see documentation here. Another reason is that trying to stay on top of your usage can be a challenging task. Prometheus query check if value exist. Youve learned about the main components of Prometheus, and its query language, PromQL. Thanks, What am I doing wrong here in the PlotLegends specification? For operations between two instant vectors, the matching behavior can be modified. I believe it's the logic that it's written, but is there any . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. an EC2 regions with application servers running docker containers. On the worker node, run the kubeadm joining command shown in the last step. See these docs for details on how Prometheus calculates the returned results. 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 order to make this possible, it's necessary to tell Prometheus explicitly to not trying to match any labels by . @zerthimon You might want to use 'bool' with your comparator AFAIK it's not possible to hide them through Grafana. Thank you for subscribing! Hmmm, upon further reflection, I'm wondering if this will throw the metrics off. Neither of these solutions seem to retain the other dimensional information, they simply produce a scaler 0. Finally, please remember that some people read these postings as an email That's the query ( Counter metric): sum (increase (check_fail {app="monitor"} [20m])) by (reason) The result is a table of failure reason and its count. 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. The containers are named with a specific pattern: I need an alert when the number of container of the same pattern (eg. First rule will tell Prometheus to calculate per second rate of all requests and sum it across all instances of our server. or Internet application, Internally all time series are stored inside a map on a structure called Head. which outputs 0 for an empty input vector, but that outputs a scalar information which you think might be helpful for someone else to understand What happens when somebody wants to export more time series or use longer labels? Note that using subqueries unnecessarily is unwise. 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. How Intuit democratizes AI development across teams through reusability. This patchset consists of two main elements. 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. Instead we count time series as we append them to TSDB. For instance, the following query would return week-old data for all the time series with node_network_receive_bytes_total name: node_network_receive_bytes_total offset 7d Operating such a large Prometheus deployment doesnt come without challenges. 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. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. By clicking Sign up for GitHub, you agree to our terms of service and but still preserve the job dimension: If we have two different metrics with the same dimensional labels, we can apply Once you cross the 200 time series mark, you should start thinking about your metrics more. 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. We use Prometheus to gain insight into all the different pieces of hardware and software that make up our global network. In the same blog post we also mention one of the tools we use to help our engineers write valid Prometheus alerting rules. 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 our free app that makes your Internet faster and safer. 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. 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. 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. positions. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Are there tables of wastage rates for different fruit and veg? We covered some of the most basic pitfalls in our previous blog post on Prometheus - Monitoring our monitoring. SSH into both servers and run the following commands to install Docker. Will this approach record 0 durations on every success? 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. 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. Well occasionally send you account related emails. 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. All rights reserved. Can airtags be tracked from an iMac desktop, with no iPhone? To learn more, see our tips on writing great answers. I cant see how absent() may help me here @juliusv yeah, I tried count_scalar() but I can't use aggregation with it. That map uses labels hashes as keys and a structure called memSeries as values. I made the changes per the recommendation (as I understood it) and defined separate success and fail metrics. Its the chunk responsible for the most recent time range, including the time of our scrape. it works perfectly if one is missing as count() then returns 1 and the rule fires. rev2023.3.3.43278. 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. Samples are compressed using encoding that works best if there are continuous updates. what error message are you getting to show that theres a problem? Asking for help, clarification, or responding to other answers. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. by (geo_region) < bool 4 attacks, keep 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? following for every instance: we could get the top 3 CPU users grouped by application (app) and process how have you configured the query which is causing problems? This selector is just a metric name. As we mentioned before a time series is generated from metrics. 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. 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). Internet-scale applications efficiently, 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. If you look at the HTTP response of our example metric youll see that none of the returned entries have timestamps. If the error message youre getting (in a log file or on screen) can be quoted 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. But you cant keep everything in memory forever, even with memory-mapping parts of data. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. If the total number of stored time series is below the configured limit then we append the sample as usual. Time series scraped from applications are kept in memory. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 . 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. 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 . Simple, clear and working - thanks a lot. Since this happens after writing a block, and writing a block happens in the middle of the chunk window (two hour slices aligned to the wall clock) the only memSeries this would find are the ones that are orphaned - they received samples before, but not anymore. This is the standard Prometheus flow for a scrape that has the sample_limit option set: The entire scrape either succeeds or fails. What video game is Charlie playing in Poker Face S01E07? (pseudocode): This gives the same single value series, or no data if there are no alerts. bay, To get a better idea of this problem lets adjust our example metric to track HTTP requests. as text instead of as an image, more people will be able to read it and help. 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. The Head Chunk is never memory-mapped, its always stored in memory. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, How Intuit democratizes AI development across teams through reusability.