How is Jesus " " (Luke 1:32 NAS28) different from a prophet (, Luke 1:76 NAS28)? It would be easier if we could do this in the original query though. without any dimensional information. @zerthimon The following expr works for me Already on GitHub? This patchset consists of two main elements. Returns a list of label values for the label in every metric. Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. But the real risk is when you create metrics with label values coming from the outside world. 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. or Internet application, ward off DDoS @juliusv Thanks for clarifying that. There is an open pull request on the Prometheus repository. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. @rich-youngkin Yes, the general problem is non-existent series. Prometheus provides a functional query language called PromQL (Prometheus Query Language) that lets the user select and aggregate time series data in real time. 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. Cadvisors on every server provide container names. Selecting data from Prometheus's TSDB forms the basis of almost any useful PromQL query before . 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. Have you fixed this issue? 11 Queries | Kubernetes Metric Data with PromQL, wide variety of applications, infrastructure, APIs, databases, and other sources. Chunks that are a few hours old are written to disk and removed from memory. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To your second question regarding whether I have some other label on it, the answer is yes I do. You can verify this by running the kubectl get nodes command on the master node. notification_sender-. These flags are only exposed for testing and might have a negative impact on other parts of Prometheus server. Now we should pause to make an important distinction between metrics and time series. To get a better idea of this problem lets adjust our example metric to track HTTP requests. We know that the more labels on a metric, the more time series it can create. Ive deliberately kept the setup simple and accessible from any address for demonstration. Since labels are copied around when Prometheus is handling queries this could cause significant memory usage increase. Passing sample_limit is the ultimate protection from high cardinality. bay, Is a PhD visitor considered as a visiting scholar? 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. The Linux Foundation has registered trademarks and uses trademarks. Why is this sentence from The Great Gatsby grammatical? an EC2 regions with application servers running docker containers. Bulk update symbol size units from mm to map units in rule-based symbology. Finally, please remember that some people read these postings as an email Under which circumstances? 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. Time arrow with "current position" evolving with overlay number. For that lets follow all the steps in the life of a time series inside Prometheus. Why are physically impossible and logically impossible concepts considered separate in terms of probability? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Lets adjust the example code to do this. By default Prometheus will create a chunk per each two hours of wall clock. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Better to simply ask under the single best category you think fits and see 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. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? your journey to Zero Trust. With any monitoring system its important that youre able to pull out the right data. What video game is Charlie playing in Poker Face S01E07? Can I tell police to wait and call a lawyer when served with a search warrant? The advantage of doing this is that memory-mapped chunks dont use memory unless TSDB needs to read them. Has 90% of ice around Antarctica disappeared in less than a decade? 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. Are there tables of wastage rates for different fruit and veg? This is a deliberate design decision made by Prometheus developers. These queries are a good starting point. Operating such a large Prometheus deployment doesnt come without challenges. 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. 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. 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. 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. This doesnt capture all complexities of Prometheus but gives us a rough estimate of how many time series we can expect to have capacity for. 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. *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. What does remote read means in Prometheus? You set up a Kubernetes cluster, installed Prometheus on it ,and ran some queries to check the clusters health. What is the point of Thrower's Bandolier? Youve learned about the main components of Prometheus, and its query language, PromQL. 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. what error message are you getting to show that theres a problem? This is because once we have more than 120 samples on a chunk efficiency of varbit encoding drops. Find centralized, trusted content and collaborate around the technologies you use most. Secondly this calculation is based on all memory used by Prometheus, not only time series data, so its just an approximation. metric name, as measured over the last 5 minutes: Assuming that the http_requests_total time series all have the labels job There is a maximum of 120 samples each chunk can hold. Redoing the align environment with a specific formatting. With this simple code Prometheus client library will create a single metric. 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. We have hundreds of data centers spread across the world, each with dedicated Prometheus servers responsible for scraping all metrics. This works fine when there are data points for all queries in the expression. which outputs 0 for an empty input vector, but that outputs a scalar Can airtags be tracked from an iMac desktop, with no iPhone? This is what i can see on Query Inspector. Windows 10, how have you configured the query which is causing problems? The main motivation seems to be that dealing with partially scraped metrics is difficult and youre better off treating failed scrapes as incidents. 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. I have a data model where some metrics are namespaced by client, environment and deployment name. To learn more, see our tips on writing great answers. In both nodes, edit the /etc/sysctl.d/k8s.conf file to add the following two lines: Then reload the IPTables config using the sudo sysctl --system command. 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 promql Share Follow edited Nov 12, 2020 at 12:27 Thank you for subscribing! I'd expect to have also: Please use the prometheus-users mailing list for questions. The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series. I am interested in creating a summary of each deployment, where that summary is based on the number of alerts that are present for each deployment. Its the chunk responsible for the most recent time range, including the time of our scrape. How to follow the signal when reading the schematic? You're probably looking for the absent function. 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. This is the last line of defense for us that avoids the risk of the Prometheus server crashing due to lack of memory. Monitor the health of your cluster and troubleshoot issues faster with pre-built dashboards that just work. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The downside of all these limits is that breaching any of them will cause an error for the entire scrape. count(container_last_seen{environment="prod",name="notification_sender.*",roles=".application-server."}) Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. If you're looking for a If this query also returns a positive value, then our cluster has overcommitted the memory.