Yeah, absent() is probably the way to go. Name the nodes as Kubernetes Master and Kubernetes Worker. Which in turn will double the memory usage of our Prometheus server. 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 Better to simply ask under the single best category you think fits and see The text was updated successfully, but these errors were encountered: This is correct. want to sum over the rate of all instances, so we get fewer output time series, The more labels we have or the more distinct values they can have the more time series as a result. *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. 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. Explanation: Prometheus uses label matching in expressions. 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 thing with a metric vector (a metric which has dimensions) is that only the series for it actually get exposed on /metrics which have been explicitly initialized. gabrigrec September 8, 2021, 8:12am #8. The simplest construct of a PromQL query is an instant vector selector. See these docs for details on how Prometheus calculates the returned results. You can run a variety of PromQL queries to pull interesting and actionable metrics from your Kubernetes cluster. Can I tell police to wait and call a lawyer when served with a search warrant? 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. Asking for help, clarification, or responding to other answers. Well occasionally send you account related emails. This works fine when there are data points for all queries in the expression. One of the most important layers of protection is a set of patches we maintain on top of Prometheus. This is one argument for not overusing labels, but often it cannot be avoided. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Basically our labels hash is used as a primary key inside TSDB. Minimising the environmental effects of my dyson brain. Simple, clear and working - thanks a lot. When you add dimensionality (via labels to a metric), you either have to pre-initialize all the possible label combinations, which is not always possible, or live with missing metrics (then your PromQL computations become more cumbersome). But I'm stuck now if I want to do something like apply a weight to alerts of a different severity level, e.g. PromQL allows you to write queries and fetch information from the metric data collected by Prometheus. an EC2 regions with application servers running docker containers. 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. Of course there are many types of queries you can write, and other useful queries are freely available. What this means is that a single metric will create one or more time series. Lets pick client_python for simplicity, but the same concepts will apply regardless of the language you use. 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. 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. Internet-scale applications efficiently, What is the point of Thrower's Bandolier? Hello, I'm new at Grafan and Prometheus. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. Use Prometheus to monitor app performance metrics. Hmmm, upon further reflection, I'm wondering if this will throw the metrics off. This would inflate Prometheus memory usage, which can cause Prometheus server to crash, if it uses all available physical memory. which version of Grafana are you using? This scenario is often described as cardinality explosion - some metric suddenly adds a huge number of distinct label values, creates a huge number of time series, causes Prometheus to run out of memory and you lose all observability as a result. What am I doing wrong here in the PlotLegends specification? what error message are you getting to show that theres a problem? So it seems like I'm back to square one. 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. If all the label values are controlled by your application you will be able to count the number of all possible label combinations. I know prometheus has comparison operators but I wasn't able to apply them. 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. Object, url:api/datasources/proxy/2/api/v1/query_range?query=wmi_logical_disk_free_bytes%7Binstance%3D~%22%22%2C%20volume%20!~%22HarddiskVolume.%2B%22%7D&start=1593750660&end=1593761460&step=20&timeout=60s, Powered by Discourse, best viewed with JavaScript enabled, 1 Node Exporter for Prometheus Dashboard EN 20201010 | Grafana Labs, https://grafana.com/grafana/dashboards/2129. That's the query (Counter metric): sum(increase(check_fail{app="monitor"}[20m])) by (reason). I used a Grafana transformation which seems to work. 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. Making statements based on opinion; back them up with references or personal experience. Even Prometheus' own client libraries had bugs that could expose you to problems like this. Doubling the cube, field extensions and minimal polynoms. 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. positions. Is it possible to rotate a window 90 degrees if it has the same length and width? to your account, What did you do? For operations between two instant vectors, the matching behavior can be modified. About an argument in Famine, Affluence and Morality. 2023 The Linux Foundation. *) in region drops below 4. Its very easy to keep accumulating time series in Prometheus until you run out of memory. 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. How to show that an expression of a finite type must be one of the finitely many possible values? But the key to tackling high cardinality was better understanding how Prometheus works and what kind of usage patterns will be problematic. 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. feel that its pushy or irritating and therefore ignore it. Windows 10, how have you configured the query which is causing problems? This helps us avoid a situation where applications are exporting thousands of times series that arent really needed. The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series. 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. You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. Thats why what our application exports isnt really metrics or time series - its samples. Is that correct? 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. With our custom patch we dont care how many samples are in a scrape. For that lets follow all the steps in the life of a time series inside Prometheus. You can query Prometheus metrics directly with its own query language: PromQL. 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. 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 Asking for help, clarification, or responding to other answers. That map uses labels hashes as keys and a structure called memSeries as values. No error message, it is just not showing the data while using the JSON file from that website. There is a single time series for each unique combination of metrics labels. Thanks, Internally time series names are just another label called __name__, so there is no practical distinction between name and labels. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. It's worth to add that if using Grafana you should set 'Connect null values' proeprty to 'always' in order to get rid of blank spaces in the graph. ncdu: What's going on with this second size column? Is a PhD visitor considered as a visiting scholar? new career direction, check out our open Returns a list of label values for the label in every metric. See this article for details. For example, this expression Is it possible to create a concave light? And this brings us to the definition of cardinality in the context of metrics. 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. 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. 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. 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. 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. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. returns the unused memory in MiB for every instance (on a fictional cluster 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. Managing the entire lifecycle of a metric from an engineering perspective is a complex process. If the error message youre getting (in a log file or on screen) can be quoted 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. Good to know, thanks for the quick response! or Internet application, I've created an expression that is intended to display percent-success for a given metric. Selecting data from Prometheus's TSDB forms the basis of almost any useful PromQL query before . The next layer of protection is checks that run in CI (Continuous Integration) when someone makes a pull request to add new or modify existing scrape configuration for their application. 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. Where does this (supposedly) Gibson quote come from? Combined thats a lot of different metrics. 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. Its not going to get you a quicker or better answer, and some people might I have a data model where some metrics are namespaced by client, environment and deployment name. source, what your query is, what the query inspector shows, and any other Youll be executing all these queries in the Prometheus expression browser, so lets get started. instance_memory_usage_bytes: This shows the current memory used. Please dont post the same question under multiple topics / subjects. 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. Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. 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. 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. In my case there haven't been any failures so rio_dashorigin_serve_manifest_duration_millis_count{Success="Failed"} returns no data points found. your journey to Zero Trust. For example, /api/v1/query?query=http_response_ok [24h]&time=t would return raw samples on the time range (t-24h . Please help improve it by filing issues or pull requests. Simply adding a label with two distinct values to all our metrics might double the number of time series we have to deal with. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. @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). Operating such a large Prometheus deployment doesnt come without challenges. Once we appended sample_limit number of samples we start to be selective. Our metrics are exposed as a HTTP response. Examples 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. How to follow the signal when reading the schematic? To learn more, see our tips on writing great answers. This had the effect of merging the series without overwriting any values. This is because the Prometheus server itself is responsible for timestamps. 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.