Lets pick client_python for simplicity, but the same concepts will apply regardless of the language you use. I cant see how absent() may help me here @juliusv yeah, I tried count_scalar() but I can't use aggregation with it. 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. However, if i create a new panel manually with a basic commands then i can see the data on the dashboard. There is a maximum of 120 samples each chunk can hold. Of course there are many types of queries you can write, and other useful queries are freely available. He has a Bachelor of Technology in Computer Science & Engineering from SRMS. Often it doesnt require any malicious actor to cause cardinality related problems. 1 Like. 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. Have a question about this project? We use Prometheus to gain insight into all the different pieces of hardware and software that make up our global network. 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. Using regular expressions, you could select time series only for jobs whose Simply adding a label with two distinct values to all our metrics might double the number of time series we have to deal with. In our example we have two labels, content and temperature, and both of them can have two different values. as text instead of as an image, more people will be able to read it and help. We had a fair share of problems with overloaded Prometheus instances in the past and developed a number of tools that help us deal with them, including custom patches. Connect and share knowledge within a single location that is structured and easy to search. The struct definition for memSeries is fairly big, but all we really need to know is that it has a copy of all the time series labels and chunks that hold all the samples (timestamp & value pairs). Another reason is that trying to stay on top of your usage can be a challenging task. In the screenshot below, you can see that I added two queries, A and B, but only . First is the patch that allows us to enforce a limit on the total number of time series TSDB can store at any time. The advantage of doing this is that memory-mapped chunks dont use memory unless TSDB needs to read them. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. what error message are you getting to show that theres a problem? 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. Once configured, your instances should be ready for access. This is because the only way to stop time series from eating memory is to prevent them from being appended to TSDB. So when TSDB is asked to append a new sample by any scrape, it will first check how many time series are already present. 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. Can I tell police to wait and call a lawyer when served with a search warrant? windows. rev2023.3.3.43278. In our example case its a Counter class object. Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. I suggest you experiment more with the queries as you learn, and build a library of queries you can use for future projects. This is because the Prometheus server itself is responsible for timestamps. Having good internal documentation that covers all of the basics specific for our environment and most common tasks is very important. Today, let's look a bit closer at the two ways of selecting data in PromQL: instant vector selectors and range vector selectors. attacks, keep There's also count_scalar(), By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. The Linux Foundation has registered trademarks and uses trademarks. 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 had the effect of merging the series without overwriting any values. 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. Second rule does the same but only sums time series with status labels equal to "500". To your second question regarding whether I have some other label on it, the answer is yes I do. However when one of the expressions returns no data points found the result of the entire expression is no data points found. I made the changes per the recommendation (as I understood it) and defined separate success and fail metrics. I can get the deployments in the dev, uat, and prod environments using this query: So we can see that tenant 1 has 2 deployments in 2 different environments, whereas the other 2 have only one. It saves these metrics as time-series data, which is used to create visualizations and alerts for IT teams. This is because once we have more than 120 samples on a chunk efficiency of varbit encoding drops. 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. 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. 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? Being able to answer How do I X? yourself without having to wait for a subject matter expert allows everyone to be more productive and move faster, while also avoiding Prometheus experts from answering the same questions over and over again. The process of sending HTTP requests from Prometheus to our application is called scraping. To learn more, see our tips on writing great answers. It enables us to enforce a hard limit on the number of time series we can scrape from each application instance. You can run a variety of PromQL queries to pull interesting and actionable metrics from your Kubernetes cluster. - I am using this in windows 10 for testing, which Operating System (and version) are you running it under? This selector is just a metric name. That map uses labels hashes as keys and a structure called memSeries as values. Examples These are the sane defaults that 99% of application exporting metrics would never exceed. (fanout by job name) and instance (fanout by instance of the job), we might 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 What is the point of Thrower's Bandolier? Asking for help, clarification, or responding to other answers. This holds true for a lot of labels that we see are being used by engineers. Why are trials on "Law & Order" in the New York Supreme Court? It would be easier if we could do this in the original query though. To avoid this its in general best to never accept label values from untrusted sources. Basically our labels hash is used as a primary key inside TSDB. This helps us avoid a situation where applications are exporting thousands of times series that arent really needed. In the following steps, you will create a two-node Kubernetes cluster (one master and one worker) in AWS. an EC2 regions with application servers running docker containers. I know prometheus has comparison operators but I wasn't able to apply them. There is an open pull request on the Prometheus repository. 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. 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. The speed at which a vehicle is traveling. 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. You must define your metrics in your application, with names and labels that will allow you to work with resulting time series easily. 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. If you're looking for a 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. It doesnt get easier than that, until you actually try to do it. 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. In Prometheus pulling data is done via PromQL queries and in this article we guide the reader through 11 examples that can be used for Kubernetes specifically. or something like that. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Well occasionally send you account related emails. Both rules will produce new metrics named after the value of the record field. 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 Youll be executing all these queries in the Prometheus expression browser, so lets get started. @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). About an argument in Famine, Affluence and Morality. 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. We will examine their use cases, the reasoning behind them, and some implementation details you should be aware of. 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. This pod wont be able to run because we dont have a node that has the label disktype: ssd. With this simple code Prometheus client library will create a single metric. the problem you have. 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. This article covered a lot of ground. With our example metric we know how many mugs were consumed, but what if we also want to know what kind of beverage it was? entire corporate networks, which Operating System (and version) are you running it under? Even i am facing the same issue Please help me on this. Thanks for contributing an answer to Stack Overflow! With any monitoring system its important that youre able to pull out the right data. 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. If this query also returns a positive value, then our cluster has overcommitted the memory. Well occasionally send you account related emails. 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 . - grafana-7.1.0-beta2.windows-amd64, how did you install it? You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. If I now tack on a != 0 to the end of it, all zero values are filtered out: 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.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 . without any dimensional information. This process helps to reduce disk usage since each block has an index taking a good chunk of disk space. I'd expect to have also: Please use the prometheus-users mailing list for questions. Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. This is an example of a nested subquery. Cadvisors on every server provide container names. Thanks for contributing an answer to Stack Overflow! Knowing that it can quickly check if there are any time series already stored inside TSDB that have the same hashed value. Time series scraped from applications are kept in memory. Returns a list of label values for the label in every metric. 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. Making statements based on opinion; back them up with references or personal experience. Managed Service for Prometheus https://goo.gle/3ZgeGxv Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. I then hide the original query. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. ncdu: What's going on with this second size column? Why are trials on "Law & Order" in the New York Supreme Court? For example, this expression Prometheus allows us to measure health & performance over time and, if theres anything wrong with any service, let our team know before it becomes a problem. Since the default Prometheus scrape interval is one minute it would take two hours to reach 120 samples. Are there tables of wastage rates for different fruit and veg? What video game is Charlie playing in Poker Face S01E07? For example, I'm using the metric to record durations for quantile reporting. This allows Prometheus to scrape and store thousands of samples per second, our biggest instances are appending 550k samples per second, while also allowing us to query all the metrics simultaneously. Does Counterspell prevent from any further spells being cast on a given turn? Is what you did above (failures.WithLabelValues) an example of "exposing"? 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. Prometheus metrics can have extra dimensions in form of labels. For that lets follow all the steps in the life of a time series inside Prometheus. Each chunk represents a series of samples for a specific time range. source, what your query is, what the query inspector shows, and any other Our HTTP response will now show more entries: As we can see we have an entry for each unique combination of labels. what does the Query Inspector show for the query you have a problem with? That way even the most inexperienced engineers can start exporting metrics without constantly wondering Will this cause an incident?. Extra fields needed by Prometheus internals. Secondly this calculation is based on all memory used by Prometheus, not only time series data, so its just an approximation. To get a better idea of this problem lets adjust our example metric to track HTTP requests. want to sum over the rate of all instances, so we get fewer output time series, Chunks that are a few hours old are written to disk and removed 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. Prometheus is an open-source monitoring and alerting software that can collect metrics from different infrastructure and applications. These queries are a good starting point. Well be executing kubectl commands on the master node only. But the key to tackling high cardinality was better understanding how Prometheus works and what kind of usage patterns will be problematic. At this point, both nodes should be ready. VictoriaMetrics handles rate () function in the common sense way I described earlier! We can add more metrics if we like and they will all appear in the HTTP response to the metrics endpoint. 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. Already on GitHub? Now we should pause to make an important distinction between metrics and time series. Next, create a Security Group to allow access to the instances. binary operators to them and elements on both sides with the same label set Prometheus - exclude 0 values from query result, How Intuit democratizes AI development across teams through reusability. For operations between two instant vectors, the matching behavior can be modified. 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. to your account, What did you do? 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. Why do many companies reject expired SSL certificates as bugs in bug bounties? job and handler labels: Return a whole range of time (in this case 5 minutes up to the query time) For example, /api/v1/query?query=http_response_ok [24h]&time=t would return raw samples on the time range (t-24h . Monitor the health of your cluster and troubleshoot issues faster with pre-built dashboards that just work. If we were to continuously scrape a lot of time series that only exist for a very brief period then we would be slowly accumulating a lot of memSeries in memory until the next garbage collection. The result is a table of failure reason and its count. Since we know that the more labels we have the more time series we end up with, you can see when this can become a problem. 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 So perhaps the behavior I'm running into applies to any metric with a label, whereas a metric without any labels would behave as @brian-brazil indicated? Return the per-second rate for all time series with the http_requests_total The real power of Prometheus comes into the picture when you utilize the alert manager to send notifications when a certain metric breaches a threshold. Subscribe to receive notifications of new posts: Subscription confirmed. Managing the entire lifecycle of a metric from an engineering perspective is a complex process. Play with bool list, which does not convey images, so screenshots etc. One Head Chunk - containing up to two hours of the last two hour wall clock slot. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. We will also signal back to the scrape logic that some samples were skipped. *) in region drops below 4. This process is also aligned with the wall clock but shifted by one hour. Our metric will have a single label that stores the request path. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. We know that time series will stay in memory for a while, even if they were scraped only once. will get matched and propagated to the output. Is a PhD visitor considered as a visiting scholar? Selecting data from Prometheus's TSDB forms the basis of almost any useful PromQL query before . You can query Prometheus metrics directly with its own query language: PromQL. 2023 The Linux Foundation. information which you think might be helpful for someone else to understand To learn more, see our tips on writing great answers. This also has the benefit of allowing us to self-serve capacity management - theres no need for a team that signs off on your allocations, if CI checks are passing then we have the capacity you need for your applications. 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 inflate Prometheus memory usage, which can cause Prometheus server to crash, if it uses all available physical memory. After running the query, a table will show the current value of each result time series (one table row per output series). The text was updated successfully, but these errors were encountered: This is correct. 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. Separate metrics for total and failure will work as expected. Using a query that returns "no data points found" in an expression. count(container_last_seen{environment="prod",name="notification_sender.*",roles=".application-server."}) *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. Prometheus is a great and reliable tool, but dealing with high cardinality issues, especially in an environment where a lot of different applications are scraped by the same Prometheus server, can be challenging. Timestamps here can be explicit or implicit. To learn more about our mission to help build a better Internet, start here. rate (http_requests_total [5m]) [30m:1m] If you do that, the line will eventually be redrawn, many times 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. Prometheus is an open-source monitoring and alerting software that can collect metrics from different infrastructure and applications. Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. This means that looking at how many time series an application could potentially export, and how many it actually exports, gives us two completely different numbers, which makes capacity planning a lot harder. So I still can't use that metric in calculations ( e.g., success / (success + fail) ) as those calculations will return no datapoints. 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. And then there is Grafana, which comes with a lot of built-in dashboards for Kubernetes monitoring. 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.