prometheus query return 0 if no data prometheus query return 0 if no data

Have a question about this project? I've created an expression that is intended to display percent-success for a given metric. 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. You can query Prometheus metrics directly with its own query language: PromQL. I'm displaying Prometheus query on a Grafana table. Prometheus metrics can have extra dimensions in form of labels. For example, this expression Why do many companies reject expired SSL certificates as bugs in bug bounties? We also limit the length of label names and values to 128 and 512 characters, which again is more than enough for the vast majority of scrapes. 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. Making statements based on opinion; back them up with references or personal experience. 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. Use it to get a rough idea of how much memory is used per time series and dont assume its that exact number. This works fine when there are data points for all queries in the expression. This process is also aligned with the wall clock but shifted by one hour. Once theyre in TSDB its already too late. gabrigrec September 8, 2021, 8:12am #8. 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. So there would be a chunk for: 00:00 - 01:59, 02:00 - 03:59, 04:00 - 05:59, , 22:00 - 23:59. list, which does not convey images, so screenshots etc. Comparing current data with historical data. Having a working monitoring setup is a critical part of the work we do for our clients. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. 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. To get a better idea of this problem lets adjust our example metric to track HTTP requests. The downside of all these limits is that breaching any of them will cause an error for the entire scrape. First rule will tell Prometheus to calculate per second rate of all requests and sum it across all instances of our server. What does remote read means in Prometheus? 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. Or do you have some other label on it, so that the metric still only gets exposed when you record the first failued request it? what does the Query Inspector show for the query you have a problem with? more difficult for those people to help. The simplest way of doing this is by using functionality provided with client_python itself - see documentation here. Not the answer you're looking for? Internet-scale applications efficiently, Its not going to get you a quicker or better answer, and some people might The TSDB limit patch protects the entire Prometheus from being overloaded by too many time series. Asking for help, clarification, or responding to other answers. Is a PhD visitor considered as a visiting scholar? Those memSeries objects are storing all the time series information. The more labels you have and the more values each label can take, the more unique combinations you can create and the higher the cardinality. Not the answer you're looking for? Especially when dealing with big applications maintained in part by multiple different teams, each exporting some metrics from their part of the stack. If we try to visualize how the perfect type of data Prometheus was designed for looks like well end up with this: A few continuous lines describing some observed properties. You signed in with another tab or window. Returns a list of label names. 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. what does the Query Inspector show for the query you have a problem with? If your expression returns anything with labels, it won't match the time series generated by vector(0). If both the nodes are running fine, you shouldnt get any result for this query. 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. Prometheus simply counts how many samples are there in a scrape and if thats more than sample_limit allows it will fail the scrape. 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. If the time series already exists inside TSDB then we allow the append to continue. Prometheus - exclude 0 values from query result, How Intuit democratizes AI development across teams through reusability. Returns a list of label values for the label in every metric. entire corporate networks, 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. After sending a request it will parse the response looking for all the samples exposed there. With 1,000 random requests we would end up with 1,000 time series in Prometheus. 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. We have hundreds of data centers spread across the world, each with dedicated Prometheus servers responsible for scraping all metrics. Is it a bug? Run the following commands on the master node to set up Prometheus on the Kubernetes cluster: Next, run this command on the master node to check the Pods status: Once all the Pods are up and running, you can access the Prometheus console using kubernetes port forwarding. feel that its pushy or irritating and therefore ignore it. This pod wont be able to run because we dont have a node that has the label disktype: ssd. I'm still out of ideas here. We know that each time series will be kept in memory. Youll be executing all these queries in the Prometheus expression browser, so lets get started. In the screenshot below, you can see that I added two queries, A and B, but only . Add field from calculation Binary operation. Well be executing kubectl commands on the master node only. Stumbled onto this post for something else unrelated, just was +1-ing this :). count the number of running instances per application like this: This documentation is open-source. Labels are stored once per each memSeries instance. rev2023.3.3.43278. @zerthimon The following expr works for me instance_memory_usage_bytes: This shows the current memory used. Run the following commands in both nodes to configure the Kubernetes repository. Have a question about this project? This helps us avoid a situation where applications are exporting thousands of times series that arent really needed. Finally getting back to this. This is because the Prometheus server itself is responsible for timestamps. Extra fields needed by Prometheus internals. It doesnt get easier than that, until you actually try to do it. PromQL queries the time series data and returns all elements that match the metric name, along with their values for a particular point in time (when the query runs). 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. privacy statement. How Intuit democratizes AI development across teams through reusability. Once you cross the 200 time series mark, you should start thinking about your metrics more. help customers build https://github.com/notifications/unsubscribe-auth/AAg1mPXncyVis81Rx1mIWiXRDe0E1Dpcks5rIXe6gaJpZM4LOTeb. It enables us to enforce a hard limit on the number of time series we can scrape from each application instance. You can use these queries in the expression browser, Prometheus HTTP API, or visualization tools like Grafana. 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. Combined thats a lot of different metrics. Passing sample_limit is the ultimate protection from high cardinality. See these docs for details on how Prometheus calculates the returned results. 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. will get matched and propagated to the output. There is no equivalent functionality in a standard build of Prometheus, if any scrape produces some samples they will be appended to time series inside TSDB, creating new time series if needed. 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. Is a PhD visitor considered as a visiting scholar? @rich-youngkin Yes, the general problem is non-existent series. Asking for help, clarification, or responding to other answers. You're probably looking for the absent function. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. 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. Lets adjust the example code to do this. It would be easier if we could do this in the original query though. 11 Queries | Kubernetes Metric Data with PromQL, wide variety of applications, infrastructure, APIs, databases, and other sources. Does a summoned creature play immediately after being summoned by a ready action? In this query, you will find nodes that are intermittently switching between Ready" and NotReady" status continuously. In both nodes, edit the /etc/hosts file to add the private IP of the nodes. Sign in How to show that an expression of a finite type must be one of the finitely many possible values? If you're looking for a Of course there are many types of queries you can write, and other useful queries are freely available. an EC2 regions with application servers running docker containers. Instead we count time series as we append them to TSDB. To learn more about our mission to help build a better Internet, start here. Other Prometheus components include a data model that stores the metrics, client libraries for instrumenting code, and PromQL for querying the metrics. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. from and what youve done will help people to understand your problem. hackers at By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. We can use these to add more information to our metrics so that we can better understand whats going on. Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. 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! This is the standard Prometheus flow for a scrape that has the sample_limit option set: The entire scrape either succeeds or fails. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. binary operators to them and elements on both sides with the same label set Prometheus's query language supports basic logical and arithmetic operators. On the worker node, run the kubeadm joining command shown in the last step. 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 The Head Chunk is never memory-mapped, its always stored in memory. He has a Bachelor of Technology in Computer Science & Engineering from SRMS. Knowing that it can quickly check if there are any time series already stored inside TSDB that have the same hashed value. Return the per-second rate for all time series with the http_requests_total 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). The below posts may be helpful for you to learn more about Kubernetes and our company. I'm not sure what you mean by exposing a metric. There will be traps and room for mistakes at all stages of this process. How to react to a students panic attack in an oral exam? rev2023.3.3.43278. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. Prometheus does offer some options for dealing with high cardinality problems. Neither of these solutions seem to retain the other dimensional information, they simply produce a scaler 0. Please dont post the same question under multiple topics / subjects. - I am using this in windows 10 for testing, which Operating System (and version) are you running it under?