What this means is that a single metric will create one or more time series. In the following steps, you will create a two-node Kubernetes cluster (one master and one worker) in AWS. 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. 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. Making statements based on opinion; back them up with references or personal experience. Especially when dealing with big applications maintained in part by multiple different teams, each exporting some metrics from their part of the stack. Variable of the type Query allows you to query Prometheus for a list of metrics, labels, or label values. I can't work out how to add the alerts to the deployments whilst retaining the deployments for which there were no alerts returned: If I use sum with or, then I get this, depending on the order of the arguments to or: If I reverse the order of the parameters to or, I get what I am after: But I'm stuck now if I want to do something like apply a weight to alerts of a different severity level, e.g. Looking to learn more? Is there a single-word adjective for "having exceptionally strong moral principles"? Prometheus Authors 2014-2023 | Documentation Distributed under CC-BY-4.0. First rule will tell Prometheus to calculate per second rate of all requests and sum it across all instances of our server. First is the patch that allows us to enforce a limit on the total number of time series TSDB can store at any time. Already on GitHub? As we mentioned before a time series is generated from metrics. Run the following commands in both nodes to disable SELinux and swapping: Also, change SELINUX=enforcing to SELINUX=permissive in the /etc/selinux/config file. PromLabs | Blog - Selecting Data in PromQL or something like that. an EC2 regions with application servers running docker containers. Prometheus does offer some options for dealing with high cardinality problems. This would inflate Prometheus memory usage, which can cause Prometheus server to crash, if it uses all available physical memory. I've created an expression that is intended to display percent-success for a given metric. However when one of the expressions returns no data points found the result of the entire expression is no data points found. For example, /api/v1/query?query=http_response_ok [24h]&time=t would return raw samples on the time range (t-24h . The advantage of doing this is that memory-mapped chunks dont use memory unless TSDB needs to read them. We know that each time series will be kept in memory. For operations between two instant vectors, the matching behavior can be modified. Is a PhD visitor considered as a visiting scholar? 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. Please open a new issue for related bugs. vishnur5217 May 31, 2020, 3:44am 1. 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. A time series is an instance of that metric, with a unique combination of all the dimensions (labels), plus a series of timestamp & value pairs - hence the name time series. No Data is showing on Grafana Dashboard - Prometheus - Grafana Labs Better to simply ask under the single best category you think fits and see 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. gabrigrec September 8, 2021, 8:12am #8. Can airtags be tracked from an iMac desktop, with no iPhone? Monitor Confluence with Prometheus and Grafana | Confluence Data Center If you need to obtain raw samples, then a range query must be sent to /api/v1/query. Hello, I'm new at Grafan and Prometheus. This means that Prometheus must check if theres already a time series with identical name and exact same set of labels present. 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. Time arrow with "current position" evolving with overlay number. Also, providing a reasonable amount of information about where youre starting SSH into both servers and run the following commands to install Docker. All rights reserved. Once theyre in TSDB its already too late. In the screenshot below, you can see that I added two queries, A and B, but only . Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, How Intuit democratizes AI development across teams through reusability. Run the following commands in both nodes to configure the Kubernetes repository. What does remote read means in Prometheus? I'm displaying Prometheus query on a Grafana table. Please help improve it by filing issues or pull requests. Since labels are copied around when Prometheus is handling queries this could cause significant memory usage increase. @rich-youngkin Yes, the general problem is non-existent series. 4 Managed Service for Prometheus | 4 Managed Service for One or more for historical ranges - these chunks are only for reading, Prometheus wont try to append anything here. new career direction, check out our open Sign up and get Kubernetes tips delivered straight to your inbox. Sign in Before that, Vinayak worked as a Senior Systems Engineer at Singapore Airlines. Thank you for subscribing! The number of times some specific event occurred. Samples are compressed using encoding that works best if there are continuous updates. The speed at which a vehicle is traveling. This works fine when there are data points for all queries in the expression. PromQL / How to return 0 instead of ' no data' - Medium What is the point of Thrower's Bandolier? 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. 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. *) in region drops below 4. alert also has to fire if there are no (0) containers that match the pattern in region. If the error message youre getting (in a log file or on screen) can be quoted Well occasionally send you account related emails. 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. Once the last chunk for this time series is written into a block and removed from the memSeries instance we have no chunks left. website Asking for help, clarification, or responding to other answers. 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. But the real risk is when you create metrics with label values coming from the outside world. The containers are named with a specific pattern: I need an alert when the number of container of the same pattern (eg. windows. 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. Ive added a data source(prometheus) in Grafana. Other Prometheus components include a data model that stores the metrics, client libraries for instrumenting code, and PromQL for querying the metrics. The Linux Foundation has registered trademarks and uses trademarks. attacks, keep Are you not exposing the fail metric when there hasn't been a failure yet? Inside the Prometheus configuration file we define a scrape config that tells Prometheus where to send the HTTP request, how often and, optionally, to apply extra processing to both requests and responses. Although, sometimes the values for project_id doesn't exist, but still end up showing up as one. 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 The way labels are stored internally by Prometheus also matters, but thats something the user has no control over. With any monitoring system its important that youre able to pull out the right data. Returns a list of label names. node_cpu_seconds_total: This returns the total amount of CPU time. Now we should pause to make an important distinction between metrics and time series. This had the effect of merging the series without overwriting any values. At this point, both nodes should be ready. Finally we do, by default, set sample_limit to 200 - so each application can export up to 200 time series without any action. Up until now all time series are stored entirely in memory and the more time series you have, the higher Prometheus memory usage youll see. 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. The most basic layer of protection that we deploy are scrape limits, which we enforce on all configured scrapes. 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. About an argument in Famine, Affluence and Morality. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Once you cross the 200 time series mark, you should start thinking about your metrics more. It would be easier if we could do this in the original query though. returns the unused memory in MiB for every instance (on a fictional cluster Theres only one chunk that we can append to, its called the Head Chunk. How can I group labels in a Prometheus query? Going back to our time series - at this point Prometheus either creates a new memSeries instance or uses already existing memSeries. Ive deliberately kept the setup simple and accessible from any address for demonstration. Which in turn will double the memory usage of our Prometheus server. In AWS, create two t2.medium instances running CentOS. Prometheus Queries: 11 PromQL Examples and Tutorial - ContainIQ Is that correct? Theres no timestamp anywhere actually. This makes a bit more sense with your explanation. *) in region drops below 4. The Prometheus data source plugin provides the following functions you can use in the Query input field. Returns a list of label values for the label in every metric. There's also count_scalar(), Of course there are many types of queries you can write, and other useful queries are freely available. We can add more metrics if we like and they will all appear in the HTTP response to the metrics endpoint. 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. Does Counterspell prevent from any further spells being cast on a given turn? We use Prometheus to gain insight into all the different pieces of hardware and software that make up our global network. Is it a bug? No error message, it is just not showing the data while using the JSON file from that website. bay, Is there a solutiuon to add special characters from software and how to do it. from and what youve done will help people to understand your problem. That's the query (Counter metric): sum(increase(check_fail{app="monitor"}[20m])) by (reason). So it seems like I'm back to square one. If all the label values are controlled by your application you will be able to count the number of all possible label combinations. Vinayak is an experienced cloud consultant with a knack of automation, currently working with Cognizant Singapore. Each chunk represents a series of samples for a specific time range. So when TSDB is asked to append a new sample by any scrape, it will first check how many time series are already present. VictoriaMetrics handles rate () function in the common sense way I described earlier! Querying examples | Prometheus Lets create a demo Kubernetes cluster and set up Prometheus to monitor it. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Are there tables of wastage rates for different fruit and veg? rev2023.3.3.43278. attacks. In our example case its a Counter class object. 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. Our HTTP response will now show more entries: As we can see we have an entry for each unique combination of labels. All they have to do is set it explicitly in their scrape configuration. it works perfectly if one is missing as count() then returns 1 and the rule fires. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. 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. Cadvisors on every server provide container names. Managed Service for Prometheus Cloud Monitoring Prometheus # ! Separate metrics for total and failure will work as expected. Use Prometheus to monitor app performance metrics. Finally you will want to create a dashboard to visualize all your metrics and be able to spot trends. Using the Prometheus data source - Amazon Managed Grafana You set up a Kubernetes cluster, installed Prometheus on it ,and ran some queries to check the clusters health. Operators | Prometheus After a chunk was written into a block and removed from memSeries we might end up with an instance of memSeries that has no chunks. 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? Simple, clear and working - thanks a lot. Basically our labels hash is used as a primary key inside TSDB. help customers build By default Prometheus will create a chunk per each two hours of wall clock. information which you think might be helpful for someone else to understand That way even the most inexperienced engineers can start exporting metrics without constantly wondering Will this cause an incident?. Is it possible to rotate a window 90 degrees if it has the same length and width? Next, create a Security Group to allow access to the instances. metric name, as measured over the last 5 minutes: Assuming that the http_requests_total time series all have the labels job This garbage collection, among other things, will look for any time series without a single chunk and remove it from memory. You can run a variety of PromQL queries to pull interesting and actionable metrics from your Kubernetes cluster. 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. So the maximum number of time series we can end up creating is four (2*2). 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. At the moment of writing this post we run 916 Prometheus instances with a total of around 4.9 billion time series. By default Prometheus will create a chunk per each two hours of wall clock. accelerate any Good to know, thanks for the quick response! Managing the entire lifecycle of a metric from an engineering perspective is a complex process. Not the answer you're looking for? 2023 The Linux Foundation. Perhaps I misunderstood, but it looks like any defined metrics that hasn't yet recorded any values can be used in a larger expression. I know prometheus has comparison operators but I wasn't able to apply them. If you look at the HTTP response of our example metric youll see that none of the returned entries have timestamps. 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. 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. How Intuit democratizes AI development across teams through reusability. These queries will give you insights into node health, Pod health, cluster resource utilization, etc. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. What happens when somebody wants to export more time series or use longer labels? Sign in Connect and share knowledge within a single location that is structured and easy to search. The below posts may be helpful for you to learn more about Kubernetes and our company. ***> wrote: You signed in with another tab or window. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Simple succinct answer. This thread has been automatically locked since there has not been any recent activity after it was closed. Can airtags be tracked from an iMac desktop, with no iPhone? To learn more about our mission to help build a better Internet, start here. The downside of all these limits is that breaching any of them will cause an error for the entire scrape. 11 Queries | Kubernetes Metric Data with PromQL, wide variety of applications, infrastructure, APIs, databases, and other sources. I made the changes per the recommendation (as I understood it) and defined separate success and fail metrics. This is in contrast to a metric without any dimensions, which always gets exposed as exactly one present series and is initialized to 0. PromQL tutorial for beginners and humans - Medium But the key to tackling high cardinality was better understanding how Prometheus works and what kind of usage patterns will be problematic. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Here at Labyrinth Labs, we put great emphasis on monitoring. By setting this limit on all our Prometheus servers we know that it will never scrape more time series than we have memory for. The idea is that if done as @brian-brazil mentioned, there would always be a fail and success metric, because they are not distinguished by a label, but always are exposed. Our patched logic will then check if the sample were about to append belongs to a time series thats already stored inside TSDB or is it a new time series that needs to be created. Is it possible to create a concave light? If so it seems like this will skew the results of the query (e.g., quantiles). There is a single time series for each unique combination of metrics labels. Windows 10, how have you configured the query which is causing problems? I have a data model where some metrics are namespaced by client, environment and deployment name. 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. 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. Using a query that returns "no data points found" in an expression. Thanks for contributing an answer to Stack Overflow! 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. So lets start by looking at what cardinality means from Prometheus' perspective, when it can be a problem and some of the ways to deal with it. To make things more complicated you may also hear about samples when reading Prometheus documentation. 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 is the point of Thrower's Bandolier? 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. 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. You saw how PromQL basic expressions can return important metrics, which can be further processed with operators and functions. Prometheus has gained a lot of market traction over the years, and when combined with other open-source tools like Grafana, it provides a robust monitoring solution. So, specifically in response to your question: I am facing the same issue - please explain how you configured your data Monitoring our monitoring: how we validate our Prometheus alert rules but viewed in the tabular ("Console") view of the expression browser. If the time series already exists inside TSDB then we allow the append to continue. Making statements based on opinion; back them up with references or personal experience. 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. With this simple code Prometheus client library will create a single metric. by (geo_region) < bool 4 Prometheus query check if value exist. All chunks must be aligned to those two hour slots of wall clock time, so if TSDB was building a chunk for 10:00-11:59 and it was already full at 11:30 then it would create an extra chunk for the 11:30-11:59 time range. 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. for the same vector, making it a range vector: Note that an expression resulting in a range vector cannot be graphed directly, This is because once we have more than 120 samples on a chunk efficiency of varbit encoding drops. There will be traps and room for mistakes at all stages of this process. 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. Once we appended sample_limit number of samples we start to be selective. This is an example of a nested subquery. 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 Neither of these solutions seem to retain the other dimensional information, they simply produce a scaler 0. Then you must configure Prometheus scrapes in the correct way and deploy that to the right Prometheus server. Already on GitHub? 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? (pseudocode): This gives the same single value series, or no data if there are no alerts. What video game is Charlie playing in Poker Face S01E07? Our metric will have a single label that stores the request path. 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 In order to make this possible, it's necessary to tell Prometheus explicitly to not trying to match any labels by . @juliusv Thanks for clarifying that. Both patches give us two levels of protection. 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. Explanation: Prometheus uses label matching in expressions. more difficult for those people to help. Minimising the environmental effects of my dyson brain. Internally time series names are just another label called __name__, so there is no practical distinction between name and labels. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Its very easy to keep accumulating time series in Prometheus until you run out of memory. On the worker node, run the kubeadm joining command shown in the last step. Blocks will eventually be compacted, which means that Prometheus will take multiple blocks and merge them together to form a single block that covers a bigger time range. the problem you have. 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. Well be executing kubectl commands on the master node only. If we let Prometheus consume more memory than it can physically use then it will crash. Although you can tweak some of Prometheus' behavior and tweak it more for use with short lived time series, by passing one of the hidden flags, its generally discouraged to do so. Setting label_limit provides some cardinality protection, but even with just one label name and huge number of values we can see high cardinality. One of the first problems youre likely to hear about when you start running your own Prometheus instances is cardinality, with the most dramatic cases of this problem being referred to as cardinality explosion.
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