How do I use service discovery with Prometheus?
If you need to use a service discovery system that is not currently supported, your use case may be best served by Prometheus' file-based service discovery mechanism, which enables you to list scrape targets in a JSON file (along with metadata about those targets). In this guide, we will: Install and run a Prometheus Node Exporter locally
How do I discover instances of Prometheus in OpenStack?
Prometheus requires an application credential to discover instances in OpenStack (see here ). When creating the credential, assign it the reader role. The Prometheus user does not need to make any changes within OpenStack, only discover from it. $ microstack.openstack application credential create --role reader prometheus_sd
How does Prometheus scrape and monitor its own health?
Prometheus collects metrics from monitored targets by scraping metrics HTTP endpoints on these targets. Since Prometheus also exposes data in the same manner about itself, it can also scrape and monitor its own health. For a complete specification of configuration options, see the configuration documentation.
What's new in Prometheus?
On the user side, Prometheus now supports new service discovery mechanisms. In addition to DNS-SRV records, it now supports Consul out of the box, and a file-based interface allows you to connect your own discovery mechanisms. Over time, we plan to add other common service discovery mechanisms to Prometheus.
What is the use of service discovery in Prometheus?
Service discovery (SD) enables you to provide that information to Prometheus from whichever database you store it in. Prometheus supports many common sources of service information, such as Consul, Amazon's EC2, and Kubernetes out of the box.
What is Prometheus service?
Prometheus Service is a managed monitoring service that is provided by Alibaba Cloud. Prometheus Service is compatible with the open source Prometheus ecosystem. Prometheus Service provides out-of-the-box dashboards for you to monitor a wide variety of components.
How does Prometheus discover Kubernetes?
Prometheus uses service discovery to discover targets to scrape. Kubernetes clusters are equipped with labels, annotations, and a mechanism for tracking status and changes for different elements. To discover targets, Prometheus needs to use the Kubernetes API.
What is scrape in Prometheus?
In Prometheus terms, an endpoint you can scrape is called an instance, usually corresponding to a single process. A collection of instances with the same purpose, a process replicated for scalability or reliability for example, is called a job.
What is metrics in Prometheus?
Metrics are a core concept of Prometheus. Instrumented systems expose them, Prometheus stores them in its time-series database and makes them available to easily query to understand how these systems behave over time. In short, a metric is an identifier linking data points together over time.
How is data stored in Prometheus?
Prometheus has a sophisticated local storage subsystem. For indexes, it uses LevelDB. For the bulk sample data, it has its own custom storage layer, which organizes sample data in chunks of constant size (1024 bytes payload). These chunks are then stored on disk in one file per time series.
What is Relabel_configs in Prometheus?
Relabel_config in a Prometheus configuration file. You can apply a relabel_config to filter and manipulate labels at the following stages of metric collection: Target selection in the relabel_configs section of a scrape_configs job.
What is node exporter in Prometheus?
August 18, 2020 | Comments(1) | Node Exporter is a Prometheus exporter for server level and OS level metrics with configurable metric collectors. It helps us in measuring various server resources such as RAM, disk space, and CPU utilization.
What is scrape timeout in Prometheus?
Every 5 minutes (scrape_interval) Prometheus will get the metrics from the given URL. It will try 30 seconds (scrape_timeout) to get the metrics if it can't scrape in this time it will time out.
What is evaluation interval in Prometheus?
Prometheus is configured to scrape metrics every 20 seconds, and the evaluation interval is 1 minute.
How do you check metrics in Prometheus?
ProcedureClick Add a source and select Add a Prometheus Server.In the New server dialog box, enter the connection settings. ... In the Select Prometheus queries dialog box, select queries that are available in the list to collect Prometheus metrics data by clicking the checkboxes. ... Follow these steps to create a query:More items...
What is Kubernetes_sd_configs?
Lastly, kubernetes_sd_config is the configuration file defines everything related to scraping targets. You can decide in the config file what kind of information you want to gather and from whom. Follow this answer to receive notifications.
Integrated service discovery mechanism
Prometheus can be integrated into many different open source Service discovery tools to dynamically discover the targets to be monitored.
File based service discovery
File based service discovery, which does not depend on any platform or third-party services, is the simplest and most common implementation. The configuration file format is as follows
Service discovery based on Kubernetes API
The Service discovery mechanism based on Kubernetes API supports monitoring resource objects under resource types such as Pod, Service, Endpoint, progress and Node in API Server as target s. These resource objects are defined by their own discovery mechanisms. They are responsible for discovering the components of each type of resource object.
Prometheus and targets
For a proper understanding of this blog post, we first need to take a look at how Prometheus labels targets.
Scrape configurations and relabeling
Aside from moving from an ASCII protocol buffer format to YAML, a fundamental change to Prometheus's configuration is the change from per-job configurations to more generalized scrape configurations. While the two are almost equivalent for simple setups, scrape configurations allow for greater flexibility in more advanced use cases.
Discovery with DNS-SRV records
Since the beginning, Prometheus has supported target discovery via DNS-SRV records. The respective configuration looked like this:
Discovery with Consul
Service discovery via Consul is now supported natively. It can be configured by defining access parameters for our Consul agent and a list of Consul services for which we want to query targets.
Custom service discovery
Finally, we added a file-based interface to integrate your custom service discovery or other common mechanisms that are not yet supported out of the box.
Conclusion
With DNS-SRV records and Consul, two major service discovery methods are now natively supported by Prometheus. We've seen that relabeling is a powerful approach to make use of metadata provided by service discovery mechanisms.
Also on Prometheus Blog
An open-source monitoring system with a dimensional data model, flexible query …
Service Discovery
Service discovery is one of the major features of Prometheus. As a monitoring tool, being up to date with the infrastructure is critical. Configuring targets manually and keeping the list up to date is a tedious work; not doing it creates a partial view of the infrastructure and alert fatigue.
File-based service discovery
For the service discovery mechanisms that are not integrated natively in Prometheus, the solution has always been file_sd. File SD is a service discovery based on files.
Drawbacks of file service discovery
The file-based service discovery mechanism has two major drawbacks: the first one is that in most cases you need an extra process running next to your Prometheus server to generate the file.
Format
The HTTP Service Discovery body format is the same as the file_sd JSON format:
Prometheus configuration
On the Prometheus server, it is simply needed to indicate the URL of your endpoint, in an http_sd_configs section:
Implementation
When implementing such a service discovery, there is a few things you should know.
Conclusion
http_sd is mainly the JSON file_sd over HTTP. We did not create a new, fancy service discovery mechanism. Instead, we have built a pragmatic solution, which is easy to use and understand. It will help a lot of people, and open new possibilities for Prometheus users.
What is OpenStack?
OpenStack is a way of running your own Infrastructure-as-a-service platform. It enables you to deploy compute, storage, networking and other resources similar to the major cloud providers. It began as a joint venture between Rackspace and NASA to provide an Open Source cloud solution.
The lab
OpenStack usually requires a fleet of high-powered servers managed as a cluster (or multiple clusters) of compute, storage and other services. If you want to test out OpenStack on a single machine, there are multiple options available: -
Terraform
Terraform has an official OpenStack Provider that allows you to manage the resources on OpenStack. It can create everything from compute instances, object storage, containers and more.
Prometheus
Now that we have our Instance created in OpenStack, we can configure Prometheus to discover it.
Grafana
Now that we have discovered the instances, we can use any Node Exporter dashboard in Grafana to view their metrics. The Node Exporter Full is always a good start when using the Node Exporter: -
Summary
For those who choose to own their cloud infrastructure, the OpenStack Service Discovery mechanism does provide a very flexible way of monitoring the hypervisors and instances.
Create an IAM User
This part might be confusing if you are not familiar with AWS IAM just because the new terms behind what is needed. Let’s talk about a few concepts first:
Configure Prometheus Service Discovery
Now we need to go back to Prometheus and change the configuration again. Remember that ec2-3-17-28.53.us-east-2.compute.amazonaws.com is the DNS value I got from my configuration and yours should be something different.
Try It Out
Let’s see if Prometheus is finding our Node-Exporter instance. Go to http://ec2-3-17-28.53.us-east-2.compute.amazonaws.com:9090/targets. You might see other instances registered since Prometheus is looking up for all the EC2 instances in the same network.
Common DNS record types
The most common DNS records are A, AAAA and PTR. An A record is a simple “name to IPv4” mapping, eg one.one.one.one would become 1.1.1.1. A AAAA record is the same, except for IPv6.
What is an SRV record?
Rather than just being a mapping from a hostname to an IP (eg A or AAAA), or the reverse (PTR), an SRV record contains hostnames, ports and the protocols (TCP/UDP). Common usage of this include SIP and Active Directory Domain Controller discovery.
How can Prometheus use this?
To monitor a host, Prometheus requires the IP/hostname, port and protocol. This is exactly what an SRV record exposes, and so can be leveraged for service discovery. The exact implementation is documented here
How to update the SRV record?
It all depends on your use case. In some cases, this may be a manual process. It can also be done by the systems themselves (Active Directory being a good example). Alternatively, use whatever automation method you feel is appropriate.
Summary
My personal preference for service discovery is definitely using Consul. However if you already have DNS records that are getting created (eg ETCD, Active Directory), or the additional complexity of Consul will not provide enough benefit, DNS service discovery could be the way to go.
Installing and Running The Node Exporter
Installing, Configuring, and Running Prometheus
- Like the Node Exporter, Prometheus is a single static binary that you can install via tarball. Download the latest releasefor your platform and untar it: The untarred directory contains a prometheus.ymlconfiguration file. Replace the current contents of that file with this: This configuration specifies that there is a job called node (for the Node Exporter) that retrieves host …
Exploring The Discovered Services' Metrics
- With Prometheus up and running, you can explore metrics exposed by the node service using the Prometheus expression browser. If you explore the up{job="node"}metric, for example, you can see that the Node Exporter is being appropriately discovered.
Changing The Targets List Dynamically
- When using Prometheus' file-based service discovery mechanism, the Prometheus instance will listen for changes to the file and automatically update the scrape target list, without requiring an instance restart. To demonstrate this, start up a second Node Exporter instance on port 9200. First navigate to the directory containing the Node Exporter bi...
Summary
- In this guide, you installed and ran a Prometheus Node Exporter and configured Prometheus to discover and scrape metrics from the Node Exporter using file-based service discovery. This documentation is open-source. Please help improve it by filing issues or pull requests.
Prometheus and Targets
Scrape Configurations and Relabeling
Discovery with DNS-SRV Records
Discovery with Consul
Custom Service Discovery
- Finally, we added a file-based interface to integrate your custom service discovery or other common mechanismsthat are not yet supported out of the box. With this mechanism, Prometheus watches a set of directories or files which define target groups.Whenever any of those files changes, a list of target groups is read from the files and scrape targe...
Conclusion