The term "Promregator" is an artifical composite of the two terms "Prometheus" and "aggregator".
Prometheus is referring to the Prometheus project, which is a toolset intended for retrieving telemetry data of running applications. It supports monitoring these metrics and triggering alerts based on thresholds.
Aggregator is referring to the aggregator concept, which you encounter several times in the Platform-as-a-Service offering of Cloud Foundry. The most prominent case of an aggregator in Cloud Foundry most likely is the Loggregator.
The Promregator project intends to provide an aggregator-like tool for the Cloud Foundry environment, which allows fetching Prometheus metrics of a set of Cloud Foundry app instances. Note that it is not the intention to facilitate scraping of metrics on platform level (e.g. for monitoring services, which are exposed via BOSH containers on the Cloud Foundry platform), but support monitoring of metrics on application level (if you are looking for platform monitoring, you might find https://github.com/pivotal-cf/prometheus-on-PCF and https://github.com/bosh-prometheus/prometheus-boshrelease interesting).
If you want to jumpstart and see what Promregator may do, please refer to our quickstart description.
Here is the list of major features provided by Promregator:
-
Standard Java-Application implemented using the Spring Framework. There is no need for administrative privileges on your Cloud Foundry installation! You can even run Promregator outside of your Cloud Foundry environment (such as behind an internal firewall), as Promregator also supports proxy servers.
-
Automatic discovery of instances and hostnames of Cloud Foundry apps supported
- Multiple CF apps in multiple Orgs and multiple spaces supported
- Multiple instances per app supported, automatically detecting up- and downscaling (results are cached, timeout of caching can be configured)
- (>= 0.4.0) Auto-detection of all applications within a CF space allows a simplified configuration
- (>= 0.4.0) Filtering of applications within a CF space based on Regular Expression allows a simplified configuration
- (>= 0.5.0) Filtering of spaces based on Regular Expression permits selection of multiple applications even if they are distributed over several spaces.
- (>= 0.5.0) Filtering of organizations based on Regular Expression permits selection of multiple applications even if they are distributed over several organizations.
- (>= 0.5.0) Auto-detection of all applications across all organizations and spaces allows a simplified configuration.
- (>= 0.5.0) Filtering of applications across all organizations and spaces based on Regular Expression allows a simplified configuration.
- (>= 0.6.0) Selecting the route to be used for scraping can be controlled by providing Regular Expressions.
-
Fetching of the Prometheus Metric endpoints of multiple app instances is performed in parallel (number of concurrent threads used for retrieving metrics can be configured).
-
Support of Authentication Schemes at the CF app's endpoint. The following Authentication schemes are currently available:
- Basic HTTP Authentication (as of RFC2617)
- JWT-based authentication (with retrieval of JWT from OAuth2 server, JWT is cached), (since >= 0.10.0 both support for basic authentication against the OAuth2 authentication server and certificate-based authentication)
- Null Authentication (not recommended for productive environments!)
The available authentication schemes are easily extensible.
(>= 0.4.0) Each target may be configured to use its own authentication scheme, thus you may authenticate to multiple CF apps using different credentials. (>= 0.9.0) Ability to specify the SSL Context used by promregator using JVM options
-
(>= 0.2.0) Support for inbound authentication (e.g. Prometheus authenticates to Promregator) using Basic HTTP Authentication.
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Configuration using standard Spring properties as defined by the Spring Framework (e.g. using
application.ymlfile). -
(>= 0.6.0) Support for encrypted passwords in configuration files including providing the encryption key via Docker Secrets
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Simple HTTP proxy support is available for contacting CF app endpoints.
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Additional metrics are provided supporting you to monitor Promregator and the communication to the Cloud Foundry applications.
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(>= 0.4.0) Cache Invalidation is possible via an (optionally auth-protected) HTTP REST endpoint.
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Promregator's endpoints (e.g.
/promregatorMetrics,/discovery) support GZIP compression, if the clients indicates to accept it. -
(>= 0.9.0) Filtering by annotations and using annotations to specify the metrics path.
Promregator is sitting between your Prometheus server on the one hand and talks to your Cloud Foundry apps on the other hand. It is converting the Prometheus' scraping requests into queries targeting your instances of your apps, which are running on Cloud Foundry.
For further details on the architecture of Promregator, please look at the architecture page.
During the course of action, we came across several other implementation alternatives. Due to one or the other reason they were not implemented. You may find a detailed discussion about these approaches on our discarded ideas page.
Promregator is currently preparing to provide a new major version. Here are the main differences from a user perspective between the two versions:
| Aspect | Version 1.x.x | Version 0.x.x |
|---|---|---|
| Java Runtime Version | JRE 17 or higher | JRE 8 or higher |
| CF CC API Version | V3 only (3.84.0 or higher required) | V2 only (special cases with V3) |
| Classic Cache | no longer supported | default, available in all minor versions |
| Caffeine Cache | default | optional, starting with 0.7.x |
| OAuth2XSUAA Authenticator with Basic Authentication | Only OAuth2XSUAABasic supported |
OAuth2XSUAA (old one) and OAuth2XSUAABasic supported (available since v0.10.0) |
| Scraping Method | Single Target Scraping supported | Single Endpoint Scraping and Single Target Scraping supported |
| Label Enrichment | not supported | supported (for Single Target Scraping) |
| Support for metrics formats at scraping targets | text/plain;version=0.0.4 and OpenMetrics 1.0.0 | text/plain;version=0.0.4 only |
| Support for INFO-typed metrics | supported (pass-through) | not supported (in some cases passed-through) |
| Support for STATESET-typed metrics | supported (pass-through) | not supported |
| Support for UNIT metric descriptor | supported (pass-through) | not supported |
| Returned format to scraping callers | pass-through as scraped | text/plain;version=0.0.4 (parsed and reformatted) |
It is recommended that you upgrade to the new major version on next occasion. An upgrade guide is provided here.
Running Promregator V1 requires:
- JRE17 or higher
- A Cloud Foundry platform supporting the Cloud Foundry API Version 3.84.0 or higher (release in June 2020).
If you cannot fulfill these requirements, you may still use Promregator V0, which requires JRE8 or higher and supprts Cloud Foundry API version 2.x.
Compiling Promregator additionally requires:
- JDK17 or higher (for Promregator V1)
- JDK8 or higher (for Promregator V0)
- Maven 3.3.0 or higher
Further dependencies required are automatically loaded when building the software. An internet connection to Maven Central is necessary for that.
Promregator has been released first on 2018-03-18. It currently provides two binary-based deliveries:
- You may download versions of the released jar file at https://github.com/promregator/promregator/releases.
- You may use the prepared Docker container which is available at https://hub.docker.com/r/promregator/promregator/. Hints on suggested parameters can be found at this page.
Furthermore, you may create your own package by downloading the source code, unpacking it into a local folder and calling
mvn clean packageThe runnable artifact will be available at target/promregator-*-SNAPSHOT.jar. It is a self-contained (e.g. including all library dependencies) JAR file, which can be copied around and executed at an arbitrary folder by calling
java -jar promregator-x.y.z-SNAPSHOT.jarA detailed documentation, including a description how you may configure Promregator, what needs to be done to integrate it with Prometheus is available at the documentation pages.
For related work, which we came across, refer to our references page.
For sending material (e.g. memory dumps) for analysis, which you do not want to (or even should not) share to/with the public, please refer to our analysis material page