prometheus

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The Prometheus monitoring system and time series database is a powerful open-source tool for monitoring and alerting on metrics. This repository contains the core functionality of the Prometheus project, including the main server executable, command-line tools, configuration management, service discovery, storage, and web UI.

The most important parts of the repository are the cmd, config, discovery, model, promql, rules, storage, tsdb, and web directories. These directories contain the essential components that make up the Prometheus monitoring system.

The …/prometheus directory is the main entry point for the Prometheus server, responsible for setting up and managing the various components of the system, handling configuration changes, and supporting experimental features. The main.go file in this directory defines the main() function, which initializes and runs all other Prometheus server components, and the reloadConfig() function, which is responsible for loading the configuration file and applying the changes to the various components.

The model directory provides the core data structures and functionality for handling the various aspects of the Prometheus data model, including Labels, Histogram, Metadata, and RuleGroups. The efficient and robust implementation of these components is essential for the overall performance and reliability of the Prometheus monitoring system.

The discovery directory contains the implementation of various service discovery mechanisms, allowing Prometheus to automatically discover and monitor targets from a wide range of sources, such as cloud providers, container orchestration platforms, and other infrastructure components. Each subdirectory in discovery (e.g., …/aws, …/azure, …/consul) implements a specific service discovery mechanism.

The promql directory contains the core functionality for parsing, evaluating, and executing Prometheus Query Language (PromQL) expressions. The Parser class in the …/parser directory is responsible for parsing PromQL expressions and building an Abstract Syntax Tree (AST) representation, while the Engine struct in engine.go is the main entry point for executing PromQL queries, handling query execution, cancellation, and resource management.

The rules directory provides the functionality for managing and evaluating recording and alerting rules in the Prometheus monitoring system. The AlertingRule struct and the Group struct are the key components in this directory, responsible for evaluating alert expressions, managing the state of active alerts, and executing a set of related rules.

The storage and tsdb directories contain the core implementation of the Prometheus Time Series Database (TSDB), which is responsible for storing and managing the time series data used by the Prometheus monitoring system. The DB struct in agent/db.go is the core of the Prometheus Agent's TSDB storage, while the …/chunkenc and …/chunks directories provide the functionality for efficiently storing and retrieving time series data.

Finally, the web directory contains the core functionality for the Prometheus web server, including the implementation of the Prometheus web API, the Prometheus web UI, and various other web-related components. The Handler struct in web.go is the main component that encapsulates the various components of the Prometheus server and is responsible for serving the different HTTP endpoints.

References: cmd

The main entry point and management of the Prometheus server is handled in the …/prometheus directory. This directory contains the core functionality for setting up and running the Prometheus server, including the command-line interface, configuration handling, and server lifecycle.

References: cmd/prometheus

The main.go file in the …/prometheus directory is the main entry point for the Prometheus server executable. It is responsible for setting up and managing the various components of the Prometheus monitoring system, including the web server, scrape manager, rule manager, notifier, and storage.

References: cmd/prometheus

The …/prometheus directory contains the main entry point for the Prometheus monitoring system, including support for various experimental features that can be enabled through command-line flags.

References: cmd/prometheus

The …/main_test.go file contains a comprehensive set of tests that ensure the reliability and correctness of the Prometheus server. These tests cover various aspects of the server's functionality, including:

References: cmd/prometheus

The query_log_test.go file in the …/prometheus directory contains tests for the query logging functionality in Prometheus. The tests cover different scenarios, including API queries, console queries, and rule queries, with various configurations such as different listen addresses, route prefixes, and whether the query log is enabled at startup.

References: model

The model directory in the Prometheus project contains various data structures and functionality related to the core data model used in the Prometheus monitoring system. This includes components for handling labels, histograms, exemplars, metadata, and rule formatting.

References: model/labels

The …/labels directory provides core functionality for working with labels, which are key-value pairs associated with metrics in the Prometheus data model. The main components in this directory include:

References: model/histogram

The …/histogram directory contains the implementation of histogram data structures and related functionality, which are used to represent high-resolution histograms in the Prometheus monitoring system.

References: model/exemplar

The core functionality for working with exemplars, which are additional information associated with time series data in Prometheus, is implemented in the …/exemplar directory.

References: model/metadata

The Metadata struct is used to store metadata information about metrics, such as type, unit, and help text. This metadata can be important for understanding the meaning and context of the metrics being collected and analyzed.

References: model/rulefmt

The …/rulefmt directory contains the core functionality for parsing and validating Prometheus rule files. The main components in this directory are:

References: model/relabel

The implementation of the relabeling functionality in the Prometheus project is handled in the …/relabel directory. This subsection explains the core functionality of the relabeling process, which allows for the transformation of labels based on configurable rules.

References: model/timestamp

The …/timestamp directory in the Prometheus project provides utility functions for working with timestamps in milliseconds, a common representation in the Prometheus ecosystem.

References: model/value

The …/value.go file in the Prometheus project defines constants and a function related to handling NaN (Not a Number) values in Prometheus.

References: discovery

The discovery directory in the Prometheus project contains the implementation of various service discovery mechanisms, allowing Prometheus to automatically discover and monitor targets from a wide range of sources.

References: discovery/kubernetes

The Kubernetes service discovery mechanism in Prometheus is implemented in the …/kubernetes directory. The main entry point for this functionality is the kubernetes.go file, which defines the Discovery struct.

References: discovery/moby

The …/moby directory contains the implementation of the Docker and Docker Swarm service discovery mechanisms for Prometheus. The main components are:

References: discovery/xds

The xDS (eXtensible Data Source) service discovery mechanism in Prometheus allows the monitoring system to discover and monitor services using the xDS protocol. This includes support for Kuma-based service discovery.

References: discovery/openstack

The OpenStack service discovery mechanism in Prometheus enables the monitoring of OpenStack hypervisors and instances. The key components of this implementation are:

References: discovery/hetzner

The Hetzner service discovery mechanism in the Prometheus monitoring system allows for the discovery and monitoring of Hetzner Cloud instances and dedicated servers. This functionality is implemented in the …/hetzner directory, which includes the following key components:

References: discovery/scaleway

The Scaleway service discovery mechanism in Prometheus enables the monitoring of Scaleway bare metal servers and virtual instances. The implementation is spread across several files in the …/scaleway directory.

References: discovery/eureka

The Eureka service discovery mechanism in Prometheus allows the monitoring system to automatically discover and monitor applications running on the Eureka service discovery platform. The core functionality is implemented in the …/eureka directory.

References: discovery/puppetdb

The PuppetDB service discovery mechanism in Prometheus allows the monitoring system to automatically discover and monitor resources from a PuppetDB server. The core functionality is implemented in the …/puppetdb directory.

References: discovery/aws

The AWS service discovery mechanism in Prometheus allows the monitoring system to automatically discover and scrape metrics from EC2 instances and Lightsail instances in the AWS cloud.

References: discovery/digitalocean

The …/digitalocean directory contains the implementation of the DigitalOcean service discovery mechanism for Prometheus. The key functionality is provided by the Discovery struct, which is responsible for periodically refreshing the list of DigitalOcean droplets (virtual machines) and converting them into Prometheus target groups.

References: discovery/nomad

The Nomad service discovery mechanism in the Prometheus monitoring system allows Prometheus to discover and monitor services running on a Nomad cluster. The core functionality is implemented in the …/nomad directory.

References: discovery/marathon

The Marathon service discovery mechanism in Prometheus enables the automatic discovery and monitoring of applications running on the Marathon platform. The key components that implement this functionality are:

References: discovery/dns

The DNS-based service discovery mechanism in Prometheus allows the monitoring system to discover targets by querying various types of DNS records, such as SRV, A, AAAA, MX, and NS records. The core implementation of this functionality is located in the …/dns directory.

References: discovery/consul

The Consul service discovery mechanism in Prometheus is implemented in the …/consul directory. The main components and functionality are:

References: discovery/zookeeper

The …/zookeeper directory in the Prometheus project provides functionality for discovering targets from Zookeeper, specifically for Twitter's Serverset and AirBnB's Nerve services.

References: discovery/targetgroup

The …/targetgroup directory in the Prometheus project provides the core functionality for representing and manipulating a set of targets with a common label set, which is a fundamental concept in the Prometheus service discovery mechanisms.

References: discovery/refresh

The Discovery struct in the …/refresh directory is responsible for periodically refreshing a set of target groups for Prometheus. The Discovery struct implements the Discoverer interface and is configured with a RefreshF function, which is used to fetch the target groups, and a refresh interval.

References: promql

The core functionality of the promql directory is to provide the parsing, evaluation, and execution of Prometheus Query Language (PromQL) expressions. This directory includes several key components:

References: promql/parser

The parser is responsible for parsing Prometheus Query Language (PromQL) expressions and building an Abstract Syntax Tree (AST) representation. The main entry point for the parser is the parser struct, which is defined in the parse.go file.

References: promql

The Engine struct is the main entry point for executing PromQL queries in the Prometheus monitoring system. It is responsible for handling the execution, cancellation, and resource management of PromQL queries.

References: promql

The …/functions.go file contains the implementation of various PromQL functions used in the Prometheus monitoring system. These functions provide a wide range of functionality, including time-series manipulation, statistical analysis, and date/time operations.

References: promql

The prometheus/promql/quantile.go file contains functionality related to calculating quantiles and working with histogram data in the Prometheus Query Language (PromQL).

References: promql

The ActiveQueryTracker struct is responsible for logging and managing active PromQL queries in the Prometheus monitoring system. It provides functionality for inserting, deleting, and retrieving information about active queries, as well as handling unfinished queries from previous runs of Prometheus.

References: promql

The promql directory contains a comprehensive testing framework for the Prometheus Query Language (PromQL). This framework allows the creation and execution of test cases that validate the correctness of the PromQL engine's behavior.

References: rules

The Prometheus monitoring system provides a flexible and extensible way to manage recording and alerting rules. The core functionality for this is implemented in the rules directory, which contains the following key components:

References: rules/alerting.go

The AlertingRule struct in the …/alerting.go file is responsible for the core functionality of evaluating alerting rules, managing the state of active alerts, and generating alert samples for the Prometheus time series database.

References: rules/recording.go

The recording.go file in the Prometheus project defines the RecordingRule struct, which represents a recording rule in Prometheus. Recording rules are used to record the results of a vector expression into new time series.

References: rules/group.go

The Group struct in the …/group.go file is responsible for managing the evaluation and execution of a set of related rules in the Prometheus monitoring system. This includes handling concurrency, state restoration, and metrics reporting for the rules within the group.

References: rules/manager.go

The Manager struct is the core component responsible for managing the lifecycle of rule groups in the Prometheus monitoring system. The Manager is responsible for the following key functionalities:

References: storage, tsdb

The core implementation of the Prometheus Time Series Database (TSDB) is responsible for storing and managing the time series data used by the Prometheus monitoring system. The key components of the TSDB implementation are:

References: tsdb

The core implementation of the Prometheus Time Series Database (TSDB) is primarily contained in the tsdb directory. The key components responsible for storing and managing the time series data are:

References: storage/remote

The …/remote directory contains the core functionality for integrating Prometheus with remote storage systems. It provides components for handling remote read and write requests, encoding and decoding data, managing write queues, and more.

References: tsdb/agent

The series management system in the Prometheus TSDB (Time Series Database) agent is implemented in the …/series.go file. This subsection explains the key components and design choices of this implementation.

References: tsdb/chunkenc

The …/chunkenc directory in the Prometheus time series database (TSDB) implementation contains the core functionality for handling different types of data chunks, including XOR-encoded chunks, histogram chunks, and float histogram chunks. The directory provides abstractions for working with time series data, allowing for efficient storage and retrieval of samples.

References: tsdb/chunks

The chunk_write_queue.go file in the …/chunks directory provides the core functionality for managing the asynchronous writing of time series data chunks to disk. The main component is the chunkWriteQueue struct, which is responsible for handling the queue of write jobs and efficiently writing the chunks to disk.

References: tsdb/wlog

The Write-Ahead Log (WAL) in the Prometheus TSDB (Time Series Database) is a crucial component responsible for storing and managing the time series data, samples, exemplars, and metadata used by the TSDB. The main functionality of the WAL is implemented in the …/wlog directory, which includes the following key components:

References: tsdb/index

The …/index directory contains the implementation of the index component for the Prometheus Time Series Database (TSDB). The index is responsible for storing and managing the metadata about the time series data, including the series labels, chunk metadata, and postings lists. This allows for efficient querying and filtering of the time series data.

References: tsdb/tsdbutil

The …/tsdbutil directory contains various utility functions and test utilities related to the Prometheus Time Series Database (TSDB) component.

References: tsdb/agent

The …/agent directory contains the implementation of the Prometheus Agent's time series database (TSDB) storage, which is a Write-Ahead Log (WAL)-only storage. The main components in this directory are:

References: web

The Prometheus web server is the central component responsible for serving the Prometheus web UI and API. The core functionality is implemented in the web directory, which includes the following key components:

References: web/ui/react-app/src/pages, web/ui/module/codemirror-promql

The …/pages directory contains the main components and functionality for the various pages in the Prometheus web UI's React application. This includes pages for displaying information about agents, alerts, configuration, flags, rules, service discovery, status, targets, and the Time Series Database (TSDB) status.

References: web/api/v1

The Prometheus web API, implemented in the …/v1 directory, provides a set of endpoints for interacting with the Prometheus monitoring and alerting system. The API allows users to query, manage, and retrieve information about the Prometheus server and its configuration.

References: web/ui/static/vendor, web/ui/react-app/src/vendor

The …/vendor directory contains several important third-party libraries and frameworks used in the Prometheus web UI, including:

References: web/ui/react-app/src/themes

The …/themes directory contains the SCSS (Sass) files that define the styles and themes for the Prometheus web UI's React application. The main functionality of this directory is to provide a consistent and customizable styling system for the application, allowing for both light and dark themes.

References: web/ui/react-app/src/components, web/ui/react-app/src/hooks

The …/components directory contains several important utility components and higher-order components (HOCs) that provide key functionality to the Prometheus web UI application.

References: web/ui/module/codemirror-promql/src

The PromQL (Prometheus Query Language) editor functionality in the Prometheus web UI is implemented in the …/src directory. This subsection discusses the key components and design choices behind the PromQL editor, including syntax highlighting, autocompletion, and linting.