CircleCI Cheat Sheet

Updated 2026-04-28

Next Topic: Configuration Drift Cheat Sheet

CircleCI is a cloud-based continuous integration and continuous delivery (CI/CD) platform that automates software testing, building, and deployment through declarative YAML configuration. It orchestrates workflows across Docker containers, Linux VMs, macOS, Windows, and self-hosted runners, enabling teams to ship code faster with parallelism, caching, and approval gates. Understanding CircleCI's configuration structure—from jobs and executors to workflows, orbs, and dynamic config—is essential for building efficient, scalable pipelines that balance speed, reliability, and cost.

What This Cheat Sheet Covers

This topic spans 20 focused tables and 112 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: Configuration FundamentalsTable 2: ExecutorsTable 3: WorkflowsTable 4: CachingTable 5: Workspaces and ArtifactsTable 6: Environment Variables and SecretsTable 7: OrbsTable 8: Parallelism and Test SplittingTable 9: Dynamic ConfigurationTable 10: Commands and ReusabilityTable 11: Docker and Remote DockerTable 12: Scheduled TriggersTable 13: Conditional ExecutionTable 14: Security and ComplianceTable 15: Self-Hosted RunnersTable 16: Triggers and WebhooksTable 17: CLI and IDE ToolsTable 18: Observability and InsightsTable 19: Pipeline OrchestrationTable 20: Optimization and Best Practices

Table 1: Configuration Fundamentals

Everything in CircleCI starts from a single .circleci/config.yml, and these are the keys that form its skeleton — the version line that unlocks features, the jobs and steps that do the work, and the run and checkout commands you'll write in nearly every pipeline. Get fluent here first; every later table builds on this vocabulary.

Element	Example	Description
config.yml	`version: 2.1` `jobs:` `build:` `docker:` `- image: cimg/node:18.0`	Main CircleCI configuration file at `.circleci/config.yml` — defines jobs, workflows, executors, and all pipeline behavior.
version	`version: 2.1`	Config file schema version. 2.1 enables orbs, parameters, reusable commands, and pipeline features.
jobs	`jobs:` `test:` `docker:` `- image: cimg/python:3.9` `steps:` `- checkout`	• Defines named step collections that run in isolated environments • can run in parallel or sequentially within workflows.
steps	`steps:` `- checkout` `- run: npm install` `- run: npm test`	Lists sequential commands within a job — includes `checkout`, `run`, `save_cache`, `restore_cache`, `store_artifacts`, etc.
run	`- run:` `name: Install deps` `command: pip install -r requirements.txt`	• Executes shell commands inside the job environment • supports `name`, `command`, `working_directory`, `shell`, `when`, `background`, and `max_auto_reruns` parameters.

Table 1: Configuration Fundamentals

Element	Example	Description
config.yml	`version: 2.1` `jobs:` `build:` `docker:` `- image: cimg/node:18.0`	Main CircleCI configuration file at `.circleci/config.yml` — defines jobs, workflows, executors, and all pipeline behavior.
version	`version: 2.1`	Config file schema version. 2.1 enables orbs, parameters, reusable commands, and pipeline features.
jobs	`jobs:` `test:` `docker:` `- image: cimg/python:3.9` `steps:` `- checkout`	• Defines named step collections that run in isolated environments • can run in parallel or sequentially within workflows.
steps	`steps:` `- checkout` `- run: npm install` `- run: npm test`	Lists sequential commands within a job — includes `checkout`, `run`, `save_cache`, `restore_cache`, `store_artifacts`, etc.
run	`- run:` `name: Install deps` `command: pip install -r requirements.txt`	• Executes shell commands inside the job environment • supports `name`, `command`, `working_directory`, `shell`, `when`, `background`, and `max_auto_reruns` parameters.