Defining Job Steps and Commands - CircleCI Tutorial

Introduction

CircleCI is a popular continuous integration and delivery (CI/CD) platform that allows developers to automate the testing and deployment of their applications. In CircleCI configuration files, you define jobs that represent the different stages of your CI/CD pipeline. Each job consists of one or more steps, which are defined using commands.

Example

Let's consider an example where we want to build and test a Node.js application:


    version: 2.1

    jobs:

      build:

        docker:

          - image: circleci/node:12

        steps:

          - checkout

          - run: npm install

          - run: npm test

Defining Job Steps and Commands

To define job steps and commands in CircleCI, follow these steps:

1. Specify the CircleCI version

Begin your configuration file by specifying the CircleCI version you are using. For example:

version: 2.1

2. Define jobs

Within the configuration file, define the jobs that make up your CI/CD pipeline. Jobs represent the different stages or tasks you want to perform. For example:

jobs:

    build:

      ...

3. Specify the job steps

Within each job, specify the steps to be executed. Steps are the individual commands that are run to complete a job. For example:

steps:

      - checkout

      - run: npm install

      - run: npm test

Common Mistakes

Missing or incorrect indentation in the configuration file
Using unsupported or deprecated commands
Not properly handling dependencies between steps

Frequently Asked Questions (FAQs)

How can I pass environment variables to job steps?

You can pass environment variables to job steps by defining them in the environment section of your configuration file. Then, you can access these variables using the $VARIABLE_NAME syntax.
Can I parallelize job steps?

Yes, you can parallelize job steps using the parallelism keyword. By specifying a value greater than 1, CircleCI will run multiple instances of the same step in parallel.
How can I run commands only for specific branches or tags?

You can use conditional execution to run commands only for specific branches or tags. For example, you can use the when keyword to specify conditions like branch or tag.

Summary

In this tutorial, you learned how to define job steps and commands in CircleCI. You now know how to specify the CircleCI version, define jobs, and specify the steps within each job. Additionally, you explored a simple example and common mistakes to avoid. Remember to consult the CircleCI documentation for more advanced usage and options.