Migrating a Linux Project from 1.0 to 2.0

This document will give you a starting place for migrating from CircleCI 1.0 to 2.0 by using a copy of your existing 1.0 configuration file and replacing the old keys with the new keys if equivalents exist.

Steps to configure required keys
Environment variables
Steps to configure workflows
Search and replace deprecated 2.0 keys
Validate YAML

The migration process may not end with this document, but the goal is to get the majority of keys replaced with the equivalent syntax nesting and to help you get started with adding new functionality.

If you do not have a circle.yml file, refer to the Sample 2.0 config.yml File to get started from scratch.

Overview

CircleCI requires that you create a .circleci/config.yml, and it adds new required keys for which values must be defined. Note: Parallelism may only be set in the .circleci/config.yml file, the parallelism setting in the CircleCI app is ignored.

If you already have a circle.yml file, the following sections describe how to make a copy of your existing file, create the new required keys, and then search and replace your 1.0 keys with 2.0 keys.

Using the 1.0 to 2.0 `config-translation` endpoint

The config-translation endpoint can help you quickly get started with converting a 1.0 config to 2.0. For more, see Using the 1.0 to 2.0 config-translation Endpoint.

Steps to configure required keys

Copy your existing circle.yml file into a new directory called .circleci at the root of your project repository.
Rename .circleci/circle.yml to .circleci/config.yml.
Add version: 2 to the top of the .circleci/config.yml file.
Add the following two lines to your config.yml file, after the version line. If your configuration includes machine:, replace machine: with the following two lines, nesting all of the sections of the old config file under build.
```
  jobs:
    build:
```
Add the language and version you want to run the primary container to your configuration using either the docker: and - image: keys in the example or by setting machine: true or by using macos. If your configuration includes language and version as shown for ruby: below, replace it as shown.
```
    ruby:
      version: 2.7
```
Replace with the following lines:
```
      docker:
        - image: circleci/ruby:2.7
          auth:
            username: mydockerhub-user
            password: $DOCKERHUB_PASSWORD  # context / project UI env-var reference
```
The primary container is an instance of the first image listed. Your job’s commands run in this container and must be declared for each job. See the Docker Getting Started if you are new to Docker containers.
```
      machine: true
```
See the Using Machine section of the Choosing an Executor Type document for details about the available VM images.
```
      macos:
        xcode: 11.3.0
```

The checkout: step is required to run jobs on your source files. Nest checkout: under steps: for every job by search and replacing

  checkout:
    post:

With the following:

      steps:
        - checkout
        - run:

For example:

  checkout:
   post:
     - mkdir -p /tmp/test-data
     - echo "foo" > /tmp/test-data/foo

becomes

      steps:
        - checkout
        - run: mkdir -p /tmp/test-data
        - run: echo "foo" > /tmp/test-data/foo

If you do not have a checkout step, you must add this step to your config.yml file.

(Optional) Add the add_ssh_keys step with fingeprint to enable SSH into builds, see the Configuring CircleCI document for details.
Validate your YAML at http://codebeautify.org/yaml-validator to check the changes.

Environment variables

In CircleCI 2.0, all defined environment variables are treated literally. It is possible to interpolate variables within a command by setting it for the current shell.

For more information, refer to the CircleCI 2.0 document Using Environment Variables.

Steps to configure workflows

To increase the speed of your software development through faster feedback, shorter re-runs, and more efficient use of resources, configure workflows using the following instructions:

To use the Workflows feature, split your build job into multiple jobs, each with a unique name. It might make sense to start by just splitting out a deploy job to prevent you from having to re-run the entire build when only the deployment fails.
As a best practice, add lines for workflows:, version: 2 and <workflow_name> at the end of the master .circleci/config.yml file, replacing <workflow_name> with a unique name for your workflow. Note: The Workflows section of the config.yml file is not nested in the config. It is best to put the Workflows at the end of the file because the Workflows version: 2 is in addition to the version: key at the top of the config.yml file.
```
  workflows:
    version: 2
    <workflow_name>:
```
Add a line for the jobs: key under <workflow_name> and add a list of all of the job names you want to orchestrate. In this example, build and test will run concurrently.
```
  workflows:
    version: 2
    <workflow_name>:
        jobs:
          - build
          - test
```
For jobs which must run sequentially depending on success of another job, add the requires: key with a nested list of jobs that must succeed for it to start. If you were using a curl command to start a job, Workflows enable you to remove the command and start the job by using the requires: key.
```
   - <job_name>:
       requires:
         - <job_name>
```
For jobs which must run on a particular branch, add the filters: key with a nested branches and only key. For jobs which must not run on a particular branch, add the filters: key with a nested branches and ignore key. Note: Workflows will ignore job-level branching, so if you have configured job-level branching and then add workflows, you must remove the branching at the job level and instead declare it in the workflows section of your config.yml, as follows:
```
  - <job_name>:
      filters:
        branches:
          only: master
  - <job_name>:
      filters:
        branches:
          ignore: master
```
Validate your YAML again at http://codebeautify.org/yaml-validator to check that it is well-formed.

Search and replace deprecated 2.0 keys

If your configuration sets a timezone, search and replace timezone: America/Los_Angeles with the following two lines:

    environment:
      TZ: "America/Los_Angeles"

If your configuration modifies $PATH, add the path to your .bashrc file and replace

    environment:
      PATH: "/path/to/foo/bin:$PATH"

With the following to load it into your shell (the file $BASH_ENV already exists and has a random name in /tmp):

    steps:
      - run: echo 'export PATH=/path/to/foo/bin:$PATH' >> $BASH_ENV
      - run: some_program_inside_bin

Search and replace the hosts: key, for example:

hosts:
    circlehost: 127.0.0.1

With an appropriate run Step, for example:

    steps:
      - run: echo 127.0.0.1 circlehost | sudo tee -a /etc/hosts

Search and replace the dependencies:, database, or test and override: lines, for example:

dependencies:
  override:
    - <installed-dependency>

Is replaced with:

      - run:
          name: <name>
          command: <installed-dependency>

Search and replace the cache_directories: key:

  cache_directories:
    - "vendor/bundle"

With the following, nested under steps: and customizing for your application as appropriate:

     - save_cache:
        key: dependency-cache
        paths:
          - vendor/bundle

Add a restore_cache: key nested under steps:.
Search and replace deployment: with the following, nested under steps:

     - deploy:

Validate YAML

When you have all the sections in .circleci/config.yml we recommend that you check that your YAML syntax is well-formed using a tool such as http://codebeautify.org/yaml-validator. Then, use the circleci CLI to validate that the new configuration is correct with regard to the CircleCI 2.0 schema. See the Using the CircleCI Command Line Interface (CLI) document for instructions. Fix up any issues and commit the updated .circleci/config.yml file. When you push a commit the job will start automatically and you can monitor it in the CircleCI app.

Next Steps

See the Tips for Migrating from 1.0 to 2.0
Refer the Deploy document for examples of deployment.
Refer to the Specifying Container Images document for more information about Docker and Machine images in CircleCI 2.0.
Refer to the Configuring CircleCI document for details on the exact syntax of CircleCI 2.0 jobs and steps and all available options.

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