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GitHub Actions Importer を使った CircleCI からの移行

GitHub Actions Importer を使って、CircleCI パイプラインの GitHub Actions への移行を自動化する方法について説明します。

この記事の内容

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About migrating from CircleCI with GitHub Actions Importer

The instructions below will guide you through configuring your environment to use GitHub Actions Importer to migrate CircleCI pipelines to GitHub Actions.

Prerequisites

  • A CircleCI account or organization with projects and pipelines that you want to convert to GitHub Actions workflows.

  • Access to create a CircleCI personal API token for your account or organization.

  • An environment where you can run Linux-based containers, and can install the necessary tools.

    Note: The GitHub Actions Importer container and CLI do not need to be installed on the same server as your CI platform.

Limitations

There are some limitations when migrating from CircleCI to GitHub Actions with GitHub Actions Importer:

  • Automatic caching in between jobs of different workflows is not supported.
  • The audit command is only supported when using an organization account. However, the dry-run and migrate commands can be used with an organization or user account.

Manual tasks

Certain CircleCI constructs must be migrated manually. These include:

  • Contexts
  • Project-level environment variables
  • Unknown job properties
  • Unknown orbs

Installing the GitHub Actions Importer CLI extension

  1. Install the GitHub Actions Importer CLI extension:

    Bash
    gh extension install github/gh-actions-importer

  2. Verify that the extension is installed:

    $ gh actions-importer -h
Options:
  -?, -h, --help  Show help and usage information

Commands:
  update     Update to the latest version of GitHub Actions Importer.
  version    Display the version of GitHub Actions Importer.
  configure  Start an interactive prompt to configure credentials used to authenticate with your CI server(s).
  audit      Plan your CI/CD migration by analyzing your current CI/CD footprint.
  forecast   Forecast GitHub Actions usage from historical pipeline utilization.
  dry-run    Convert a pipeline to a GitHub Actions workflow and output its yaml file.
  migrate    Convert a pipeline to a GitHub Actions workflow and open a pull request with the changes.

Configuring credentials

The configure CLI command is used to set required credentials and options for GitHub Actions Importer when working with CircleCI and GitHub.

  1. Create a GitHub personal access token. For more information, see "Managing your personal access tokens."

    Your token must have the workflow scope.

    After creating the token, copy it and save it in a safe location for later use.

  2. Create a CircleCI personal API token. For more information, see Managing API Tokens in the CircleCI documentation.

    After creating the token, copy it and save it in a safe location for later use.

  3. In your terminal, run the GitHub Actions Importer configure CLI command:

    gh actions-importer configure

    The configure command will prompt you for the following information:

    • For "Which CI providers are you configuring?", use the arrow keys to select CircleCI, press Space to select it, then press Enter.
    • For "Personal access token for GitHub", enter the value of the personal access token that you created earlier, and press Enter.
    • For "Base url of the GitHub instance", enter the URL for your GitHub Enterprise Server instance, and press Enter.
    • For "Personal access token for CircleCI", enter the value for the CircleCI personal API token that you created earlier, and press Enter.
    • For "Base url of the CircleCI instance", press Enter to accept the default value (https://circleci.com).
    • For "CircleCI organization name", enter the name for your CircleCI organization, and press Enter.

    An example of the configure command is shown below:

    $ gh actions-importer configure
✔ Which CI providers are you configuring?: CircleCI
Enter the following values (leave empty to omit):
✔ Personal access token for GitHub: ***************
✔ Base url of the GitHub instance: https://github.com
✔ Personal access token for CircleCI: ********************
✔ Base url of the CircleCI instance: https://circleci.com
✔ CircleCI organization name: mycircleciorganization
Environment variables successfully updated.

  4. In your terminal, run the GitHub Actions Importer update CLI command to connect to GitHub Packages Container registry and ensure that the container image is updated to the latest version:

    gh actions-importer update

    The output of the command should be similar to below:

    Updating ghcr.io/actions-importer/cli:latest...
ghcr.io/actions-importer/cli:latest up-to-date

Perform an audit of CircleCI

You can use the audit command to get a high-level view of all projects in a CircleCI organization.

The audit command performs the following steps:

  1. Fetches all of the projects defined in a CircleCI organization.
  2. Converts each pipeline to its equivalent GitHub Actions workflow.
  3. Generates a report that summarizes how complete and complex of a migration is possible with GitHub Actions Importer.

Running the audit command

To perform an audit of a CircleCI organization, run the following command in your terminal:

gh actions-importer audit circle-ci --output-dir tmp/audit

Inspecting the audit results

The files in the specified output directory contain the results of the audit. See the audit_summary.md file for a summary of the audit results.

The audit summary has the following sections.

Pipelines

The "Pipelines" section contains a high-level statistics regarding the conversion rate done by GitHub Actions Importer.

Listed below are some key terms that can appear in the "Pipelines" section:

  • Successful pipelines had 100% of the pipeline constructs and individual items converted automatically to their GitHub Actions equivalent.
  • Partially successful pipelines had all of the pipeline constructs converted, however, there were some individual items that were not converted automatically to their GitHub Actions equivalent.
  • Unsupported pipelines are definition types that are not supported by GitHub Actions Importer.
  • Failed pipelines encountered a fatal error when being converted. This can occur for one of three reasons:
    • The pipeline was misconfigured and not valid in Bamboo.
    • GitHub Actions Importer encountered an internal error when converting it.
    • There was an unsuccessful network response that caused the pipeline to be inaccessible, which is often due to invalid credentials.

Build steps

The "Build steps" section contains an overview of individual build steps that are used across all pipelines, and how many were automatically converted by GitHub Actions Importer.

Listed below are some key terms that can appear in the "Build steps" section:

  • A known build step is a step that was automatically converted to an equivalent action.
  • An unknown build step is a step that was not automatically converted to an equivalent action.
  • An unsupported build step is a step that is either:
    • Fundamentally not supported by GitHub Actions.
    • Configured in a way that is incompatible with GitHub Actions.
  • An action is a list of the actions that were used in the converted workflows. This can be important for:
    • If you use GitHub Enterprise Server, gathering the list of actions to sync to your instance.
    • Defining an organization-level allowlist of actions that are used. This list of actions is a comprehensive list of actions that your security or compliance teams may need to review.

Manual tasks

The "Manual tasks" section contains an overview of tasks that GitHub Actions Importer is not able to complete automatically, and that you must complete manually.

Listed below are some key terms that can appear in the "Manual tasks" section:

  • A secret is a repository or organization-level secret that is used in the converted pipelines. These secrets must be created manually in GitHub Actions for these pipelines to function properly. For more information, see "Using secrets in GitHub Actions."
  • A self-hosted runner refers to a label of a runner that is referenced in a converted pipeline that is not a GitHub-hosted runner. You will need to manually define these runners for these pipelines to function properly.

Files

The final section of the audit report provides a manifest of all the files that were written to disk during the audit.

Each pipeline file has a variety of files included in the audit, including:

  • The original pipeline as it was defined in GitHub.
  • Any network responses used to convert the pipeline.
  • The converted workflow file.
  • Stack traces that can be used to troubleshoot a failed pipeline conversion.

Additionally, the workflow_usage.csv file contains a comma-separated list of all actions, secrets, and runners that are used by each successfully converted pipeline. This can be useful for determining which workflows use which actions, secrets, or runners, and can be useful for performing security reviews.

Forecast potential GitHub Actions usage

You can use the forecast command to forecast potential GitHub Actions usage by computing metrics from completed pipeline runs in CircleCI.

Running the forecast command

To perform a forecast of potential GitHub Actions usage, run the following command in your terminal. By default, GitHub Actions Importer includes the previous seven days in the forecast report.

gh actions-importer forecast circle-ci --output-dir tmp/forecast_reports

Inspecting the forecast report

The forecast_report.md file in the specified output directory contains the results of the forecast.

Listed below are some key terms that can appear in the forecast report:

  • The job count is the total number of completed jobs.

  • The pipeline count is the number of unique pipelines used.

  • Execution time describes the amount of time a runner spent on a job. This metric can be used to help plan for the cost of GitHub-hosted runners.

    This metric is correlated to how much you should expect to spend in GitHub Actions. This will vary depending on the hardware used for these minutes. You can use the GitHub Actions pricing calculator to estimate the costs.

  • Queue time metrics describe the amount of time a job spent waiting for a runner to be available to execute it.

  • Concurrent jobs metrics describe the amount of jobs running at any given time. This metric can be used to define the number of runners you should configure.

Additionally, these metrics are defined for each queue of runners in CircleCI. This is especially useful if there is a mix of hosted or self-hosted runners, or high or low spec machines, so you can see metrics specific to different types of runners.

Perform a dry-run migration of a CircleCI pipeline

You can use the dry-run command to convert a CircleCI pipeline to an equivalent GitHub Actions workflow. A dry-run creates the output files in a specified directory, but does not open a pull request to migrate the pipeline.

To perform a dry run of migrating your CircleCI project to GitHub Actions, run the following command in your terminal, replacing my-circle-ci-project with the name of your CircleCI project.

gh actions-importer dry-run circle-ci --output-dir tmp/dry-run --circle-ci-project my-circle-ci-project

You can view the logs of the dry run and the converted workflow files in the specified output directory.

If there is anything that GitHub Actions Importer was not able to convert automatically, such as unknown build steps or a partially successful pipeline, you might want to create custom transformers to further customize the conversion process. For more information, see "Extending GitHub Actions Importer with custom transformers."

Perform a production migration of a CircleCI pipeline

You can use the migrate command to convert a CircleCI pipeline and open a pull request with the equivalent GitHub Actions workflow.

Running the migrate command

To migrate a CircleCI pipeline to GitHub Actions, run the following command in your terminal, replacing the target-url value with the URL for your GitHub repository, and my-circle-ci-project with the name of your CircleCI project.

gh actions-importer migrate circle-ci --target-url https://github.com/octo-org/octo-repo --output-dir tmp/migrate --circle-ci-project my-circle-ci-project

The command's output includes the URL to the pull request that adds the converted workflow to your repository. An example of a successful output is similar to the following:

$ gh actions-importer migrate circle-ci --target-url https://github.com/octo-org/octo-repo --output-dir tmp/migrate --circle-ci-project my-circle-ci-project
[2022-08-20 22:08:20] Logs: 'tmp/migrate/log/actions-importer-20220916-014033.log'
[2022-08-20 22:08:20] Pull request: 'https://github.com/octo-org/octo-repo/pull/1'

Inspecting the pull request

The output from a successful run of the migrate command contains a link to the new pull request that adds the converted workflow to your repository.

Some important elements of the pull request include:

  • In the pull request description, a section called Manual steps, which lists steps that you must manually complete before you can finish migrating your pipelines to GitHub Actions. For example, this section might tell you to create any secrets used in your workflows.
  • The converted workflows file. Select the Files changed tab in the pull request to view the workflow file that will be added to your GitHub Enterprise Server repository.

When you are finished inspecting the pull request, you can merge it to add the workflow to your GitHub Enterprise Server repository.

Reference

This section contains reference information on environment variables, optional arguments, and supported syntax when using GitHub Actions Importer to migrate from CircleCI.

Using environment variables

GitHub Actions Importer uses environment variables for its authentication configuration. These variables are set when following the configuration process using the configure command. For more information, see the "Configuring credentials" section.

GitHub Actions Importer uses the following environment variables to connect to your CircleCI instance:

  • GITHUB_ACCESS_TOKEN: The personal access token used to create pull requests with a converted workflow (requires repo and workflow scopes).
  • GITHUB_INSTANCE_URL: The URL to the target GitHub instance (for example, https://github.com).
  • CIRCLE_CI_ACCESS_TOKEN: The CircleCI personal API token used to authenticate with your CircleCI instance.
  • CIRCLE_CI_INSTANCE_URL: The URL to the CircleCI instance (for example, https://circleci.com). If the variable is left unset, https://circleci.com is used as the default value.
  • CIRCLE_CI_ORGANIZATION: The organization name of your CircleCI instance.
  • CIRCLE_CI_PROVIDER: The location where your pipeline's source file is stored (such as github). Currently, only GitHub is supported.
  • CIRCLE_CI_SOURCE_GITHUB_ACCESS_TOKEN (Optional): The personal access token used to authenticate with your source GitHub instance (requires repo scope). If not provided, the value of GITHUB_ACCESS_TOKEN is used instead.
  • CIRCLE_CI_SOURCE_GITHUB_INSTANCE_URL (Optional): The URL to the source GitHub instance. If not provided, the value of GITHUB_INSTANCE_URL is used instead.

These environment variables can be specified in a .env.local file that is loaded by GitHub Actions Importer when it is run.

Optional arguments

There are optional arguments you can use with the GitHub Actions Importer subcommands to customize your migration.

--source-file-path

You can use the --source-file-path argument with the forecast, dry-run, or migrate subcommands.

By default, GitHub Actions Importer fetches pipeline contents from source control. The --source-file-path argument tells GitHub Actions Importer to use the specified source file path instead.

For example:

gh actions-importer dry-run circle-ci --output-dir ./output/ --source-file-path ./path/to/.circleci/config.yml

If you would like to supply multiple source files when running the forecast subcommand, you can use pattern matching in the file path value. For example, gh forecast --source-file-path ./tmp/previous_forecast/jobs/*.json supplies GitHub Actions Importer with any source files that match the ./tmp/previous_forecast/jobs/*.json file path.

--config-file-path

You can use the --config-file-path argument with the audit, dry-run, and migrate subcommands.

By default, GitHub Actions Importer fetches pipeline contents from source control. The --config-file-path argument tells GitHub Actions Importer to use the specified source files instead.

The --config-file-path argument can also be used to specify which repository a converted composite action should be migrated to.

Audit example

In this example, GitHub Actions Importer uses the specified YAML configuration file to perform an audit.

gh actions-importer audit circle-ci --output-dir ./output/ --config-file-path ./path/to/circle-ci/config.yml

To audit a CircleCI instance using a config file, the config file must be in the following format, and each repository_slug must be unique:

source_files:
  - repository_slug: circle-org-name/circle-project-name
    path: path/to/.circleci/config.yml
  - repository_slug: circle-org-name/some-other-circle-project-name
    path: path/to/.circleci/config.yml
Dry run example

In this example, GitHub Actions Importer uses the specified YAML configuration file as the source file to perform a dry run.

The pipeline is selected by matching the repository_slug in the config file to the value of the --circle-ci-organization and --circle-ci-project options. The path is then used to pull the specified source file.

gh actions-importer dry-run circle-ci --circle-ci-project circle-org-name/circle-project-name --output-dir ./output/ --config-file-path ./path/to/circle-ci/config.yml
Specify the repository of converted composite actions

GitHub Actions Importer uses the YAML file provided to the --config-file-path argument to determine the repository that converted composite actions are migrated to.

To begin, you should run an audit without the --config-file-path argument:

gh actions-importer audit circle-ci --output-dir ./output/

The output of this command will contain a file named config.yml that contains a list of all the composite actions that were converted by GitHub Actions Importer. For example, the config.yml file may have the following contents:

composite_actions:
  - name: my-composite-action.yml
    target_url: https://github.com/octo-org/octo-repo
    ref: main

You can use this file to specify which repository and ref a reusable workflow or composite action should be added to. You can then use the --config-file-path argument to provide the config.yml file to GitHub Actions Importer. For example, you can use this file when running a migrate command to open a pull request for each unique repository defined in the config file:

gh actions-importer migrate circle-ci --circle-ci-project my-project-name --output-dir output/ --config-file-path config.yml --target-url https://github.com/my-org/my-repo

--include-from

You can use the --include-from argument with the audit subcommand.

The --include-from argument specifies a file that contains a line-delimited list of repositories to include in the audit of a CircleCI organization. Any repositories that are not included in the file are excluded from the audit.

For example:

gh actions-importer audit circle-ci --output-dir ./output/ --include-from repositories.txt

The file supplied for this parameter must be a a line-delimited list of repositories, for example:

repository_one
repository_two
repository_three

Supported syntax for CircleCI pipelines

The following table shows the type of properties that GitHub Actions Importer is currently able to convert.

CircleCI PipelinesGitHub ActionsStatus
cron triggers
  • on.schedule
Supported
environment
  • env
  • jobs.<job_id>.env
  • jobs.<job_id>.steps.env
Supported
executors
  • runs-on
Supported
jobs
  • jobs
Supported
job
  • jobs.<job_id>
  • jobs.<job_id>.name
Supported
matrix
  • jobs.<job_id>.strategy
  • jobs.<job_id>.strategy.matrix
Supported
parameters
  • env
  • workflow-dispatch.inputs
Supported
steps
  • jobs.<job_id>.steps
Supported
when, unless
  • jobs.<job_id>.if
Supported
triggers
  • on
Supported
executors
  • container
  • services
Partially Supported
orbs
  • actions
Partially Supported
executors
  • self hosted runners
Unsupported
setupNot applicableUnsupported
versionNot applicableUnsupported

For more information about supported CircleCI concept and orb mappings, see the github/gh-actions-importer repository.

Environment variable mapping

GitHub Actions Importer uses the mapping in the table below to convert default CircleCI environment variables to the closest equivalent in GitHub Actions.

CircleCIGitHub Actions
CI$CI
CIRCLE_BRANCH${{ github.ref }}
CIRCLE_JOB${{ github.job }}
CIRCLE_PR_NUMBER${{ github.event.number }}
CIRCLE_PR_REPONAME${{ github.repository }}
CIRCLE_PROJECT_REPONAME${{ github.repository }}
CIRCLE_SHA1${{ github.sha }}
CIRCLE_TAG${{ github.ref }}
CIRCLE_USERNAME${{ github.actor }}
CIRCLE_WORKFLOW_ID${{ github.run_number }}
CIRCLE_WORKING_DIRECTORY${{ github.workspace }}
<< pipeline.id >>${{ github.workflow }}
<< pipeline.number >>${{ github.run_number }}
<< pipeline.project.git_url >>$GITHUB_SERVER_URL/$GITHUB_REPOSITORY
<< pipeline.project.type >>github
<< pipeline.git.tag >>${{ github.ref }}
<< pipeline.git.branch >>${{ github.ref }}
<< pipeline.git.revision >>${{ github.event.pull_request.head.sha }}
<< pipeline.git.base_revision >>${{ github.event.pull_request.base.sha }}

Portions have been adapted from https://github.com/github/gh-actions-importer/ under the MIT license:

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