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How to migrate an existing project created with cookiecutter to Copier


This how-to guide assumes that the Copier tool has been installed as described in the how-to guide for preparing your system.


For this operation it is necessary to know answers that were used initially. Over time, the list of options may change. Please see of the corresponding boilerplate project for more information.


In some cases it might be difficult to migrate project to Copier, as files and content were changed heavily over time.

In order to add Copier to the existing project (e.g. project created with Cookiecutter) you need to perform the following steps:

  1. Create a local branch in the project. Make sure there's no changes waiting to pushed.

    # Check everything is committed and there is no pending changes
    git status
    # pull latest changes from GitLab
    git pull
    # Create a new branch
    git checkout b migrate-to-copier
  2. In the root folder of your project create file .copier-answers.yml.

  3. Put all answers, you gave when created the project from template along with _commit and _src_path. It is recommended that _commit be a git tag from one of the boilerplate project repositories."


    There are two copier-based boilerplate projects:

    Two examples are provided below:

    For webapp-boilerplate:

    _commit: 2.0.1 # Boilerplate tag. It makes sense to use lates available at the moment.
    _src_path: git+
    api_module: #put_answer_here
    api_name: #put_answer_here
    api_slug: #put_answer_here
    application_module: #put_answer_here
    application_name: #put_answer_here
    application_slug: #put_answer_here
    include_api: #put_answer_here
    include_ui: #put_answer_here
    max_line_length: #put_answer_here
    project_module: #put_answer_here
    project_name: #put_answer_here
    project_repo: #put_answer_here
    project_slug: #put_answer_here
    python_version: #put_answer_here
    respect_x_forward_header: #put_answer_here
    secret_key: #put_answer_here
    ui_module: #put_answer_here
    ui_name: #put_answer_here
    ui_slug: #put_answer_here

    For gcp-deploy-boilerplate:

    _commit: 2.0.1 # Boilerplate tag. It makes sense to use lates available at the moment.
    _src_path: git+
    database_type: #put_answer_here
    gitlab_webapp_project_id: #put_answer_here
    notification_channel: #put_answer_here
    product_configuration_bucket: #put_answer_here
    product_configuration_path: #put_answer_here
    product_name: #put_answer_here
    product_slug: #put_answer_here
    terraform_state_sa_email: #put_answer_here
    use_cloud_load_balancer: #put_answer_here
  4. Run copier recopy --trust and answer a number of questions (Overwrite <filename>? [Y/n]). Answer Y to all.


    Why do I need to use the --trust flag?

    Our copier templates include some custom code which is used to pre-populate poetry lock files, etc. The --trust flag is required to allow copier to run this custom code.

  5. Carefully review the output from git diff. You may need to manually fix up any changes which Copier missed or got wrong. The CHANGELOG for the boilerplate template or a git log for the tag you used should alert you to any significant changes.

  6. Test the changes which were made. The testing procedure depend on project, for example for projects derives from gcp-infra-boilerplate it make sense to apply terraform code to the development workspace.

  7. Make a commit to the project repository.