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How to migrate an existing project created with cookiecutter to Copier

Info

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

Info

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

Warning

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."

    Info

    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+https://gitlab.developers.cam.ac.uk/uis/devops/webapp-boilerplate.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+https://gitlab.developers.cam.ac.uk/uis/devops/gcp-deploy-boilerplate.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.

    Question

    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.