Optimize Recursive chown Execution Time on WORKDIR with Many Files

[giant995]

Description

The production Dockerfile uses a chown command to recursively change the owner of the WORKDIR directory:

cookiecutter-django/{{cookiecutter.project_slug}}/compose/production/django/Dockerfile

Line 120 in ed59d08

RUN chown -R django:django ${APP_HOME}

When starting a new project, this command runs relatively fast. As the project grows, the quantity of files inevitably grows, increasing the execution time.

The recursive flag -R should be removed and the same result would be achieved:

RUN chown django:django ${APP_HOME}

Rationale

I currently maintain a mature project that was started with an earlier version of this cookiecutter. I often update the project with the patterns found in the upstream, to keep up with the current standards. Now, recursively changing the owner of the WORKDIR directory takes 2 minutes to complete.

On the preceding lines, both commands use the --chown=django:django argument to copy all files and directories with the django user as the owner:

cookiecutter-django/{{cookiecutter.project_slug}}/compose/production/django/Dockerfile

Lines 113 to 117 in ed59d08

	{%- if cookiecutter.frontend_pipeline in ['Gulp', 'Webpack'] %}
	COPY --from=client-builder --chown=django:django ${APP_HOME} ${APP_HOME}
	{% else %}
	COPY --chown=django:django . ${APP_HOME}
	{%- endif %}

In both cases, the /app directory itself is owned by root while its subdirectories and subfiles are all owned by the django user. Removing the recursive flag -R to only change the owner of /app will drastically reduce the execution time and achieve the same result as before.