Deployment#

Some aspects to pay attention to when considering the deployment of MXCuBE-Web into a production environment.

Python backend part of the web application#

The Python backend part of MXCuBE-Web uses Poetry as development workflow tool. One of Poetry’s features is support for a so-called lockfile. Poetry’s lockfile is the poetry.lock file one can see at the root of the source code tree of MXCuBE-Web.

This lockfile helps create repeatable installations. By taking advantage of Poetry’s lockfile it should be possible to minimize the chances of dependency issues from happening. Indeed, the lockfile contains pinned versions of the dependencies along with some info about the dependency artefacts to be installed and some additional metadata.

By using a command like poetry install, it is ensured that the dependency versions installed are well known, and for example that they are the ones used during development phase and during automated tests.

Install without using Poetry#

Poetry is a tool meant for development, it is not an installer, like pip for example. It is debatable whether it is a good idea to use Poetry’s poetry install command to install and deploy in a production environment. Some might prefer to use a dedicated installer tool, like pip for such a task.

But Poetry’s lockfile format is not standardized, its content is specific to Poetry. So this file is not immediately usable by other installers and tools. For example pip can not understand poetry.lock and completely ignores it. When running a command like pip install mxcubeweb it will NOT choose the versions pinned in poetry.lock.

To circumvent this, one could use a command like poetry export to generate a requirements.txt file compatible with pip (and some other tools). With a series of commands like the following, it should be possible to approximate the behaviour of installing with Poetry’s lockfile.

Let Poetry export its lockfile into a pip-compatible requirements file
```
poetry export --format=requirements.txt > requirements.txt
```
Note that the pre-commit hooks are configured to automatically generate an exported requirements.txt file and keep it in sync with poetry.lock. So this step could be skipped.
Move the requirements.txt file to the deployment target system
On the deployment system, let pip install MXCuBE-Web via the exported requirements file
1. Install the dependencies
```
python -m pip install --no-deps --requirement requirements.txt
```
2. Install MXCuBE-Web itself, and make sure to skip the dependencies (with the --no-deps flag) since they are now already installed
  - For example as editable
    python -m pip install --no-deps --editable mxcubeweb
  - Or not
    python -m pip install --no-deps mxcubeweb