# Python

## Package Caching Proxy

Instead of accessing pypi.org directly PSI provides a caching proxy for pypi packages. There are some advantages in using this instead of directly accessing pypi.org:

1. Speed - the caching proxy might/will improve the dependency resolution and download speed for installing packages
2. Once downloaded/installed packages will still be available even if they are not accessible on the internet any more.
3. Accessibility - pypi.psi.ch is accessible from all PSI networks (including the ones without internet access)

###  Usage
The url to use the CachingProxy is: https://pypi.psi.ch/simple:

!!! note 
    All managed RHEL systems at PSI do have the proxy configured by default for the system wide pip installation. Therefore no additional configuration is needed on those systems.

You can manually specify the url while using the `pip` command as follows:
pip install --index-url=https://pypi.psi.ch/simple pandas


To fix the default url for your user to the proxy you can create the following config file within your users home directory:

```bash
% cat ~/.config/pip/pip.conf 
[global]
timeout = 60
index-url = https://pypi.psi.ch/simple
```

To change the default for the whole system edit: `/etc/pip.conf`
(also see: https://pip.pypa.io/en/stable/topics/configuration/#location) 

To check whether your pip client is using this address you can simply issue a:

```bash
pip install -h
```

Check what's written in the descripiton of the option --index-url:

```bash
% pip install -h | grep -A5 index-url 
  -i, --index-url <url>       Base URL of the Python Package Index (default
                              https://pypi.psi.ch/simple). This should point
                              to a repository compliant with PEP 503 (the
                              simple repository API) or a local directory laid
                              out in the same format.
...
```

or do a `pip config list`

```bash
% pip config list
global.index-url='https://pypi.psi.ch/simple'
global.timeout='60'
```