[Freeipa-devel] [DESIGN] Text-based rules for CSR autogeneration using Jinja2

[Ben Lipton]

Hi,

I have updated the design page 
http://www.freeipa.org/page/V4/Automatic_Certificate_Request_Generation/Mapping_Rules 
with my plan for implementing user-configurable rules for mapping IPA 
data into certificate requests. In brief: we will use Jinja2 for 
templating. Data rules (which map individual data items) and syntax 
rules (which group them into certificate fields) will both be snippets 
of Jinja2 markup. The formatting process will be as follows:
1. Syntax rules will be rendered using Jinja2. Data rules (rule text, 
not rendered) will be passed as the datarules attribute.
2. Rendered syntax rules will be processed by the Formatter class for 
the selected CSR generation helper (e.g. openssl or certutil). The 
formatter combines these partial rules into a full template for the config.
3. The template will be rendered using Jinja2. Relevant data from the 
IPA database will be available in the context for this rendering.
4. The final rendered template will be returned to the caller, labeled 
with its function (e.g. a command line or a config file).

Are there any comments or objections to this approach? Here's an example 
to show what it might look like in practice.

Example data rules:
email={{subject.email}}
O={{config.ipacertificatesubjectbase}}\nCN={{subject.username}}

Example syntax rule:
subjectAltName=@{% section %}{{datarules|join('\n')}}{% endsection %}

Example composed config template:
[ req ]
prompt = no
encrypt_key = no

distinguished_name = {% section %}O={{config.ipacertificatesubjectbase}}
CN={{subject.username}}{% endsection %}

req_extensions = exts

[ exts ]
subjectAltName=@{% section %}email={{subject.email}}{% endsection %}

There's a lot more information about the thinking behind this at 
http://blog.benjaminlipton.com/2016/07/19/csr-generation-templating.html 
if you're interested, as well.

Thanks,
Ben