[openstack-dev] [congress] Using congress to improve the consistency of configuration files.

Eric K ekcs.openstack at gmail.com
Thu Jul 6 23:16:23 UTC 2017

Hi Valentin,

Very cool to hear about your use case and vision! It definitely sounds
like the kind of use case Congress is well-equipped to solve using a
flexible, declarative rule language.

I'd love to explore the use case further (and where it fits along side
config management systems as Clint mentioned). I'm especially curious to
learn more about the prototype and see how I can be of help from Congress

I did not see the blueprint link in the original message; missed paste

-Eric Kao (ekcs)

On 7/4/17, 6:29 AM, "valentin.matton at orange.com"
<valentin.matton at orange.com> wrote:

>We would like to use congress to check the consistency of the
>configuration files used by the various Openstack services on different
>Although installers do a great job for ensuring that the initial
>definition of those files are correct, it may be necessary to tweak
>those files on running instances
>or to use templates that are out of the bounds of the pre-configured
>use-cases. Then the administrator must modify the configuration without
>any safety net.
>Congress is such a safety net but it ensures policies on live resources
>deployed in the cloud, not on how the cloud is configured but we think
>that it could be extended
>to perform such verification with the adequate datasource.
>So we propose a new datasource that will query each node to fetch its
>configuration files as long as they follow oslo.config requirements and
>As a first step we propose to use agents deployed on the different nodes
>explicitly configured with the list of configuration files that push
>those files to the central
>congress service. Later on, oslo.config could be modified to provide a
>hook used to push config files directly from running services.
>The new datasource displays not only the option values, the file, host
>where they are defined but also the associated metadata so that generic
>rules can be defined.
>It is then possible to define rules:
>- that constrain the value of options between different nodes
>- that constrain the values between different services or different
>service plugins.
>- it is even possible to use the knowledge of those configuration
>options to check policies on live resources (for example when there is a
>limitation or a bug in a given
>We have a working prototype and the corresponding specification along
>those principles that we would like to share. An initial blueprint has
>been submitted here:
>Please feel free to react
>V. Matton
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