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Does your project use option value interpolation ? As I know, nova use it.
we also disccussed in oslo team, should we deprecate this feature ?
Any thoughts ?

2016-07-08 22:14 GMT+08:00 ChangBo Guo <glongwave at gmail.com>:

> Hi ALL,
>
> I have been working a bug [1] about option value interpolation in
> oslo.config[2], in short, option value interpolation can't handle password
> containing special characters from environment variable and I  proposed a
> fix of provide way to forbid option value interpolation explicitly[3].
>
> copy of Doug Hellmann's coments:
>
> "The problem is that the end user who is setting the value of the option
> cannot control whether the option will do interpolation or not. So the
> programmer who defines the option has to make that choice, and then we
> can't change it because that would break existing deployments. The result
> is that end users won't know for any given option whether interpolation
> works or not, and if not why (did they do something wrong, or is it not
> supported).
>
> I've set -2 on this patch because I think it's a bad approach. I see 2
> other ways we could solve the problem you describe (and I agree that it's
> an issue we should help with).
>
> 1. We could have an option that turns off interpolation globally, and let
> the user control that by setting the flag in their configuration file. I'm
> not sure I like this, but it does give you what you're looking for at the
> risk of breaking applications that are relying on interpolation, like the
> nova example.
>
> 2. We could disable interpolation when we get values from environment
> variables. That would be a big behavioral change, so we would need to think
> about how to roll it out carefully. For example, do we provide a helper
> function to give to application developers who are setting default values
> to environment variables so the variable value can be escaped to avoid
> interpolation? Or do we build it into the Opt class somehow? I think I like
> the helper function approach but we should give it more thought."
> I would like to collect more suggestions to decide the direction to fix
> similar bug. Any thoughts ?
>
> [1]https://bugs.launchpad.net/oslo.config/+bug/1577731
> [2]
> http://docs.openstack.org/developer/oslo.config/cfg.html#option-value-interpolation
> [3]https://review.openstack.org/#/c/338668/
>
>
> --
> ChangBo Guo(gcb)
>



-- 
ChangBo Guo(gcb)
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