[Freeipa-devel] Data source-agnostic parameters

[John Dennis]

On 08/06/2012 10:27 AM, Jan Cholasta wrote:
> Dne 6.8.2012 16:10, Alexander Bokovoy napsal(a):
>> On Mon, 06 Aug 2012, Jan Cholasta wrote:
>>> Dne 6.8.2012 15:20, Simo Sorce napsal(a):
>>>> On Mon, 2012-08-06 at 10:55 +0200, Jan Cholasta wrote:
>>>>> Hi,
>>>>>
>>>>> while thinking about <https://fedorahosted.org/freeipa/ticket/2933>, I
>>>>> had an idea how to make loading data from files available for all
>>>>> parameters:
>>>>>
>>>>> I think we can use URI-like strings in parameter values that the CLI
>>>>> would interpret and extract the wanted information from them
>>>>> (similar to
>>>>> what openssl does in the -pass command line option, see PASS PHRASE
>>>>> ARGUMENTS in openssl(1)).
>>>>>
>>>>> So, instead of adding a new parameter as a file-accepting
>>>>> alternative to
>>>>> any existing parameter (i.e. what is suggested in the ticket), the user
>>>>> would be able to specify the file in a URI-like string:
>>>>>
>>>>> (use new parameter --sshpubkeyfile)
>>>>> $ ipa user-mod --sshpubkey="ssh-rsa AAAA ..."
>>>>> $ ipa user-mod --sshpubkeyfile=.ssh/id_rsa.pub
>>>>>
>>>>> vs.
>>>>>
>>>>> (use file URI-like string)
>>>>> $ ipa user-mod --sshpubkey="ssh-rsa AAAA ..."
>>>>> $ ipa user-mod --sshpubkey=file:.ssh/id_rsa.pub
>>>>>
>>>>> and the CLI would take care of reading the file and using its contents
>>>>> as the parameter value.
>>>>>
>>>>> This could be extended with additional URI(-like) schemes:
>>>>>
>>>>>     - data:<data> - use <data> as the value (useful for escaping values
>>>>> that look like URIs, but you don't want them to be treated as such)
>>>>>     - base64:<data> - use the value of base64 decoded <data> (useful for
>>>>> --delattr on ugly raw binary values)
>>>>>     - fd:<num> - read value from file descriptor <num>
>>>>>     - env:<var> - read value from environment variable <var>
>>>>>     - ask: - always prompt interactively for the value
>>>>>     - default: - use default value, never prompt interactively
>>>>>
>>>>> Thoughts?
>>>>
>>>> How do you handle values that are actually URI strings, how do you tell
>>>> the command to not interpret them ?
>>>>
>>>> Simo.
>>>>
>>>
>>> You can escape them like this: --someparam data:actual://uri/string
>>>
>>> As for backward compatibility, this change has the potential to break
>>> things (user scripts which use the CLI, etc.), but AFAIK there is no
>>> parameter in IPA which expects URI string values specifically, so the
>>> impact would be miminal IMHO.
>>
>> I don't think you need to invent anything here. RFC2397 is available for
>> long time and provides already effective way to represent any data in
>> URI.
>>
>> http://tools.ietf.org/html/rfc2397
>>
>
> I have considered this, but given that these URL-like strings would be
> mainly used directly by users on the command-line, I think that
> "base64:<stuff>" is more user friendly than "data:;base64,<stuff>".

Hmm... user friendly to me means not having to remember odd proprietary 
exceptions. It's easier to remember what's a standard because in theory 
it will always be the same no matter what piece of software is I'm using.


-- 
John Dennis <jdennis at redhat.com>

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