Re: [PATCH] credential doc: make multiple-helper behavior more prominent (Re: [PATCH] clone: handle empty config values in -c)

[Brandon Williams <bmwill@google.com>]

On 05/01, Jonathan Nieder wrote:
> Subject: credential doc: make multiple-helper behavior more prominent
> 
> Git's configuration system works by reading multiple configuration
> files in order, from general to specific:
> 
>  - first, the system configuration /etc/gitconfig
>  - then the user's configuration (~/.gitconfig or ~/.config/git/config)
>  - then the repository configuration (.git/config)
> 
> For single-valued configuration items, the latest value wins.  For
> multi-valued configuration items, values accumulate in that order.
> 
> For example, this allows setting a credential helper globally in
> ~/.gitconfig that git will try to use in all repositories, regardless
> of whether they additionally provide another helper.  This is usually
> a nice thing --- e.g. I can install helpers to use my OS keychain and
> to cache credentials for a short period of time globally.
> 
> Sometimes people want to be able to override an inherited setting.
> For the credential.helper setting, this is done by setting the
> configuration item to empty before giving it a new value.  This is
> already documented by the documentation is hard to find ---
> git-config(1) says to look at gitcredentials(7) and the config
> reference in gitcredentials(7) doesn't mention this issue.
> 
> Move the documentation to the config reference to make it easier to
> find.
> 
> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
> ---
> Brandon Williams wrote:
> 
> >> Noticed while trying to set credential.helper during a clone to use a
> >> specific helper without inheriting from ~/.gitconfig and
> >> /etc/gitconfig.  That is, I ran
> >>
> >> 	git clone -c credential.helper= \
> >> 		-c credential.helper=myhelper \
> >> 		https://example.com/repo
> >>
> >> intending to produce the configuration
> >>
> >> 	[credential]
> >> 		helper =
> >> 		helper = myhelper
> >>
> >> Without this patch, the 'helper =' line is not included and the
> >> credential helper from /etc/gitconfig gets used.
> >>
> >> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
> >> ---
> >> Thoughts?
> >
> > After reading this I'm still a little fuzzy on why the empty helper line
> > is needed to avoid using the credential helper from /etc/gitconfig.
> 
> See "git help credentials":
> 
>        If there are multiple instances of the credential.helper configuration
>        variable, each helper will be tried in turn, and may provide a
>        username, password, or nothing. Once Git has acquired both a username
>        and a password, no more helpers will be tried.
> 
>        If credential.helper is configured to the empty string, this resets the
>        helper list to empty (so you may override a helper set by a
>        lower-priority config file by configuring the empty-string helper,
>        followed by whatever set of helpers you would like).
> 
> That's a bit obscure, though --- I didn't find it when I looked in "git
> help config".  How about this patch?
> 
> Tested using 'make -C Documentation gitcredentials.7'.
> 
>  Documentation/gitcredentials.txt | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
> index f3a75d1ce1..f970196bc1 100644
> --- a/Documentation/gitcredentials.txt
> +++ b/Documentation/gitcredentials.txt
> @@ -101,16 +101,6 @@ $ git help credential-foo
>  $ git config --global credential.helper foo
>  -------------------------------------------
>  
> -If there are multiple instances of the `credential.helper` configuration
> -variable, each helper will be tried in turn, and may provide a username,
> -password, or nothing. Once Git has acquired both a username and a
> -password, no more helpers will be tried.
> -
> -If `credential.helper` is configured to the empty string, this resets
> -the helper list to empty (so you may override a helper set by a
> -lower-priority config file by configuring the empty-string helper,
> -followed by whatever set of helpers you would like).
> -
>  
>  CREDENTIAL CONTEXTS
>  -------------------
> @@ -162,6 +152,16 @@ helper::
>  	shell (so, for example, setting this to `foo --option=bar` will execute
>  	`git credential-foo --option=bar` via the shell. See the manual of
>  	specific helpers for examples of their use.
> ++
> +If there are multiple instances of the `credential.helper` configuration
> +variable, each helper will be tried in turn, and may provide a username,
> +password, or nothing. Once Git has acquired both a username and a
> +password, no more helpers will be tried.
> ++
> +If `credential.helper` is configured to the empty string, this resets
> +the helper list to empty (so you may override a helper set by a
> +lower-priority config file by configuring the empty-string helper,
> +followed by whatever set of helpers you would like).

Thanks, this clears up the confusion.

>  
>  username::
>  
> -- 
> 2.13.0.rc1.294.g07d810a77f
> 

-- 
Brandon Williams