Re: [PATCH v7 1/5] Documentation/git-config.txt: add SCOPES section

[Glen Choo <chooglen@google.com>]

Junio C Hamano <gitster@pobox.com> writes:

> "Glen Choo via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
>> From: Glen Choo <chooglen@google.com>
>>
>> In a subsequent commit, we will introduce "protected configuration",
>> which is easiest to describe in terms of configuration scopes (i.e. it's
>> the union of the 'system', 'global', and 'command' scopes). This
>> description is fine for ML discussions, but it's inadequate for end
>> users because we don't provide a good description of "configuration
>> scopes" in the public docs.
>>
>> 145d59f482 (config: add '--show-scope' to print the scope of a config
>> value, 2020-02-10) introduced the word "scope" to our public docs, but
>> that only enumerates the scopes and assumes the user can figure out
>> those values mean.
>
> Probably: "figure out those values mean" -> "figure out what those
> values mean"
>
>> Add a SCOPES section to Documentation/git-config.txt that describes the
>> configuration scopes, their corresponding CLI options, and mentions that
>> some configuration options are only respected in certain scopes. Then,
>> use the word "scope" to simplify the FILES section and change some
>> confusing wording.
>>
>> Signed-off-by: Glen Choo <chooglen@google.com>
>> ---
>>  Documentation/git-config.txt | 65 ++++++++++++++++++++++++++++--------
>>  1 file changed, 51 insertions(+), 14 deletions(-)
>>
>> diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
>> index 9376e39aef2..c4ce61a0493 100644
>> --- a/Documentation/git-config.txt
>> +++ b/Documentation/git-config.txt
>> @@ -297,8 +297,8 @@ The default is to use a pager.
>>  FILES
>>  -----
>>  
>> -If not set explicitly with `--file`, there are four files where
>> -'git config' will search for configuration options:
>> +By default, 'git config' will read configuration options from multiple
>> +files:
>>  
>>  $(prefix)/etc/gitconfig::
>>  	System-wide configuration file.
>> @@ -322,27 +322,64 @@ $GIT_DIR/config.worktree::
>>  	This is optional and is only searched when
>>  	`extensions.worktreeConfig` is present in $GIT_DIR/config.
>>  
>> -If no further options are given, all reading options will read all of these
>> -files that are available. If the global or the system-wide configuration
>> -file are not available they will be ignored. If the repository configuration
>> -file is not available or readable, 'git config' will exit with a non-zero
>> -error code. However, in neither case will an error message be issued.
>> +You may also provide additional configuration parameters when running any
>> +git command by using the `-c` option. See linkgit:git[1] for details.
>
> Listing "-c" as another one in addition to these files is probably a
> good simplification, instead of "-c override others" in the original,
> as we would need to say "more specific ones override less specific
> ones" anyway.
>
>> +Options will be read from all of these files that are available. If the
>> +global or the system-wide configuration file are not available they will be
>> +ignored. If the repository configuration file is not available or readable,
>> +'git config' will exit with a non-zero error code. Note that neither case
>> +produces an error message.
>
> Problem inherited from the original, but I suspect that rephrasing
> "not available" to "missing" (or "does not exist") may make it
> easier to follow.  Also, "global" in the preceding description is
> explained as one of the user-specific configuration files, so it may
> be better to avoid it, e.g.
>
> 	If the user-specific or the system-wide configuration files
> 	are missing, they will be ignored.  If the repository
> 	configuration file is missing or unreadable, ...
>
> Alternatively, we may want to tighten the description of
> $XDG_CONFIG_HOME/git/config and ~/.gitconfig a bit better,
> e.g. something along the lines of ...
>
> 	$XDG_CONFIG_HOME/git/config::
> 	$HOME/.gitconfig::
> 		User-specific configuration file.  When the
> 		XDG_CONFIG_HOME environment variable is not set or
> 		empty, $HOME/.config/ is used as $XDG_CONFIG_HOME.
> 	+
> 	These are often called the "global" configuration file.
> 	When either or both of them exist(s), both files are read.
>
> Note that I deliberately omitted the mehtion that our $XDG support
> may be too recent and $HOME/.gitconfig may be preferred for
> portability.  It came from 21cf3227 (config: read (but not write)
> from $XDG_CONFIG_HOME/git/config file, 2012-06-22) but sufficient
> number of years have passed.
>
> Also note that I originally wrote the following immediately after
> the above
>
> 	+
> 	When writing to the "--global" scope (see below),
> 	$XDG_CONFIG_HOME/git/config is used if it exists; otherwise
> 	$HOME/.gitconfig is used.
>
> but decided to discard it, since the OPTIONS -> "--global" covers
> it well enough.
>
> With a tightening of the definition of what "global" is,, we can
> rephrase "If the global or the system configuration files are
> missing...".

Makes sense. I think this is simpler and more coherent with your
suggested changes.

The only change I'd suggest is to expand "missing" -> "missing or
unreadable". The original wording is "not available", which could be
interpreted to cover both cases. We'd obviously also have to amend
"not available or readable" accordingly.

>> +You can limit which configuration sources are read from or written to by
>> +specifying the path of a file with the `--file` option, or by specifying a
>> +configuration scope with `--system`, `--global`, `--local`, or `--worktree`.
>> +For more, see <<OPTIONS>> above.
>> +
>> +SCOPES
>> +------
>> +
>> +Each configuration source falls within a configuration scope. The scopes
>> +are:
>> +
>> +system::
>> +	$(prefix)/etc/gitconfig
>> +
>> +global::
>> +	$XDG_CONFIG_HOME/git/config
>> ++
>> +~/.gitconfig
>> +
>> +local::
>> +	$GIT_DIR/config
>> +
>> +worktree::
>> +	$GIT_DIR/config.worktree
>> +
>> +command::
>> +	environment variables
>
> We'd need to tighten this a bit, like:
>
> 	GIT_CONFIG_{COUNT,KEY,VALUE} environment varialbes (see below)
>
> GIT_CONFIG_GLOBAL or GIT_CONFIG_SYSTEM environment varialbes and
> others are listed in the ENVIRONMENT section that comes after this
> section, but you do not want the readers to be confused into
> thinking that we'd give them more precedence over others.

Ah, good point.

>> ++
>> +the `-c` option
>
>> +With the exception of 'command', each scope corresponds to a command line
>> +option: `--system`, `--global`, `--local`, `--worktree`.
>> +
>> +When reading options, specifying a scope will only read options from the
>> +files within that scope. When writing options, specifying a scope will write
>> +to the files within that scope (instead of the repository specific
>> +configuration file). See <<OPTIONS>> above for a complete description.
>>  
>> +Most configuration options are respected regardless of the scope it is
>> +defined in, but some options are only respected in certain scopes. See the
>> +respective option's documentation for the full details.
>>  
>>  ENVIRONMENT
>>  -----------
>
> Overall it was a pleasant read.  Thanks, will queue.

Thanks! Shall I apply your suggestions, or were you planning to apply
them yourself?