Turn on/off the git connection feature by configuration

[pkiraly]

If the git directory is not set properly (and I do not know how to set it properly), the apache error log is full with suggestions how to use git (see below), which makes error detection difficult. So I initialize a flag that could be used as a trigger to turn on and off this feature.

$ sudo tail -f /var/log/apache2/error.log
fatal: detected dubious ownership in repository at '/home/qa_admin/git/qa-catalogue-web'
To add an exception for this directory, call:

	git config --global --add safe.directory /home/qa_admin/git/qa-catalogue-web
warning: Not a git repository. Use --no-index to compare two paths outside a working tree
usage: git diff --no-index [<options>] <path> <path>

Diff output format options
    -p, --patch           generate patch
    -s, --no-patch        suppress diff output
    -u                    generate patch
    -U, --unified[=<n>]   generate diffs with <n> lines context
    -W, --function-context
                          generate diffs with <n> lines context
    --raw                 generate the diff in raw format
    --patch-with-raw      synonym for '-p --raw'
    --patch-with-stat     synonym for '-p --stat'
    --numstat             machine friendly --stat
    --shortstat           output only the last line of --stat
    -X, --dirstat[=<param1,param2>...]
                          output the distribution of relative amount of changes for each sub-directory
    --cumulative          synonym for --dirstat=cumulative
    --dirstat-by-file[=<param1,param2>...]
                          synonym for --dirstat=files,param1,param2...
    --check               warn if changes introduce conflict markers or whitespace errors
    --summary             condensed summary such as creations, renames and mode changes
    --name-only           show only names of changed files
    --name-status         show only names and status of changed files
    --stat[=<width>[,<name-width>[,<count>]]]
                          generate diffstat
    --stat-width <width>  generate diffstat with a given width
    --stat-name-width <width>
                          generate diffstat with a given name width
    --stat-graph-width <width>
                          generate diffstat with a given graph width
    --stat-count <count>  generate diffstat with limited lines
    --compact-summary     generate compact summary in diffstat
    --binary              output a binary diff that can be applied
    --full-index          show full pre- and post-image object names on the "index" lines
    --color[=<when>]      show colored diff
    --ws-error-highlight <kind>
                          highlight whitespace errors in the 'context', 'old' or 'new' lines in the diff
    -z                    do not munge pathnames and use NULs as output field terminators in --raw or --numstat
    --abbrev[=<n>]        use <n> digits to display object names
    --src-prefix <prefix>
                          show the given source prefix instead of "a/"
    --dst-prefix <prefix>
                          show the given destination prefix instead of "b/"
    --line-prefix <prefix>
                          prepend an additional prefix to every line of output
    --no-prefix           do not show any source or destination prefix
    --inter-hunk-context <n>
                          show context between diff hunks up to the specified number of lines
    --output-indicator-new <char>
                          specify the character to indicate a new line instead of '+'
    --output-indicator-old <char>
                          specify the character to indicate an old line instead of '-'
    --output-indicator-context <char>
                          specify the character to indicate a context instead of ' '

Diff rename options
    -B, --break-rewrites[=<n>[/<m>]]
                          break complete rewrite changes into pairs of delete and create
    -M, --find-renames[=<n>]
                          detect renames
    -D, --irreversible-delete
                          omit the preimage for deletes
    -C, --find-copies[=<n>]
                          detect copies
    --find-copies-harder  use unmodified files as source to find copies
    --no-renames          disable rename detection
    --rename-empty        use empty blobs as rename source
    --follow              continue listing the history of a file beyond renames
    -l <n>                prevent rename/copy detection if the number of rename/copy targets exceeds given limit

Diff algorithm options
    --minimal             produce the smallest possible diff
    -w, --ignore-all-space
                          ignore whitespace when comparing lines
    -b, --ignore-space-change
                          ignore changes in amount of whitespace
    --ignore-space-at-eol
                          ignore changes in whitespace at EOL
    --ignore-cr-at-eol    ignore carrier-return at the end of line
    --ignore-blank-lines  ignore changes whose lines are all blank
    -I, --ignore-matching-lines <regex>
                          ignore changes whose all lines match <regex>
    --indent-heuristic    heuristic to shift diff hunk boundaries for easy reading
    --patience            generate diff using the "patience diff" algorithm
    --histogram           generate diff using the "histogram diff" algorithm
    --diff-algorithm <algorithm>
                          choose a diff algorithm
    --anchored <text>     generate diff using the "anchored diff" algorithm
    --word-diff[=<mode>]  show word diff, using <mode> to delimit changed words
    --word-diff-regex <regex>
                          use <regex> to decide what a word is
    --color-words[=<regex>]
                          equivalent to --word-diff=color --word-diff-regex=<regex>
    --color-moved[=<mode>]
                          moved lines of code are colored differently
    --color-moved-ws <mode>
                          how white spaces are ignored in --color-moved

Other diff options
    --relative[=<prefix>]
                          when run from subdir, exclude changes outside and show relative paths
    -a, --text            treat all files as text
    -R                    swap two inputs, reverse the diff
    --exit-code           exit with 1 if there were differences, 0 otherwise
    --quiet               disable all output of the program
    --ext-diff            allow an external diff helper to be executed
    --textconv            run external text conversion filters when comparing binary files
    --ignore-submodules[=<when>]
                          ignore changes to submodules in the diff generation
    --submodule[=<format>]
                          specify how differences in submodules are shown
    --ita-invisible-in-index
                          hide 'git add -N' entries from the index
    --ita-visible-in-index
                          treat 'git add -N' entries as real in the index
    -S <string>           look for differences that change the number of occurrences of the specified string
    -G <regex>            look for differences that change the number of occurrences of the specified regex
    --pickaxe-all         show all changes in the changeset with -S or -G
    --pickaxe-regex       treat <string> in -S as extended POSIX regular expression
    -O <file>             control the order in which files appear in the output
    --rotate-to <path>    show the change in the specified path first
    --skip-to <path>      skip the output to the specified path
    --find-object <object-id>
                          look for differences that change the number of occurrences of the specified object
    --diff-filter [(A|C|D|M|R|T|U|X|B)...[*]]
                          select files by diff type
    --output <file>       Output to a specific file

[nichtich]

What are you refering to as "git connection feature". Does classes/Utils/GitVersion.php trigger the error? The error could be catched if no git information can be retrieved for whatever reason. Maybe adding 2>/dev/null already helps.

[pkiraly]

Maybe I wrongly name the phenomenon, but the effect is simple: every page load generates this kind of output into the Apache error log. The problem is www-data can not read these information from git, AND it copies the part of Git help message to the log.
The feature will be quite useful, once we figured out how to set up directories properly.
The flag I sugeest is called extractGitVersion, and by default is true, so the workflow of your instance will not change.

[nichtich]

Adding more configuration options makes the application more complicated and does not fix the issue. It should just

• show git information if available
• not show otherwise and not print any error message

The current fix does not turn off error messages but it turns of the whole feature. This is a temporary solution so keep this issue open.

[pkiraly]

Yes, my intention was to introduce it until we can fix communication between www-data and git without any side effect.

[nichtich]

The purpose of the git feature is to show which version of qa-catalouge-web is running. Maybe better add a configuration field to show an explicit version given as plain string to not determine the version from git.

[nichtich]

I've removed extractGitVersion - to disable checking via git, create a file version.ini - this can be done automatically at build time because there won't be .git in a Docker container neither.

[pkiraly]

It would be great if you could also explain how to turn it on? It needs some special directory mode, but I was unable to set it properly. I would love to use this feature, but I was not able to enable it, and it has a serious side effect if it not working properly: it puts lots of error messages into the server's error.log.

[nichtich]

If local file version.ini exists (even if empty) then the version comes from this file instead of trying to execute git.

[pkiraly]

I got it but that suppress (or froze) the git version. I want the opposite: to read the actual git version.