Writing custom buildpacks on Windows can lead to some unnecessary frustrations. Today I would like to cover one of those frustrations: buildpack scripts not being executable on PCF. Creating buildpack scripts on windows can lead to cryptic errors during buildpack execution like "access denied" or "permission denied".
The problem is caused by the fact that any new file created on Windows is automatically set to mode 644 aka rw-r--r-- (linux standards), but at the same type is automatically executable (-rwxr-xr-x) by windows standards.
Result? Listing your buildpack scripts using git bash on windows you see:
drwxr-xr-x 1 Piotr_Justyna 1049089 0 Feb 13 20:46 ./ drwxr-xr-x 1 Piotr_Justyna 1049089 0 Feb 13 20:44 ../ -rwxr-xr-x 1 Piotr_Justyna 1049089 137 Feb 13 20:44 detect* -rwxr-xr-x 1 Piotr_Justyna 1049089 40 Feb 13 20:46 finalize* -rwxr-xr-x 1 Piotr_Justyna 1049089 102 Feb 13 20:44 release* -rwxr-xr-x 1 Piotr_Justyna 1049089 135 Feb 13 20:46 supply*
While in fact all of them are by default mode 644 (rw-r--r--). Trying to execute those scripts on PCF will result in "access denied" errors. It is pretty annoying, so I prepared a little cheat sheet for those of you who work with custom buildpacks, windows and git bash:
Executable files:
- DON'T:
chmod +x file
- DO:
git update-index --chmod=+x file
List files with their access modes:
- DON'T:
ls -la
- DO:
git ls-files -s
Copying files:
- DON'T:
cp file file_copy (that defaults the access mode of the copy to 644 even if the file is e.g. 755)
- DO:
cp file file_copy *and then* git update-index --chmod=+x file_copy
