[Documentation] Explain how to add patches

[ShalokShalom]

See also: #2561 (comment)

[eeyun]

Looks like my original comment didn't get submitted appropriately. Whoops!

We should likely expose that habitat supports build time patching like other software build systems and perhaps link to the core plans that are utilizing that kind of patching behavior.

I'd heartily suggest avoiding diving too deep into this because patching software will be completely dependent upon the type of software being built and those behaviors are not specific to habitat.

[ShalokShalom]

Then i am a little bit curious, since i thought that i can simply reuse the patches of specific distributions in an easy way. So, this means easy patching like in PKGBUILDs will never be the case?

Regarding to the closed issue. How that? Isnt patching something very essential in packaging?

[reset]

@ShalokShalom sure, you can re-use patches from anyone including other distributions. What @eeyun is suggesting is that applying patches to software isn't a direct concern of Habitat itself but instead of the patch tool itself.

I don't mind if this makes it into some sort of "deep continued learning section" of our docs but we shouldn't try to recreate man pages for Patch itself ;)

[ShalokShalom]

I really love to see a dedicated patch function in Habitat, which got refused in the past :P

Thanks, i will close this.

[ShalokShalom]

Here is a proposal:

1. Add this patch options

_patch_files=(URL)
_patch_shasums=()

2. Now add this additional code into the specific Callbacks:

To do_download()

 do_default_download

  for i in $(seq 0 $((${#_patch_files[@]} - 1))); do
    p="${_patch_files[$i]}"
    download_file $p $(basename $p) ${_patch_shasums[$i]}
  done; unset i p

To do_verify()

do_default_verify

  for i in $(seq 0 $((${#_patch_files[@]} - 1))); do
    verify_file $(basename ${_patch_files[$i]}) ${_patch_shasums[$i]}
  done; unset i

And to do_prepare()

do_default_prepare

  for p in "${_patch_files[@]}"; do
    build_line "Applying patch $(basename $p)"
    patch -p0 -i $HAB_CACHE_SRC_PATH/$(basename $p)
  done

[robbkidd]

I reckon the docs could demonstrate at least the two patching patterns—patching with patches versioned with the plan and patching with patches retrieved from elsewhere at build time—shown in the plans linked to by @eeyun over on #2561 (😵 hard to follow all the issues opened about this).

[ShalokShalom]

The proposal here is generic and lend by the bash version.

[robbkidd]

Indeed. That is probably roughly what would get documented for an example of retrieving and applying patches at build time.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. We value your input and contribution. Please leave a comment if this issue still affects you.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. We value your input and contribution. Please leave a comment if this issue still affects you.

[ShalokShalom]

So far as I know, got Habitat proper patch support, a few months after this issue was raised.