Add Webhook authorization header (#20926)

_This is a different approach to #20267, I took the liberty of adapting
some parts, see below_

## Context

In some cases, a weebhook endpoint requires some kind of authentication.
The usual way is by sending a static `Authorization` header, with a
given token. For instance:

- Matrix expects a `Bearer <token>` (already implemented, by storing the
header cleartext in the metadata - which is buggy on retry #19872)
- TeamCity #18667
- Gitea instances #20267
- SourceHut https://man.sr.ht/graphql.md#authentication-strategies (this
is my actual personal need :)

## Proposed solution

Add a dedicated encrypt column to the webhook table (instead of storing
it as meta as proposed in #20267), so that it gets available for all
present and future hook types (especially the custom ones #19307).

This would also solve the buggy matrix retry #19872.

As a first step, I would recommend focusing on the backend logic and
improve the frontend at a later stage. For now the UI is a simple
`Authorization` field (which could be later customized with `Bearer` and
`Basic` switches):


![2022-08-23-142911](https://user-images.githubusercontent.com/3864879/186162483-5b721504-eef5-4932-812e-eb96a68494cc.png)

The header name is hard-coded, since I couldn't fine any usecase
justifying otherwise.

## Questions

- What do you think of this approach? @justusbunsi @Gusted @silverwind 
- ~~How are the migrations generated? Do I have to manually create a new
file, or is there a command for that?~~
- ~~I started adding it to the API: should I complete it or should I
drop it? (I don't know how much the API is actually used)~~

## Done as well:

- add a migration for the existing matrix webhooks and remove the
`Authorization` logic there


_Closes #19872_

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: delvh <dev.lh@web.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/docs/content/doc/features/webhooks.en-us.md b/docs/content/doc/features/webhooks.en-us.md
index 2dba7b7f83..ecbe13c3ad 100644
--- a/docs/content/doc/features/webhooks.en-us.md
+++ b/docs/content/doc/features/webhooks.en-us.md
@@ -188,3 +188,7 @@ if (json_last_error() !== JSON_ERROR_NONE) {
 ```
 
 There is a Test Delivery button in the webhook settings that allows to test the configuration as well as a list of the most Recent Deliveries.
+
+### Authorization header
+
+**With 1.19**, Gitea hooks can be configured to send an [authorization header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Authorization) to the webhook target.