Prepend application url to app proxy url if it starts with /

[murray-andrew-r]

WHY are these changes introduced?

Closes https://github.com/shop/issues-develop/issues/12741#issue-3249208952

This puts us at parity with webhook subscription URLs, which already have this feature.

WHAT is this pull request doing?

Appends the application url to the start of the proxy URL if the proxy URL starts with / .

Updates validations to allow / leading proxy URLs. Also ensures that only HTTP proxies are used.

How to test your changes?

1. pnpm shopify app init
2. In app.toml add
   [app_proxy]
   url = "https://www.api.example.com/api/proxy2"
   subpath = "store-pickup"
   prefix = "apps"

Substituting focused-share-holder app with your app name:

1. pnpm shopify app deploy --path=./focused-shareholder-app should succeed
2. In dev dash, confirm that the app proxy URL is https://www.api.example.com/api/proxy2
3. Update url to http://www.api.example.com/api/proxy2
4. pnpm shopify app deploy --path=./focused-shareholder-app should fail with an HTTP validation.
5. Update url to /api/proxy2
6. pnpm shopify app deploy --path=./focused-shareholder-app should succeed
7. In dev dash, confirm that the proxy url is https://example/com/api/proxy2

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	78.32% (+0.03% 🔼)	13173/16819
🟡	Branches	72.39% (+0.09% 🔼)	6425/8876
🟡	Functions	78.4% (+0.02% 🔼)	3419/4361
🟡	Lines	78.69% (+0.03% 🔼)	12464/15839

Show new covered files 🐣

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / url_prepender.ts	100%	100%	100%	100%

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / app_config_webhook_subscription.ts	100%	50% (-16.67% 🔻)	100%	100%

Test suite run success

3121 tests passing in 1324 suites.

Report generated by 🧪jest coverage report action from 6efb593

[isaacroldan]

Let's investigate if this can be done server side

[isaacroldan]

🎩 'ed and worked as expected.

[pt2pham]

LGTM. Note for future lurkers that this is a compromise in the CLI and it would be ideal to do a better platform solution for relative URLs across app config/extensions in the future.

[jackseok]

LGTM just left a small comment