mount-point for clean URLs

[amitu]

Status: Done

Follow: #526

PR: #587

With endpoint support, if we have a dependency:

-- fpm.package: abrark.com
-- fpm.dependency: fifthtry.github.io/todos
end-point: https://abrark-todos.herokuapps.com

Then todo app gets deployed on: abrark.com/-/fifthtry.github.io/todos/. This is also the case if you are using any package as static package, say you wanted a package fifthtry.github.io/icons/ and it has exposed an icon close.png, you have to use the URL: abrark.com/-/fifthtry.github.io/icons/close.png.

This way of constructing URLs give us name spacing, so we can add any number of packages and apps without worrying about conflict. But these URLs are ugly, especially if we want to share the URL with others.

mount-point

To solve this we support mount-point.

-- fpm.package: abrark.com
-- fpm.dependency: fifthtry.github.io/todos
end-point: https://abrark-todos.herokuapps.com
mount-point: /todos/

mount-point can be added to any dependency. When constructing URL the normal rule of <package-name>/-/<dependency-package> would not be used if mount-point is used, instead we will use the rule <package-name><dependency-package-mount-point> instead.

Both URLs will be served by fpm serve, but if mount-point is defined, when fpm is constructing a URL it will use the mount-point url.

Multiple Dependencies

We can install any number of dependencies, each with their own end-point, and mount-point settings. mount-point must be unique for each of them, if not we will give an error.

Proper URL Handling in End-Point

When a request to abrark.com/-/fifthtry.github.io/todos/ or abrark.com/todos/ is made with this setup, the request will proxy-passed to the endpoint (https://abrark-todos.herokuapps.com).

Normalised Path

The path parameter should be normalised. Since both URLs are valid, which URL would django use in urls.py? One option is we strip out both /todos/ and /-/fifthtry.github.io/todos/, and pass just the part that comes after to django as PATH parameter.

So if request came to /todos/1/, django will get /1/.

Generating URLs

Django needs to generate URLs as well. To generate URLs django must use the value of header named X-FPM-MOUNT-POINT. So instead of including /1/ in JSON/HTML, django will use: request.headers["X-FPM-MOUNT-POINT"] + "/1/".

Endpoint should block content-type HTML

So django etc an only be used for providing APIs and not web pages.

[AbrarNitk]

mount-point Implementation

Let's say if we have packages abrark.com and fifthtry.github.io/todos. abrark.com uses fifthtry.github.io/todos.

-- ftd.code: With mount-point
land: ftd

-- fpm.package: abrark.com

-- fpm.dependency: fifthtry.github.io/todos
end-point: https://abrark-todos.herokuapps.com
mount-point: /todos/

-- fpm.sitemap:

# Home:
- Study: /study/
- Work: /work/
- Todos: /todos/

-- ftd.code: Without mount-point
land: ftd

-- fpm.package: abrark.com

-- fpm.dependency: fifthtry.github.io/todos
end-point: https://abrark-todos.herokuapps.com

-- fpm.sitemap:

# Home:
- Study: /study/
- Work: /work/
- Todos: /-/fifthtry.github.io/todos/

-- ftd.code: FPM.ftd
land: ftd

-- fpm.package: fifthtry.github.io/todos
needs-end-point: true

;; Apis will be
;; /api/add-todo/
;; /api/update-todo/
;; /api/todos/

-- fpm.sitemap:

# Todos: /
- Add Todo: /add-todo/
- Update Todo: /update-todo/

Implementation Details

Let's if request come for url abrark.com/todos/add-todo/. First It will check
if url prefix matches with any of dependency's mount-point in current
package(abrark.com).

If url prefix matches to anyone one them, so it will lookup to mount-point's
package sitemap.

Here it matches with dependency todos.com, so now it look up in todos.com
package's sitemap with removed prefix /add-todo/. It can also go recursive, by
checking even todos.com dependencies.

If mount-point is specified both abrark.com/-/fifthtry.github.io/todos/logo.png
and abrark.com/todos/logo.png must work.

For Static File Serve it, For FTD file redirect it.

abrark.com/-/fifthtry.github.io/todos/logo.png -> abrark.com/todos/logo.png

[AbrarNitk]

FPM Apps

Discussion: https://github.com/ftd-lang/fpm/discussions/599