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https://github.com/ppkrauss/postgrest-writeapi

Translate your OpenAPI specification into a NGinx config-file to implement your PostgREST system
https://github.com/ppkrauss/postgrest-writeapi

agile nginx openapi postgresql postgrest

Last synced: about 12 hours ago
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Translate your OpenAPI specification into a NGinx config-file to implement your PostgREST system

Host: GitHub
URL: https://github.com/ppkrauss/postgrest-writeapi
Owner: ppKrauss
License: mit
Created: 2017-03-07T19:34:37.000Z (over 7 years ago)
Default Branch: master
Last Pushed: 2017-03-26T11:43:46.000Z (over 7 years ago)
Last Synced: 2024-10-31T21:42:12.567Z (8 days ago)
Topics: agile, nginx, openapi, postgresql, postgrest
Language: JavaScript
Size: 1010 KB
Stars: 41
Watchers: 3
Forks: 4
Open Issues: 3
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

README

We use the best, [Nginx](https://nginx.org/) and [PostgREST](https://postgrest.com), to translate your [OpenAPI specification](https://www.openapis.org/specification) into a **plug-and-play [back-end](https://en.wikipedia.org/wiki/Front_and_back_ends)** system.

The project offers automatic generation of the main piece for implementation of your *endpoints*, the *Nginx configuration script* — that acts as a primary dispatcher or controller, for PostgREST and for your system. In the context of a "microservices ecosystem", this controller do the *microservices orchestration*.

![](https://github.com/ppKrauss/my-sandbox/raw/master/OpenAPI-Gateway-codegen/assets/Reverse_proxy2.svg.png)

Terminological note: usually this piece of software is named [*reverse proxy*](https://en.wikipedia.org/wiki/Reverse_proxy) or "**API gateway**".

## Illustrating usage

After check pre-requisites (NodeJS v4.2), `git clone` this repo, you can generate an Nginx config-file with
```sh
cd PostgREST-writeAPI
node writeApi.js --tpl=01 --api=petstore-expanded | more
```
Edit `api-spec/petstore-expanded.json` and `nginx-tpl/tpl01-baseBreak.mustache` to try variations. What it do: transforms original *localhost endpoints* into specified endpoints.

Original endpoint | Expected by [API-specification](api-spec/petstore-expanded.json)
------------ | -------------
`http://localhost:3000/pets` | `petstore.swagger.io/api/pets` or `petstore.swagger.io/api/darlings`
`http://localhost:3000/pets?id=eq.`_id_ | `petstore.swagger.io/api/pets/{id}`

So *PostgREST-writeAPI* generates the code below, a [Nginx rewrite module script](http://nginx.org/en/docs/http/ngx_http_rewrite_module.html) that implements the expected API‑gateway specification:

```sh
server {

server_name petstore.swagger.io;
root /var/www/petstore.swagger.io/html;

# publishing by default the HTML for API description and related files for navigation
index index.html index.htm;

location / {
try_files $uri $uri/ @proxy;
}

location @proxy {
### endpoints defined by OpenAPI spec of this app:

rewrite # endpoint "pets" for get,post
^/api/(pets?|darlings?)$
http://localhost:3000/pets
break;

rewrite # endpoint "pets/{id}" for get,delete
^/api/pets/([0-9]+)
http://localhost:3000/pets?id=eq.$1
break;

# endpoint insects (automatic PostgREST) for get

rewrite # endpoint "fishes TO OTHER PROXY" for get
^/api/fishes
http://localhost:4000
break;

### default and auxiliar endpoint, for all other requests for PostgREST-queries
rewrite ^/api/(.*)$ /$1 break;

### proxy configurations:
proxy_pass http://localhost:3000; # my PostREST is here!
...
}
}
```
It is obtained by [tpl01-baseBreak](nginx-tpl/tpl01-baseBreak.mustache) template and [this spec](api-spec/petstore-expanded.json) as input, as required by `--tpl=01 --api=petstore-expanded` options.

Variations can be obtained changing the template. Example: to stop to use the *PostgREST queryes* (eg. `petstore.swagger.io/api/otherTable`) you can use `--tpl=02` in the command line, that will generate script by [tpl02-baseBreak-noQuery](nginx-tpl/tpl02-baseBreak-noQuery.mustache) template, eliminating the last ` rewrite` clause.

## Motivations

PostgREST *endpoints* are ready-for-use, but, sometimes you can't reuse directally its "complex URL" endpoints, or need compliance with system requirements — already expressed in an formal specification.

This project was developed to simplify this PostgREST use case: to obey the OpenAPI specification of your project.

### Need for fast prototipation

PostgreSQL is not an "[agile](https://en.wikipedia.org/wiki/Agile_software_development) tool"? We can go from scratch to a set of endpoints serving a database, in minutes? We can use only the database, alone, to implement *web-application [prototypes](https://en.wikipedia.org/wiki/Software_prototyping)*?

With PostgREST we can (!!) and the goal of this project is to expand the spectrum of applications. We can extend the PostgREST capabilties to "plug-and-play" endpoints, by its OpenAPI specifications.

## OpenAPI addictions to specify your system

Your application can use full stack PostgREST (the URL-SQLquery syntax) for default endpoints,
and two new fields must be included in your OpenAPI spec (your `swagger.json`), to describe the endpoints with non-default PostgREST behaviour:

* `x-rewrite_regex`: the regular expression that in fact represents the endpoint is a concatenation of *basePath*, *localPath* and *rewrite_regex*.

* `x-rewrite_url`: the target-URL with optional regex-variables (eg. $1).

* `x-proxy_url`: the URL of the "root" that is handling the `x-rewrite_url`, when is not PostgREST (the default proxy).

When one or both are declared at JSON's API description, it is translated to Nginx *rewrite* directive. Else default PostgREST is adopted.
The `x-` prefix is the ["vendor extension" of OpenAPI](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#vendorExtensions).

## Methodology

As the project is alpha version, have good methodology but not an automatic procedure. Simple steps:

1. Prepare an OpenAPI specification of your system or application. Use basic PostgREST where is possible, where is not, two alternatives: rewrite to proxy-PostgREST or implement in it in other "proxy"... So, express also in the API specification the fields `x-proxy_url`, `x-rewrite_regex` and `x-rewrite_url`.

2. Check what templete you need (or colabore creating a new one!). See [nginx-tpl](nginx-tpl) folder with some examples (or use template `01` as first try).

3. Save your API specification (`swagger.json`) at [api-spec](api-spec) with your project's name (eg. `myproj.json`), and edit it ading the fields xx and yy.

4. run `node writeApi.js > subdomain.conf` with correct parameters. It will generate the Nginx's script for your server's ` /etc/nginx/sites-available`.

5. do next steps as usual Nginx implementation

## OpenAPI stadanrds and parallel initiatives

Please help to start, at *Swagger-API* community, via [this *swagger-codegen* approved proposal](https://github.com/swagger-api/swagger-codegen/issues/5034), a new code generator, like here, but plugged into an ecosystem of standard code generators.