🚀 [Feature]: add envvar expose middleware (#2054)

* add envvar expose middleware

* fix readme remove redundant word

* change hard coded json marshal to app config marshaller

* update readme

* update all lang readme

* change t.setenv to os.setenv as backward compability reason

* change io.readall to ioutil.readall

* Update envvar.go

* remove get method that only used in test

* remove unused method from envvar struct

* remove path variable from config, update readme, add new test case

Co-authored-by: RW <rene@gofiber.io>

.github/README.md

@@ -595,13 +595,14 @@ func main() {
 Here is a list of middleware that are included within the Fiber framework.
 
 | Middleware                                                                             | Description                                                                                                                                                                  |
-| :------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+|:---------------------------------------------------------------------------------------|:-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | [basicauth](https://github.com/gofiber/fiber/tree/master/middleware/basicauth)         | Basic auth middleware provides an HTTP basic authentication. It calls the next handler for valid credentials and 401 Unauthorized for missing or invalid credentials.        |
 | [cache](https://github.com/gofiber/fiber/tree/master/middleware/cache)                 | Intercept and cache responses                                                                                                                                                |
 | [compress](https://github.com/gofiber/fiber/tree/master/middleware/compress)           | Compression middleware for Fiber, it supports `deflate`, `gzip` and `brotli` by default.                                                                                     |
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_ckb.md

@@ -601,6 +601,7 @@ func main() {
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_de.md

@@ -571,6 +571,7 @@ Hier finden Sie eine Liste der Middleware, die im Fiber-Framework enthalten ist.
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_es.md

@@ -571,6 +571,7 @@ Aquí está una lista del middleware incluido en el marco web Fiber.
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_fa.md

@@ -686,6 +686,7 @@ func main() {
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   |فعال سازی هدر های cross-origin با گزینه های مختلف.|
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   |در برابر حملات CSRF ایمنی ایجاد میکند.|
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) |مقادیر کوکی هارا رمزنگاری میکند.|
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | با ارائه تنظیمات اختیاری، متغیرهای محیط را در معرض دید قرار دهید.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | میدلور ETag به کش ها اجازه میدهد کارآمد تر عمل کرده و در پهنای باند صرفه جویی کنند.  به عنوان یک وب سرور نیازی به دادن پاسخ کامل نیست اگر محتوا تغییر نکرده باشد. |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | میدلور Expvar میتواند متغیر هایی را تعریف کرده و مقادیر انها را در زمان اجرا با فرمت JSON به شما نشان دهد. |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | جلوگیری و یا کش کردن درخواست های favicon در صورتی که مسیر یک فایل را داده باشید.|

.github/README_fr.md

@@ -573,6 +573,7 @@ Here is a list of middleware that are included within the Fiber framework.
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_he.md

@@ -689,6 +689,7 @@ Here is a list of middleware that are included within the Fiber framework.
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |

.github/README_id.md

@@ -574,6 +574,7 @@ Kumpulan `middleware` yang ada didalam kerangka kerja Fiber.
 | [cors](https://github.com/gofiber/fiber/tree/master/middleware/cors)                   | Enable cross-origin resource sharing \(CORS\) with various options.                                                                                                          |
 | [csrf](https://github.com/gofiber/fiber/tree/master/middleware/csrf)                   | Protect from CSRF exploits.                                                                                                                                                  |
 | [encryptcookie](https://github.com/gofiber/fiber/tree/master/middleware/encryptcookie) | Encrypt middleware which encrypts cookie values.                                                                                                                             |
+| [envvar](https://github.com/gofiber/fiber/tree/master/middleware/envvar)               | Expose environment variables with providing an optional config.                                                                                                              |
 | [etag](https://github.com/gofiber/fiber/tree/master/middleware/etag)                   | ETag middleware that lets caches be more efficient and save bandwidth, as a web server does not need to resend a full response if the content has not changed.               |
 | [expvar](https://github.com/gofiber/fiber/tree/master/middleware/expvar)               | Expvar middleware that serves via its HTTP server runtime exposed variants in the JSON format.                                                                               |
 | [favicon](https://github.com/gofiber/fiber/tree/master/middleware/favicon)             | Ignore favicon from logs or serve from memory if a file path is provided.                                                                                                    |