Adding upstream version 2.52.6.

Signed-off-by: Daniel Baumann <daniel@debian.org>

docs/api/middleware/envvar.md

@@ -0,0 +1,69 @@
+---
+id: envvar
+---
+
+# EnvVar
+
+EnvVar middleware for [Fiber](https://github.com/gofiber/fiber) that can be used to expose environment variables with various options.
+
+## Signatures
+
+```go
+func New(config ...Config) fiber.Handler
+```
+
+## Examples
+
+Import the middleware package that is part of the Fiber web framework
+
+```go
+import (
+  "github.com/gofiber/fiber/v2"
+  "github.com/gofiber/fiber/v2/middleware/envvar"
+)
+```
+
+After you initiate your Fiber app, you can use the following possibilities:
+
+```go
+// Initialize default config
+app.Use("/expose/envvars", envvar.New())
+
+// Or extend your config for customization
+app.Use("/expose/envvars", envvar.New(
+	envvar.Config{
+		ExportVars:  map[string]string{"testKey": "", "testDefaultKey": "testDefaultVal"},
+		ExcludeVars: map[string]string{"excludeKey": ""},
+	}),
+)
+```
+
+:::note
+You will need to provide a path to use the envvar middleware.
+:::
+
+## Response
+
+Http response contract:
+```
+{
+  "vars": {
+    "someEnvVariable": "someValue",
+    "anotherEnvVariable": "anotherValue",
+  }
+}
+
+```
+
+## Config
+
+| Property    | Type                | Description                                                                  | Default |
+|:------------|:--------------------|:-----------------------------------------------------------------------------|:--------|
+| ExportVars  | `map[string]string` | ExportVars specifies the environment variables that should be exported.      | `nil`   |
+| ExcludeVars | `map[string]string` | ExcludeVars specifies the environment variables that should not be exported. | `nil`   |
+
+## Default Config
+
+```go
+Config{}
+```