Create proxy with gleam

Author: MarcoDaniels

.github/workflows/test.yml

@@ -1,20 +1,35 @@
 import gleam/bit_builder
 import gleam/erlang/process
+import gleam/erlang/os
 import gleam/http/request.{Request}
 import gleam/http/response.{Response}
 import mist.{Connection, ResponseData}
 import gleam/httpc
-import gleam/http.{Get, Http}
-import gleam/string.{join}
+import gleam/http.{Method, Scheme}
+import gleam/string
+import gleam/io
+import gleam/option.{Option, unwrap}
+import gleam/result
+import gleam/int
 
-fn handle_website(segments: List(String)) -> Response(ResponseData) {
+pub type Website {
+  Website(
+    target_host: String,
+    target_port: Int,
+    scheme: Scheme,
+    method: Method,
+    path: String,
+  )
+}
+
+fn handle_website(config: Website) -> Response(ResponseData) {
   let result =
     request.new()
-    |> request.set_scheme(Http)
-    |> request.set_method(Get)
-    |> request.set_host("localhost")
-    |> request.set_port(1234)
-    |> request.set_path(join(segments, "/"))
+    |> request.set_scheme(config.scheme)
+    |> request.set_method(config.method)
+    |> request.set_host(config.target_host)
+    |> request.set_port(config.target_port)
+    |> request.set_path(config.path)
     |> httpc.send
 
   case result {
@@ -27,15 +42,97 @@ fn handle_website(segments: List(String)) -> Response(ResponseData) {
   }
 }
 
+type Image {
+  Image(
+    base_url: String,
+    api_token: String,
+    path: List(String),
+    query: Option(String),
+  )
+}
+
+fn handle_images(config: Image) -> Response(ResponseData) {
+  let url =
+    "/api/cockpit/image?token=" <> config.api_token <> "&src=" <> config.base_url <> "/storage/uploads/" <> string.join(
+      config.path,
+      "/",
+    ) <> "&" <> unwrap(config.query, "")
+
+  let result =
+    request.new()
+    |> request.set_host(string.replace(config.base_url, "https://", ""))
+    |> request.set_path(url)
+    |> request.set_body(<<>>)
+    |> httpc.send_bits
+
+  case result {
+    Ok(r) ->
+      response.new(200)
+      |> response.set_body(mist.Bytes(bit_builder.from_bit_string(r.body)))
+    Error(_) ->
+      response.new(404)
+      |> response.set_body(mist.Bytes(bit_builder.from_string("<h1>nope</h1>")))
+  }
+}
+
+type Configuration {
+  Configuration(
+    base_url: String,
+    api_token: String,
+    target_host: String,
+    target_port: Int,
+    port: Int,
+  )
+}
+
+fn load_configuration() -> Result(Configuration, String) {
+  case
+    result.all([
+      os.get_env("COCKPIT_BASE_URL"),
+      os.get_env("COCKPIT_API_TOKEN"),
+      os.get_env("TARGET_HOST"),
+      os.get_env("TARGET_PORT"),
+      os.get_env("PORT"),
+    ])
+  {
+    Ok([base_url, api_token, target_host, target_p, p]) ->
+      case result.all([int.parse(target_p), int.parse(p)]) {
+        Ok([target_port, port]) ->
+          Ok(Configuration(base_url, api_token, target_host, target_port, port))
+        Error(_) -> Error("Port values are not numbers")
+      }
+    Error(_) -> Error("Missing environment variables")
+  }
+}
+
 pub fn main() {
-  fn(req: Request(Connection)) -> Response(ResponseData) {
-    case request.path_segments(req) {
-      _ as segments -> handle_website(segments)
+  case load_configuration() {
+    Ok(config) -> {
+      fn(req: Request(Connection)) -> Response(ResponseData) {
+        case request.path_segments(req) {
+          ["image", "api", ..path] ->
+            handle_images(Image(
+              config.base_url,
+              config.api_token,
+              path,
+              req.query,
+            ))
+          _ ->
+            handle_website(Website(
+              config.target_host,
+              config.target_port,
+              req.scheme,
+              req.method,
+              req.path,
+            ))
+        }
+      }
+      |> mist.new
+      |> mist.port(config.port)
+      |> mist.start_http
+
+      process.sleep_forever()
     }
+    Error(message) -> io.print_error(message)
   }
-  |> mist.new
-  |> mist.port(8000)
-  |> mist.start_http
-
-  process.sleep_forever()
 }