Extract shared configuration helpers into Infrastructure.Configuration library (#248)

web/backend/Infrastructure/Infrastructure.Configuration/ConfigurationHelpers.cs

@@ -0,0 +1,32 @@
+using Microsoft.Extensions.Configuration;
+
+namespace Infrastructure.Configuration;
+
+public static class ConfigurationHelpers
+{
+    public static string GetKeyOrThrow(IConfiguration configuration, string key) =>
+        configuration[key]
+        ?? throw new InvalidOperationException($"The {key} environment variable is not set.");
+
+    public static bool GetBooleanKeyOrThrow(IConfiguration configuration, string key)
+    {
+        string value = GetKeyOrThrow(configuration, key);
+
+        return bool.TryParse(value, out bool result)
+            ? result
+            : throw new InvalidOperationException(
+                $"The {key} environment variable is set to '{value}', which is not a valid boolean."
+            );
+    }
+
+    public static int GetIntKeyOrThrow(IConfiguration configuration, string key)
+    {
+        string value = GetKeyOrThrow(configuration, key);
+
+        return int.TryParse(value, out int result)
+            ? result
+            : throw new InvalidOperationException(
+                $"The {key} environment variable is set to '{value}', which is not a valid integer."
+            );
+    }
+}