refactor: env validation typescript and common package (#1912)

apps/nextjs/src/env.ts

@@ -0,0 +1,38 @@
+import { createEnv } from "@t3-oss/env-nextjs";
+import { z } from "zod";
+
+import { shouldSkipEnvValidation } from "@homarr/common/env-validation";
+
+export const env = createEnv({
+  shared: {
+    PORT: z.coerce.number().default(3000),
+    NODE_ENV: z.enum(["development", "production", "test"]).default("development"),
+  },
+  /**
+   * Specify your server-side environment variables schema here. This way you can ensure the app isn't
+   * built with invalid env vars.
+   */
+  server: {
+    // Comma separated list of docker hostnames that can be used to connect to query the docker endpoints (localhost:2375,host.docker.internal:2375, ...)
+    DOCKER_HOSTNAMES: z.string().optional(),
+    DOCKER_PORTS: z.string().optional(),
+  },
+  /**
+   * Specify your client-side environment variables schema here.
+   * For them to be exposed to the client, prefix them with `NEXT_PUBLIC_`.
+   */
+  client: {
+    // NEXT_PUBLIC_CLIENTVAR: z.string(),
+  },
+  /**
+   * Destructure all variables from `process.env` to make sure they aren't tree-shaken away.
+   */
+  runtimeEnv: {
+    PORT: process.env.PORT,
+    NODE_ENV: process.env.NODE_ENV,
+    DOCKER_HOSTNAMES: process.env.DOCKER_HOSTNAMES,
+    DOCKER_PORTS: process.env.DOCKER_PORTS,
+    // NEXT_PUBLIC_CLIENTVAR: process.env.NEXT_PUBLIC_CLIENTVAR,
+  },
+  skipValidation: shouldSkipEnvValidation(),
+});