respect API_HOST & API_PORT env vars for dev

Using Vite's proxy option allows us to avoid CORS issues when the host
for Uvicorn doesn't match the host for Vite, e.g. localhost vs. 127.0.0.1.

scripts/dev

@@ -2,6 +2,12 @@
 
 cd "$RUN_DIR"
 
+# Make Uvicorn defaults explicit.
+: "${API_PORT:=8000}"
+: "${API_HOST:=127.0.0.1}"
+export API_PORT
+export API_HOST
+
 [ -z "${DEBUG:-}" ] || set -x
 
 exec honcho start

scripts/dev-server

@@ -4,4 +4,9 @@ cd "$RUN_DIR"
 
 [ -z "${DEBUG:-}" ] || set -x
 
-exec uvicorn unwind:create_app --factory --reload
+exec uvicorn \
+    --host "$API_HOST" \
+    --port "$API_PORT" \
+    --reload \
+    --factory \
+    unwind:create_app

scripts/server

@@ -11,4 +11,5 @@ export UNWIND_PORT
 exec uvicorn \
     --host 0.0.0.0 \
     --port "$UNWIND_PORT" \
-    --factory unwind:create_app
+    --factory \
+    unwind:create_app

unwind-ui/vite.config.ts

@@ -1,13 +1,29 @@
 import { defineConfig } from "vite"
 import vue from "@vitejs/plugin-vue"
 
+// Vite defaults.
+const vite_host = "localhost"
+const vite_port = 3000
+
+const base = process.env.BASE_URL || "/"
+const proxied_api_url = `http://${vite_host}:${vite_port}/api/`
+const real_api_url = `http://${process.env.API_HOST}:${process.env.API_PORT}/api/`
+
 // https://vitejs.dev/config/
 export default defineConfig({
-  base: process.env.BASE_URL || "/",
+  base,
   define: {
-    "process.env.API_URL": JSON.stringify(
+    "process.env.API_URL": JSON.stringify(process.env.API_URL || proxied_api_url),
-      process.env.API_URL || "http://localhost:8000/api/",
+  },
-    ),
+  server: {
+    host: vite_host,
+    port: vite_port,
+    proxy: {
+      [`${base}api`]: {
+        target: real_api_url,
+        prependPath: false,
+      },
+    },
   },
   plugins: [vue()],
 })