# Run a Server Manually { #run-a-server-manually }

## Use the `fastapi run` Command { #use-the-fastapi-run-command }

In short, use `fastapi run` to serve your FastAPI application:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>

  <span style="background-color:#009485"><font color="#D3D7CF"> FastAPI </font></span>  Starting production server 🚀

/// tip | Consejo

No tienes que agregar metadata para todas las etiquetas que uses.

///

### Usar tus etiquetas

Usa el parámetro `tags` con tus *path operations* (y `APIRouter`s) para asignarlas a diferentes etiquetas:

{* ../../docs_src/metadata/tutorial004.py hl[21,26] *}

/// info | Información

///

This is of course not the frontend for the final users, but it's a great automatic tool to document interactively all your API.

It can be used by the frontend team (that can also be yourself).

It can be used by third party applications and systems.

And it can also be used by yourself, to debug, check and test the same application.

## The `password` flow { #the-password-flow }

set_java_home() {
  # For Cygwin and MinGW, ensure paths are in Unix format before anything is touched
  if [ -n "${JAVA_HOME-}" ]; then
    if [ -x "$JAVA_HOME/jre/sh/java" ]; then
      # IBM's JDK on AIX uses strange locations for the executables
      JAVACMD="$JAVA_HOME/jre/sh/java"
      JAVACCMD="$JAVA_HOME/jre/sh/javac"
    else
      JAVACMD="$JAVA_HOME/bin/java"
      JAVACCMD="$JAVA_HOME/bin/javac"

When one of these security schemes uses OAuth2, you can also declare and use scopes.

Each "scope" is just a string (without spaces).

They are normally used to declare specific security permissions, for example:

* `users:read` or `users:write` are common examples.
* `instagram_basic` is used by Facebook / Instagram.
* `https://www.googleapis.com/auth/drive` is used by Google.

/// info

        assertNotNull(queryRescorer.evaluate(params)); // Fourth call - even
    }

    /**
     * Creates a mock RescorerBuilder for testing purposes.
     * Uses QueryRescorerBuilder with a simple query.
     */
    private RescorerBuilder<?> createMockRescorerBuilder() {
        return new QueryRescorerBuilder(new MatchAllQueryBuilder());
    }

        // Test setting a custom instance
        LogStream.setInstance(testStream);
        LogStream instance = LogStream.getInstance();
        assertNotNull(instance);

        // Write something to verify it uses our test stream
        instance.println("test message");
        instance.flush();
        String output = testOutput.toString();
        assertTrue(output.contains("test message"));
    }

    @Test

 *   The Promise class has then and error methods that allow you to register callbacks
 *   for successful and unsuccessful computations, respectively.
 * </p>
 *
 * <p>
 *   The Deferred class uses a CountDownLatch to allow you to wait for the computation to complete.
 *   The resolve and reject methods decrement the CountDownLatch, allowing the getResponse method
 *   to return the result of the computation.
 * </p>
 *

   *
   * <p><b>Warning:</b> Typical uses of the resulting iterator may produce an infinite loop. You
   * should use an explicit {@code break} or be certain that you will eventually remove all the
   * elements.
   *
   * <p>To cycle over the iterable {@code n} times, use the following: {@code
   * Iterables.concat(Collections.nCopies(n, iterable))}
   *

    private static final String HANDLER_PKGS_PROPERTY = "java.protocol.handler.pkgs";

    /**
     * Vendor-specific default packages. If no packages are specified in
     * "java.protocol.handler.pkgs", the VM uses one or more default
     * packages, which are vendor specific. Sun's is included below
     * for convenience; others could be as well. If a particular vendor's
     * package isn't listed, it can be specified in