### Deploy your app (optional) { #deploy-your-app-optional }

You can optionally deploy your FastAPI app to <a href="https://fastapicloud.com" class="external-link" target="_blank">FastAPI Cloud</a>, go and join the waiting list if you haven't. 🚀

If you already have a **FastAPI Cloud** account (we invited you from the waiting list 😉), you can deploy your application with one command.

Before deploying, make sure you are logged in:

    * ...and more.

### Deploy your app (optional)

You can optionally deploy your FastAPI app to <a href="https://fastapicloud.com" class="external-link" target="_blank">FastAPI Cloud</a>, go and join the waiting list if you haven't. 🚀

If you already have a **FastAPI Cloud** account (we invited you from the waiting list 😉), you can deploy your application with one command.

Before deploying, make sure you are logged in:

/**
 * Caches extension class realms. <strong>Warning:</strong> This is an internal utility interface that is only public
 * for technical reasons, it is not part of the public API. In particular, this interface can be changed or deleted
 * without prior notice.
 *
 */
public interface ExtensionRealmCache {
    /**
     * A cache key.
     */
    interface Key {
        // marker interface for cache keys
    }

If you want to secure your API, there are several better things you can do, for example:

* Make sure you have well defined Pydantic models for your request bodies and responses.
* Configure any required permissions and roles using dependencies.
* Never store plaintext passwords, only password hashes.

# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# When run as (for example)
#
#	GOOS=linux GOARCH=ppc64 bootstrap.bash
#
# this script cross-compiles a toolchain for that GOOS/GOARCH
# combination, leaving the resulting tree in ../../go-${GOOS}-${GOARCH}-bootstrap.
# That tree can be copied to a machine of the given target type

  /**
   * The current state of the service. This should be written with the lock held but can be read
   * without it because it is an immutable object in a volatile field. This is desirable so that
   * methods like {@link #state}, {@link #failureCause} and notably {@link #toString} can be run
   * without grabbing the lock.
   *

## **4. Run Sample Applications**

After installing Hive, Hadoop and Spark successfully, we can now proceed to run some sample applications to see if they are configured appropriately.  We can use Spark Pi and Spark WordCount programs to validate our Spark installation. We can also explore how to run Spark jobs from the command line and Spark shell.

### **4.1 Spark Pi**

   * Encapsulates the action to be taken when a potential deadlock is encountered. Clients can use
   * one of the predefined {@link Policies} or specify a custom implementation. Implementations must
   * be thread-safe.
   *
   * @since 13.0
   */
  public interface Policy {

    /**
     * Called when a potential deadlock is encountered. Implementations can throw the given {@code
     * exception} and/or execute other desired logic.

        HTTP_REQ_TOO_LONG,
        HTTP_NOT_IMPLEMENTED,
        HTTP_PERM_REDIRECT,
        -> {
          // These codes can be cached unless headers forbid it.
        }

        HTTP_MOVED_TEMP,
        HTTP_TEMP_REDIRECT,
        -> {
          // These codes can only be cached with the right response headers.
          // http://tools.ietf.org/html/rfc7234#section-3

```java
OkHttpClient client = new OkHttpClient.Builder()
    .connectionSpecs(Arrays.asList(ConnectionSpec.MODERN_TLS, ConnectionSpec.COMPATIBLE_TLS))
    .build();
```