# Sub Applications - Mounts

If you need to have two independent FastAPI applications, with their own independent OpenAPI and their own docs UIs, you can have a main app and "mount" one (or more) sub-application(s).

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

### Use cases: external service

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

      required: true

  - type: textarea
    id: expected-behavior
    attributes:
      label: "What did you expect to see?"
      description: Why is the current output incorrect, and any additional context we may need to understand the issue.
    validations:

argument to the bazel command:

```
bazel run //ci/official/requirements_updater:requirements.update --repo_env=HERMETIC_PYTHON_VERSION=3.12 -- --pre
```

If you need to upgrade all of the packages in requirements lock file, just pass
the `--upgrade` parameter:

```
bazel run //ci/official/requirements_updater:requirements.update --repo_env=HERMETIC_PYTHON_VERSION=3.12 -- --upgrade
```

and it is possible to gradually move apps from Istio 1.0/1.1 to the new environments and
across environments ( for example canary -> prod )

Note: there are still some cluster roles that may need to be fixed, most likely cluster permissions
will need to move to the security component.

## Everything is Optional

Each component in the new installer is optional. Users can install the component defined in the new installer,

        // like following/not following symlinks.)
        return new AsCharSource(charset) {
          @SuppressWarnings({
            "FilesLinesLeak", // the user needs to close it in this case
            /*
             * If users use this when they shouldn't, we hope that NewApi will catch subsequent
             * Stream calls.
             *

        // like following/not following symlinks.)
        return new AsCharSource(charset) {
          @SuppressWarnings("FilesLinesLeak") // the user needs to close it in this case
          @Override
          public Stream<String> lines() throws IOException {
            return Files.lines(path, charset);
          }
        };
      }

            return 0;
        }
        bufferIndex += len + 1;
        // win98 observed not returning nativeFileSystem
/* Problems here with iSeries returning ASCII even though useUnicode = true
 * Fortunately we don't really need nativeFileSystem for anything.
        if( byteCount > bufferIndex - start ) {
            nativeFileSystem = readString( buffer, bufferIndex );
            bufferIndex += stringWireLength( nativeFileSystem, bufferIndex );

import org.codehaus.plexus.personality.plexus.lifecycle.phase.Contextualizable;

/**
 * A conflict resolver factory that obtains instances from a plexus container.
 *
 * TODO you don't need the container in here with the active maps (jvz).
 * @since 3.0
 */
@Named
@Singleton
@Deprecated
public class DefaultConflictResolverFactory implements ConflictResolverFactory, Contextualizable {

        }
        if (outputStream instanceof PrintStream ps) {
            return ps;
        }
        return new PrintStream(outputStream);
    }

    //
    // These are the only methods we need in our primordial logger
    //

    @Override
    public void log(Level level, String message, Throwable error) {
        PrintWriter pw = level == Level.ERROR ? err : level == Level.WARN ? out : null;