### Writing controllers

Istio provides a few helper libraries to get started writing a controller. While these libraries help, there are still a lot of subtleties in correctly writing (and testing!) a controller properly.

To get started writing a controller, review the [Example Controller](../../pkg/kube/controllers/example_test.go).

### Controllers overview

    model_config = {"extra": "forbid"}

    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: Annotated[FilterParams, Query()]):

app.include_router(items.router)
app.include_router(
    admin.router,
    prefix="/admin",
    tags=["admin"],
    dependencies=[Depends(get_token_header)],
    responses={418: {"description": "I'm a teapot"}},
)


@app.get("/")
async def root():

        return new ByteArrayInputStream(content.getBytes(StandardCharsets.UTF_8));
    }

    @Override
    public String getLocation() {
        return location;
    }

    /**
     * Gets the content of this source.
     *
     * @return The underlying character stream, never {@code null}.
     */
    public String getContent() {
        return content;
    }

    @Override

    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("We don't swallow the internal error here, we raise again 😎")
        raise


@app.get("/items/{item_id}")
def get_item(item_id: str, username: str = Depends(get_username)):
    if item_id == "portal-gun":
        raise InternalError(
            f"The portal gun is too dangerous to be owned by {username}"

    )


async def get_current_user(token: str = Depends(oauth2_scheme)):
    user = fake_decode_token(token)
    return user


@app.get("/users/me")
async def read_users_me(current_user: User = Depends(get_current_user)):

    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("We don't swallow the internal error here, we raise again 😎")
        raise


@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):
    if item_id == "portal-gun":
        raise InternalError(
            f"The portal gun is too dangerous to be owned by {username}"

import okhttp3.internal.publicsuffix.PublicSuffixDatabase

/**
 * [DNS over HTTPS implementation][doh_spec].
 *
 * > A DNS API client encodes a single DNS query into an HTTP request
 * > using either the HTTP GET or POST method and the other requirements
 * > of this section.  The DNS API server defines the URI used by the
 * > request through the use of a URI Template.
 *

// and options for creating keys.
type CreateKeyRequest struct {
	// Name is the name of the key that gets created.
	Name string
}

// DeleteKeyRequest is a structure containing fields
// and options for deleting keys.
type DeleteKeyRequest struct {
	// Name is the name of the key that gets deleted.
	Name string
}

// GenerateKeyRequest is a structure containing fields
// and options for generating data keys.

    public static <T> T getValue(final Map<String, Object> doc, final String key, final Class<T> clazz) {
        if (doc == null || key == null) {
            return null;
        }

        final Object value = doc.get(key);
        if (value == null) {
            return null;
        }

        if (value instanceof List) {
            if (clazz.isAssignableFrom(List.class)) {
                return (T) value;
            }