### Single Container

If you have a simple setup, with a **single container** that then starts multiple **worker processes** (or also just one process), then you could run those previous steps in the same container, right before starting the process with the app. The official Docker image supports this internally.

## Previous Steps Before Starting

There are many cases where you want to perform some steps **before starting** your application.

For example, you might want to run **database migrations**.

But in most cases, you will want to perform these steps only **once**.

So, you will want to have a **single process** to perform those **previous steps**, before starting the application.

Let's check back those deployment concepts from before:

* Security - HTTPS
* Running on startup
* Restarts
* **Replication (the number of processes running)**
* Memory
* Previous steps before starting

Up to this point, with all the tutorials in the docs, you have probably been running a **server program** like Uvicorn, running a **single process**.

## you can define additional policies with custom supported actions and resources
policies: []
## writeexamplepolicy policy grants creation or deletion of buckets with name
## starting with example. In addition, grants objects write permissions on buckets starting with
## example.
# - name: writeexamplepolicy
#   statements:
#     - effect: Allow  # this is the default
#       resources:
#         - 'arn:aws:s3:::example*/*'

	cniServer := startCniPluginServer(ctx, pluginSocket, s.handlers, s.dataplane)
	err = cniServer.Start()
	if err != nil {
		return nil, fmt.Errorf("error starting cni server: %w", err)
	}
	s.cniServerStopFunc = cniServer.Stop

	return s, nil
}

func (s *Server) Ready() {
	s.isReady.Store(true)
}

func (s *Server) NotReady() {

!!! tip
    If you know perfectly how imports work, continue to the next section below.

A single dot `.`, like in:

```Python
from .dependencies import get_token_header
```

would mean:

* Starting in the same package that this module (the file `app/routers/items.py`) lives in (the directory `app/routers/`)...
* find the module `dependencies` (an imaginary file at `app/routers/dependencies.py`)...

		if cfg.InstallConfig.AmbientEnabled {
			// Start ambient controller

			// node agent will spawn a goroutine and watch the K8S API for events,
			// as well as listen for messages from the CNI binary.
			log.Info("Starting ambient node agent with inpod redirect mode")
			ambientAgent, err := nodeagent.NewServer(ctx, watchServerReady, cfg.InstallConfig.CNIEventAddress,
				nodeagent.AmbientArgs{
					SystemNamespace: nodeagent.PodNamespace,

// the kernel can be out of sync with the CLI utility, leading to errors like:
//
// ipset v7.10: Argument `comment' is supported in the kernel module of the set type hash:ip
// starting from the revision 3 and you have installed revision 1 only.
// Your kernel is behind your ipset utility.
//
// This happens with kernels as recent as Fedora38, e.g: 6.4.11-200.fc38.aarch64

//     tags:
//       - key: "name"
//         value: "pick*" # match objects with tag 'name', with all values starting with 'pick'
//     metadata:
//       - key: "content-type"
//         value: "image/*" # match objects with 'content-type', with all values starting with 'image/'
//     kmskey: "key-id" # match objects with KMS key-id (applicable only for sse-kms)
//   notify:

//	backed by this underlying array.
//	Map: An empty map is allocated with enough space to hold the
//	specified number of elements. The size may be omitted, in which case
//	a small starting size is allocated.
//	Channel: The channel's buffer is initialized with the specified
//	buffer capacity. If zero, or the size is omitted, the channel is
//	unbuffered.
func make(t Type, size ...IntegerType) Type