> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mythic-c2.net/llms.txt
> Use this file to discover all available pages before exploring further.

# OnContainerStart

> onContainerStart Functionality

## What is it?

OnContainerStartFunction and on\_container\_start are functions you can optionally implement in any container to get execution, per operation, when the container starts up. This is helpful when your container needs to do some housekeeping and prep an agent, c2 profile, or even eventing before anything else happens.

## Where is it?

This function is one you can implement as part of the definition for your container (PayloadType, C2Profile, Eventing, etc).

## What does it do?

This function gets an APIToken that is valid for 5 minutes and has the permissions of a spectator. This allows your container to query everything it needs, but not make any modifications.

## When is it called?

This function is called when your container first comes online and syncs with Mythic. It's also called (as of Mythic 3.3.1-rc26) when anybody adds/removes/edits a file inside of your container through the UI. This allows you, the container developer, to be reactive to changes users make to files that might affect things like configurations.

<CodeGroup>
  ```python Python theme={"system"}
  class ContainerOnStartMessage:
      def __init__(self,
                   container_name: str = "",
                   operation_id: int = 0,
                   server_name: str = "",
                   apitoken: str = "",
                   **kwargs):
          self.ContainerName = container_name
          self.OperationID = operation_id
          self.ServerName = server_name
          self.APIToken = apitoken

      def to_json(self):
          return {
              "container_name": self.ContainerName,
              "operation_id": self.OperationID,
              "server_name": self.ServerName,
              "apitoken": self.APIToken
          }

  class ContainerOnStartMessageResponse:
      def __init__(self,
                   ContainerName: str = "",
                   EventLogInfoMessage: str = "",
                   EventLogErrorMessage: str = ""):
          self.ContainerName = ContainerName
          self.EventLogInfoMessage = EventLogInfoMessage
          self.EventLogErrorMessage = EventLogErrorMessage

      def to_json(self):
          return {
              "container_name": self.ContainerName,
              "stdout": self.EventLogInfoMessage,
              "stderr": self.EventLogErrorMessage
          }
  # define this function inside of any Payload Type, C2 Profile, Eventing, etc etc class
  async def on_container_start(self, message: ContainerOnStartMessage) -> ContainerOnStartMessageResponse:
          return ContainerOnStartMessageResponse(ContainerName=self.name)
  ```

  ```go Golang theme={"system"}
  type ContainerOnStartMessage struct {
  	ContainerName string `json:"container_name"`
  	OperationID   int    `json:"operation_id"`
  	OperationName string `json:"operation_name"`
  	ServerName    string `json:"server_name"`
  	APIToken      string `json:"apitoken"`
  }

  type ContainerOnStartMessageResponse struct {
  	ContainerName        string `json:"container_name"`
  	EventLogInfoMessage  string `json:"stdout"`
  	EventLogErrorMessage string `json:"stderr"`
  }
  OnContainerStartFunction func(sharedStructs.ContainerOnStartMessage) sharedStructs.ContainerOnStartMessageResponse `json:"-"`
  ```
</CodeGroup>