Octant Container Exec

Add the ability to execute a command in a container.

Summary

Motivation

Currently executing a command in a container would be done using a tool such as kubectl. Executing a command in a container includes having to pass multiple arguments such as pod name, command, and namespace to kubectl exec. Octant intends to make this an easy one or two click operation from the Pod view.

Goals

• Allow interactive and non-interactive.
• For interactive, provide a list of defaults to choose from:
  • sh, bash, zsh?, fish?
• Allow custom commands to be entered.
• Allow command to be executed across all containers.
  • a new terminal component with the output from each exec command would be created

Non-Goals

• Aggregating results from multiple containers.

Proposal

Implementation Details

Container Exec Action

An action that holds the details of the command to execute will be created.

This action will be generated from the Pod view and include the container(s), the command to run, and if the resulting terminal should be interactive interactive.

The result of the action will be rendered as TerminalComponent(s). These will be displaed as new tabs on the Pod view.

The tabs will be flagged closable and have a close action that will end the context for interactive sessions.

TabComponent

Add an isClosable and closeAction to tabs.

TerminalComponent

Create a new TerminalComponent using https://xtermjs.org/ for the frontend.

The backend component will include the stream name for the component which will associate the output from the executor with a given TerminalComponent.

Container Command Executor

Create an Executor using https://github.com/kubernetes/client-go/blob/master/tools/remotecommand/remotecommand.go

We will create a factory that assembles SPDYExector given a desired container and command to execute.

More specifically that factory will use remotecommand.NewSPDYExecutor to create a SPDYExecutor and create unique stream names for each executor. Calling the Stream method we will send output to our TerminalComponent using websockets.

These executors will have contexts to ensure they are cleaned up properly when the terminal goes away or Octant is closed.

User Interface

Add a listing page of all currently open temrinals. This page will allow you easily jump to an open terminal as well as close open terminals (including disconncted terminals).

Disconnects and Timeouts

Terminals will timeout after a set idle period of 300 seconds. Alerts will be used to notify a user of when a terminal has timed out or disconnceted. Terminals that are disconnceted due to timeout or communication error will remain present in the UI.