kcdctl

This is the source code for the demo done as part of the talk "Imperative, Declarative and Kubernetes" at the Kubernetes Community Days, Bengaluru 2021 conferernce.

Talk and Slides

• The talk recording can be found here.
• The slides used for the talk can be found here.

Pre-requisites

To run the demo, you will need the following installed:

• Docker
• Go

Installation

Install using go get

go get -u github.com/MadhavJivrajani/kcdctl

Note: This will install the kcdctl executable which can be used anywhere in the termnial provided $GOPATH/bin is in your PATH.

Install from source

git clone https://github.com/MadhavJivrajani/kcdctl.git && cd kcdctl
go build -o kcdctl main.go
mv kcdctl /usr/local/bin # to make the executable available system wide

Usage

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A tool to help demo imperative and declarative systems as part of the KCD Bangalore Conference

Usage:
  kcdctl [command]

Available Commands:
  apply       applies a configuarion to the system
  cleanup     cleanup removes all containers that were created as part of a given configuration file
  help        Help about any command
  spawn       spawn creates containers

Flags:
      --config string   config file (default is $HOME/.kcdctl.yaml)
  -h, --help            help for kcdctl

Use "kcdctl [command] --help" for more information about a command.

apply

applies a configuarion to the system

Usage:
  kcdctl apply [flags]

Flags:
  -f, --file string   file is the yaml configuarion file that the user wants to apply on the system
  -h, --help          help for apply
  -m, --mode string   mode is the mode the system should be run in: imperative/declarative (default "declarative")

Global Flags:
      --config string   config file (default is $HOME/.kcdctl.yaml)

An example of a configuration file can be found here.

To run in declarative mode:

# don't really need to mention mode for declarative.
kcdctl apply -f examples/cluster.yaml --mode=declarative

To run in imperative mode:

kcdctl apply -f examples/cluster.yaml --mode=imperative

The first step in either of the modes is BootstrapHost, in which:

• A docker network called kcd-bangalore-demo is created and the load balancer container is attached to this network.
• A load balancer is created in accordance with the config provided by the user.

Note:

If an excess number of containers than the desired state are created, nothing is done, excess container deletion isn't taken care of, but ideally should happen.

spawn

spawn creates containers

Usage:
  kcdctl spawn [flags]

Flags:
  -d, --diff int      diff is the number of containers to spawn (right now, assumed to be +ve) (default 1)
  -f, --file string   file is the yaml configuarion file that the user wants to apply on the system
  -h, --help          help for spawn

Global Flags:
      --config string   config file (default is $HOME/.kcdctl.yaml)

spawn is assumed to be used when in an imperative mode. In a declarative mode, spawning of containers is handled automatically.

cleanup

cleanup removes all containers that were created as part of a given configuration file

Usage:
  kcdctl cleanup [flags]

Flags:
  -f, --file string   file is the yaml configuarion file using which containers will be cleaned up
  -h, --help          help for cleanup

Global Flags:
      --config string   config file (default is $HOME/.kcdctl.yaml)

cleanup performs the following steps:

• First stop containers that are running the application.
• Next stop the load balancer container.
• Finally delete the docker network that was created during BootstrapHost

Images used:

• The image used for the application running can be found here.
• The image used for the loadbalancer can be found here.