kubectl

Hoop can be configured to use the kubectl command line for managing resources and executing actions on workloads in Kubernetes.

Connection Configuration

Name	Type	Description
`KUBECONFIG`	filesystem	A kubeconfig file with permission to exec into pods in a namespace

Connection Command

shell
hoop admin create conn k8s -a <agent> -- kubectl

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The assumption is that the service account, where the agent is deployed, has the necessary permissions to interact with the Kubernetes API. Alternatively, create the connection passing your local KUBECONFIG. Example:

shell
hoop admin create conn k8s \
	-a <agent> \
	-e b64-filesystem:KUBECONFIG=$(cat $HOME/.kube/config |base64) \
	-- kubectl

How to Use

bash
# view pods in the default namespace
hoop exec k8s -- get pods
# restart an app
hoop exec k8s -- rollout restart deployment/myapp
# scale up an app
hoop exec k8s -- scale --replicas=3 deployment/myapp

It’s possible to narrow down the commands in distinct connections, this gives a better user experience

Update the connection with the command bellow

shell
hoop admin create conn k8s -a <agent> -- \
  kubectl --namespace prod rollout

Then it’s possible

shell
hoop exec k8s -- restart deployment/myapp
hoop exec k8s -- undo deployment/myapp

Interactive

kubectl provides ways of creating interactive sessions with pods. It’s possible to map these commands to Hoop to obtain interactive sessions allocating a pseudo TTY.

Connection Command

shell
hoop admin create conn k8s-exec -a <agent> -- \
  kubectl exec --tty --stdin deployment/myapp --

How to Use

Start an interactive bash session with a deployment/pod

shell
hoop connect myapp -- bash

This will open an interactive session with the deployment myapp. It’s possible to map any command that spawns an interactive session.

Then, it’s possible to gain a rails console session

shell
hoop connect myapp -- rails console

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Note that kubectl exec is used with -tty and --stdin arguments. These flags are required when using hoop connect

One-off scripts

Processes can be spawned in an ad-hoc manner using kubectl exec. However, in some cases, an interactive shell may be overly permissive.

Connection Configuration

Name	Type	Description
`KUBECONFIG`	filesystem	A kubeconfig file with permission to exec into pods in a namespace

Connection Command

shell
hoop admin create conn exec-oneoff -a <agent> -- \
	kubectl exec --stdin deployment/myapp --

How to Use

This example executes an one-off process using ruby.

shell
hoop exec exec-oneoff -- rails runner 'puts Rails.env'

Narrowing down the exec arguments, allow passing the stdin and executing ruby scripts.

Edit the connection command with the bellow content

shell
hoop admin create conn exec-oneoff -a <agent> -- \
	kubectl exec --stdin deployment/myapp -- rails runner -

Then, it’s possible

shell
hoop exec exec-oneoff <<EOF
myvar='Hello'
puts myvar
EOF

The connection now runs one-off process accepting ruby scripts from the standard input.