Full Code of yokawasa/kubectl-plugin-ssh-jump for AI

Repository: yokawasa/kubectl-plugin-ssh-jump
Branch: master
Commit: b6472ca90666
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Directory structure:
gitextract_r71_3ox3/

├── .gitignore
├── LICENSE
├── README.md
├── VERSION
├── kubectl-ssh-jump
└── ssh-jump.yaml

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FILE: README.md
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# kubectl-plugin-ssh-jump

[![kubectl plugin](https://img.shields.io/badge/kubectl-plugin-blue.svg)](https://github.com/topics/kubectl-plugin)

A kubectl plugin to access Kubernetes nodes or remote services using a SSH jump Pod

A `jump host` Pod is an intermediary Pod or an SSH gateway to Kubernetes node machines, through which a connection can be made to the node machines or remote services.

Here is an scenario where you want to connect to Kubernetes nodes or remote services, but you have to go through a jump host Pod, because of firewalling, access privileges. etc. There is a number of valid reasons why the jump hosts are needed...

**CASE 1: SSH into Kubernetes nodes via SSH jump Pod**
![](assets/ssh-jump-node-ssh-login.png)

**CASE 2: Connect to remote serivces via SSH local port forwarding**. SSH local port forwarding allows to forward the traffic form local machine to SSH jump then SSH jump will forward the traffic to remote services (host:port)s. 
![](assets/ssh-jump-ssh-tunnel.png)

> [NOTE]
> - Kubectl versions >= `1.12.0` (Preferred)
>   - As of Kubernetes 1.12, kubectl now allows adding external executables as subcommands. For more detail, see [Extend kubectl with plugins](https://kubernetes.io/docs/tasks/extend-kubectl/kubectl-plugins/)
>   - You can run the plugin with `kubectl ssh-jump ...`
> - Kubectl versions < `1.12.0`
>   - You still can run the plugin directly with `kubectl-ssh-jump ...`


**Table of Content**
<!-- TOC -->

- [kubectl-plugin-ssh-jump](#kubectl-plugin-ssh-jump)
	- [Pre-requistes](#pre-requistes)
	- [Installation](#installation)
		- [Install through krew](#install-through-krew)
		- [Manual Installation](#manual-installation)
	- [How to use](#how-to-use)
		- [Usage](#usage)
			- [Option parameters Cache](#option-parameters-cache)
			- [SSH Agent ssh-agent](#ssh-agent-ssh-agent)
		- [Customize SSH jump pod](#customize-ssh-jump-pod)
		- [Examples](#examples)
			- [CASE 1: SSH into Kubernetes nodes via SSH jump Pod](#case-1-ssh-into-kubernetes-nodes-via-ssh-jump-pod)
				- [-1 - You have private & public SSH key on your side](#-1---you-have-private--public-ssh-key-on-your-side)
				- [-2 - You have .pem file but you don't have public key on your side](#-2---you-have-pem-file-but-you-dont-have-public-key-on-your-side)
			- [CASE 2: Access remote serivces via SSH local port forwarding](#case-2-access-remote-serivces-via-ssh-local-port-forwarding)
				- [-1 - Configuring SSH local port forwarding with --args or -a option](#-1---configuring-ssh-local-port-forwarding-with---args-or--a-option)
	- [Useful Links](#useful-links)
	- [Contributing](#contributing)

<!-- /TOC -->


## Pre-requistes
This plugin needs the following programs:
* ssh(1)	
* ssh-agent(1)
* ssh-keygen(1)

## Installation

### Install through krew
This is a way to install kubectl-ssh-jump through [krew](https://krew.sigs.k8s.io/). After installing krew by following [this](https://krew.sigs.k8s.io/docs/user-guide/setup/install/), you can install kubectl-ssh-jump like this:

```sh
$ kubectl krew install ssh-jump
```

Expected output would be like this:
```
Updated the local copy of plugin index.
Installing plugin: ssh-jump
CAVEATS:
\
 |  This plugin needs the following programs:
 |  * ssh(1)
 |  * ssh-agent(1)
 |
 |  Please follow the documentation: https://github.com/yokawasa/kubectl-plugin-ssh-jump
/
Installed plugin: ssh-jump
```

Once it's installed, run:
```sh
$ kubectl plugin list

The following kubectl-compatible plugins are available:

/Users/yoichi.kawasaki/.krew/bin/kubectl-krew
/Users/yoichi.kawasaki/.krew/bin/kubectl-ssh_jump

$ kubectl ssh-jump
```

### Manual Installation

Install the plugin by copying the script in the $PATH of your shell.

```sh
# Get source
$ git clone https://github.com/yokawasa/kubectl-plugin-ssh-jump.git
$ cd kubectl-plugin-ssh-jump
$ chmod +x kubectl-ssh-jump
# Add kubeclt-ssh-jump to the install path.
$ sudo cp -p kubectl-ssh-jump /usr/local/bin
```

Once in the $PATH, run:
```sh
$ kubectl plugin list

The following kubectl-compatible plugins are available:
/usr/local/bin/kubectl-ssh-jump

$ kubectl ssh-jump
```

## How to use

### Usage

```TXT
Usage: 
  kubectl ssh-jump <dest_node> [options]

Options:
  <dest_node>                     Destination node name or IP address
                                  dest_node must start from the following letters:
                                  ASCII letters 'a' through 'z' or 'A' through 'Z',
                                  the digits '0' through '9', or hyphen ('-').
                                  NOTE: Setting dest_node as 'jumphost' allows to
                                  ssh into SSH jump Pod as 'root' user
  -u, --user <sshuser>            SSH User name
  -i, --identity <identity_file>  Identity key file, or PEM(Privacy Enhanced Mail)
  -p, --pubkey <pub_key_file>     Public key file
  -P, --port <port>               SSH port for target node SSH server
                                  Defaults to 22
  -a, --args <args>               Args to exec in ssh session
  -n, --namespace <ns>            Namespace for jump pod
  --context <context>             Kubernetes context
  --pod-template <file>           Path to custom sshjump pod definition
  -l, --labels <key>=<val>[,...]  Find a pre-existing sshjump pod using labels
  --skip-agent                    Skip automatically starting SSH agent and adding
                                  SSH Identity key into the agent before SSH login
                                  (=> You need to manage SSH agent by yourself)
  --cleanup-agent                 Clearning up SSH agent at the end
                                  The agent is NOT cleaned up in case that
                                  --skip-agent option is given
  --cleanup-jump                  Clearning up sshjump pod at the end
                                  Defaults to skip cleaning up sshjump pod
  -v, --verbose                   Run ssh in verbose mode (=ssh -vvv)
  -h, --help                      Show this message

Example:
  Scenario1 - You have private & public SSH key on your side
  $ kubectl ssh-jump -u myuser -i ~/.ssh/id_rsa -p ~/.ssh/id_rsa.pub hostname

  Scenario2 - You have .pem file but you don't have public key on your side
  $ kubectl ssh-jump -u ec2-user -i ~/.ssh/mykey.pem hostname
```

#### Option parameters Cache

`username`, `identity`, `pubkey`, `port` options are cached, therefore you can omit these options afterward. The options are stored in a file named `$HOME/.kube/kubectlssh/options`

```sh
$ cat $HOME/.kube/kubectlssh/options
sshuser=myuser
identity=/Users/yoichi.kawasaki/.ssh/id_rsa_k8s
pubkey=/Users/yoichi.kawasaki/.ssh/id_rsa_k8s.pub
port=22
```

#### SSH Agent (ssh-agent)

The plugin automatically check if there are any `ssh-agents` started running by the plugin, and starts `ssh-agent`if it doesn't find any `ssh-agent` running and adds SSH Identity key into the agent before SSH login. If the command find that ssh-agent is already running, it doesn't start a new agent, and re-use the agent.
Add `--cleanup-agent` option if you want to kill the created agent at the end of command.

In addtion, add `--skip-agent` option if you want to skip automatic starting `ssh-agent`. This is actually a case where you already have ssh-agent managed or you want to manually start the agent.

### Customize SSH jump pod

You can customize the sshjump pod created by `kubectl ssh-jump` by setting the `--pod-template` flag to the path to a pod template on disk.
However, customized sshjump pods must be named `sshjump` and run in the current namespace or `kubectl ssh-jump` won't be able to find them without the required flags.
If you change the pod name, you must give the pod a unique set of labels and provide them on the command line by setting the `--labels` flag.

You can also specify the namespace and context used by `kubectl ssh-jump` by setting the `--namespace` and `--context` flags respectively.

### Examples

Show all node list. Simply executing `kubectl ssh-jump` gives you the list of destination nodes as well as command usage

```sh
$ kubectl ssh-jump

Usage: 
  kubectl ssh-jump <dest_node> [options]

...snip...

List of destination node...
Hostname                    Internal-IP
aks-nodepool1-18558189-0    10.240.0.4
...snip...
```


#### CASE 1: SSH into Kubernetes nodes via SSH jump Pod

##### 1-1 - You have private & public SSH key on your side

Suppose you have private & public SSH key on your side and you want to SSH to a node named `aks-nodepool1-18558189-0`, execute the plugin with options like this:

- usernaem: `azureuser`
- identity:`~/.ssh/id_rsa_k8s`
- pubkey:`~/.ssh/id_rsa_k8s.pub`)

```sh
$ kubectl ssh-jump aks-nodepool1-18558189-0 \
  -u azureuser -i ~/.ssh/id_rsa_k8s -p ~/.ssh/id_rsa_k8s.pub
```

> [NOTE] you can try SSH into a node using node IP address (`Internal-IP`) instead of `Hostname`

As explained in usage secion, `username`, `identity`, `pubkey` options will be cached, therefore you can omit these options afterward.

```sh
$ kubectl ssh-jump aks-nodepool1-18558189-0
```

You can pass the commands to run in the destination node like this (Suppose that `username`, `identity`, `pubkey` options are cached):
```sh
echo "uname -a" | kubectl ssh-jump aks-nodepool1-18558189-0

(Output)
Linux aks-nodepool1-18558189-0 4.15.0-1035-azure #36~16.04.1-Ubuntu SMP Fri Nov 30 15:25:49 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
```

You can pass commands with `--args` or `-a` option
``` sh
kubectl ssh-jump aks-nodepool1-18558189-0 --args "uname -a"

(Output)
Linux aks-nodepool1-18558189-0 4.15.0-1035-azure #36~16.04.1-Ubuntu SMP Fri Nov 30 15:25:49 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
```

You can clean up sshjump pod at the end of the command with `--cleanup-jump` option, otherwise, the sshjump pod stay running by default.

```sh
$ kubectl ssh-jump aks-nodepool1-18558189-0 \
  -u azureuser -i ~/.ssh/id_rsa_k8s -p ~/.ssh/id_rsa_k8s.pub \
  --cleanup-jump
```

You can clean up ssh-agent at the end of the command with `--cleanup-agent` option, otherwise, the ssh-agent process stay running once it's started.

```sh
$ kubectl ssh-jump aks-nodepool1-18558189-0 \
  -u azureuser -i ~/.ssh/id_rsa_k8s -p ~/.ssh/id_rsa_k8s.pub \
  --cleanup-agent
```

You can skip starting `ssh-agent` by giving `--skip-agent`. This is actually a case where you already have ssh-agent managed. Or you can start new ssh-agent and add an identity key to the ssh-agent like this:

```sh
# Start ssh-agent manually
$ eval `ssh-agent`
# Add an arbitrary private key, give the path of the key file as an argument to ssh-add
$ ssh-add ~/.ssh/id_rsa_k8s
# Then, run the plugin with --skip-agent
$ kubectl ssh-jump aks-nodepool1-18558189-0 \
  -u azureuser -i ~/.ssh/id_rsa_k8s -p ~/.ssh/id_rsa_k8s.pub \
  --skip-agent

# At the end, run this if you want to kill the current agent
$ ssh-agent -k
```

##### 1-2 - You have .pem file but you don't have public key on your side

From v0.4.0, the plugin supports PEM (Privacy Enhanced Mail) scenario where you create key-pair but you only have .pem / private key (downloaded from AWS, for example) and you don't have the public key on your side.

Suppose you've already downloaded a pem file and you want to ssh to your EKS worker node (EC2) named `ip-10-173-62-96.ap-northeast-1.compute.internal` using the pem, execute the plugin with options like this:

- usernaem: `ec2-user`
- identity: `~/.ssh/mykey.pem`

```sh
$ kubectl ssh-jump -u ec2-user -i ~/.ssh/mykey.pem ip-10-173-62-96.ap-northeast-1.compute.internal
```
#### CASE 2: Access remote serivces via SSH local port forwarding

SSH local port forwarding allows to forward the traffic form local machine to SSH jump then SSH jump will forward the traffic to remote services (host:port)s.
##### 2-1 - Configuring SSH local port forwarding with --args or -a option

Suppose you have private & public SSH key on your side and you want to access a remote server (IP: `10.100.10.8`) using `3389`/TCP port which is not accessible directly but accessible via SSH jump, execute the plugin with options like this, at first:

- identity:`~/.ssh/id_rsa_k8s`
- pubkey:`~/.ssh/id_rsa_k8s.pub`)

 The command below allows to forward the traffic form local machine (`localhost:13200`) to SSH jump then SSH jump will forward the traffic to the remote server (`10.100.10.8:3389`). 
```sh
$ kubectl ssh-jump sshjump \
  -i ~/.ssh/id_rsa_k8s -p ~/.ssh/id_rsa_k8s.pub \
  -a "-L 13200:10.100.10.8:3389"
```
> - `sshjump` is the hostname for SSH jump Pod
> -  The value for `--arg` or `-a` should be in this format: "-L local_port:remote_address:remote_port"

Now, you're ready to access to the remote server at port 13200 at local machine.

## Useful Links

- [Extend kubectl with plugins](https://kubernetes.io/docs/tasks/extend-kubectl/kubectl-plugins/)
- [Write your own kubectl subcommands](https://ahmet.im/blog/kubectl-plugins/)
- [SSH-AGENT - SINGLE SIGN-ON USING SSH](https://www.ssh.com/ssh/agent)

## Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/yokawasa/kubectl-plugin-ssh-jump


================================================
FILE: VERSION
================================================
0.7.3


================================================
FILE: kubectl-ssh-jump
================================================
#!/usr/bin/env bash
# vim: sw=2:
#
# A kubectl plugin to ssh into Kubernetes nodes using a SSH jump host Pod
#

[[ -n $DEBUG ]] && set -x -e

PLUGIN_DIR="${HOME}/.kube/kubectlssh"
PLUGIN_SSH_OPTIONS_FILE="${PLUGIN_DIR}/options"
MAX_POD_CREATION_TIME=10   # unit: second
SSH_AGENT_ENV_FILE="${PLUGIN_DIR}/sshagent-env"
SSH_AGENT_PID_FILE="${PLUGIN_DIR}/sshagent-pid"

help(){
  echo "Usage: "
  echo "  kubectl ssh-jump <dest_node> [options]"
  echo ""
  options
}

options(){
  cat <<"EOF"
Options:
  <dest_node>                     Destination node name or IP address
                                  dest_node must start from the following letters:
                                  ASCII letters 'a' through 'z' or 'A' through 'Z',
                                  the digits '0' through '9', or hyphen ('-').
                                  NOTE: Setting dest_node as 'jumphost' allows to 
                                  ssh into SSH jump Pod as 'root' user 
  -u, --user <sshuser>            SSH User name
  -i, --identity <identity_file>  Identity key file, or PEM(Privacy Enhanced Mail)
  -p, --pubkey <pub_key_file>     Public key file
  -P, --port <port>               SSH port for target node SSH server
                                  Defaults to 22
  -a, --args <args>               Args to exec in ssh session
  -n, --namespace <ns>            Namespace for jump pod
  --context <context>             Kubernetes context
  --pod-template <file>           Path to custom sshjump pod definition
  -l, --labels <key>=<val>[,...]  Find a pre-existing sshjump pod using labels
  --skip-agent                    Skip automatically starting SSH agent and adding 
                                  SSH Identity key into the agent before SSH login
                                  (=> You need to manage SSH agent by yourself)
  --cleanup-agent                 Clearning up SSH agent at the end
                                  The agent is NOT cleaned up in case that
                                  --skip-agent option is given
  --cleanup-jump                  Clearning up sshjump pod at the end
                                  Defaults to skip cleaning up sshjump pod
  -v, --verbose                   Run ssh in verbose mode (=ssh -vvv)
  -h, --help                      Show this message

Example:
  Scenario1 - You have private & public SSH key on your side
  $ kubectl ssh-jump -u myuser -i ~/.ssh/id_rsa -p ~/.ssh/id_rsa.pub hostname

  Scenario2 - You have .pem file but you don't have public key on your side
  $ kubectl ssh-jump -u ec2-user -i ~/.ssh/mykey.pem hostname

EOF
}

read_options(){
  if [[ -f "${PLUGIN_SSH_OPTIONS_FILE}" ]]; then
    source ${PLUGIN_SSH_OPTIONS_FILE}
  fi  
}

write_options(){
  local sshuser="$1"
  local identity="$2"
  local pubkey="$3"
  local port="$4"

  cat << EOF > ${PLUGIN_SSH_OPTIONS_FILE}
sshuser=${sshuser}
identity=${identity}

pubkey=${pubkey}
port=${port}
EOF
}

get_node_list(){
  echo "List of destination node..."
  kubectl "${k_args[@]}" get no -o custom-columns=Hostname:.metadata.name,Internal-IP:'{.status.addresses[?(@.type=="InternalIP")].address}'
  echo ""
}

get_openssh_verion_number() {
  ssh -V 2>&1 | awk -F'[_,]' '{print $2+0}'
}

cleanup_sshjump_pod(){
  echo "Clearning up SSH Jump host (Pod)..."
  kubectl "${k_args[@]}" delete pod sshjump
}

check_and_start_agent(){
  local identity="$1"

  is_alive="no"
  if [ -f ${SSH_AGENT_PID_FILE} ]; then
    SSH_AGENT_PID=$(cat ${SSH_AGENT_PID_FILE})
    source ${SSH_AGENT_ENV_FILE}
    if [ ${SSH_AGENT_PID} -gt 0 ] && ps -p ${SSH_AGENT_PID} > /dev/null
    then
      echo "ssh-agent is already running"
      is_alive="yes"
    fi
  fi
  if [ "${is_alive}" = "no" ]; then
    ssh-agent > ${SSH_AGENT_ENV_FILE}
    agent_pid=$(cat ${SSH_AGENT_ENV_FILE} | grep 'echo Agent pid' |sed 's/echo Agent pid //; s/;//')
    echo "Started ssh-agent: pid=${agent_pid}"
    echo ${agent_pid} > ${SSH_AGENT_PID_FILE}
    source ${SSH_AGENT_ENV_FILE}
    ssh-add ${identity}
  fi
}

cleanup_agent(){
  echo "Killing ssh-agent..."
  ssh-agent -k
  if [ -f ${SSH_AGENT_PID_FILE} ]; then
    rm ${SSH_AGENT_PID_FILE}
  fi 
  if [ -f ${SSH_AGENT_ENV_FILE} ]; then
    rm ${SSH_AGENT_ENV_FILE}
  fi 
}

create_jump_pod(){
  local pod_template
  if [[ -n "${jump_pod_template:-}" && -e "${jump_pod_template}" ]]; then
    pod_template=$(<"${jump_pod_template}")
  fi
  if [[ -z "${pod_template}" ]]; then
    pod_template=$(cat <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: sshjump
  labels:
    env: test
spec:
  containers:
  - name: sshjump
    image: corbinu/ssh-server
    ports:
    - containerPort: 22
  nodeSelector:
    kubernetes.io/os: linux
    kubernetes.io/arch: amd64
EOF
)
  fi
  echo "Creating SSH jump host (Pod)..."
  echo "${pod_template}" | kubectl "${k_args[@]}" apply -f -
}

run_ssh_node(){
  local destnode="$1"
  local sshuser="$2"
  local identity="$3"
  local pubkey="$4"
  local port="$5"
  local sshargs="$6"
  local pod_labels="$7"

  local pod_name
  if [[ -n "${pod_labels}" ]]; then
    pods=($(kubectl "${k_args[@]}" get pods -l "${pod_labels}" -o custom-columns=:metadata.name --no-headers 2>/dev/null))
    if [[ "${#pods[@]}" -eq 0 ]]; then
      echo "Error: failed to find pods with labels ${pod_labels}" >&2
      exit 1
    fi
    pod_name="${pods[0]}"
    echo "Using SSH jump pod ${pod_name}..."
  else
    pod_name=sshjump
    # Install an SSH Server if not yet installed
    if ! kubectl "${k_args[@]}" get pod "${pod_name}" &>/dev/null; then
      create_jump_pod
      # Wait until sshjump gets ready
      c=1
      while [[ ${c} -le ${MAX_POD_CREATION_TIME} ]];
      do
        pod_status=$(kubectl "${k_args[@]}" get pod "${pod_name}" -o jsonpath='{.status.phase}')
        if [[ "${pod_status}" == "Running" ]]; then
          break
        fi
        (( c++ ))
        sleep 1
      done
    fi
  fi

  local identity_sshjump=${identity}
  local pubkey_sshjump=${pubkey}
  if [ ! -f "${pubkey_sshjump}" ]; then
    # Generate temp private/public key to ssh to the sshjump if the pubkey isn't given
    identity_sshjump=${PLUGIN_DIR}/id_rsa_sshjump
    pubkey_sshjump=${PLUGIN_DIR}/id_rsa_sshjump.pub
    if [ ! -f "${pubkey_sshjump}" ]; then
      echo "Generating nopass SSH pri/pub key to ssh to the sshjump ..."
      ssh-keygen -t rsa -f ${identity_sshjump} -N '' > /dev/null
    fi
  fi

  # Setup portforward
  kubectl "${k_args[@]}" port-forward "${pod_name}" 2222:22 2>/dev/null &
  pid_port_forward=$!

  # Wait a bit for the port forwarding to get ready for connection handling for 2222
  sleep 2

  # Inject public SSH key to sshjump
  cat ${pubkey_sshjump} | \
    kubectl "${k_args[@]}" exec -i "${pod_name}" -- /bin/bash -c "cat > /root/.ssh/authorized_keys"

  # Add default ssh option
  sshargs="${sshargs} -o StrictHostKeyChecking=no"
 
  # Add RSA workaround options if the local OpenSSH version >= 8.5
  sshversion=$(get_openssh_verion_number)
  if [ $(echo "${sshversion} >= 8.5" | bc) -eq 1 ]; then
    sshargs="${sshargs} -o HostkeyAlgorithms=+ssh-rsa -o PubkeyAcceptedAlgorithms=+ssh-rsa"
  fi

  if [ "${destnode}" = "sshjump" ]; then
    ssh ${sshuser}@127.0.0.1 -p 2222 -i ${identity_sshjump} ${sshargs}
  else
    # Using the SSH Server as a jumphost (via port-forward proxy), ssh into the desired Node
    ssh -i ${identity} -p ${port} ${sshuser}@${destnode} \
      -o "ProxyCommand ssh root@127.0.0.1 -p 2222 -i ${identity_sshjump} ${sshargs} \"nc %h %p\"" ${sshargs}
  fi
  # Stop port-forward
  kill -3 ${pid_port_forward} 2>/dev/null
}

plugin_main() {
  skip_agent=no
  cleanup_jump=no
  cleanup_agent=no
  pod_labels=
  sshargs=""
  k_args=()
  while [ $# -gt 0 ] ; do
    nSkip=1
    case $1 in
      "-h" | "--help")
        help
        exit 0
	      ;;
      "-v" | "--verbose" )
        sshargs="${sshargs} -vvv"
        ;;
     "--cleanup-jump")
        cleanup_jump=yes
        ;;
      "--cleanup-agent")
        cleanup_agent=yes
        ;;
      "--skip-agent")
        skip_agent=yes
        ;;
      "-u" | "--user" )
        c_sshuser=$2
        nSkip=2
        ;;
      "-i" | "--identity" )
        c_identity=$2
        nSkip=2
        ;;
      "-p" | "--pubkey" )
        c_pubkey=$2
        nSkip=2
        ;;
      "-P" | "--port")
        c_port=$2
        nSkip=2
        ;;
      "-a" | "--args" )
        sshargs="${sshargs} $2"
        nSkip=2
        ;;
      "-n" | "--namespace" | "--context")
         k_args+=("$1" "$2")
         nSkip=2
         ;;
      "--pod-template")
         jump_pod_template="$2"
         nSkip=2
         ;;
      "-l" | "--labels")
        pod_labels="$2"
        nSkip=2
        ;;
      [0-9a-zA-Z-]*)
        destnode=$1
        ;;
      *)
        help >&2
        exit 1
        ;;
    esac
    shift $nSkip
  done

  if [[ "$(type kubectl &>/dev/null; echo $?)" -eq 1 ]]; then
    echo "Error: missing kubectl command" >&2
    echo "Please install kubectl (https://kubernetes.io/docs/tasks/tools/install-kubectl/)" >&2
    exit 1
  fi

  if [ ! -n "${destnode}" ]; then
    help >&2
    echo ""
    get_node_list
    exit 1
  fi
  if [ "${destnode}" = "sshjump" ]; then
    echo "Setting destination name as 'jumphost' allows to ssh into SSH jump Pod as 'root' user"
    c_sshuser=root
  fi

  if [ ! -d ${PLUGIN_DIR} ]; then
    mkdir -p ${PLUGIN_DIR}
  fi
  read_options

  if [ ! -n "${c_sshuser}" ]; then
    if [ ! -n "${sshuser}" ]; then
      c_sshuser="${USER}"  # default: Current executing user
    fi
    echo "using: sshuser=${sshuser}"
    c_sshuser="${sshuser}"
  fi
  if [ ! -f "${c_identity}" ]; then
    if [ ! -f "${identity}" ]; then
      echo "Error: identity file is required" >&2
      help >&2
      exit 1
    fi
    echo "using: identity=${identity}"
    c_identity="${identity}"
  fi
  if [ ! -f "${c_pubkey}" ]; then
    # From v0.4.0 pubkey file is optional to support PEM scenario
    # where you don't have public key on your side
    #if [ ! -n "${pubkey}" ]; then
    #  help >&2
    #  exit 1
    #fi
    if [ -f "${pubkey}" ]; then
      echo "using: pubkey=${pubkey}"
      c_pubkey="${pubkey}"
    fi
  fi
  if [ ! -n "${c_port}" ]; then
    if [ ! -n "${port}" ]; then
      port="22"    # default: 22
    fi
    echo "using: port=${port}"
    c_port="${port}"
  fi

  if [ "${sshargs}" != "" ]; then
    echo "using: args=${sshargs}"
  fi

  if [ "${jump_pod_template}" != "" ]; then
     echo "using: pod-template=${jump_pod_template}"
  fi

  # Caching current ssh options
  write_options "${c_sshuser}" "${c_identity}" "${c_pubkey}" "${c_port}"

  if [ "${skip_agent}" = "no" ]; then
    check_and_start_agent ${c_identity}
  fi
  # SSH Logging into desitnation node via Jump host
  run_ssh_node "${destnode}" "${c_sshuser}" "${c_identity}" "${c_pubkey}" "${c_port}" "${sshargs}" "${pod_labels}"

  # Cleaning up resources if needed
  if [[ "${cleanup_jump}" == "yes" && -z "${pod_labels}" ]]; then
    cleanup_sshjump_pod
  fi
  if [[ "${skip_agent}" = "no" && "${cleanup_agent}" = "yes" ]]; then
    cleanup_agent
  fi
}

plugin_main "$@"


================================================
FILE: ssh-jump.yaml
================================================
apiVersion: krew.googlecontainertools.github.com/v1alpha2
kind: Plugin
metadata:
  name: ssh-jump
spec:
  version: "v0.6.0"
  homepage: https://github.com/yokawasa/kubectl-plugin-ssh-jump
  platforms:
  - selector:
      matchExpressions:
      - {key: os, operator: In, values: [darwin, linux]}
    uri: https://github.com/yokawasa/kubectl-plugin-ssh-jump/archive/0.6.0.zip
    sha256: "a24149bb1b1ccba91ae87c86d21625adf9e110b9e81a0ab58ec84343e0f99ede"
    files:
    - from: "./*/kubectl-ssh-jump"
      to: .
    - from: "./*/LICENSE"
      to: .
    bin: "./kubectl-ssh-jump"
  shortDescription: Access nodes or services using SSH jump Pod
  caveats: |
    This plugin needs the following programs:
    * ssh(1)
    * ssh-agent(1)

    Please follow the documentation: https://github.com/yokawasa/kubectl-plugin-ssh-jump
  description: |
    A kubectl plugin to access Kubernetes nodes or remote services using a SSH jump Pod.
    A jump Pod is an intermediary Pod or an SSH gateway to Kubernetes node machines or
    remote services, through which a connection can be made.