caruccio

Namespaces

List all resources within a namespace

NS=some-namespace

kubectl api-resources --verbs=list --namespaced -o name \
  | xargs -n 1 kubectl get --show-kind --ignore-not-found -n $NS

caruccio

#!/usr/bin/python

from __future__ import print_function
import sys

def usage(argv):
    print('Usage: %s [commands][resources][options][parameters]' % argv[0], file=sys.stderr)
    print('\nCommands:', file=sys.stderr)
    for s, l in commands:
        print('  %s (%s)' % (s, l), file=sys.stderr)

caruccio

#!/bin/bash

if [ $# -lt 3 ]; then
    echo "Usage: $0 pod-name-suffix source-pvc-name destination-pvc-name [rsync options...]"
    exit 1
fi

POD_SUFFIX=${1}
PVC_FROM=${2}
PVC_TO=${3}

caruccio

Kubectl output options

Let's look at some basic kubectl output options.

Our intention is to list nodes (with their AWS InstanceId) and Pods (sorted by node).

We can start with:

kubectl get no

caruccio

This example shows how to read options and positional arguments from a bash script (same principle can be applied for other shells).

# some global var we want to overwrite with options
force=false
help=false
log=info
ARGS=() ### this array holds any positional arguments, i.e., arguments not started with dash

while [ $# -gt 0 ]; do

caruccio

## Ever had to add something to your shell's config files (i.e. .bashrc)
## and open a new shell? Well, that may be fine, but you can achieve the
## same result, plus without having to open a new window/tab
## or execute a child process.
##
## Idea taken from https://learn.hashicorp.com/vault/getting-started/install

## lets check if any command `hello` exists
$ hello
bash: hello: command not found

caruccio

$ function spread_parameter {
  local p="$1"
  shift
  local IFS=","
  eval "echo $(echo "$p\ {$*}")"
}

$ spread_parameter --include '*.jpg' '*.gif' '*.svg'
--include *.jpg --include *.gif --include *.svg

caruccio

# Switch kubernetes namespaces withou touching ~/.kube/config
# Example:
#
#   $ on kube-system
#   NAME          STATUS    AGE
#   kube-system   Active    1y
#   $ k get pod
#

on()

caruccio

#!/usr/bin/env python

## If you see messages like this on your kubelet journal:
##
## Mar 25 22:36:44 ip-10-0-3-67.ec2.internal dockerd-current[28612]: time="2018-03-25T22:36:44.419126265Z" level=error msg="Handler for GET /v1.24/containers/60532fa8184bdf41e52788194faa1253f1168e3ad4f54f7c159192fe66c4bb1d/json returned error: No such container: 60532fa8184bdf41e52788194faa1253f1168e3ad4f54f7c159192fe66c4bb1d"
##
## use this script to remove dockershim container files from /var/lib/dockershim/sandbox

import os, glob, subprocess

caruccio

#!/bin/bash

set -eu

NAMESPACE=$1
PVCNAME=$2
TARGETZONE=$3
DEPLOYMENTOBJ=$4
PVNAME=$(oc -n $NAMESPACE get pvc $PVCNAME --template={{.spec.volumeName}})
VOLUMEID=$(oc -n $NAMESPACE get pv $PVNAME --template={{.spec.awsElasticBlockStore.volumeID}} | cut -d/ -f 4)