Florian schneefisch

Docker: JVM Memory Debugging

Prerequisites

In the Dockerfile use the JVM debugging container as base-container e.g.

FROM gcr.io/distroless/java:11-debug

and add -XXNativeMemoryTracking=summary to the startup-parameters e.g.

Various ways to restart pods

Restart deployment

The most gracefull way is to trigger a restart for the deployment. In this case, a pod will only be terminated once the new pod is ready. It will slowly replace all pods one after the other.

kubectl rollout restart deployment <deployment-name>

Restart pods in a statefulset

OpenSSL Basics

Certificate information

Print certificate information. Works for .pem, .crt, .cer formats

openssl x509 -text -noout -in <domain.crt>

Print private-key information:

	#!/bin/bash

	# how to configure Ubuntu, see:
	# https://support.yubico.com/support/solutions/articles/15000011355-ubuntu-linux-login-guide-challenge-response

	# configure a yubikey
	ykman otp chalresp -g 2

	# associate a yubikey with your account
	ykpamcfg -2

	#!/usr/bin/env bash
	#
	# IMPORTANT: Update the STANDALONE_Version variable
	#
	# LINK:
	# how to install selenium and chrome-driver on Ubuntu
	# https://gist.github.com/ziadoz/3e8ab7e944d02fe872c3454d17af31a5
	#
	# https://developers.supportbee.com/blog/setting-up-cucumber-to-run-with-Chrome-on-Linux/
	# https://gist.github.com/curtismcmullan/7be1a8c1c841a9d8db2c

	#!/usr/bin/env bash

	# encrypt file for specific key
	gpg --output doc.gpg --encrypt --recipient [email protected] doc
	# encrypt with multiple recipients
	gpg --output doc.gpg --encrypt --recipient [email protected] --recipient [email protected] doc

	# decrypt file
	gpg --output doc --decrypt doc.gpg

	# list databases
	db2 list db directory

	# start db2
	db2start

	# Stop db2
	# stop all dbs in this instance
	db2stop

	# view document metadata with bash

	# mdls -name KEY FILEPATH
	mdls <FILEPATH>

	# to store into a textfile
	mdls <FILEPATH> > metadata.txt

	#!/usr/bin/env bash
	#

	# show file system usages
	df -h

	# disk usage (graphical)
	ncdu

	# prozess / system monitor

	#!/usr/bin/env bash

	# securely overwrite data (default: 3 iterations of random data)
	shred -v <path_to_your_file>

	# only overwrite once with zeros
	shred -vzn 0 <path_to_your_file>


	# alternative, for also securely deleting directories