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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.

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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

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#!/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

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#!/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

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#!/usr/bin/env bash

# encrypt file for specific key
gpg --output doc.gpg --encrypt --recipient blake@cyb.org doc
# encrypt with multiple recipients
gpg --output doc.gpg --encrypt --recipient blake@cyb.org --recipient bob@example.com doc

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

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# list databases
db2 list db directory

# start db2
db2start

# Stop db2
# stop all dbs in this instance
db2stop

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# view document metadata with bash

# mdls -name KEY FILEPATH
mdls <FILEPATH>

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

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#!/usr/bin/env bash
#

# show file system usages
df -h

# disk usage (graphical)
ncdu

# prozess / system monitor

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#!/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

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OpenSSL Basics

Certificate information

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

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

Print private-key information: