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Table of Contents

• set -e, -u, -x, -o pipefail
• set -e
• set -x
• set -u
• set -o pipefail
• Setting IFS
• Original Reference

set -e, -u, -x, -o pipefail

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Bridge

a bridge network uses a software bridge which allows containers connected to the same bridge network to communicate, while providing isolation from containers which are not connected to that bridge network. The Docker bridge driver automatically installs rules in the host machine so that containers on different bridge networks cannot communicate directly with each other.

Bridge networks apply to containers running on the same Docker daemon host. For communication among containers running on different Docker daemon hosts, you can either manage routing at the OS level, or you can use an overlay network.

• User-defined bridges provide better isolation and interoperability between containerized applications.
• User-defined bridges provide automatic DNS resolution between containers.

Reference click here

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Following table captures the main differences between Compose versions:

Feature	Compose v1	Compose v2	Compose v3
Docker engine version	1.9.1+	1.10.0+	1.13.0+
Compose version	Compose up to 1.6.x	Compose 1.6.0+	Compose 1.10.0+
Connect containers	Bridge network, need links	Overlay supported, networks can be used to connect containers	Overlay supported, networks can be used to connect containers
Volume	No named volume	Named volume supported	Named volume supported
Swarm capability	Older swarm	Older swarm	Swarm mode

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Node Installation

• Copy Tar file
• Untar tar file

$ tar -xvf <file name>

• Change name from node-v6.9.5-linux.**** to node-v6.9.5

$ mv node-v6.9.5-linux-x64 node

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Setup Nagios on RHEL 7.4:

Note:

Make sure EPEL repository is enabled on both server and client for installing packages:

sudo rpm -ivh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

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1. jmap

jmap prints heap dumps into a specified file location. This tool is packaged within JDK. It can be found in \bin folder.

Here is how you should invoke jmap:

jmap -dump:format=b,file=<file-path> <pid>

where
pid: is the Java Process Id, whose heap dump should be captured

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https://www.blazemeter.com/blog/how-to-setup-scalable-jenkins-on-top-of-a-kubernetes-cluster

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• You can ignore SSL errors by setting pypi.org and files.pythonhosted.org as trusted hosts.

pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org <package_name>

Note: Sometime during April 2018, the Python Package Index was migrated from pypi.python.org to pypi.org. This means "trusted-host" commands using the old domain no longer work.

• Permanent Fix: You may want to add the trusted hosts and proxy to your config file.

mkdir -p ~/.config/pip

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#!/usr/bin/env bash
set -o errexit
set -o nounset
set -o pipefail

# Set magic variables for current file & dir
__dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
echo "INFO : __dir is ${__dir}"
__file="${__dir}/$(basename "${BASH_SOURCE[0]}")"

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Installation of Docker-CE on RHEL

• Pre-req: Need sudo access

Verify OS

• Verify sudo access by running below command

sudo ls