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Troubleshooting Docker

You're reading from   Troubleshooting Docker Develop, test, automate, and deploy production-ready Docker containers

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Product type Paperback
Published in Mar 2017
Publisher Packt
ISBN-13 9781783552344
Length 290 pages
Edition 1st Edition
Tools
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Authors (4):
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John Wooten John Wooten
Author Profile Icon John Wooten
John Wooten
Navid Ahmed Shaikh Navid Ahmed Shaikh
Author Profile Icon Navid Ahmed Shaikh
Navid Ahmed Shaikh
Vaibhav Kohli Vaibhav Kohli
Author Profile Icon Vaibhav Kohli
Vaibhav Kohli
Rajdeep Dua Rajdeep Dua
Author Profile Icon Rajdeep Dua
Rajdeep Dua
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Toc

Table of Contents (11) Chapters Close

Preface 1. Understanding Container Scenarios and an Overview of Docker FREE CHAPTER 2. Docker Installation 3. Building Base and Layered Images 4. Devising Microservices and N-Tier Applications 5. Moving Around Containerized Applications 6. Making Containers Work 7. Managing the Networking Stack of a Docker Container 8. Managing Docker Containers with Kubernetes 9. Hooking Volume Baggage 10. Docker Deployment in a Public Cloud - AWS and Azure

Troubleshooting communication between containers and the external network


Packets can only pass between containers if the ip_forward parameter is set to 1. Usually, you will simply leave the Docker server at its default setting of --ip-forward=true and Docker will set ip_forward to 1 for you when the server starts up. To check the settings, use the following command:

    # cat /proc/sys/net/ipv4/ip_forward
0  
# echo 1 > /proc/sys/net/ipv4/ip_forward 
# cat /proc/sys/net/ipv4/ip_forward 
1

By enabling ip-forward, users can make communication between containers and the external world possible; it will also be needed for inter-container communication if you are in a multiple bridge setup:

ip-forward = true forwards all the packets to/from the container to the external network

Docker will not delete or modify any pre-existing rules from Docker filter chain. This allows users to create rules to restrict access to containers. Docker uses docker0 bridge for packet flow between all containers...

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