Category Archives: Containers & Kubernetes

Docker in Docker and play-with-docker

Containers & Kubernetes,

For folks who want to get started with Docker, there is the initial hurdle of installing Docker. Even though Docker has made it extremely simple to install Docker on different OS like Linux, Windows and Mac, the installation step prevents folks from getting started with Docker. With Play with Docker, that problem also goes away. Play with Docker provides a web based interface to create multiple Docker hosts and be able to run Containers. This project is started by Docker captain Marcos Nils and is an open source project. Users can run regular containers or build Swarm cluster between the Docker hosts and create container services on the Swarm cluster. The application can also be installed in the local machine. This project got me interested in trying to understand the internals of the Docker host used within the application. I understood that Docker hosts are implemented as Docker in Docker(Dind) containers. In this blog, I have tried to cover some details on Dind and Play with Docker.

Docker in Docker(Dind)

Docker in Docker(Dind) allows Docker engine to run as a Container inside Docker. This link is the official repository for Dind. When there is a new Docker version released, corresponding Dind version also gets released. This link from Jerome is an excellent reference on Docker in Docker that explains issues with Dind, cases where Dind can be used and cases where Dind should not be used.

Following are the two primary scenarios where Dind can be needed:

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Vault – Use cases

Cloud Platforms, Containers & Kubernetes, DevOps & Automation, Distributed Systems, Security, , , ,

This blog is a continuation of my previous blog on Vault. In the first blog, I have covered overview of Vault. In this blog, I will cover some Vault use cases that I tried out.

Pre-requisites:

Install and start Vault

I have used Vault 0.6 version for the examples here. Vault can be used either in development or production mode. In development mode, Vault is unsealed by default and secrets are stored only in memory. Vault in production mode needs manual unsealing and supports backends like Consul, S3.

Start Vault server:

Following command starts Vault server in development mode. We need to note down the root key that will be used later.

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Docker for AWS – Deployment options

Cloud Platforms, Containers & Kubernetes,

In this blog, I will cover 5 different options to deploy Docker Containers in AWS infrastructure. There are pros and cons of each option and the goal in this blog is not to suggest that some options are better than others, but to highlight the suitable option for a particular use case. I have taken a sample multi-container application and deployed in all the 5 different models to illustrate this. Following are the 5 options/models discussed in this blog:

  1. Docker Machine for AWS
  2. Docker for AWS
  3. Docker Cloud for AWS
  4. Docker Datacenter for AWS
  5. AWS ECS

I have separate blog for each of the above deployment options which are linked to this blog.

Sample application

Following is the sample application used in this blog:

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AWS ECS – Docker Container service

Cloud Platforms, Containers & Kubernetes,

In this blog, I will cover AWS ECS Docker Container service. ECS is an AWS product. This blog is part of my Docker for AWS series and uses the sample voting application for illustration.

AWS has EC2 Container service(ECS) for folks who want to deploy Docker containers in AWS infrastructure. For basics of AWS ECS, you can refer to my previous blog here. With ECS, Amazon provides its own scheduler to manage Docker containers. ECS integrates very well with other AWS services including load balancer, logging service, cloudformation templates etc. AWS recently introduced Application load balancer(ALB) that does L7 load balancing and this integrates well with ECS. Using ALB, we can load balance services directly across Containers. With ECS, users get charged for the EC2 instances and not for the Containers.

To demonstrate ECS usage, we will deploy voting service application in ECS cluster.

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Docker Datacenter for AWS

Cloud Platforms, Containers & Kubernetes,

In this blog, I will cover Docker datacenter usage with AWS. This blog is part of my Docker for AWS series and uses the sample voting application for illustration.

Docker Datacenter is Docker’s enterprise grade CaaS(Container as a service) solution where they have integrated their open source software with some proprietary software and support to make it into a commercial product. Docker Datacenter can be deployed on-premise or in cloud providers like AWS. Docker Datacenter is available free for 30 day trial period.

Docker Datacenter Architecture

Following picture shows the core components of Docker Datacenter:

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Docker Cloud for AWS

Cloud Platforms, Containers & Kubernetes, ,

In this blog, I will cover Docker cloud usage with AWS. This blog is part of my Docker for AWS series and uses the sample voting application for illustration.

Docker cloud is a hosted service from Docker to manage Containers. Docker cloud is free to try for 1 private repository and node and is chargeable after that. Docker cloud was originally an acquisition from Tutum. Docker cloud can be used to manage infrastructure nodes in the cloud or nodes in the local data center. For basics on Docker cloud/Tutum, please refer to my earlier blog here. Since Docker cloud was an acquisition, it does not use some of the Docker ecosystem software. Following are some important differences:

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Docker for AWS beta

Cloud Platforms, Containers & Kubernetes,

In this blog, I will cover “Docker for AWS” beta service launched by Docker. This blog is part of my Docker for AWS series and uses the sample voting application for illustration.

As part of Docker 1.12 announcement, Docker released AWS Docker integration as beta software. With this software, Docker is trying to  simplify AWS integration by better integrating Docker with AWS services like load balancer, security groups, logs etc. Docker launched similar integration service with Microsoft Azure as well. Docker 1.12 RC4 is available as part of this integration, so Swarm mode feature can be used.
Following are some features that Docker has added as part of this integration with AWS:

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Docker-machine for AWS

Containers & Kubernetes

In this blog, I will use docker-machine to deploy and manage Containers in AWS cloud. This blog is part of my Docker for AWS series and uses the sample voting application for illustration.

Docker-machine has EC2 driver for creating a Docker node out of AWS. Docker node in this context means a AWS VM instance with Docker pre-installed. With default options, docker-machine picks up T2-micro EC2 node with Ubuntu 15.10 OS and installs latest Docker engine on the AWS instance. docker-machine also takes care of configuring appropriate certificates which allows us to access the AWS VM securely.

If we have to do the steps manually, we first need to create EC2 instance with appropriate OS, install Docker, manage ssh keys etc. docker-machine takes care of automating this whole process.

Following are the summary of steps used here:

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Service Discovery and Load balancing Internals in Docker 1.12

Containers & Kubernetes, Distributed Systems, , ,

Docker 1.12 release has revamped its support for Service Discovery and Load balancing. Prior to 1.12 release, support for Service discovery and Load balancing was pretty primitive in Docker. In this blog, I have covered the internals of Service Discovery and Load balancing in Docker release 1.12. I will cover DNS based load balancing, VIP based load balancing and Routing mesh.

Technology used

Docker service discovery and load balancing uses iptables and ipvs features of Linux kernel. iptables is a packet filtering technology available in Linux kernel. iptables can be used to classify, modify and take decisions based on the packet content. ipvs is a transport level load balancer available in the Linux kernel.

Sample application

Following is the sample application used in this blog:

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Comparing Swarm, Swarmkit and Swarm Mode

Containers & Kubernetes, ,

One of the big features in Docker 1.12 release is Swarm mode. Docker had Swarm available for Container orchestration from 1.6 release. Docker released Swarmkit as an opensource project for orchestrating distributed systems few weeks before Docker 1.12(RC) release. I had some confusion between these three projects. In this blog, I have tried to put my perspective on the similarities and differences between these three software components. I have also created a sample application and deployed it using the three approaches which makes it easier to compare.

Docker Swarm mode is fundamentally different from Swarm and it is confusing to use the same name Swarm. It would have been good if Docker could have renamed this to something different. Another point adding to the confusion is that native Swarm functionality will continue to be supported in Docker 1.12 release, this is done to preserve backward compatibility. In this blog, I have used the term “Swarm” to refer to traditional Swarm functionality, “SwarmNext” to refer to new Swarm mode added in 1.12, “Swarmkit” to refer to the plumbing open source orchestration project.

Swarm, SwarmNext and Swarmkit

Following table compares Swarm and SwarmNext:

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