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Category Archives for "Systems"

Docker at Connect(); // 2015

Connect(); //2015, Microsoft’s virtual event devoted to developers, happened one day after DockerCon EU 2015, and started with an epic demo where Scott Hanselman deployed an ASP.NET 5 app from Visual Studio to a Docker container on Azure on Linux. … Continued

An Introduction to Terraform

In this post, I’m going to provide a quick introduction to Terraform, a tool that is used to provision and configure infrastructure. Terraform allows you to define infrastructure configurations and then have those configurations implemented/created by Terraform automatically. In this respect, you could compare Terraform to similar solutions like OpenStack Heat, AWS CloudFormation, and others.

Before I continue, though, allow me to first address this question: why Terraform?

Why Terraform?

This is a fair question, and one that you should be asking. After all, if Terraform is considered similar to OpenStack Heat or AWS CloudFormation, then why use Terraform instead of one of the comparable solutions? I believe there are a couple (related) reasons why you might consider Terraform over a similar solution:

  1. Within a single Terraform definition, you can orchestrate across multiple cloud services. For example, you could create instances with a cloud provider (AWS, DigitalOcean, etc.), create DNS records with a DNS provider, and register key/value entries in Consul. Heat and CloudFormation are, quite naturally, designed to work almost exclusively with OpenStack and AWS, respectively. (Astute readers will know that Heat supports CloudFormation templates, but you get the idea.) Therefore, one reason to use Terraform Continue reading

Bootstrapping Cloud Instances into Ansible

A while ago, I wrote an article about bootstrapping servers into Ansible—in other words, how to prepare servers to be managed via Ansible. In order for a server to be managed via Ansible, you usually must first create a user account for Ansible, populate the appropriate SSH keys, and grant the new Ansible user sudo permissions. The process I described in my earlier blog post works great for manually-built servers (physical or virtual), but I recently needed to revisit this process for cloud instances. Was it possible to use the process I’d found to bootstrap cloud instances into Ansible?

Cloud instances are a slightly different beast than manually-built servers primarily because password authentication isn’t an option—generally speaking, you’re required to use SSH keys when working with cloud instances. Ansible is SSH-based, as you probably already know, so this shouldn’t be an issue, but it was still something I hadn’t tested or verified. After a bit of testing, I found the bootstrap process I described in my earlier post can be easily adapted for cloud instances.

For reference, here’s the command I use when bootstrapping manually-built servers into Ansible:

ansible-playbook bootstrap.yml -k -K --extra-vars 
"hosts=newhost.domain.com user=admin"

Continue reading

Using an SSH Bastion Host

Secure Shell, or SSH, is something of a “Swiss Army knife” when it comes to administering and managing Linux (and other UNIX-like) workloads. In this post, I’m going to explore a very specific use of SSH: the SSH bastion host. In this sort of arrangement, SSH traffic to servers that are not directly accessible via SSH is instead directed through a bastion host, which proxies the connection between the SSH client and the remote servers.

At first, it may sound like the use of an SSH bastion host is a pretty specialized use case. In reality, though, I believe this is a design pattern that can actually be useful in a variety of situations. I plan to explore the use cases for an SSH bastion host in a future blog post.

This diagram illustrates the concept of using an SSH bastion host to provide access to Linux instances running inside some sort of cloud network (like an OpenStack Neutron tenant network or an AWS VPC):

SSH bastion host diagram

Let’s take a closer look at the nuts and bolts of actually setting up an SSH bastion host.

First, you’ll want to ensure you have public key authentication properly configured, both on the bastion host Continue reading

TOWER 2.4 NOW AVAILABLE

We’re happy to announce the release of Ansible Tower 2.4. In this release, we’ve focused on some core improvements for our customers operating in spaces like government and security who have specific needs around authentication and tracking, but we expect these features will be useful to much of our general user base as well.

OAUTH, VIA GITHUB AND GOOGLE

No one wants to manage their users in multiple places, and many groups today use external providers for handling their identity and authentication. We’ve added support for pulling users and teams from either GitHub or Google Apps, using OAuth2. With this, you don’t need to add users directly to Tower - they can use the accounts they already have and are using in your organization.

ADDITIONAL ENTERPRISE AUTHENTICATION

Previously, for Enterprise users who have a standard corporate infrastructure Tower has included support for connecting to an LDAP or Active Directory server for user and team information. But not everyone exposes their LDAP for use with all internal services. With Tower 2.4, we’ve extended that enterprise authentication support to also include support for authenticating to a SAML 2.0 identity provider, and to authenticate against a RADIUS server. With this, Continue reading

Technology Short Take #56

Welcome to Technology Short Take #56! In this post, I’ve collected a few links on various data center technologies, news, events, and trends. I hope you find something useful here.

Networking

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