Succeeding through Laziness and Open Source

Back in mid-2014 I was in the midst of Docker-izing the build process at Virtual Instruments. As part of that work I’d open sourced one component of that system, the Docker-in-Docker Jenkins build slave which I’d created.


While claiming that I was driven by altruistic motivations when posting this code to GitHub (GH) would make for a great ex-post narrative, I have to admit that the real reasons for making the code publicly available were much more practical:

  • At the time the Docker image repositories on the Docker Hub Registry had to be tied to a GitHub repo (They’ve added Bitbucket support since then).
  • I was too cheap to pay for a private GitHub repo.

… And thus the code for the Docker-in-Docker Jenkins slave became open source! 😀

Unfortunately, making this image publicly available presented some challenges soon thereafter: Folks started linking their blog posts to it, people I’d never met emailed me asking for help in getting set up w/this system, others started filing issues against me on either GH or the Docker Hub Registry, and I started receiving pull-requests (PRs) to my GH repo.

Having switched employers just a few months after posting the code to GH, dealing with the issues and PRs was a bit of a challenge: My new employer didn’t have a Dockerized build system (yet), and short of setting up my own personal Jenkins server and Dockerized build slaves, there was no way for me to verify issues/fixes/PRs for this side-project. And so “tehranian/dind-jenkins-slave” stagnated on GH with relatively little participation from me.

Having largely forgotten about this project, I was quite surprised a few weeks ago when perusing the GH repo for Disqus. I accidentally discovered that the engineering team at Disqus had forked my repo and had been actively committing changes to their fork!

Their changes had:

  • Optimized the container’s layers to make it smaller in size,
  • Updated the image to work with new versions of Docker,
  • And also modified some environment variable names to avoid collisions with names that popular frameworks would use.

Prompted by this, I went back to my own GH repo, looked at the graph of all other forks, and saw that several others had forked my GH repo as well.

One such fork had updated my image to work with Docker Swarm and also to be able to easily use SSH keys for authenticating with the build slave instead of using password-based auth.

“How cool!”, I thought. I’d put an idea into the public domain a year ago, others had found it, and improved it in ways that I couldn’t have imagined. Further, their improvements were now available for myself and others to use!

My Delphix colleague Michael Coyle summed this all up very nicely, saying “As a software developer I can only realistically work for one organization at a time. Open source allows developers from different organizations to collaborate with each other without boundaries. In that way one actually can contribute to more than one organization at once.”

In hindsight I’m absolutely delighted that my unwillingness to purchase a private GitHub repo led to me contributing the Docker-in-Docker Jenkins slave to the public domain. There was nothing proprietary that Virtual Instruments could have used in its product, and by making it available other organizations like Disqus, CloudBees have been able to benefit, along with software developers on the other side of the planet. How exciting!


Managing Secrets with Ansible Vault – The Missing Guide (Part 2 of 2)

(This post is part 2/2 in a series. For part 1 see: Managing Secrets with Ansible Vault – The Missing Guide (Part 1 of 2))

How to use Ansible Vault with Test Kitchen

Once you’ve codified all of your secrets into Ansible “var files” and encrypted them with Ansible Vault, you’ll probably want to test the deployment of these secrets with Test Kitchen. Unfortunately you will quickly find that Test Kitchen does not play with Vault in an ideal way: In order for Test Kitchen to run “ansible-playbook” it now needs the password to your Vault in order to decrypt the secrets within the var files.

How does the “kitchen-ansible” plugin expect to receive the password to your Vault? Via a plain-text file on your filesystem, as specified by the “ansible_vault_password_file” parameter in your “.kitchen.yml” file. Oh boy!

This does not seems like a scalable solution to me… I hardly trust myself to manage a plain-text file with the password to our Vault. Beyond that, I would be terrified to let an entire organization of folks know the password to the Vault and instruct them to store that password in a plain-text file in their own respective file systems just so that they could run Test Kitchen tests as they iterate w/Ansible. In practice this would be only marginally better than simply checking in the secrets as plain-text into git, as all this structure around Vault and Ansible vars would only be pushing the problem of secret management one level higher.

So how can we test with Test Kitchen when using Ansible Vault? Here’s a nifty solution to the problem that builds upon the solution that we implemented in Part 1 of this guide:

  • Define a well-known Unix hostname for your Test Kitchen VM. Ex: “test-kitchen”
  • Create two versions of your vars files: One for production which is encrypted, the other for your test environment which is unencrypted. The structure of the files will be largely the same (ex. the files to be placed, w/their respective owner, group, mode), but the contents of the files for production will differ from the files for your test environment.
  • In “tasks/main.yml”, use “include_vars” to include the appropriate var file for whichever environment you happen to be in. This can be done by using the “with_first_found” arg to “include_vars”. See example below.
# .kitchen.yml
# Set the hostname of our Test Kitchen-created VM to be “test-kitchen”
  name: vagrant
  vm_hostname: test-kitchen


# vars/vpn-secrets-prod.yml - A Vault-encrypted file

# vars/vpn-secrets-test-kitchen.yml
    owner: root
    group: root
    mode: "u=r,go="
    content: |
      -----BEGIN PRIVATE KEY-----
      -----END PRIVATE KEY-----
    owner: root
    group: root
    mode: "u=r,go="
    content: |
      -----BEGIN PRIVATE KEY-----
      -----END PRIVATE KEY-----


# tasks/main.yml
# Leverage the fact that our ".kitchen.yml" file is setting the hostname of
# test VMs to "test-kitchen". Using "with_first_found" we can load the
# unencrypted "vpn-secrets-test-kitchen.yml" for test VMs, otherwise load the
# Ansible Vault-encrypted "vpn-secrets-prod.yml" file.
# Use "no_log: true" to keep from echoing the key contents to stdout.
# See:
- name: VPN Server | Load VPN secret keys
  include_vars: "{{ item }}"
  no_log: true
    - "vpn-secrets-{{ ansible_hostname }}.yml"
    - "vpn-secrets-prod.yml"

- name: VPN Server | Copy secret files
    dest="{{ item.key }}"
    content="{{ item.value.content }}"
    owner="{{ item.value.owner }}"
    group="{{ }}"
    mode="{{ item.value.mode }}"
  with_dict: vpn_secret_files
  no_log: true
    - restart openvpn

The magic lies in the “with_first_found” argument above. In the Test Kitchen environment “vpn-secrets-{{ ansible_hostname }}.yml” will interpolate to “vpn-secrets-test-kitchen.yml” because of our well-defined hostname. Since this “vpn-secrets-test-kitchen.yml” file exists in unencrypted form under “vars/”, Ansible will grab that var file for your Test Kitchen environment. If the hostname is something other than “test-kitchen” (ie. production), then Ansible’s “with_first_found” will reach the “vpn-secrets-prod.yml” var file, which is encrypted with Vault and will require a password to unlock and proceed.

Sanity Checking Ourselves with Serverspec

Now that we have Vault working nicely with Test Kitchen, a final step would be to add automated tests to make sure that we are indeed deploying files with the correct permissions, now and in the future. For more details on using Ansible & Test Kitchen with Serverspec, see Testing Ansible Roles with Test Kitchen. Here’s what a Serverspec test for our above files would look like:

# test/integration/default/serverspec/secret_keys_spec.rb

require 'serverspec'

# Secret keys should not be world readable.
secret_keys = [

for secret_key in secret_keys
  describe file(secret_key) do
    it { should be_file }
    it { should be_mode 400 }
    it { should be_owned_by 'root' }
    it { should be_grouped_into 'root' }

Deploying to Production with Jenkins

A final piece of the puzzle to figure out was how to actually run “ansible-playbook” with a code base that utilizes Ansible Vault within the context of a job-runner like Jenkins. In order words, how to provide Jenkins with the password to unlock the Vault. I found a couple of options here:

  • Put the Vault password into a locked-down file (mode 400) on your Jenkins slaves that run Ansible. This only works if your Jenkins slaves have some level of security around the users that Jenkins uses. I’m not crazy about passwords in text files, but in theory this shouldn’t be any worse than a locked-down, 400-mode file like those in “/etc/sudoers.d/…”.
  • Modify the Jenkins job that runs Ansible to require a Password parameter, run “ansible-playbook” within that job with that password parameter being echo’d in, and then use the Jenkins Mask Passwords plugin to mask the contents of that password from your build logs. The downside of this is that it complicates automated execution of the Jenkins job that invokes Ansible as it now requires a password to be invoked.
  • Store the Ansible Vault password in another secret management system like HashiCorp’s Vault. This starts to get pretty meta 🙂

Ultimately you have to decide which of these three options fits best within your infrastructure and workflow.


There you have it, my two-part guide to using Ansible Vault from soup to nuts. Hopefully you’ve found these notes to be useful in getting an end to end system for securely managing your infrastructure’s secrets. Please let me know in the comments if I’ve left anything out. Thanks!


VMware AppCatalyst First Impressions

As previously mentioned in my DockerCon 2015 Wrap-Up, one of the more practical
announcements from last week’s DockerCon was that VMware announced a free variant of Fusion called AppCatalyst. The availability of AppCatalyst along with a corresponding plugin for Vagrant written by Fabio Rapposelli gives developers a less buggy and more performant alternative to using Oracle’s VirtualBox as their VM provider for Vagrant. vmware_cloud_logo

Here is the announcement itself along with William Lam‘s excellent guide to getting started w/AppCatalyst & the AppCatalyst Vagrant plugin.

Taking AppCatalyst for a Test Drive

One of the first things I did when I returned to work after DockerCon was to download AppCatalyst and its Vagrant plugin, and take them for a spin. By and large, it works as advertised. Getting the VMware Project Photon VM running in Vagrant per William’s guide was a cinch.

Having gotten that Photon VM working, I immediately turned my attention to getting an arbitrary “vmware_desktop” Vagrant box from HashiCorp’s Atlas working. Atlas is HashiCorp’s commercial service, but they make a large collection of community-congtributed Vagrant boxes for various infrastructure platforms freely-available. I figured that I should be able to use Vagrant to automatically download one of the “vmware_desktop” boxes from Atlas and then spin it up locally with AppCatalyst using only a single command, “vagrant up”.

In practice, I hit an issue which Fabio was quick to provide me with a workaround for:

The crux of the issue is that AppCatalyst is geared towards provisioning Linux VMs and not other OS types, ex. Windows. This is quite understandable as VMware would not want to cannibalize Fusion sales for folks that buy Fusion to run Windows on their Macs. Unfortunately this OS identification logic seems to be coming from the “guestos” setting in the box’s .VMX file, and apparently many of the “vmware_desktop” boxes on Altas do not use a value for that VMX key that AppCatalyst will accept. As Fabio suggested, the work-around was to override that setting from the VMX file to a value that AppCatalyst will accept.

A Tip for Starting the AppCatalyst Daemon Automatically

Another minor issue I hit when trying AppCatalyst for the first time was that I’d forgotten to manually start the AppCatalyst daemon, “/opt/vmware/appcatalyst/bin/appcatalyst-daemon”. D’oh!

Because I found it annoying to launch a separate terminal window to start this daemon every time I wanted to interact with AppCatalyst, I followed through on a co-worker’s suggestion to automate the starting of this process on my Mac via launchd. (Thanks Dan K!)

Here’s how I did it:

$ cat >~/Library/LaunchAgents/com.vmware.appcatalyst.daemon.plist <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">

After logging out and logging back in, the AppCatalyst daemon should be running and its log file will be at “/tmp/appcatalyst.log”. Ex:

$ tail -f /tmp/appcatalyst.log
2015/06/30 09:41:03 DEFAULT_VM_PATH=/Users/dtehranian/Documents/AppCatalyst
2015/06/30 09:41:03 DEFAULT_PARENT_VM_PATH=/opt/vmware/appcatalyst/photonvm/photon.vmx
2015/06/30 09:41:03 DEFAULT_LOG_PATH=/Users/dtehranian/Library/Logs/VMware
2015/06/30 09:41:03 PORT=8080
2015/06/30 09:41:03 Swagger path: /opt/vmware/appcatalyst/bin/swagger
2015/06/30 09:41:03 appcatalyst daemon started.

Since AppCatalyst is still in Tech Preview, I’m hoping VMware adds this sort of auto-start functionality for the daemon before the final release of the software.


If you or your development team is using VirtualBox as your VM provider for Vagrant, go try out AppCatalyst. It’s based on the significantly better technical core of Fusion and if it grows in popularity maybe one day it could be the default provider for Vagrant! 🙂

DockerCon 2015 Wrap-Up

I attended DockerCon 2015 in San Francisco from June 22-23. The official wrap-ups for Day 1 and Day 2 are available from Docker, Inc. Keynote videos are posted here. Slides from every presentation are available here.

Here are my personal notes and take-aways from the conference:

The Good

  • Attendance was much larger than I expected, reportedly at 2,000 attendees. It reminded me a lot of VMworld back in 2007. Lots of buzz.
  • There were many interesting announcements in the keynotes:
    • Diogo Mónica unveiled and demoed Notary, a tool for publishing and verifying the authenticity of content. (video)
    • Solomon Hykes announced that service discovery is being added into the Docker stack. Currently one needs to use an external tools like registrator, Consul, and etcd for this.
    • Solomon announced that multi-host networking is coming.
    • Solomon announced that Docker is splitting out its internal plumbing from the Docker daemon. First up is splitting out the container runtime plumbing into a new project called RunC. The net effect is that this creates a reusable component that other software can use for running containers. This will also make it easy to run containers without the full Docker daemon as well.
    • Solomon announced the Open Container Project & Open Container Format – Basically Docker, Inc. and CoreOS have buried the hatchet and are working with the Linux Foundation and over a dozen other companies to create open standards around containers. Libcontainer and RunC are bring donated to this project by Docker, while CoreOS is contributing the folks who were working on AppC. More info on the announcement here.
    • Docker revealed how they will start to monetize their success. They announced an on-prem Docker registry with a support plan starting at $150/month for 10 hosts.
  • Diptanu Choudhury unveiled Netflix’s Titan system in Reliably Shipping Containers in a Resource Rich World using Titan. Titan is a combination of Docker and Apache Mesos, providing a highly resilient and dynamic PaaS that is native to public clouds and runs across multiple geographies.
  • VMware announced he availability of AppCatalyst, a free, CLI-only version of VMware Fusion. That software, combined with the Vagrant plugin for AppCatalyst that Fabio Rapposelli released, means that developers no-longer need to pay for VMware Fusion in order to have a more stable and performant alternative to Oracle’s VirtualBox for use with Vagrant. William Lam has written a great Getting Started Guide for AppCatalyst.
  • The prize for most entertaining presentation goes to Bryan Cantrill for Running Aground: Debugging Docker in Production. Praise for his talk & funny excerpts from that talk were all over Twitter:

The Bad

I was pretty disappointed with most of the content of the presentations on the “Advanced” track. There were a lot of fluffy talks about micro-services, service discovery, and auto-scaling groups. Besides not getting into great technical detail, I was frustrated by these talks because there was essentially no net-new content for anyone who frequents meetups in the Bay Area, follows Hacker News, or follows a few key accounts on Twitter.

Speaking to other attendees, I found that I was not the only one who felt that these talks were very high-level and repetitive. Bryan Cantrill even eluded to this in his own talk when he mentioned “micro-services” for the first time, adding, “Don’t worry, this won’t be one of those talks.”

Closing Thoughts

I had a great time at DockerCon 2015. The announcements and presentations around security and network were particularly interesting to me because there were new things being announced in those areas. I could have done w/o all of the fluffy talks about micro-services and auto-scaling.

It was also great to meet new people and catch up with former colleagues. I got to hear a lot of interesting ways developers are using Docker in their development and production environments and can’t wait to implement some of the things I learned at my current employer.

Testing Ansible Roles with Test Kitchen

Recently while attending DevOps Days Austin 2015, I participated in a breakout session focused on how to test code for configuration management tools like Puppet, Chef, and Ansible. Having started to use Ansible to manage our infrastructure at Delphix I was searching for a way to automate the testing of our configuration management code across a variety of platforms, including Ubuntu, CentOS, RHEL, and Delphix’s custom Illumos-based OS, DelphixOS. Dealing with testing across all of those platforms is a seemingly daunting task to say the least!

Intro to Test Kitchen

The conversation in that breakout session introduced me to Test Kitchen (GitHub), a tool that I’ve been very impressed by and have had quite a bit of fun writing tests for. Test Kitchen is a tool for automated testing of configuration management code written for tools like Ansible. It automates the process of spinning up test VMs, running your configuration management tool against those VMs, executing verification tests against those VMs, and then tearing down the test VMs.

What’s makes Test Kitchen so powerful and useful is its modular design:

Using Test Kitchen

After learning about Test Kitchen at the DevOps Days conference, I did some more research and stumbled across the following presentation which was instrumental in getting started with Test Kitchen and Ansible: Testing Ansible Roles with Test Kitchen, Serverspec and RSpec (SlideShare).

In summary one needs to add three files to their Ansible role to begin using Test Kitchen:

  • A “.kitchen.yml” file at the top-level. This file describes:
    • The driver to use for VM provisioning. Ex: Vagrant, AWS, Docker, etc.
    • The provisioner to use. Ex: Puppet, Chef, Ansible.
    • A list of 1 or more operating to test against. Ex: Ubuntu 12.04, Ubuntu 14.04, CentOS 6.5, or even a custom VM image specified by URL.
    • A list of test suites to run.
  • A “test/integration/test-suite-name/test-suite-name.yml” file which contains the Ansible playbook to be applied.
  • One or more test files in “test/integration/test-suite-name/test-driver-name/”. For example, when using the BATS test-runner to run a test suite named “default”: “test/integration/default/bats/my-test.bats”.

Example Code

A full example of Test Kitchen w/Ansible is available via the delphix.package-caching-proxy Ansible role in Delphix’s GitHub repo. Here are direct links to the aforementioned files/directories:682240

Running Test Kitchen

Using Test Kitchen couldn’t be easier. From the directory that contains your “.kitchen.yml” file, just run “kitchen test” to automatically create your VMs, configure them, and run tests against them:

$ kitchen test
-----> Starting Kitchen (v1.4.1)
-----> Cleaning up any prior instances of 
-----> Destroying ...
 Finished destroying  (0m0.00s).
-----> Testing 
-----> Creating ...
 Bringing machine 'default' up with 'virtualbox' provider...
 ==> default: Importing base box 'opscode-ubuntu-14.04'...
==> default: Matching MAC address for NAT networking...
 ==> default: Setting the name of the VM: kitchen-ansible-package-caching-proxy-default-ubuntu-1404_default_1435180384440_80322
 ==> default: Clearing any previously set network interfaces...
 ==> default: Preparing network interfaces based on configuration...
 default: Adapter 1: nat
 ==> default: Forwarding ports...
 default: 22 => 2222 (adapter 1)
 ==> default: Booting VM...
 ==> default: Waiting for machine to boot. This may take a few minutes...

..  ...

-----> Running bats test suite
 ✓ Accessing the apt-cacher-ng vhost should load the configuration page for Apt-Cacher-NG
 ✓ Hitting the apt-cacher proxy on the proxy port should succeed
 ✓ The previous command that hit should have placed some files in the cache
 ✓ Accessing the devpi server on port 3141 should return a valid JSON response
 ✓ Accessing the devpi server via the nginx vhost should return a valid JSON response
 ✓ Downloading a Python package via our PyPI proxy should succeed
 ✓ We should still be able to install Python packages when the devpi contianer's backend is broken
 ✓ The vhost for the docker registry should be available
 ✓ The docker registry's /_ping url should return valid JSON
 ✓ The docker registry's /v1/_ping url should return valid JSON
 ✓ The front-end serer's root url should return http 204
 ✓ The front-end server's /_status location should return statistics from our web server
 ✓ Accessing through our proxy should always return a cache miss
 ✓ Downloading a file that is not in the cache should result in a cache miss
 ✓ Downloading a file that is in the cache should result in a cache hit
 ✓ Setting the header 'X-Refresh: true' should result in a bypass of the cache
 ✓ Trying to purge when it's not in the cache should return 404
 ✓ Downloading the file again after purging from the cache should yield a cache miss
 ✓ The yum repo's vhost should return HTTP 200

 19 tests, 0 failures
 Finished verifying  (1m52.26s).
-----> Kitchen is finished. (1m52.49s)

And there you have it, one command to automate your entire VM testing workflow!

Next Steps

Giving individual developers on our team the ability to quickly run a suite of automated tests is a big win, but that’s only the first step. The workflow we’re planning is to have Jenkins also run these automated Ansible tests every time someone pushes to our git repo. If those tests succeed we can automatically trigger a run of Ansible against our production inventory. If, on the other hand, the Jenkins job which runs the tests is failing (red), we can use that to prevent Ansible from running against our production inventory. This would be a big win for validating infrastructure changes before pushing them to production.


How Should I Get Application Configuration into my Docker Containers?

A commonly asked question by folks that are deploying their first Docker containers into production is, “How should I get application configuration into my Docker container?” The configuration in question could be settings like the number of worker processes for a web service to run with, JVM max heap size, or the connection string for a database. The reality is that there are several standard ways to do this, each with their own pros and cons.

The ~3.5 Ways to Send Configuration to your Dockerized Apps

1. Baking the Configuration into the Container

Baking your application’s configuration into a Docker image is perhaps the easiest pattern to understand. Basically one can use commands within the “Dockerfile” to drop configuration files into the right places via the Dockerfile’s COPY directive, or modify those configuration files at image build time with “sed” or ”echo” via the RUN command.

If there’s a container available on the Docker Hub Registry that does everything you want save for one or two config settings, you could fork that “Dockerfile” on GitHub, make modifications to the “Dockerfile” in your GitHub fork to drop in whatever configuration changes you want, then add it as a new container on the Docker Hub Registry.

That is what I did for:



  • Since the configuration is baked into the image, any future configuration changes will require additional modifications to the image’s build file (its “Dockerfile”) and a new build of the container image itself.

2a. Setting the Application Configuration Dynamically via Environment Variables

This is a commonly-used pattern for images on the Docker Hub Registry. For an example, see the environment variables “POSTGRES_USER” and “POSTGRES_PASSWORD” for the official PostgreSQL Docker image.

Basically, when you “docker run” you will pass in pre-defined environment variables like so: "docker run -e SETTING1=foo -e SETTING2=bar ... <image name>". From there, the container’s entry point (startup script) will look for those environment variables, and “sed” or “echo” them into whatever relevant config files the application uses before actually starting the app.

It’s worth mentioning that the container’s entry point script should contain reasonable defaults for each of those environment variables if the invoker does not pass those environment variables in, so that the container will always be able to start successfully. 


  • This approach makes your container more dynamic in terms of configuration. 


  • You are sacrificing dev/prod parity because now folks can configure the container to behave differently in dev & prod.
  • Some configurations are too complex to model with simple key/value pairs, for example an nginx/apache virtual host configuration.

2b. Setting the Application Configuration Dynamically via Environment Variables

This is a similar idea to using environment variables to pass in configuration, but instead the container’s startup script will reach out to a key-value (KV) store on the network like Consul or etcd to get configuration parameters.

This makes it possible to do more complex configurations than is possible with simple environment variables, because the KV store can have a hierarchical structure of many levels. It’s worth noting that widely-used tooling exists for grabbing the values from the KV store substituting them into your config files. Tools like confd even allow for automatic app-reloading upon changes to the KV configuration. This allows you to make your app’s configuration truly dynamic!



  • This approach makes your container more dynamic in terms of configuration.
  • The KV store allows for more complex & dynamic configuration information 


  • This introduces an external dependency of the KV store, which must be highly-available.
  • You are sacrificing dev/prod parity because now folks can configure the container to behave differently in dev & prod.

3. Map the Config Files in Directly via Docker Volumes

Docker Volumes allow you to map any file/directory from the host OS into a container, like so: “docker run -v <source path>:<dest path> ...”

Therefore if the config file(s) for your containerized app happened to be available on the filesystem of the base OS, then you could map that config file (or dir) into the container. Ex:

“docker run -v /home/dan/my_statsd_config.conf:/etc/statsd.conf hopsoft/graphite-statsd”


  • You don’t have to modify the container to get arbitrary configurations in.


  • You lose dev/prod parity because now your app’s config can be anything
  • If you’re doing this in production, now you have to get that external config file onto the base OS for sharing into the container (a configuration management tool like Ansible, Chef, or Puppet comes in handy here)


As you can see, there are many potential ways to get application configuration to your Dockerized apps, each with their own trade-offs. Which way is best? It really depends on how much dynamism you require and whether or not you want the extra burden of managing dependencies like a KV store.

Ansible vs Puppet – Hands-On with Ansible

This is part 2/2 in a series. For part #1 see: Ansible vs Puppet – An Overview of the Solutions.

Notes & Findings From Going Hands-On with Ansible

After playing with Ansible for a week to Ansible-ize Graphite/Grafana (via Docker) and Jenkins (via an Ansible Galaxy role), here are my notes about Ansible:

  • “Batteries Included” and OSS Module Quality
    • While Ansible does include more modules out of the box, the “batteries included” claim is misleading. IMO an Ansible shop will have to rely heavily upon Ansible Galaxy to find community-created modules (Ex: for installing Jenkins, dockerd, or ntp), just as a Puppet shop would have to rely upon PuppetForge.
    • The quality and quantity of the modules on Ansible Galaxy is about on par with what is available at PuppetForge. Just as with PuppetForge, there are multiple implementations for any given module (ex: nginx, ntp, jenkins), each with their own quirks, strengths, and deficiencies.
    • Perhaps this is a deficiency of all of the configuration management systems. Ultimately a shop’s familiarity with Python or Ruby may add some preference here.
  • Package Installations
    • Coming from Puppet-land this seemed worthy of pointing out: Ansible does not abstract an OS’s package manager the same way that Puppet does with the “package” resource. Users explicitly call out the package manager to be used. Ex: the “apt” module or “yum” module. One can see that Ansible provides a tad bit less abstraction. FWIW a package installed via “pip” or “gem” in Puppet still requires explicit naming of the package provider. Not saying that either is better or worse here. Just a noticable difference to an Ansible newbie.
  • Programming Language Constructs
  • Noop Mode
  • Agent-less
    • Ansible’s agent-less, SSH-based push workflow actually was notably easier to deal with than a Puppetmaster, slave agents, SSL certs, etc.
  • Learning Curve
    • If I use my imagination and pretend that I was starting to use a configuration management tool for the first time, I perceive that I’d have an easier time picking up Ansible. Even though I’m not a fan of YAML by any stretch of the imagination, Ansible playbooks are a bit easier to write & understand than Puppet manifests.


After three years of using Puppet at VMware and Virtual Instruments, the thought of not continuing to use the market leader in configuration management tools seemed like a radical idea when it was first suggested to me. After spending several weeks researching Ansible and using it hands-on, I came to the conclusion that Ansible is a perfectly viable alternative to Puppet. I tend to agree with Lyft’s conclusion that if you have a centralized Ops team in change of deployments then they can own a Puppet codebase. On the other hand if you want more wide-spread ownership of your configuration management scripts, a tool with a shallower learning curve like Ansible is a better choice.