Did you know you can tag a host in Splunk ?? I didn’t !! Do you know how much time tags would have saved me from having to craft a most excellent Splunk search to capture just the right hosts ?? Me neither — but I’m guessing it’s a lot ..
So instead of my searches looking like this:
# get all staging RMI nodes -- hard index=* ( host=rmi1.s.* OR host=rmi2.s.* OR host=rmi3.s.* ) source=*tomcat* earliest=-1h
They can now look like this:
# get all staging RMI nodes -- easy index=* tag=rmi tag=stage source=*tomcat* earliest=-1h
I know, I know — I could achieve the same level of excellence using targeted indexes (index=rmi_stage) and/or various regex filters .. Some of that, unfortunately, is out of my control ..
OK .. So how can you manage this without having to use the GUI ?? Easy !! You just need to drop a config file in the proper location (for me it’s: /opt/splunk/etc/system/local/tags.conf) on the search head, and away you go .. The syntax is pretty basic:
# tagging host login.example.net with PROD, TOMCAT, and LOGIN [host=login.example.net] prod = enabled tomcat = enabled login = enabled
Below’s a nice little example of how I automated this using Ansible (big surprise there 🙂 and the EC2 dynamic inventory script ..
So I want to share !!
I can’t get into too many details, but the overall concept was that every customer would be running a micro instance with our custom Hubot code installed .. This instance would pull code updates, if any, every 5 minutes and infrastructure updates, if any, every 15 minutes .. In addition, a customer could participate in pilot programs — AKA branch work ..
I really liked how I was able to mitigate the use of a “command node” and just run Ansible locally and on a schedule .. Also, I was able to automate pretty much everything — from VPC creation all the way to autoscaling groups ..
Anyway, here’s the link: https://github.com/gkspranger/failed-chatbot .. Maybe it will help one of you out there in Internets land ..
Sooo .. You are monitoring a fleet of AWS EC2 hosts via Nagios, and have yet to find an easy way to manage their host definitions .. Good news (if you happen to be using Ansible dynamic inventories) !! I created an Ansible template that loops thru all your EC2s and creates them for you ..
In addition, you can easily define Nagios service dependencies, helping you zero in on the root problem more quickly ..
Afraid of having too many AWS EC2 images and/or snapshots, thus running up your bill ?? Fear not !! I have you covered:
Nagios Plugins to Check AWS EC2 Images
Nagios Plugin to Check AWS EC2 Snapshots
So I have been using Ansible for over two years now .. I use it for damn near everything — provisioning infrastructure, configuring nodes, deploying Web applications, testing whatever I can, and other ad hoc tasks (sadly, I’m still working on a “get me beer” playbook) .. Long story short, it’s been a game changer .. Problem is, as my (and my team’s — hi guys !!) Ansible usage grows (50+ playbooks and 130+ roles) — so does my desire to organize it in a way that is scaleable ..
There are many ways you can setup your Ansible project (one, two, three, four, etc ..) — which is great !! That said, I love me some simplicity .. After trying out a few setups, I finally settled on one that works for me .. You can see it here ..
The view from 30,000 feet:
- All of my inventory files, static and dynamic, will be children of the inventories directory
- Group and other variables
- the group_vars directory can be relative to an inventory file, no matter where the playbook is .. since I like to add some structure to my playbook organization, it makes sense to put it here
- variable files (i.e. Ansible Vault) that need to be explicitly loaded go in the vars directory
- IN THEORY: you could also put a host_vars directory here .. but as y’all know, host_vars are the devil
- Let me explain my logic here .. In my work, I essentially perform five functions: 1) provision infrastructure, 2) configure infrastructure, 3) deploy to infrastructure, 4) test infrastructure (and other things), and 5) save the world (i.e. ad hoc tasks) .. Knowing this:
- these are the bits and pieces that make up a useful piece of infrastructure .. for example, we have resource roles for AEM, Bitbucket, CPANm, .forward, Java (1.6, 1.7, and 1.8), Apache, Netcat, Nagios, NRPE, etc .. all solid implementations .. all reusable ..
- STYLE ALERT: we DON’T use Ansible Galaxy — directly .. we often refer to it for inspiration — but always end up using our own implementation
- this is a “completed”piece of infrastructure .. the sum of the (resource) parts .. the cherry on top .. for example, we have primary roles for user_web_api_server, internal_dns_server, aem_author_server, aem_publish_server, etc ..
- this is what I “do” to my infrastructure that doesn’t maintain any real “resource” …. for example, we have action roles for silencing/unsilencing Nagios, deploying code, restarting application servers, taking data centers offline, etc ..
The view from 30 feet:
- PROBLEM: “I want my playbooks to be able to refer to my roles in a way that is consistent and easy” .. Great idea !! The problem is, your playbooks and roles are gonna be all over the place — so you can’t take advantage of the “relative referencing” you can do in a traditional project structure .. Let’s also assume you don’t want to define an absolute path in the config file ..
- SOLUTION: Hello bootstrap !! Take a path that will always be consistent (inventory_dir) and use it to define other paths with some regex magic .. When finished, shove it all into a external variables file ..
- FINALLY: Refer to the bootstrap, early and often, in every playbook you create, ..
Again, this project setup works for me .. “Me” being myself and 4 other sys admins ..
Anywho — I need to get back to work on that “get me beer” playbook ..
Hal is my Hubot chatbot .. He’s awesome !! He gets me beer !!
He also does things like restart app servers, deploy code, and show me pictures of grumpy cats .. He’s so cool, I’ve started making non-humans to talk to him .. “Greg, what do you mean ??” .. Well, let me show you ..
- I have a Nagios server
- It monitors (allthethings)
- When the “logged in users” alert is triggered, Nagios sends a message to my chat service using hipsaint
- “logged in users” is a monitor I have that alerts me when more than 3 users are logged into a server
- I see the alert and the server in question
- I SSH into the server
- I type who
- I then determine if I need to care
- If not, move on with my life
- If so, dig deeper
The thing is, I have more than 2,200 active monitors .. That means Nagios can and will send many, many messages to my chat service — depending on the day .. So how can I make my life easier ??
Here’s an easy one: ask Hal who’s on a server ..
My stack is HipChat -> Hubot -> Jenkins -> Ansible .. That means I can damn near do anything I want, all from my chat client ..
Remember what I said earlier — about making non-humans talk to Hal ?? What I did was create a Nagios event handler that sends a message to my chat service using HipChat CLI .. Therefore, I AM NOT asking Hal who’s on a server, it’s NAGIOS WHO IS doing it ..
It doesn’t stop there !! You can create scripted Splunk alerts as well .. Before you know it, you will be making (allthethings) talk to Hal ..
So one of our AEM nodes was freaking out the other day .. No, not the election results .. Some code was deployed to it that had runaway processes, thus gorging itself on CPU and memory .. EEEKK !! What to do ?? If you’ve been around AEM for awhile, you know how we love our raw thread dumps .. That being said, I really dislike the process on how to obtain them:
- Log into the node
- Get the Java PID
- Execute jstack and output to a log file
- Repeat every 10 seconds for at least one minute
- Compress the log file
- Share the compressed log file
- Typically via email
So how can I automate this ?? Easy !!
Create a Bash script that will generate the thread dumps for you ..
Create an Ansible playbook that will execute the script, compress the log file, and email it