This tutorial will provide a walkthrough to install Gremlin on Ubuntu 16.04 and then perform a Chaos Engineering experiment using a Gremlin CPU attack.
Before you begin this tutorial, you'll need the following:
- An Ubuntu 16.04 server
- A Gremlin account
apt-transport-httpspackage to be able to install gremlin from our repo via HTTPS.
Step 1 - Installing Gremlin
In this step, you'll install Gremlin
First, ssh into your host and add the gremlin repo:
ssh username@your_server_ip echo "deb https://deb.gremlin.com/ release non-free" | sudo tee /etc/apt/sources.list.d/gremlin.list
Import the GPG key:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys C81FC2F43A48B25808F9583BDFF170F324D41134 9CDB294B29A5B1E2E00C24C022E8EF3461A50EF6
Then install the Gremlin client and daemon:
sudo apt-get update && sudo apt-get install -y gremlin gremlind
Step 2 - Validating Installation
Run the following command to confirm you have all the necessary components installed on your host for Gremlin to function correctly:
You'll see the output from the Gremlin checks in your console:
Checking resource gremlins ... Checking CPU gremlin ... Attack on cpu_1 completed successfully CPU gremlin OK
Step 3 - Registering with Gremlin
You'll need to register with the Gremlin control plane to create a new Gremlin client session. Gremlin offers tags, a feature allowing you to apply custom labels to a Gremlin client. You can tag more than one Gremlin client with the same label, then use it to view a filtered list of Gremlin clients that share that particular tag. In addition to filtering, the Gremlin Control Panel and API allow you to initiate an action across multiple Gremlin clients with the same tag. Identifying groups of Gremlin clients and administering all of them at once reduces the time required to manage hosts.
Start by initializing Gremlin and assigning tags with the following command. Substitute your desired tag name for
gremlin init --tag tag_name1=tag_value1 \ --tag tag_name2=tag_value2
This will create a new Gremlin client with the tags tagname and tagname applied.
Example: Adding tags to a Gremlin client
Suppose that you have a collection of hosts and you want to tag them by their service, service-version and service-type.
Initialize Gremlin and assigning tags with the following command:
gremlin init \ --tag service=api \ --tag service-version=1.0.0 \ --tag service-type=http
This will set tags as
If you are using an AWS EC2 instance, Gremlin will also auto-populate tags for
Login to the Gremlin Control Panel using your Company name and sign-on credentials. These details were emailed to you when you signed up to start using Gremlin.
Next click on your name and select Settings in the Gremlin Control Panel.
You will find your Team ID on the left under your company name, then click to generate your Team Secret. We recommend you store your Team Secret somewhere safe since it is only available once. If you lose your Team Secret you will be able to reset it.
On your computer, open your terminal and paste your Team ID and then Team Secret:
Please input your Team ID: Please input your Team Secret:
You are now ready to create attacks using the Gremlin Control Panel.
Step 4 - Creating attacks using the Gremlin Control Panel
Login to the Gremlin Control Panel using your Company name and sign-on credentials. These details were emailed to you when you created your Gremlin account.
Example: The Hello World of Chaos Engineering (a CPU attack)
The Hello World of Chaos Engineering is the CPU Resource Attack. To create a CPU Resource Attack select Resource and then CPU in the dropdown menu.
The CPU Resource Attack will consume CPU resources based on the settings you select. The most popular default settings for a CPU Resource Attack are pre-selected, a default attack will utilize 1 core for 60 seconds. Before you can run the Gremlin attack you will need to click either Exact hosts to run the attack on or click the Random attack option.
Click Exact and select a Gremlin Client in the list.
On your server, run
top to check the impact of the Gremlin Attack:
$ top top - 06:26:47 up 7 days, 7:00, 1 user, load average: 0.28, 0.07, 0.02 Tasks: 105 total, 1 running, 104 sleeping, 0 stopped, 0 zombie %Cpu(s): 79.7 us, 20.3 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 1016120 total, 127140 free, 93956 used, 795024 buff/cache KiB Swap: 0 total, 0 free, 0 used. 712192 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 23768 gremlin 20 0 13268 11136 3576 S 99.3 1.1 0:14.05 gremlin 23766 root 20 0 40388 3600 3072 R 0.3 0.4 0:00.03 top 1 root 20 0 37760 5760 3940 S 0.0 0.6 0:13.74 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root 20 0 0 0 0 S 0.0 0.0 0:01.28 ksoftirqd/0 5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 7 root 20 0 0 0 0 S 0.0 0.0 0:06.14 rcu_sched 8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh 9 root rt 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 10 root rt 0 0 0 0 S 0.0 0.0 0:04.09 watchdog/0
When your attack is complete it will move to Completed Attacks.
Step 5 - Halting a CPU resource attack using the Gremlin Control Panel
You've installed Gremlin on a server running Ubuntu 16.04 and validated that Gremlin works by running the Hello World of Chaos Engineering, the CPU Resource attack. You now possess tools that make it possible for you to explore additional Gremlin Attacks including attacks that impact State and Network.
Gremlin's Developer Guide is a great resource and reference for using Gremlin to do Chaos Engineering. You can also explore the Gremlin Blog for more information on how to use Chaos Engineering with your application infrastructure.