Dashboard
Getting Started

Enabling DNS collection

Gremlin can collect information about the DNS queries on the Linux machines where the Gremlin Agent is installed. This DNS query information is a new way to define Services in Gremlin Reliability Management and helps inform Gremlin's Service features.

What is collected?

For every DNS query visible to the Gremlin Agent, Gremlin will collect:

  • container ID
  • hostname in query
  • returned aliases from query
  • returned ip addresses from query

Requirements

Using this feature requires the following:

  • Gremlin Agent version 2.40.1
  • Gremlin Kubernetes Chao version 0.3+
  • Gremlin must run within the PID namespace of the host; for Kubernetes this means setting hostPID=true
  • Gremlin needs the CAP_NET_RAW capability

DNS collection is experimental for Windows. User installation of WinPcap, Npcap, or Win10Pcap is required.

Enable DNS Collection

To enable DNS Collection, use one of the following methods:

  • set GREMLIN_COLLECT_DNS=true in the Gremlin agent environment (by writing to /etc/default/gremlind)
  • set collect_dns: true in /etc/gremlin/config.yaml

Examples

The following sections show examples for enabling DNS Collection on your platform.

Existing installation

SHELL

sudo echo GREMLIN_COLLECT_DNS=true | sudo tee -a /etc/default/gremlind \
  && sudo systemctl restart gremlind

APT

SHELL

echo "deb https://deb.gremlin.com/ release non-free" | sudo tee /etc/apt/sources.list.d/gremlin.list
   && sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9CDB294B29A5B1E2E00C24C022E8EF3461A50EF6
   && sudo apt update
   && GREMLIN_COLLECT_DNS=true sudo -E apt install gremlin gremlind

YUM

SHELL

sudo curl https://rpm.gremlin.com/gremlin.repo -o /etc/yum.repos.d/gremlin.repo \
  && GREMLIN_COLLECT_DNS=true sudo -E yum install gremlin gremlind

Kubernetes

If you’re upgrading an existing Helm installation of the Gremlin Agent, run the following command with helm upgrade instead of helm install.

SHELL

helm repo add gremlin https://helm.gremlin.com
helm repo update
helm install gremlin gremlin/gremlin \
  --namespace gremlin \
  --set      gremlin.hostPID=true \
  --set      gremlin.collect.dns=true \
  --set      gremlin.secret.managed=true \
  --set      gremlin.secret.type=secret \
  --set      gremlin.secret.clusterID=my-cluster \
  --set      gremlin.secret.teamID=$GREMLIN_TEAM_ID \
  --set      gremlin.secret.teamSecret=$GREMLIN_TEAM_SECRET

Docker

SHELL

docker run -d \
  --net=host \
  --pid=host \
  --cap-add=CAP_NET_RAW \
  -v /var/lib/gremlin:/var/lib/gremlin \
  -v /var/log/gremlin:/var/log/gremlin \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e GREMLIN_TEAM_ID \
  -e GREMLIN_TEAM_SECRET \
  -e GREMLIN_IDENTIFIER \
  -e GREMLIN_COLLECT_dns=true \
  gremlin/gremlin daemon

Disable DNS Collection

DNS collection is disabled by default. To disable DNS Collection, use one of the following methods:

  • set GREMLIN_COLLECT_DNS=false in the Gremlin agent environment (by writing to /etc/default/gremlind)
  • set collect_dns: false in /etc/gremlin/config.yaml

Examples

The following sections show examples for disabling DNS Collection on your platform.

Existing installation

SHELL

echo GREMLIN_COLLECT_DNS=false | sudo tee -a /etc/default/gremlind \
  && sudo systemctl restart gremlind

APT

SHELL

echo "deb https://deb.gremlin.com/ release non-free" | sudo tee /etc/apt/sources.list.d/gremlin.list \
  && sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9CDB294B29A5B1E2E00C24C022E8EF3461A50EF6 \
  && sudo apt update \
  && GREMLIN_COLLECT_DNS=false sudo -E apt install gremlin gremlind

YUM

SHELL

sudo curl https://rpm.gremlin.com/gremlin.repo -o /etc/yum.repos.d/gremlin.repo \
  && GREMLIN_COLLECT_DNS=false sudo -E yum install gremlin gremlind

Kubernetes

If you’re upgrading an existing Helm installation of the Gremlin Agent, run the following command with helm upgrade instead of helm install.

SHELL

helm repo add gremlin https://helm.gremlin.com
helm repo update
helm install gremlin gremlin/gremlin \
  --namespace gremlin \
  --set      gremlin.hostPID=true \
  --set      gremlin.collect.dns=false \
  --set      gremlin.secret.managed=true \
  --set      gremlin.secret.type=secret \
  --set      gremlin.secret.clusterID=my-cluster \
  --set      gremlin.secret.teamID=$GREMLIN_TEAM_ID \
  --set      gremlin.secret.teamSecret=$GREMLIN_TEAM_SECRET

Docker

SHELL

docker run -d \
  --pid=host \
  --cap-add=NET_RAW \
  -v /var/lib/gremlin:/var/lib/gremlin \
  -v /var/log/gremlin:/var/log/gremlin \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e GREMLIN_TEAM_ID \
  -e GREMLIN_TEAM_SECRET \
  -e GREMLIN_IDENTIFIER \
  -e GREMLIN_COLLECT_DNS=false \
  gremlin/gremlin daemon
No items found.
Previous
Next
Previous
This is some text inside of a div block.
Compatibility
Installing the Gremlin Agent
Authenticating the Gremlin Agent
Configuring the Gremlin Agent
Managing the Gremlin Agent
User Management
Integrations
Health Checks
Notifications
Command Line Interface
Updating Gremlin
Quick Start Guide
Services and Dependencies
Detected Risks
Reliability Tests
Reliability Score
Targets
Experiments
Scenarios
GameDays
Overview
Deploying Failure Flags on AWS Lambda
Deploying Failure Flags on AWS ECS
Deploying Failure Flags on Kubernetes
Classes, methods, & attributes
API Keys
Examples
Container security
General
Linux
Windows
Chao
Helm
Glossary
Alfi
Additional Configuration for Helm
Amazon CloudWatch Health Check
AppDynamics Health Check
Application Level Fault Injection (ALFI)
Blackhole Experiment
CPU Experiment
Certificate Expiry
Custom Health Check
Custom Load Generator
DNS Experiment
Datadog Health Check
Disk Experiment
Dynatrace Health Check
Grafana Cloud Health Check
Grafana Cloud K6
IO Experiment
Install Gremlin on Kubernetes manually
Install Gremlin on OpenShift 4
Installing Gremlin on AWS - Configuring your VPC
Installing Gremlin on Kubernetes with Helm
Installing Gremlin on Windows
Installing Gremlin on a virtual machine
Installing the Failure Flags SDK
Jira
Latency Experiment
Memory Experiment
Network Tags
New Relic Health Check
Overview
Overview
Overview
Overview
Overview
Packet Loss Attack
PagerDuty Health Check
Preview: Gremlin in Kubernetes Restricted Networks
Private Network Integration Agent
Process Collection
Process Killer Experiment
Prometheus Health Check
Role Based Access Control
Running Failure Flags experiments
Scheduling Scenarios
Shared Scenarios
Shutdown Experiment
Slack
Teams
Time Travel Experiment
Troubleshooting Gremlin on OpenShift
User Authentication via SAML and Okta
Users
Webhooks
Integration Agent for Linux
Test Suites
Restricting Testing Times
Reports
Enabling DNS collection