Start your 30 day free trial.

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.

Configuring the Gremlin Agent

Managing the Gremlin Agent