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Getting Started

Additional Configuration for Helm

Some environments require additional configuration. Review the following sections to find the best configuration for your environment and then verify your installation.

Declare container driver

Gremlin currently has 4 different drivers for integrating with the underlying container runtime powering Kubernetes, as shown in the following table. Gremlin automatically chooses any of the cgroup drivers when the associated requirements are met.

When using Helm, you can declare the intended container driver with the following:

11--set gremlin.container.driver=$driver
DriverRequirements and file accessNotes
containerd-runcConnect: /run/containerd/containerd.sockUsed with containerd container runtime
Write: /run/containerd/runc/
Write: host's cgroup root
Access to the host's PID namespace
crio-runcConnect: /run/crio/crio.sockUsed with Cri-O container runtime
Write: /run/runc
Write: host's cgroup root
Access to the host's PID namespace
dockerConnect: /var/run/docker.sockNo support for systemd cgroup driver
docker-runcConnect: /var/run/docker.sockRecommended for Docker runtime
Write: /run/docker/runtime-runc/moby
Write: host's cgroup root
Minimum Docker version: 17.11.0

Enable Gremlin on the Kubernetes Master

Most Kubernetes deployments configure master nodes with the taint. You can run the following command to see if any of your nodes have this taint:

1kubectl get no,TAINTS:.spec.taints
2kube-01 [map[effect:NoSchedule]]
3kube-02 <none>

To install Gremlin on a Kubernetes master that has been tainted, add those tolerations to your Helm arguments:

1--set tolerations\[0\].effect=NoSchedule \
2--set tolerations\[0\] \
3--set tolerations\[0\].operator=Exists

Add AppArmor support

If your cluster has AppArmor enabled (for example, Azure Kubernetes Service), add the following line to your Helm deployment to allow the Gremlin container to run without a security profile:

1--set gremlin.apparmor=unconfined

Use a PodSecurityPolicy

Gremlin does not support running within the restricted PodSecurityPolicy (PSP) that is configured by default on clusters that enable such policies. You can install a gremlin PodSecurityPolicy to grant chao and gremlin everything they need, and nothing they don't need. When installing Gremlin with Helm, you can supply --set gremlin.podSecurity.podSecurityPolicy.create=true to install Gremlin's custom pod security policies. Check out Gremlin's Helm Chart Repository for full documentation and usage.

Use a custom seccomp policy

All Gremlin behavior works under Docker's default seccomp policy. However some environments use seccomp profiles that are more restrictive, and prevent Gremlin behavior when using their default seccomp profile.

Gremlin has a custom seccomp profile which can be automatically installed when you install with Helm and pass --set gremlin.podSecurity.seccomp.enabled=true. Check out Gremlin's Helm Chart Repository for full documentation and usage.

Configure a proxy

Both Gremlin and Chao can be configured to use a proxy for outgoing HTTP traffic. The conventional https_proxy and no_proxy variables can be passed as environment variables for this purpose.

Proxy certificate authorities

When proxies support HTTPS communication, or are otherwise configured with a TLS certificate, it can be necessary to configure Gremlin to trust the proxy's certificate authority. This is done by passing the SSL_CERT_FILE environment variable where the value is a path on the file system to a PEM encoded file containing the certificate authority's certificate.

Configuring Gremlin

1- name: https_proxy
2 value: http://proxy.local:3128
3# Pass SSL_CERT_FILE when the proxy requires trusting a TLS certificate
4- name: SSL_CERT_FILE
5 value: /etc/gremlin/ssl/proxy-ca.pem

Configuring the Gremlin Kubernetes Agent

Because the Gremlin Kubernetes Agent (Chao) communicates with the local Kubernetes ApiServer in addition to the internet, it's important to bypass internet proxies for traffic bound to apiserver

1- name: https_proxy
2 value: http://proxy.local:3128
3- name: no_proxy
5# Pass SSL_CERT_FILE when the proxy requires trusting a TLS certificate
6- name: SSL_CERT_FILE
7 value: /etc/gremlin/ssl/proxy-ca.pem
8# Pass SSL_CERT_DIR when SSL_CERT_FILE contains only the proxy certificate. This will ensure Chao trusts
9# The value of SSL_CERT_DIR varies depending on the operating system on which the cluster hosts run
10# See /docs/infrastructure-layer/kubernetes/#ssl_cert_dir
11- name: SSL_CERT_DIR
12 value: /etc/ssl/

Supplying SSL_CERT_DIR ensures Chao is still configured with the necessary certificate authories to trust However it is not needed for most Gremlin installations because Chao will trust Gremlin servers by default. This variable is only required for Chao deployments when both of the following conditions are true:

  • Chao is configured with https_proxy and this proxy is configured to accept TLS connections
  • Chao is also configured with SSL_CERT_FILE, and the file it points to contains only the certificate authority for the https proxy

The value of SSL_CERT_DIR should point to the root of the certificate authority directory for the operating system on which Chao runs.

/etc/pki/tls/Fedora/RHEL 6/OpenELEC
/etc/ssl/OpenSUSE / Alpine Linux
/etc/pki/ca-trust/extracted/pem/CentOS/RHEL 7

Share namespaces

With the Gremlin Kubernetes Agent installed on your cluster you can share individual namespaces with other Gremlin teams. Once installed head to the Agents list in the Gremlin web app to view all of the clusters installed across your company.

By sharing individual namespaces to teams across your company, you can provide access for users to run experiments only on relevant services while also limiting access to the hosts or nodes themselves.

Managing Cluster access

As the Team Manager on a team where a Kubernetes cluster is installed or as a Company Manager, you can click the gear icon to manage access. On the cluster view, to share a namespace with a team use the search box to filter down the list of available teams. Then use the search box on the team row and click on the namespace you'd like to share. Use the options menu to share all of the namespaces.

To remove access of a namespace to a team, click on the x on the blue namesapce bubbles. Using the options menu you can also remove all namespaces at once.

Requesting Namespace access

As a member of a different team of your company, you can view the list of clusters installed across your company. To request access to a namespace on one of these clusters not installed on your team, click the Request Access button. You can then check off the namespaces you'd like access to, or you can use the select all switch.

You can also request access to a namespace within a cluster when creating an experiment. Once you've selected a cluster, the drop down list of namespaces will have an option to request access.

Approving access requests

To approve or deny an access request, you must be a Team Manager. Navigate to the Agents list, locate your cluster, and click the gear icon to the right. On the Manage Cluster Access page, you'll see any pending requests from your company.