How to adjust Memory and CPU of ConnectInject pods in Consul k8s.

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Introduction

This is a guide to increase CPU and memory resources in connect inject pods. The initial Helm chart defaults for the Consul containers are a bare minimum requirement to get Consul up and running for a multitude of environments, and Kubernetes resource tuning may be necessary to better suit your environment's needs as seen below.  

Expected Outcome

Increasing the default resource of Consul connectInject pod will provide faster service registration and discovery times in the Envoy sidecar.

Prerequisites 

• k8s administrative privileges to Consul namespace.
• connect enabled

Use Case

In the event, there are high delays during Envoy service registration and discovery, and if any performance increase is to occur, the resources allocated to this component should help improve your case.

Procedure

Below are two types of procedures to adjust Memory and CPU on connectInject pods.

Adjust the CPU/memory on the connectInject deployment replicaSet

1. Get the connect-inject deployment.
   

   $ kubectl get deployment consul-connect-injector -n consul
   NAME                     READY UP-TO-DATE AVAILABLE AGE
   consul-connect-injector   1/1      1        1       47m

2.  Edit the consul-connect-injector deployment.
   

   $ kubectl edit deployment consul-connect-injector -n consul

3. Adjust "resources" for cpu and memory to desired limits. Increments of 50 are acceptable.
   

   resources:
   limits:
   cpu: 200m
   memory: 150Mi
   requests:
   cpu: 100m
   memory: 100Mi

4. Save the file and run the command to see the new connect-inject pod coming up with desired resources.
   

   kubectl get pods -n consul

Adjust the CPU/memory on the connectInject pod using the helm upgrade command

1. Create a values.yaml file with desired CPU/Memory values using your favorite editor e.g VIM.
   

   connectInject:
     enabled: true
     resources:
       requests:
         memory: "100Mi"
         cpu: "100m"
       limits:
         memory: "150Mi"
         cpu: "200m"

2.  Use the helm command to upgrade with new values with your consul-k8s version.
   

   helm upgrade consul hashicorp/consul -n consul -f values.yaml --version '1.1.0'

3.  Run the command to see the new connect-inject pod coming up with desired resources.
   

   kubectl get pods -n consul

4. Additionally, we can increase metrics for sidecarProxy and Connect injected init container with helm upgrade command using the below yaml.
   

   connectInject:
     initContainer:
       resources:
         requests:
           memory: "150Mi"
           cpu: "150m"
         limits:
           memory: "200Mi"
           cpu: "200m"
     sidecarProxy: #specific to envoy sidecars when scaling
       resources:
         requests:
           memory: "100Mi"
           cpu: "100m"
         limits:
           memory: "100Mi"
           cpu: "100m"
   

More information about these metrics can be found in the following article: Service Mesh Registration Time Tuning - Consul K8s Control Plane Resources.

References

1. Kubernetes site for kubectl edit
2. Service Mesh Registration Time Tuning - Consul K8s Control Plane Resources