A sidecar is a container that extends or enhances the main container in a pod. The main container and the sidecar share a pod, and therefore share the same network space and storage. You can add sidecars to existing workloads by using the Add a Sidecar option.
From the Global view, open the project running the workload you want to add a sidecar to.
Click Resources > Workloads.
Find the workload that you want to extend. Select ⋮ icon (…) > Add a Sidecar.
Enter a Name for the sidecar.
Select a Sidecar Type. This option determines if the sidecar container is deployed before or after the main container is deployed.
The sidecar container is deployed after the main container.
The sidecar container is deployed before the main container.
From the Docker Image field, enter the name of the Docker image that you want to deploy in support of the main container. During deployment, Rancher pulls this image from Docker Hub. Enter the name exactly as it appears on Docker Hub.
Set the remaining options. You can read about them in Deploying Workloads.
Result: The sidecar is deployed according to your parameters. Following its deployment, you can view the sidecar by selecting ⋮ icon (…) > Edit for the main deployment.