Is it possible to run side containers or init containers in Google Cloud Run or App Engine? I couldn't find any documentation of this and trying to ask this on GCP support forums I was directed to ask at stack-overflow. If possible how would you accomplish this? I came across this repo but it wasn't helpful.
I know it is possible with GKS but trying to do the same with these services.
As John mentioned, the answer is no. Cloud run and App Engine both provide you a simple way to deploy a containerized application int the cloud and have it run.
To keep this as simple and streamlined as possible, additional features that you see in pod specs are not available (such as init containers or running multiple containers).
For more complex deployments, it is recommended to use GKE
You can't, for now, running a Pod on Cloud Run, you can only run a container. However, it's possible to run a multi process container for helping you to achieve this.
You can find here and here a post from Ahmet for running several process in the same container.
Note: Ahmet is one of Cloud Run engineers at Google, you can rely on his articles!