On Demand Container Serving With GCP

Question

I have a Docker image that will execute different logic depending on the environment variables that it is run with. You can imagine that running it with VAR=A will produce slightly different logic compared to running it with VAR=B.

We have an application that is meant to allow users to kick off tasks that are defined within this Docker image. Depending on the user attributes, different environment variables will need to be passed into the Docker container when it is run. The task is meant to run each time an event is generated through user action and then the container should shut down/be removed.

I'm trying to determine if GCP has any container services that best match what I'm looking for. My understanding of some of the services is:

• Cloud Functions - can work well for consuming events and taking specific actions each time an event is triggered, but it is not suited for containerized workloads.
• Cloud Run - a serverless way of deploying containers. As I understand it, a deployment on cloud run spins up a "service", and the environment variables must be passed in as part of the service definition. Because we may have a large number of combinations of environment variables (many of which may need to be running at once), it seems that this would end up creating a large number of services, which feels potentially clunky. This approach seems better for deploying a single service with static environment variables that needs to be auto-scaled by GCP.
• GKE - another container orchestration platform. This is what I'm considering at the moment. The idea is that we would define a single job definition that can vary according to environment variables that are passed into it. The problem is that these jobs would need to be kicked off dynamically via code. This is a fairly straightforward process with kubectl, but the Kubernetes REST API seems fairly underdeveloped (or at least not that well documented). And the lack of information online on how to start jobs on-demand through the Kubernetes API makes me question whether this is the best approach.

Are there any tools that I'm missing that would be useful in spinning up containers on-demand with dynamic sets of environment variables and removing them when done?