July 22, 2024


Typically, you have to run a bit of code for hours, days, and even weeks. Cloud Capabilities and Cloud Run are my default decisions to run code. Nonetheless, they each have limitations on how lengthy a operate or container can run. This guidelines out the concept of executing long-running code in a serverless method. 

Because of Workflows and Compute Engine, you possibly can have an nearly serverless expertise with lengthy operating code. 

Right here’s the concept:

  1. Containerize the long-running job, so it may possibly run wherever.

  2. Plan to run the container on a Compute Engine VM with no time limitations.

  3. Use Workflows to automate VM creation, operating the container on the VM, and VM deletion.

With this strategy, you merely execute the workflow and get again the results of the long-running job. The underlying lifecycle of the VM and operating of the container are all abstracted away. That is nearly serverless!

Let’s take a look at a concrete instance.

Lengthy-running job: Prime quantity generator

The long-running job for this instance is a first-rate quantity generator. You possibly can check out the supply right here. 

The code implements a intentionally inefficient prime quantity generator and a easy net API outlined in PrimeGenController.cs as follows: 

  • /begin: Begins calculating the most important prime.

  • /cease: Stops calculating the most important prime.

  • /: Returns the most important prime calculated thus far.

There’s additionally a Dockerfile to run it as a container.

You should utilize gcloud to construct and push the container think about:

gcloud builds submit --tag gcr.io/$PROJECT_ID/primegen-service

The container may also want HTTP and port 80 for its net API. Add a firewall rule for it in your challenge:

gcloud compute firewall-rules create default-allow-http --allow tcp:80

Construct the workflow

Let’s construct the workflow to automate operating the container on a Compute Engine VM. The total supply is in prime-generator.yaml.

First, learn in some arguments, such because the identify of the VM to create and the variety of seconds to run the VM. The workSeconds argument determines how lengthy to execute the long-running container:

Subsequent, create a container-optimized VM with an exterior IP and the precise scopes to have the ability to run the container. Additionally specify the precise container picture to run. 

That is the trickiest a part of the workflow. It is advisable to determine the precise parameters for the REST name you want for the Compute Engine VM. One trick is to create the VM manually from Google Cloud console after which click on Equal REST to get the REST command with the precise parameters you have to create the VM.

Equivalent REST in Compute Engine section

You possibly can then convert that REST command into YAML for the Workflows Compute Engine connector. Ultimately, you’ll find yourself with one thing like this:

As soon as the VM is created and operating, you have to get the exterior IP of the service and construct the beginning/cease/get URLs for the net API:

You possibly can then begin the prime quantity technology and watch for the top situation. On this case, Workflows merely waits for the desired variety of seconds.  Nonetheless, the top situation could possibly be primarily based on polling an API within the container or a callback from the container.

When the sleep is finished, cease the prime quantity technology and get the most important calculated prime:

Lastly, delete the VM and return the end result:

Deploy and execute the workflow

When you’ve constructed the workflow, you’re able to deploy it:


gcloud workflows deploy $WORKFLOW_NAME --source=prime-generator.yaml

After which execute the workflow for one hour:

gcloud workflows run $WORKFLOW_NAME --data=""

This creates a VM and begins the container.

Prime number generator VM

When the time is up, the VM will likely be deleted and you will note the outcomes of the calculation:

Although it’s not potential at this time to execute long-running code on Cloud Capabilities or Cloud Run, you should utilize Workflows to orchestrate a Compute Engine VM and have code operating with no closing dates. It’s nearly serverless! As at all times, be at liberty to achieve out to me on Twitter @meteatamel with questions or suggestions.

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