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Datum’s Application Load Balancer (ALB) serves public HTTP and HTTPS traffic to your workload. Instances have private IPv6 addresses only, so the internet can’t reach them directly. --http-port is the quickest way to attach an ALB to a workload: it declares the port your container serves HTTP on and creates an HTTPProxy for the workload. Datum terminates TLS at the ALB, sends each request to the nearest location with a healthy Instance, and connects to your Instances over plain HTTP on your private network.
Compute is in preview, and the v1alpha API can change.

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Before you begin

  • Select a project, install the compute plugin, and get access to Compute. For more information, see Set up your project.
  • Make sure that you have permission to create networking resources in the project, in addition to compute resources. The Network Admin role includes the permissions that publishing needs. The Gateway Admin role alone isn’t enough.
  • Make sure that your app serves plain HTTP, not HTTPS, on the port that you publish, and listens on IPv6.

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Attach an ALB with datumctl

To attach an ALB to a workload, run datumctl compute deploy with --http-port:
Replace the following:
  • WORKLOAD_NAME: the name of your workload.
  • IMAGE: the full image reference, including the registry host.
  • LOCATION: one or more locations, separated by commas.
  • PORT: the port that your container serves HTTP on, such as 8080.
--http-port works when you create a workload and when you update one that you deployed with flags.
A flag-based datumctl compute deploy replaces the workload’s whole template and placements with what the flags describe. It removes environment variables, volumes, registry credentials, custom commands, and extra placements that you set in a manifest, and it sets the Instance count to the --min value, which defaults to 1. To publish a workload that you manage with a manifest, see Publish a workload you manage with manifests.
The command declares the port on the container, waits for the rollout, and then prints the publishing progress and the ALB’s hostname as the last line of output:
Your hostname is different. A new hostname can take a few minutes to resolve. If a request fails with a name resolution error, wait and try again. If you press Control+C while the command publishes, publishing continues in the background.

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Find your workload’s ALB hostname

To see the ALB hostname of every workload in your project, run the following command:
The hostname is in the URL column. To see the hostname and the health of the Instances behind it in each location, run the following command:
If you have jq installed, you can read the hostname in a script. Run the following command:
Replace WORKLOAD_NAME with the name of your workload.

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Change or remove the ALB

The ALB keeps its hostname when you redeploy the workload. If you run datumctl compute deploy without --http-port, the workload keeps its current port and the ALB keeps its hostname. To change or remove the ALB, do one of the following:
  • To serve on a different port, run datumctl compute deploy again with the new --http-port value. The hostname stays the same.
  • To stop serving the workload publicly, run datumctl compute deploy with --no-http. This removes the ALB, and the hostname stops responding.
Datum generates the hostname when it creates the ALB. If you remove the ALB and publish again, the workload gets a new hostname. datumctl compute destroy removes the workload’s ALB along with the workload and its Instances. A plain datumctl delete workload deletes the workload and its Instances, but leaves the ALB in place. For more information, see Delete a workload.

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Use a custom domain

You can serve a published workload on your own domain, such as api.example.com, in addition to its generated hostname. The ALB is an HTTPProxy resource named after the workload. For more on custom hostnames, TLS, and WAF protection, see ALB. To add a custom domain, follow these steps:
  1. Add and verify your domain in Datum. For more information, see Domains.
  2. To open the workload’s HTTPProxy for editing, run the following command:
    Replace WORKLOAD_NAME with the name of your workload.
  3. Add your hostname to spec.hostnames, and then save and close the file:
  4. Point your hostname at the workload’s generated hostname with a CNAME record. If Datum hosts your DNS, see DNS setup for Application Load Balancer.
datumctl compute deploy keeps custom hostnames when it updates a workload. datumctl compute destroy removes the ALB, including its custom hostnames, but keeps your domain resources.

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Publish a workload you manage with manifests

A workload manifest can’t declare an ALB, and datumctl compute deploy -f doesn’t create or remove one. To attach an ALB to a manifest-managed workload, follow these steps:
  1. Create the workload with datumctl compute deploy and --http-port, as described in Attach an ALB with datumctl. The command saves the workload to workload.yaml in the current directory.
  2. Rename workload.yaml, and make your changes in the renamed file. Keep the container port that you published.
  3. To apply later changes, run datumctl compute deploy -f FILE, where FILE is the path to your manifest. The workload keeps its ALB.

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Limitations

In addition to the limitations that apply to all of Compute, the ALB has the following limitations:
  • Clients always connect over HTTPS. Datum connects to your Instances over plain HTTP, and TLS between Datum and your Instances isn’t supported.
  • datumctl compute deploy attaches one ALB to each workload, on one port.

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What’s next

Last modified on September 23, 2026