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Launch templates

A launch template keeps an instance's settings, so you can start one to ten instances like it in one step: location, size, image, network, security groups and rules, SSH key, server group, new data volumes, public IP, load balancer and user data.

Use it for instances you start often, and as the source of an instance group.

Find them under Compute → Launch templates.

Launch templates: name, size, image and current version
Launch templates: name, size, image and current version

Save a template

  1. Choose Create launch template.
  2. Give it a name, an optional description and the prefix its instances are named with.
  3. Choose the instance settings, as on the instance create page.
  4. Choose Save launch template. Nothing is created until you launch it.

You can also fill in the instance create page and choose Save as launch template under the summary.

server is what POST …/servers takes, without a fixed address, an existing public IP or existing volumes.

curl -sS -X POST "$NUBESTACK_API/v1/orgs/$ORG/projects/$PROJECT/launch-templates" \
  -H "Authorization: Bearer $NUBESTACK_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "web",
    "description": "Web front end, joins web-pool",
    "server": {
      "location": "loc_01jbkhi", "display_name": "web", "offering": "medium",
      "image": "ubuntu-24-04", "network_id": "net_01jbapp",
      "security_group_ids": ["sgr_01jbweb"], "ssh_key_id": "ssh_01jbayesha",
      "load_balancer": {"pool_id": "lbp_01jbwebpool", "port": 8080}
    }
  }'

The answer is 201 Created.

A template keeps nothing only one instance can use. Each instance launched from it gets a new public IP and new volumes, if the template asks for them.

User data is kept with the template, encrypted, and never shown again. It is sent to each instance you launch and deleted with the template. Keep secrets out of user data where you can; fetch them at boot instead.

A template's page: what each instance gets, its versions, and Launch
A template's page: what each instance gets, its versions, and Launch

Launch instances

Choose Manage → Launch… on the template, then how many instances (1 to 10). Or, on the instance create page, choose Start from: A launch template, pick the template and version, and say how many.

curl -sS -X POST "$NUBESTACK_API/v1/orgs/$ORG/projects/$PROJECT/instance-launches" \
  -H "Authorization: Bearer $NUBESTACK_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{"count": 3, "template": {"id": "ltp_01jbweb", "version": 2}}'

The answer is 202 Accepted. Follow the launch with GET …/instance-launches/{launch_id}: each instance's operation, and the launch's state.

How a launch works:

  • Instances are named after the template: web-1, web-2 and so on, using the next numbers no instance of the project has yet.
  • They are admitted together or not at all. If the project's quota cannot take all of them, nothing is created and the page says which quota is short.
  • Each is then created on its own. If one fails, the others carry on. A launch is succeeded when every instance succeeded, failed when none did, and partially succeeded otherwise.

Change a template

Every save is a new version; Versions on the template's page lists them, and Show opens an older one. A launch always uses the version current when it started. In the API, PATCH …/launch-templates/{id} with If-Match renames the template or saves a new version.

A template can go out of date when a network or image it names is deleted. Launching it is then refused, naming the setting; save a new version.

Delete a template

Choose Manage → Delete… and confirm. Instances launched from it stay.

curl -sS -X DELETE "$NUBESTACK_API/v1/orgs/$ORG/projects/$PROJECT/launch-templates/ltp_01jbweb" \
  -H "Authorization: Bearer $NUBESTACK_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H 'If-Match: "3"'

What blocks a delete

Refusal Why Resolve
launch_template_in_use A launch has not yet created its instances, or an instance group uses the template Wait for the launch to create its instances; delete the instance group that uses it

Limits and good practice

  • Up to 50 templates per project. Names are unique in the project, ignoring case.
  • Test a new version with a one-instance launch before an instance group uses it.