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Stack Variables

All fields in stacks can be replaced by stack variables.

To define a stack variable wrap the variable name in curly braces. Ex: {{variable-name}}

These variable names (keys) can be made up of:

  • a-z
  • 0-9
  • -

The following example show's both a normal use case (frontend-source-id) and a more exaggerated use case (config-1).

{
    "version": "1.0",
    "containers": {
      "frontend": {
        "name": "frontend",
        "image": {
          "name": "frontend",
          "origin": {
            "type": "docker-file",
            "details": {
              "existing": {
                  "source_id": "{{frontend-source-id}}"
              }
            }
          }
        },
        "config": {{config-1}}
      }    
  }
}

What you'll notice is that the {{variable}} will be injected into the stack file exactly how its defined in the stack. So for the frontend-source-id, it needed to be wrapped in a string (as its a string value), whereas the config is just json and thus does not need anything.

On the portal variable defaults lives under the variables tab.

Stack Variables

You can add new variables by using the Add button and then saving with the Update Variable Defaults

Overriding Default Variables​

The variable definitions live as part of the stack. Unlike pipelines, stack variables can be defined once and reused across all builds.

BUT

If you'd like to override a default value without changing it you can use Variable Overrides. In the portal, this menu is accessible by clicking the V arrow next to the Create Build button.

Variable Override

After updating the variables you wish to override, create the build and that build will use those variables in place of the default.