additional_build_groups_config

Description

The additional_build_groups_config parameter allows you to configure dedicated build node pools for your AKS cluster. Build node pools are automatically tainted with dedicated=build:NoSchedule, which keeps application Pods off them.

Builds tolerate that taint, but nothing directs them to a build pool. A Build runs on a build pool when the App's BuildLabels app parameter selects the pool's label. Without BuildLabels, a Build can run on the default node pool, on an additional node pool that has no taint, or on any build pool.

Default Value

The default value for additional_build_groups_config is an empty array.

Use Cases

• Build Isolation: Separate build workloads from application workloads so that builds don't consume application resources.
• Cost Optimization: Use differently sized VMs or Spot instances for build workloads.
• Performance: Use larger VM sizes for builds to reduce build times without sizing up your entire cluster.

Configuration Format

The additional_build_groups_config parameter takes a JSON array of build node pool configurations:

Field	Required	Description	Default
type	Yes	The Azure VM size to use for the build node pool
disk	No	The OS disk size in GB for the nodes	Same as main node disk (default: 30)
capacity_type	No	Whether to use regular or spot VMs. Accepts ON_DEMAND, SPOT, Regular, or Spot, matched exactly. Lowercase forms such as spot are rejected	ON_DEMAND (Regular)
min_size	No	Minimum number of nodes	0
max_size	No	Maximum number of nodes	100
label	No	Custom label value. Applied as convox.io/label: <label-value>	custom-build
id	No	A unique integer identifier for the node pool	The entry's position in the array
tags	No	Custom Azure tags as comma-separated key-value pairs	None
zones	No	Comma-separated list of Azure availability zones. Requires a convox CLI at 3.25.3 or newer	None

zones requires a convox CLI at 3.25.3 or newer. Earlier CLIs dropped the zones key from the configuration before it reached Terraform, so a value set with an older CLI had no effect and no error.

Build node pools automatically get the following labels and taints:

• Label: convox-build: true
• Label: convox.io/label: <label> (defaults to custom-build)
• Taint: dedicated=build:NoSchedule

Setting Parameters

Using a JSON File (Recommended)

$ convox rack params set additional_build_groups_config=/path/to/build-config.json -r rackName
Updating parameters... OK

Example JSON file:

[
  {
    "id": 201,
    "type": "Standard_D8s_v3",
    "disk": 100,
    "capacity_type": "ON_DEMAND",
    "min_size": 0,
    "max_size": 3,
    "label": "builds"
  }
]

Using a Raw JSON String

$ convox rack params set 'additional_build_groups_config=[{"id":201,"type":"Standard_D8s_v3","disk":100,"min_size":0,"max_size":3,"label":"builds"}]' -r rackName
Updating parameters... OK

Directing an App's Builds to the Pool

Set BuildLabels on each App whose Builds should run on the pool:

$ convox apps params set BuildLabels=convox.io/label=builds -a myapp
Updating parameters... OK

Arm Build Pools

On Rack version 3.25.12 or later, a build pool can use an Arm VM size, such as Standard_D4ps_v5. Build pools have no dedicated key, so any App's Build can run on an Arm build pool. When a Build of an App without the BuildArch app parameter runs there, it produces an arm64-only image, and that App's Processes then fail on x86 nodes. Set BuildArch on every App on the Rack before you add an Arm build pool.

CLI 3.25.12 or later accepts an Arm build pool and prints:

WARNING: additional_build_groups_config type Standard_D4ps_v5 is an Arm machine type. Builds of apps without the BuildArch app parameter can run on it and produce Arm-only images.

To build one App natively on Arm without exposing other Apps' Builds to Arm nodes, point that App's BuildLabels at a dedicated Arm node pool instead; see Arm Node Pools.

Additional Information

For general-purpose node pools, see the additional_node_groups_config parameter.