Unnecessary single-node cluster warning when using is_single_node: true

[wannte]

Describe the issue

When using is_single_node: true with kind: CLASSIC_PREVIEW in a job cluster configuration, the CLI still emits a warning about single-node cluster misconfiguration. This warning is unnecessary because is_single_node: true automatically sets the required spark_conf, custom_tags, and num_workers values.

The validation logic appears to check for manual single-node configuration (num_workers: 0 + spark_conf + custom_tags) without considering that is_single_node: true handles this automatically.

Configuration

  resources:
    jobs:
      my_job:
        name: "My Job"
        job_clusters:
          - job_cluster_key: "single_node_cluster"
            new_cluster:
              kind: CLASSIC_PREVIEW
              is_single_node: true
              spark_version: "15.4.x-scala2.12"
              node_type_id: "m5.xlarge"
              num_workers: 0
        tasks:
          - task_key: "my_task"
            job_cluster_key: "single_node_cluster"
            # ... task configuration

Steps to reproduce the behavior

1. Create a bundle with a job cluster using is_single_node: true and kind: CLASSIC_PREVIEW
2. Run databricks bundle validate or databricks bundle deploy
3. See warning:
   Warning: Single node cluster is not correctly configured
   at resources.jobs.<job_name>.job_clusters[0].new_cluster
   in resources/init.py:49:1

num_workers should be 0 only for single-node clusters. To create a
valid single node cluster please ensure that the following properties
are correctly set in the cluster specification:

spark_conf:
  spark.databricks.cluster.profile: singleNode
  spark.master: local[*]

custom_tags:
  ResourceClass: SingleNode

Expected Behavior

When is_single_node: true is set with kind: CLASSIC_PREVIEW, the CLI should recognize this as a valid single-node cluster configuration and not emit the warning. The is_single_node option was specifically introduced to simplify single-node cluster configuration by automatically setting the required spark_conf, custom_tags, and num_workers values.

Actual Behavior

The CLI emits a warning suggesting manual configuration of spark_conf and custom_tags, even though is_single_node: true already handles this automatically. This creates confusion and unnecessary noise in the output.

OS and CLI version

• CLI version: v0.281.0
• OS: macOS 15.5

Related issues:

• DAB deployment fails with Error: cannot create job: NumWorkers could be 0 only for SingleNode clusters #1546 - Original single-node cluster deployment issue