Port of databricks/databricks-sdk-go#1512. Adds an explicit `cloud`
field to `Config` populated from /.well-known/databricks-config (or
DATABRICKS_CLOUD env var). is_aws/is_azure/is_gcp now check this field
first, falling back to DNS-based hostname inference for unset cases.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

## 🥞 Stacked PR
Use this
[link](https://github.com/databricks/databricks-sdk-py/pull/1320/files)
to review incremental changes.
-
[**stack/cloud-from-host-metadata**](#1320)
[[Files
changed](https://github.com/databricks/databricks-sdk-py/pull/1320/files)]
-
[stack/resolve-token-audience-from-host-metadata](#1321)
[[Files
changed](https://github.com/databricks/databricks-sdk-py/pull/1321/files/e846874ec446c75225cfb26864de20a8906b34fd..56f3705b9513f9b1fe43ea27ffacc7463865b1fe)]
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[stack/google-auth-use-host-metadata](#1322)
[[Files
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---------
## Summary

Port of
[databricks-sdk-go#1512](databricks/databricks-sdk-go#1512).
Adds an explicit `cloud` field to `Config` (and `HostMetadata`) that is
populated from `/.well-known/databricks-config`. `is_aws`, `is_azure`,
and `is_gcp` now prefer this field over DNS-based hostname inference.

## Why

`is_aws()`, `is_azure()`, and `is_gcp()` previously inferred the cloud
provider by suffix-matching the workspace hostname against a hardcoded
list of known DNS zones (e.g. `.azuredatabricks.net`,
`.gcp.databricks.com`). This works for standard deployments but silently
misclassifies non-standard hostnames — vanity domains, unified hosts, or
any future topology where the hostname doesn't encode the cloud
provider. In those cases the SDK fell back to `DefaultEnvironment`
(AWS), which is wrong.

The `/.well-known/databricks-config` endpoint is already the
authoritative source for host metadata and returns a `cloud` field, but
the SDK was discarding it. Threading that value through to `Config` lets
the SDK make correct cloud-detection decisions without relying on
hostname patterns.

## What changed

### Interface changes

- **`Config.cloud: Cloud`** — new optional `ConfigAttribute` (env:
`DATABRICKS_CLOUD`). Accepts `"AWS"`, `"AZURE"`, or `"GCP"`
(case-insensitive). When set — either explicitly or auto-populated from
metadata — `is_aws`, `is_azure`, and `is_gcp` use this value directly.
- **`Cloud.parse(value: str) -> Optional[Cloud]`** — new classmethod on
the `Cloud` enum for case-insensitive parsing. Returns `None` for empty
or unrecognized values (forward-compatible with future cloud values the
API may introduce).
- **`HostMetadata.cloud: Optional[Cloud]`** — new field, populated from
the `"cloud"` key in the discovery response.

### Behavioral changes

- `is_aws`, `is_azure`, `is_gcp` now check `Config.cloud` first. If
unset they fall back to DNS-based detection — no change for existing
deployments with standard hostnames.
- `azure_workspace_resource_id` continues to take precedence over
`Config.cloud` for `is_azure`, preserving existing Azure MSI behavior.
- Auto-discovery note: the new endpoint has not been rolled out to all
hosts yet, so `cloud` will remain unset for most deployments until
broader rollout.

### Internal changes

- **`databricks/sdk/environments.py`**: Added `Cloud.parse()`
classmethod.
- **`databricks/sdk/oauth.py`**: Added `cloud` field to `HostMetadata`;
`from_dict` and `as_dict` updated accordingly.
- **`databricks/sdk/config.py`**: Added `_parse_cloud` helper, `cloud`
`ConfigAttribute`, updated `is_aws/is_azure/is_gcp` to check
`self.cloud` first, added `cloud` back-fill in `_resolve_host_metadata`.
- **`tests/test_config.py`**: 10 new tests covering case-insensitive
parsing, explicit `cloud` overriding DNS detection for each provider,
DNS fallback, `azure_workspace_resource_id` precedence, and metadata
population/non-overwrite.

## How is this tested?

Unit tests in `tests/test_config.py` and `tests/test_oauth.py`. No
integration tests — the endpoint is not yet available on all hosts.

NO_CHANGELOG=true

Co-authored-by: Claude Sonnet 4.6 <[email protected]>

## 🥞 Stacked PR

- [**#710 Add cloud field to
HostMetadata**](#710)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/710/files)]
- [#711 Fix GetWorkspaceClient for unified account
hosts](#711)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/711/files)]
- [#712 Add test for GetWorkspaceClient with SPOG
host](#712)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/712/files)]
- [#713 Call resolveHostMetadata on Config
init](#713)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/713/files)]
- [#714 Resolve TokenAudience from host metadata for account
hosts](#714)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/714/files)]
- [#718 Make GCP SA token refresh
non-blocking](#718)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/718/files)]
- [#719 Add integration test for host metadata
resolution](#719)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/719/files)]
- [#720 Remove unified flag usage, rely on host
metadata](#720)
[[Files](https://github.com/databricks/databricks-sdk-java/pull/720/files)]

---------
## Summary

Port of Go SDK
[#1512](databricks/databricks-sdk-go#1512).

Adds a `cloud` field to `HostMetadata` that is populated from the
`/.well-known/databricks-config` discovery endpoint.

**Why:** Today, `isAws()`, `isAzure()`, and `isGcp()` infer cloud type
by suffix-matching the workspace hostname against a hardcoded list of
known DNS zones. This works for standard deployments but fails for
non-standard hostnames (custom vanity domains, unified hosts, etc.). The
discovery endpoint is the authoritative source and already returns a
`cloud` field, but the SDK was discarding it.

**Changes:**
- `HostMetadata`: new `cloud` field (`@JsonProperty("cloud")`), getter,
and 4-arg constructor
- `HostMetadataTest`: deserialization with/without cloud, constructor
tests

`NO_CHANGELOG=true`

## Test plan
- [x] `HostMetadataTest`: 4 tests for cloud field deserialization and
constructors