Fix handling of bare DATABRICKS_HOST environment variables.

Some environments (e.g. Workbench) set `DATABRICKS_HOST` to the bare
hostname and omit the HTTPS prefix; this breaks when we later expect it
to be an actual URL.

So this commit updates `databricks_workspace()` to handle both cases.
Similar code exists in all of the other Databricks packages and SDKs
that I am aware of, so this is nothing new; I just missed it.

Unit tests are included.

Signed-off-by: Aaron Jacobs <[email protected]>

NEWS.md

@@ -7,6 +7,9 @@
 * `chat_azure()` now has a `credentials` argument to make authentication against
   Azure more flexible (#248, @atheriel).
 
+* `chat_databricks()` now handles the `DATABRICKS_HOST` environment variable
+  correctly whether it includes an HTTPS prefix or not (#252, @atheriel).
+
 # ellmer 0.1.0
 
 * New `chat_vllm()` to chat with models served by vLLM (#140).

R/provider-databricks.R

@@ -167,7 +167,11 @@ method(as_json, list(ProviderDatabricks, ContentText)) <- function(provider, x)
 }
 
 databricks_workspace <- function() {
-  key_get("DATABRICKS_HOST")
+  host <- key_get("DATABRICKS_HOST")
+  if (!is.null(host) && !grepl("^https?://", host)) {
+    host <- paste0("https://", host)
+  }
+  host
 }
 
 # Try various ways to get Databricks credentials. This implements a subset of

tests/testthat/test-provider-databricks.R

@@ -83,3 +83,20 @@ test_that("M2M authentication requests look correct", {
   })
   expect_equal(databricks_token(), "token")
 })
+
+test_that("workspace detection handles URLs with and without an https prefix", {
+  withr::with_envvar(
+    c(DATABRICKS_HOST = "example.cloud.databricks.com"),
+    expect_equal(
+      databricks_workspace(),
+      "https://example.cloud.databricks.com"
+    )
+  )
+  withr::with_envvar(
+    c(DATABRICKS_HOST = "https://example.cloud.databricks.com"),
+    expect_equal(
+      databricks_workspace(),
+      "https://example.cloud.databricks.com"
+    )
+  )
+})