Add inline script execution support to bundle run (#2413)

## Changes
This PR adds the ability to execute scripts inline using the `databricks
bundle run` command. This allows users to execute commands with the same
authentication credentials as the bundle is configured to use..

Note: The auth credentials are passed to child processes via environment
variables.

## Why
Configuring downstream tools like DBConnect to use the same
authentication credentials as your bundle can be challenging. Having
this command allows users to directly run `databricks bundle run -t foo
-- uv run pytest` (or equivalent) to directly run integration tests
against the configured target without having to worry about how to pass
authentication credentials to DBConnect.

## Tests
Acceptance tests.

Author: shreyas-goenka

NEXT_CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Release v0.250.0
 
 ### Notable Changes
+* Added inline script execution support to bundle run. You can now run scripts in the same authentication context as a DAB using the databricks bundle run command. ([#2413](https://github.com/databricks/cli/pull/2413))
 
 ### Dependency updates
 

acceptance/bundle/help/bundle-run/output.txt

@@ -19,8 +19,23 @@ parameter names.
 If the specified job does not use job parameters and the job has a Python file
 task or a Python wheel task, the second example applies.
 
+---------------------------------------------------------
+
+You can also use the bundle run command to execute scripts / commands in the same
+authentication context as the bundle.
+
+Authentication to the input command will be provided by setting the appropriate
+environment variables that Databricks tools use to authenticate.
+
+Example usage:
+1. databricks bundle run -- echo "hello, world"
+2. databricks bundle run -- /bin/bash -c "echo hello"
+3. databricks bundle run -- uv run pytest
+
+---------------------------------------------------------
+
 Usage:
-  databricks bundle run [flags] KEY
+  databricks bundle run [flags] [KEY]
 
 Job Flags:
       --params stringToString   comma separated k=v pairs for job parameters (default [])

acceptance/bundle/run/inline-script/basic/databricks.yml

@@ -0,0 +1,2 @@
+bundle:
+  name: foobar

acceptance/bundle/run/inline-script/basic/output.txt

@@ -0,0 +1,21 @@
+
+>>> [CLI] bundle run -- echo hello, world
+hello, world
+
+>>> [CLI] bundle run -- --help
+Error: looking up "--help" failed: exec: "--help": executable file not found in PATH
+
+Exit code: 1
+
+>>> [CLI] bundle run -- bash -c exit 5
+
+Exit code: 5
+
+>>> cat stderr.txt
+Hello
+
+>>> cat -
+abc
+
+>>> [CLI] bundle run -- printf hello
+hello<EOL>

acceptance/bundle/run/inline-script/basic/script

@@ -0,0 +1,24 @@
+trace $CLI bundle run -- echo "hello, world"
+
+# The CLI should not parse the --help flag and should try to run it as an executable
+# instead.
+errcode trace $CLI bundle run -- --help
+
+# The error message should include the exit code.
+errcode trace $CLI bundle run -- bash -c "exit 5"
+
+# stderr should also be passed through.
+$CLI bundle run -- python3 -c "import sys; print('Hello', file=sys.stderr)" 2> stderr.txt
+trace cat stderr.txt
+rm stderr.txt
+
+# stdin should be passed through
+echo "abc" > abc.txt
+trace cat - < abc.txt
+rm abc.txt
+
+# no newline
+trace $CLI bundle run -- printf "hello"
+
+# print newline to comply with whitespace linter
+printf "<EOL>\n"

acceptance/bundle/run/inline-script/basic/test.toml

@@ -0,0 +1,7 @@
+[[Repls]]
+Old = "\\$PATH"
+New = "PATH"
+
+[[Repls]]
+Old = "%PATH%"
+New = "PATH"

acceptance/bundle/run/inline-script/cwd/a/b/c/.gitkeep

@@ -0,0 +1,2 @@
+bundle:
+  name: foobar

acceptance/bundle/run/inline-script/cwd/databricks.yml

@@ -0,0 +1,8 @@
+
+>>> cd a/b/c
+
+>>> python3 -c import os; print(os.getcwd())
+[TEST_TMP_DIR]/a/b/c
+
+>>> [CLI] bundle run -- python3 -c import os; print(os.getcwd())
+[TEST_TMP_DIR]/a/b/c

acceptance/bundle/run/inline-script/cwd/output.txt

@@ -0,0 +1,6 @@
+trace cd a/b/c
+
+trace python3 -c 'import os; print(os.getcwd())'
+
+# Scripts that bundle run executes should run from the bundle root.
+trace $CLI bundle run -- python3 -c 'import os; print(os.getcwd())'