New hidden install-pipelines-cli command that creates pipelines symlink to databricks (#3009)

## Changes

- **New file:** `pipelines.go` (package `pipelines`)
- **New file:** `install_pipelines_cli.go` (package `pipelines`)
- To `databricks`, implements a hidden `install-pipelines-cli` command
that creates a symlink named `pipelines` pointing to the real
`databricks` binary.
- Handles symlink creation, permission checks, and error handling for
existing files/symlinks.
- **New folder:** `pipelines/install-pipelines-cli` acceptance test
- `main.go` returns a root depending on if the binary is invoked as
`pipelines`/`pipelines.exe` or `databricks`

## Why

- **Symlink installation:** This enables users to invoke `pipelines` as
a standalone CLI, which internally points to the main `databricks`
binary. This is a step towards a dedicated Pipelines CLI experience,
while minimizing code duplication.
- **Stub CLI:** Lays groundwork for future pipelines-specific commands
and workflows
- **Testing:** Acceptance test.

## Tests

- Added acceptance tests for `install-pipelines-cli` in pipelines to
check if success message `pipelines successfully installed` is printed
- **Test descriptions:**
  1. **Fresh installation:**  
Creates temporary directory and verifies successful symlink creation.
     Validates CLI output and stub command functionality.
  2. **Already installed scenario:**  
     Confirms graceful handling when symlink already exists.
  3. **File collision test:**  
     Ensures installation fails when regular file exists at target path.
  4. **Aliased binary execution:**  
Verifies installation works when databricks binary is renamed/called via
alias.

Author: alyssa-db

acceptance/pipelines/install-pipelines-cli/output.txt

@@ -0,0 +1,36 @@
+
+=== install pipelines cli
+>>> errcode [CLI] install-pipelines-cli -d ./subdir
+pipelines successfully installed in directory "./subdir"
+
+>>> errcode ./subdir/pipelines
+Pipelines CLI (stub, to be filled in)
+
+Usage:
+  pipelines [flags]
+
+Flags:
+  -h, --help   help for pipelines
+
+=== pipelines already installed
+>>> errcode [CLI] install-pipelines-cli -d ./subdir
+pipelines already installed in directory "./subdir"
+
+=== pipelines file exists, should not overwrite
+>>> errcode [CLI] install-pipelines-cli -d ./subdir
+Error: cannot install pipelines CLI: "subdir/pipelines" already exists
+
+Exit code: 1
+
+=== databricks executable called with alias
+>>> errcode ./subdir/notdatabricks install-pipelines-cli -d ./subdir
+pipelines successfully installed in directory "./subdir"
+
+>>> errcode ./subdir/pipelines
+Pipelines CLI (stub, to be filled in)
+
+Usage:
+  pipelines [flags]
+
+Flags:
+  -h, --help   help for pipelines

acceptance/pipelines/install-pipelines-cli/script

@@ -0,0 +1,25 @@
+tmpdir="./subdir"
+pipelines="$tmpdir/pipelines"
+mkdir -p $tmpdir
+
+title "install pipelines cli"
+trace errcode $CLI install-pipelines-cli -d $tmpdir
+trace errcode $pipelines
+
+title "pipelines already installed"
+trace errcode $CLI install-pipelines-cli -d $tmpdir
+rm -f $pipelines
+
+title "pipelines file exists, should not overwrite"
+touch $pipelines
+trace errcode $CLI install-pipelines-cli -d $tmpdir
+rm -f $pipelines
+
+title "databricks executable called with alias"
+cp $CLI $tmpdir/notdatabricks
+trace errcode $tmpdir/notdatabricks install-pipelines-cli -d $tmpdir
+trace errcode $pipelines
+
+# Cleanup
+rm -f $tmpdir/notdatabricks $pipelines
+rm -rf $tmpdir

acceptance/pipelines/install-pipelines-cli/test.toml

@@ -0,0 +1,8 @@
+# Fix path with reverse slashes in the output for Windows.
+[[Repls]]
+Old = '\\\\'
+New = '/'
+
+[[Repls]]
+Old = '\\'
+New = '/'

cmd/cmd.go

@@ -11,6 +11,7 @@ import (
 	"github.com/databricks/cli/cmd/configure"
 	"github.com/databricks/cli/cmd/fs"
 	"github.com/databricks/cli/cmd/labs"
+	"github.com/databricks/cli/cmd/pipelines"
 	"github.com/databricks/cli/cmd/root"
 	"github.com/databricks/cli/cmd/selftest"
 	"github.com/databricks/cli/cmd/sync"
@@ -106,6 +107,7 @@ func New(ctx context.Context) *cobra.Command {
 	cli.AddCommand(sync.New())
 	cli.AddCommand(version.New())
 	cli.AddCommand(selftest.New())
+	cli.AddCommand(pipelines.InstallPipelinesCLI())
 
 	// Add workspace command groups, filtering out empty groups or groups with only hidden commands.
 	allGroups := workspace.Groups()

cmd/pipelines/install_pipelines_cli.go

@@ -0,0 +1,66 @@
+package pipelines
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/databricks/cli/libs/cmdio"
+	"github.com/spf13/cobra"
+)
+
+func installPipelinesSymlink(ctx context.Context, directory string) error {
+	path, err := os.Executable()
+	if err != nil {
+		return err
+	}
+	realPath, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		return err
+	}
+
+	dir := directory
+	if dir == "" {
+		dir = filepath.Dir(path)
+	}
+	pipelinesPath := filepath.Join(dir, "pipelines")
+
+	_, err = os.Lstat(pipelinesPath)
+	if err != nil {
+		if !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+		err = os.Symlink(realPath, pipelinesPath)
+		if err != nil {
+			return err
+		}
+		cmdio.LogString(ctx, fmt.Sprintf("pipelines successfully installed in directory %q", dir))
+		return nil
+	}
+
+	target, err := filepath.EvalSymlinks(pipelinesPath)
+	if err != nil {
+		return err
+	}
+	if realPath == target {
+		cmdio.LogString(ctx, fmt.Sprintf("pipelines already installed in directory %q", dir))
+		return nil
+	}
+	return fmt.Errorf("cannot install pipelines CLI: %q already exists", pipelinesPath)
+}
+
+func InstallPipelinesCLI() *cobra.Command {
+	var directory string
+	cmd := &cobra.Command{
+		Use:    "install-pipelines-cli",
+		Short:  "Install Pipelines CLI",
+		Hidden: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return installPipelinesSymlink(cmd.Context(), directory)
+		},
+	}
+	cmd.Flags().StringVarP(&directory, "directory", "d", "", "Directory in which to install pipelines CLI (defaults to databricks CLI's directory)")
+	return cmd
+}

cmd/pipelines/pipelines.go

@@ -0,0 +1,18 @@
+package pipelines
+
+import (
+	"github.com/spf13/cobra"
+)
+
+func New() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "pipelines",
+		Short: "Pipelines CLI",
+		Long:  "Pipelines CLI (stub, to be filled in)",
+		Run: func(cmd *cobra.Command, args []string) {
+			_ = cmd.Help()
+		},
+	}
+
+	return cmd
+}

main.go

@@ -3,14 +3,30 @@ package main
 import (
 	"context"
 	"os"
+	"path/filepath"
+	"strings"
 
 	"github.com/databricks/cli/cmd"
+	"github.com/databricks/cli/cmd/pipelines"
 	"github.com/databricks/cli/cmd/root"
+	"github.com/spf13/cobra"
 )
 
+// If invoked as 'pipelines' (or 'pipelines.exe' on Windows), returns pipelines-specific commands,
+// otherwise returns the databricks CLI commands. This is used to allow the same
+// binary to be used for both pipelines and databricks CLI commands.
+func getCommand(ctx context.Context) *cobra.Command {
+	invokedAs := filepath.Base(os.Args[0])
+	if strings.HasPrefix(invokedAs, "pipelines") {
+		return pipelines.New()
+	}
+	return cmd.New(ctx)
+}
+
 func main() {
 	ctx := context.Background()
-	err := root.Execute(ctx, cmd.New(ctx))
+	command := getCommand(ctx)
+	err := root.Execute(ctx, command)
 	if err != nil {
 		os.Exit(1)
 	}