Add user agent detection for direct deployment (#3611)

## Why?
We can analyze whether requests use direct deployment or Terraform
deployment.

## Tests
New acceptance test.

Author: shreyas-goenka

acceptance/bundle/user_agent/out.test.toml

@@ -0,0 +1,4 @@
+engine/direct-exp
+engine/direct-exp
+engine/direct-exp
+engine/direct-exp

acceptance/bundle/user_agent/out.user_agent.direct-exp.txt

@@ -0,0 +1,4 @@
+engine/terraform
+engine/terraform
+engine/terraform
+engine/terraform

acceptance/bundle/user_agent/out.user_agent.terraform.txt

@@ -0,0 +1,19 @@
+
+>>> [CLI] bundle validate
+Name: test-bundle
+Target: default
+Workspace:
+  User: [USERNAME]
+  Path: /Workspace/Users/[USERNAME]/.bundle/test-bundle/default
+
+Validation OK!
+
+=== API request paths
+>>> cat out.requests.txt
+"/api/2.0/preview/scim/v2/Me"
+"/api/2.0/workspace/get-status"
+"/api/2.0/workspace/mkdirs"
+"/api/2.0/workspace/get-status"
+
+=== write engine value in user agent to file
+>>> cat out.requests.txt

acceptance/bundle/user_agent/output.txt

@@ -0,0 +1,9 @@
+trace $CLI bundle validate
+
+title "API request paths"
+trace cat out.requests.txt | jq .path
+
+title "write engine value in user agent to file"
+trace cat out.requests.txt | jq -r '.headers["User-Agent"][0] | split(" ") | map(select(startswith("engine/"))) | .[0]'  > out.user_agent.$DATABRICKS_BUNDLE_ENGINE.txt
+
+rm out.requests.txt

acceptance/bundle/user_agent/script

@@ -0,0 +1,8 @@
+RecordRequests = true
+Local = true
+EnvVaryOutput = "DATABRICKS_BUNDLE_ENGINE"
+
+IncludeRequestHeaders = ["User-Agent"]
+
+[EnvMatrix]
+DATABRICKS_BUNDLE_ENGINE = ["terraform", "direct-exp"]

acceptance/bundle/user_agent/test.toml

@@ -2,7 +2,6 @@ package phases
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/databricks/cli/bundle/config/mutator/resourcemutator"
 
@@ -18,7 +17,6 @@ import (
 	"github.com/databricks/cli/bundle/permissions"
 	"github.com/databricks/cli/bundle/scripts"
 	"github.com/databricks/cli/bundle/trampoline"
-	"github.com/databricks/cli/libs/env"
 	"github.com/databricks/cli/libs/log"
 	"github.com/databricks/cli/libs/logdiag"
 )
@@ -27,16 +25,8 @@ import (
 // Interpolation of fields referring to the "bundle" and "workspace" keys
 // happens upon completion of this phase.
 func Initialize(ctx context.Context, b *bundle.Bundle) {
-	var err error
-
 	log.Info(ctx, "Phase: initialize")
 
-	b.DirectDeployment, err = IsDirectDeployment(ctx)
-	if err != nil {
-		logdiag.LogError(ctx, err)
-		return
-	}
-
 	bundle.ApplySeqContext(ctx, b,
 		// Reads (dynamic): resource.*.*
 		// Checks that none of resources.<type>.<key> is nil. Raises error otherwise.
@@ -223,18 +213,3 @@ func Initialize(ctx context.Context, b *bundle.Bundle) {
 	// Executes the post_init script hook defined in the bundle configuration
 	bundle.ApplyContext(ctx, b, scripts.Execute(config.ScriptPostInit))
 }
-
-func IsDirectDeployment(ctx context.Context) (bool, error) {
-	deployment := env.Get(ctx, "DATABRICKS_BUNDLE_ENGINE")
-	// We use "direct-exp" while direct backend is not suitable for end users.
-	// Once we consider it usable we'll change the value to "direct".
-	// This is to prevent accidentally running direct backend with older CLI versions where it was still considered experimental.
-	switch deployment {
-	case "direct-exp":
-		return true, nil
-	case "terraform", "":
-		return false, nil
-	default:
-		return false, fmt.Errorf("unexpected setting for DATABRICKS_BUNDLE_ENGINE=%#v (expected 'terraform' or 'direct-exp' or absent/empty which means 'terraform')", deployment)
-	}
-}

bundle/phases/initialize.go

@@ -2,14 +2,17 @@ package utils
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/databricks/cli/bundle"
 	"github.com/databricks/cli/bundle/config/validate"
 	"github.com/databricks/cli/bundle/deployplan"
 	"github.com/databricks/cli/bundle/phases"
 	"github.com/databricks/cli/cmd/root"
 	"github.com/databricks/cli/libs/diag"
+	"github.com/databricks/cli/libs/env"
 	"github.com/databricks/cli/libs/logdiag"
+	"github.com/databricks/databricks-sdk-go/useragent"
 	"github.com/spf13/cobra"
 )
 
@@ -39,9 +42,38 @@ func ConfigureBundleWithVariables(cmd *cobra.Command) *bundle.Bundle {
 	// Initialize variables by assigning them values passed as command line flags
 	configureVariables(cmd, b, variables)
 
+	engine, err := deploymentEngine(ctx)
+	if err != nil {
+		logdiag.LogError(ctx, err)
+		return b
+	}
+
+	// We use "direct-exp" while direct backend is not suitable for end users.
+	// Once we consider it usable we'll change the value to "direct".
+	// This is to prevent accidentally running direct backend with older CLI versions where it was still considered experimental.
+	b.DirectDeployment = engine == "direct-exp"
+
+	// Set the engine in the user agent
+	ctx = useragent.InContext(ctx, "engine", engine)
+	cmd.SetContext(ctx)
 	return b
 }
 
+func deploymentEngine(ctx context.Context) (string, error) {
+	engine := env.Get(ctx, "DATABRICKS_BUNDLE_ENGINE")
+
+	// By default, use Terraform
+	if engine == "" {
+		return "terraform", nil
+	}
+
+	if engine != "terraform" && engine != "direct-exp" {
+		return "", fmt.Errorf("unexpected setting for DATABRICKS_BUNDLE_ENGINE=%#v (expected 'terraform' or 'direct-exp' or absent/empty which means 'terraform')", engine)
+	}
+
+	return engine, nil
+}
+
 func GetPlan(ctx context.Context, b *bundle.Bundle) (*deployplan.Plan, error) {
 	phases.Initialize(ctx, b)
 	if logdiag.HasError(ctx) {