hashicorp packer with Azrure ARM: view generated ARM template

I am using packer with azure arm, I am wondering is there a way to see the generated ARM template that is getting deployed?

The reason I am asking is because I get this error, but I want to see the generated ARM template to debug it.

==> azure-arm: unexpected status 400 (400 Bad Request) with error: InvalidTemplateDeployment: The template deployment failed because of policy violation. Please see details for more information

Solution

I solved the problem by forking azure-arm plugin of packer, and doing this modification to it and building it back. After running go build you should get an exe file

copy it to C:\Users\<user>\AppData\Roaming\packer.d\plugins\github.com\hashicorp\azure and
update SHA256 checksum as well Get-FileHash -Path ".\packer-plugin-azure_v2.1.7_x5.0_windows_386.exe"

This now outputs the generated arm parameter and template.

diff --git a/builder/azure/arm/template_factory.go b/builder/azure/arm/template_factory.go
index c06cc37..2e3798b 100644
--- a/builder/azure/arm/template_factory.go
+++ b/builder/azure/arm/template_factory.go
@@ -8,6 +8,8 @@ import (
     "encoding/json"
     "errors"
     "fmt"
+    "io/ioutil"
+    "math/rand"
     "time"
 
     hashiVMSDK "github.com/hashicorp/go-azure-sdk/resource-manager/compute/2022-03-01/virtualmachines"
@@ -380,6 +382,18 @@ func createDeploymentParameters(doc string, parameters *template.TemplateParamet
         return nil, err
     }
 
+    suffix := rand.Int()
+
+    err = ioutil.WriteFile(fmt.Sprintf("deployment-%d.json", suffix), []byte(doc), 0644)
+    if err != nil {
+        fmt.Println("Error writing deployment file:", err)
+    }
+
+    err = ioutil.WriteFile(fmt.Sprintf("parameter-%d.json", suffix), bs, 0644)
+    if err != nil {
+        fmt.Println("Error writing parameter file:", err)
+    }
+
     return &deployments.Deployment{
         Properties: deployments.DeploymentProperties{
             Mode:       deployments.DeploymentModeIncremental,