Libguestfs - Jan 2022 - [PATCH v2v] Restore message about setting up the input and output

Old virt-v2v would print a summary of the input and output options
before connecting to the input/output, looking something like this:

  [   0.2] Opening the source -i libvirt -ic [etc]

This gave reassurance that virt-v2v was doing something in the case
where the source was slow or unreachable.  In particular if you use
-i libvirt with a vCenter URL, and the URL is wrong, libvirt hangs for
a few minutes without printing anything.

Modular virt-v2v rearranged things so the connecting phase was silent,
which meant that in the case above virt-v2v appeared to hang for a few
minutes printing nothing at all.

This change adds to_string functions to all the input and output
methods and uses them to print a message like:

  [   0.0] Setting up the source: -i libvirt -ic [etc]

Note the old "Opening the source" message now refers to the libguestfs
handle open and connection to the NBD source disk pipeline.  The hang
still happens, but at least it's clearer what it's doing.

Typical full output looks like this:

  $ virt-v2v -i disk /var/tmp/fedora-35.img -o disk -os /var/tmp/out
  [   0.0] Setting up the source: -i disk /var/tmp/fedora-35.img
  [   1.1] Opening the source
  [   5.9] Inspecting the source
  [  11.5] Checking for sufficient free disk space in the guest
  [  11.5] Converting Fedora Linux 35 (Thirty Five) to run on KVM
  virt-v2v: warning: /files/boot/grub2/device.map/hd0 references unknown
  device "vda".  You may have to fix this entry manually after
conversion.
  virt-v2v: This guest has virtio drivers installed.
  [  57.4] Mapping filesystem data to avoid copying unused and blank areas
  [  61.0] Closing the overlay
  [  61.7] Assigning disks to buses
  [  61.7] Checking if the guest needs BIOS or UEFI to boot
  [  61.7] Setting up the destination: -o disk -os /var/tmp/out
  [  62.8] Copying disk 1/1
  ? 100% [****************************************]
  [  81.7] Creating output metadata
  [  81.7] Finishing off

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2041886
Reported-by: Xiaodai Wang
---
 input/input.ml               |  1 +
 input/input.mli              |  4 ++++
 input/input_disk.ml          |  2 ++
 input/input_libvirt.ml       | 10 ++++++++++
 input/input_ova.ml           |  2 ++
 input/input_vcenter_https.ml |  9 +++++++++
 input/input_vddk.ml          |  9 +++++++++
 input/input_vmx.ml           |  2 ++
 input/input_xen_ssh.ml       |  9 +++++++++
 output/output.ml             |  1 +
 output/output.mli            |  4 ++++
 output/output_disk.ml        |  6 ++++++
 output/output_glance.ml      |  2 ++
 output/output_json.ml        |  6 ++++++
 output/output_libvirt.ml     |  6 ++++++
 output/output_null.ml        |  2 ++
 output/output_openstack.ml   |  2 ++
 output/output_qemu.ml        |  6 ++++++
 output/output_rhv.ml         |  2 ++
 output/output_rhv_upload.ml  |  9 +++++++++
 output/output_vdsm.ml        |  2 ++
 v2v/v2v.ml                   |  4 ++++
 22 files changed, 100 insertions(+)

diff --git a/input/input.ml b/input/input.ml
index 00474becb1..b1175fa32f 100644
--- a/input/input.ml
+++ b/input/input.ml
@@ -26,6 +26,7 @@ type options = {
 }
 
 module type INPUT = sig
+  val to_string : options -> string list -> string
   val setup : string -> options -> string list -> Types.source
   val query_input_options : unit -> unit
 end
diff --git a/input/input.mli b/input/input.mli
index 4f899b1d1c..b61df3e9fa 100644
--- a/input/input.mli
+++ b/input/input.mli
@@ -26,6 +26,10 @@ type options = {
 }
 
 module type INPUT = sig
+  val to_string : options -> string list -> string
+  (** [to_string options args] converts the source to a printable
+      string (for messages). *)
+
   val setup : string -> options -> string list -> Types.source
   (** [setup dir options args]
 
diff --git a/input/input_disk.ml b/input/input_disk.ml
index bcdaf78c55..2b21950a2a 100644
--- a/input/input_disk.ml
+++ b/input/input_disk.ml
@@ -142,6 +142,8 @@ and detect_local_input_format { input_format } filenames    
get_format formats
 
 module Disk = struct
+  let to_string options args = String.concat " " ("-i disk"
:: args)
+
   let setup dir options args      disk_source dir options args
 
diff --git a/input/input_libvirt.ml b/input/input_libvirt.ml
index f20082c2fa..33f61086ec 100644
--- a/input/input_libvirt.ml
+++ b/input/input_libvirt.ml
@@ -129,6 +129,14 @@ and libvirt_xml_source _ args    source, disks
 
 module Libvirt_ = struct
+  let to_string options args +    let xs = "-i libvirt" :: args in
+    let xs +      match options.input_conn with
+      | Some ic -> ("-ic " ^ ic) :: xs
+      | None -> xs in
+    String.concat " " xs
+
   let setup dir options args      let source, data = libvirt_source options
args in
     libvirt_servers dir data;
@@ -139,6 +147,8 @@ module Libvirt_ = struct
 end
 
 module LibvirtXML = struct
+  let to_string options args = String.concat " " ("-i
libvirtxml" :: args)
+
   let setup dir options args      let source, data = libvirt_xml_source options
args in
     libvirt_servers dir data;
diff --git a/input/input_ova.ml b/input/input_ova.ml
index 0115f771cb..19c22d550e 100644
--- a/input/input_ova.ml
+++ b/input/input_ova.ml
@@ -229,6 +229,8 @@ and error_missing_href href    error (f_"-i ova: OVF
references file ?%s? which was not found in the OVA archive") href
 
 module OVA = struct
+  let to_string options args = String.concat " " ("-i ova"
:: args)
+
   let setup dir options args      ova_source dir options args
 
diff --git a/input/input_vcenter_https.ml b/input/input_vcenter_https.ml
index 24ac927dda..bcefed16db 100644
--- a/input/input_vcenter_https.ml
+++ b/input/input_vcenter_https.ml
@@ -117,6 +117,15 @@ let rec vcenter_https_source dir options args    source
 
 module VCenterHTTPS = struct
+  let to_string options args +    let xs = args in
+    let xs +      match options.input_conn with
+      | Some ic -> ("-ic " ^ ic) :: xs
+      | None -> xs in
+    let xs = "-i libvirt" :: xs in
+    String.concat " " xs
+
   let setup dir options args      vcenter_https_source dir options args
 
diff --git a/input/input_vddk.ml b/input/input_vddk.ml
index 1cfb7f5ec3..b9a0b8bf5c 100644
--- a/input/input_vddk.ml
+++ b/input/input_vddk.ml
@@ -193,6 +193,15 @@ and vddk_source dir options args    source
 
 module VDDK = struct
+  let to_string options args +    let xs = "-it vddk" :: args in
+    let xs +      match options.input_conn with
+      | Some ic -> ("-ic " ^ ic) :: xs
+      | None -> xs in
+    let xs = "-i libvirt" :: xs in
+    String.concat " " xs
+
   let setup dir options args      vddk_source dir options args
 
diff --git a/input/input_vmx.ml b/input/input_vmx.ml
index 9065e8571d..6e8948f9d5 100644
--- a/input/input_vmx.ml
+++ b/input/input_vmx.ml
@@ -118,6 +118,8 @@ and absolute_path_from_other_file other_filename filename   
else (Filename.dirname (absolute_path other_filename)) // filename
 
 module VMX = struct
+  let to_string options args = String.concat " " ("-i vmx"
:: args)
+
   let setup dir options args      vmx_source dir options args
 
diff --git a/input/input_xen_ssh.ml b/input/input_xen_ssh.ml
index cb8b1f9124..f18ac5cf40 100644
--- a/input/input_xen_ssh.ml
+++ b/input/input_xen_ssh.ml
@@ -112,6 +112,15 @@ let rec xen_ssh_source dir options args    source
 
 module XenSSH = struct
+  let to_string options args +    let xs = args in
+    let xs +      match options.input_conn with
+      | Some ic -> ("-ic " ^ ic) :: xs
+      | None -> xs in
+    let xs = "-i libvirt" :: xs in
+    String.concat " " xs
+
   let setup dir options args      xen_ssh_source dir options args
 
diff --git a/output/output.ml b/output/output.ml
index 101da82a70..659d20ac31 100644
--- a/output/output.ml
+++ b/output/output.ml
@@ -38,6 +38,7 @@ type options = {
 
 module type OUTPUT = sig
   type t
+  val to_string : options -> string
   val setup : string -> options -> Types.source -> t
   val finalize : string -> options ->
                  Types.source -> Types.inspect -> Types.target_meta ->
diff --git a/output/output.mli b/output/output.mli
index 03d71daf67..ced2216106 100644
--- a/output/output.mli
+++ b/output/output.mli
@@ -30,6 +30,10 @@ module type OUTPUT = sig
   type t
   (** Opaque data used by the output mode. *)
 
+  val to_string : options -> string
+  (** [to_string options] converts the destination to a printable
+      string (for messages). *)
+
   val setup : string -> options -> Types.source -> t
   (** [setup dir options source]
 
diff --git a/output/output_disk.ml b/output/output_disk.ml
index eca3c727b7..386d031b46 100644
--- a/output/output_disk.ml
+++ b/output/output_disk.ml
@@ -96,6 +96,12 @@ and disk_finalize dir source inspect target_meta
 module Disk = struct
   type t = unit
 
+  let to_string options +    "-o disk" ^
+      match options.output_storage with
+      | Some os -> " -os " ^ os
+      | None -> ""
+
   let setup dir options source      if options.output_options <> [] then
       error (f_"no -oo (output options) are allowed here");
diff --git a/output/output_glance.ml b/output/output_glance.ml
index 0d7838dd38..85cbe58ea5 100644
--- a/output/output_glance.ml
+++ b/output/output_glance.ml
@@ -122,6 +122,8 @@ and glance_finalize dir source inspect target_meta
output_format tmpdir  module Glance = struct
   type t = string
 
+  let to_string options = "-o glance"
+
   let setup dir options source      if options.output_options <> [] then
       error (f_"no -oo (output options) are allowed here");
diff --git a/output/output_json.ml b/output/output_json.ml
index bb0cdfeb5a..88fb4778d4 100644
--- a/output/output_json.ml
+++ b/output/output_json.ml
@@ -134,6 +134,12 @@ and json_path os output_name json_disks_pattern i  module
Json = struct
   type t = unit
 
+  let to_string options +    "-o json" ^
+      match options.output_storage with
+      | Some os -> " -os " ^ os
+      | None -> ""
+
   let setup dir options source      let data = json_parse_options options in
     let output_name = get_output_name options source in
diff --git a/output/output_libvirt.ml b/output/output_libvirt.ml
index 52c4540130..20333363b7 100644
--- a/output/output_libvirt.ml
+++ b/output/output_libvirt.ml
@@ -198,6 +198,12 @@ and target_features_of_capabilities_doc doc arch  module
Libvirt_ = struct
   type t = string * string
 
+  let to_string options +    "-o libvirt" ^
+      match options.output_storage with
+      | Some os -> " -os " ^ os
+      | None -> ""
+
   let setup dir options source      if options.output_options <> [] then
       error (f_"no -oo (output options) are allowed here");
diff --git a/output/output_null.ml b/output/output_null.ml
index 34fbd6e148..56fb7ec63c 100644
--- a/output/output_null.ml
+++ b/output/output_null.ml
@@ -76,6 +76,8 @@ and null_servers dir disks output_name  module Null = struct
   type t = unit
 
+  let to_string options = "-o null"
+
   let setup dir options source      if options.output_options <> [] then
       error (f_"no -oo (output options) are allowed here");
diff --git a/output/output_openstack.ml b/output/output_openstack.ml
index 334a1fc2ae..1798548dc3 100644
--- a/output/output_openstack.ml
+++ b/output/output_openstack.ml
@@ -462,6 +462,8 @@ and iso_time  module Openstack = struct
   type t = string list
 
+  let to_string options = "-o openstack"
+
   let setup dir options source      let data = openstack_parse_options options
in
     let output_name = get_output_name options source in
diff --git a/output/output_qemu.ml b/output/output_qemu.ml
index 0aac1eba2b..3d5d67820e 100644
--- a/output/output_qemu.ml
+++ b/output/output_qemu.ml
@@ -315,6 +315,12 @@ and qemu_finalize dir source inspect target_meta
 module QEMU = struct
   type t = unit
 
+  let to_string options +    "-o qemu" ^
+      match options.output_storage with
+      | Some os -> " -os " ^ os
+      | None -> ""
+
   let setup dir options source      let data = qemu_parse_options options in
     let output_name = get_output_name options source in
diff --git a/output/output_rhv.ml b/output/output_rhv.ml
index 6a67b7aa15..a386b9a58d 100644
--- a/output/output_rhv.ml
+++ b/output/output_rhv.ml
@@ -266,6 +266,8 @@ and check_storage_domain domain_class os mp  module RHV =
struct
   type t = string * string * string * string list * string list * int64 list
 
+  let to_string options = "-o rhv"
+
   let setup dir options source      if options.output_options <> [] then
       error (f_"no -oo (output options) are allowed here");
diff --git a/output/output_rhv_upload.ml b/output/output_rhv_upload.ml
index 91e7be45bc..4d8dc1c135 100644
--- a/output/output_rhv_upload.ml
+++ b/output/output_rhv_upload.ml
@@ -444,6 +444,15 @@ module RHVUpload = struct
            JSON.field list * string option * string option *
            string option * string
 
+  let to_string options +    "-o rhv-upload" ^
+      (match options.output_conn with
+       | Some oc -> " -oc " ^ oc
+       | None -> "") ^
+      (match options.output_storage with
+       | Some os -> " -os " ^ os
+       | None -> "")
+
   let setup dir options source      let data = rhv_upload_parse_options options
in
     let output_name = get_output_name options source in
diff --git a/output/output_vdsm.ml b/output/output_vdsm.ml
index ce0d5b5e4b..676ecf0010 100644
--- a/output/output_vdsm.ml
+++ b/output/output_vdsm.ml
@@ -212,6 +212,8 @@ and vdsm_finalize dir source inspect target_meta
 module VDSM = struct
   type t = string * string * int64 list
 
+  let to_string options = "-o vdsm"
+
   let setup dir options source      let data = vdsm_parse_options options in
     let output_name = get_output_name options source in
diff --git a/v2v/v2v.ml b/v2v/v2v.ml
index 47e6e9371a..d74cc21f0a 100644
--- a/v2v/v2v.ml
+++ b/v2v/v2v.ml
@@ -532,6 +532,8 @@ read the man page virt-v2v(1).
   } in
 
   (* Start the input module (runs an NBD server in the background). *)
+  message (f_"Setting up the source: %s")
+    (Input_module.to_string input_options args);
   let source = Input_module.setup tmpdir input_options args in
 
   (* If --print-source then print the source metadata and exit. *)
@@ -548,6 +550,8 @@ read the man page virt-v2v(1).
   unlink (tmpdir // "convert");
 
   (* Start the output module (runs an NBD server in the background). *)
+  message (f_"Setting up the destination: %s")
+    (Output_module.to_string output_options);
   let output_t = Output_module.setup tmpdir output_options source in
 
   (* Debug the v2vdir. *)
-- 
2.32.0

On 01/19/22 14:37, Richard W.M. Jones wrote:
> Old virt-v2v would print a summary of the input and output options
> before connecting to the input/output, looking something like this:
> 
>   [   0.2] Opening the source -i libvirt -ic [etc]
> 
> This gave reassurance that virt-v2v was doing something in the case
> where the source was slow or unreachable.  In particular if you use
> -i libvirt with a vCenter URL, and the URL is wrong, libvirt hangs for
> a few minutes without printing anything.
> 
> Modular virt-v2v rearranged things so the connecting phase was silent,
> which meant that in the case above virt-v2v appeared to hang for a few
> minutes printing nothing at all.
> 
> This change adds to_string functions to all the input and output
> methods and uses them to print a message like:
> 
>   [   0.0] Setting up the source: -i libvirt -ic [etc]
> 
> Note the old "Opening the source" message now refers to the
libguestfs
> handle open and connection to the NBD source disk pipeline.  The hang
> still happens, but at least it's clearer what it's doing.
> 
> Typical full output looks like this:
> 
>   $ virt-v2v -i disk /var/tmp/fedora-35.img -o disk -os /var/tmp/out
>   [   0.0] Setting up the source: -i disk /var/tmp/fedora-35.img
>   [   1.1] Opening the source
>   [   5.9] Inspecting the source
>   [  11.5] Checking for sufficient free disk space in the guest
>   [  11.5] Converting Fedora Linux 35 (Thirty Five) to run on KVM
>   virt-v2v: warning: /files/boot/grub2/device.map/hd0 references unknown
>   device "vda".  You may have to fix this entry manually after
conversion.
>   virt-v2v: This guest has virtio drivers installed.
>   [  57.4] Mapping filesystem data to avoid copying unused and blank areas
>   [  61.0] Closing the overlay
>   [  61.7] Assigning disks to buses
>   [  61.7] Checking if the guest needs BIOS or UEFI to boot
>   [  61.7] Setting up the destination: -o disk -os /var/tmp/out
>   [  62.8] Copying disk 1/1
>   ? 100% [****************************************]
>   [  81.7] Creating output metadata
>   [  81.7] Finishing off
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2041886
> Reported-by: Xiaodai Wang
> ---
>  input/input.ml               |  1 +
>  input/input.mli              |  4 ++++
>  input/input_disk.ml          |  2 ++
>  input/input_libvirt.ml       | 10 ++++++++++
>  input/input_ova.ml           |  2 ++
>  input/input_vcenter_https.ml |  9 +++++++++
>  input/input_vddk.ml          |  9 +++++++++
>  input/input_vmx.ml           |  2 ++
>  input/input_xen_ssh.ml       |  9 +++++++++
>  output/output.ml             |  1 +
>  output/output.mli            |  4 ++++
>  output/output_disk.ml        |  6 ++++++
>  output/output_glance.ml      |  2 ++
>  output/output_json.ml        |  6 ++++++
>  output/output_libvirt.ml     |  6 ++++++
>  output/output_null.ml        |  2 ++
>  output/output_openstack.ml   |  2 ++
>  output/output_qemu.ml        |  6 ++++++
>  output/output_rhv.ml         |  2 ++
>  output/output_rhv_upload.ml  |  9 +++++++++
>  output/output_vdsm.ml        |  2 ++
>  v2v/v2v.ml                   |  4 ++++
>  22 files changed, 100 insertions(+)
> 
> diff --git a/input/input.ml b/input/input.ml
> index 00474becb1..b1175fa32f 100644
> --- a/input/input.ml
> +++ b/input/input.ml
> @@ -26,6 +26,7 @@ type options = {
>  }
>  
>  module type INPUT = sig
> +  val to_string : options -> string list -> string
>    val setup : string -> options -> string list -> Types.source
>    val query_input_options : unit -> unit
>  end
> diff --git a/input/input.mli b/input/input.mli
> index 4f899b1d1c..b61df3e9fa 100644
> --- a/input/input.mli
> +++ b/input/input.mli
> @@ -26,6 +26,10 @@ type options = {
>  }
>  
>  module type INPUT = sig
> +  val to_string : options -> string list -> string
> +  (** [to_string options args] converts the source to a printable
> +      string (for messages). *)
> +
>    val setup : string -> options -> string list -> Types.source
>    (** [setup dir options args]
>  
> diff --git a/input/input_disk.ml b/input/input_disk.ml
> index bcdaf78c55..2b21950a2a 100644
> --- a/input/input_disk.ml
> +++ b/input/input_disk.ml
> @@ -142,6 +142,8 @@ and detect_local_input_format { input_format }
filenames >       get_format formats
>  
>  module Disk = struct
> +  let to_string options args = String.concat " " ("-i
disk" :: args)
> +
>    let setup dir options args >      disk_source dir options args
>  
> diff --git a/input/input_libvirt.ml b/input/input_libvirt.ml
> index f20082c2fa..33f61086ec 100644
> --- a/input/input_libvirt.ml
> +++ b/input/input_libvirt.ml
> @@ -129,6 +129,14 @@ and libvirt_xml_source _ args >    source, disks
>  
>  module Libvirt_ = struct
> +  let to_string options args > +    let xs = "-i libvirt" ::
args in
> +    let xs > +      match options.input_conn with
> +      | Some ic -> ("-ic " ^ ic) :: xs
> +      | None -> xs in
> +    String.concat " " xs
> +
>    let setup dir options args >      let source, data = libvirt_source
options args in
>      libvirt_servers dir data;
> @@ -139,6 +147,8 @@ module Libvirt_ = struct
>  end
>  
>  module LibvirtXML = struct
> +  let to_string options args = String.concat " " ("-i
libvirtxml" :: args)
> +
>    let setup dir options args >      let source, data =
libvirt_xml_source options args in
>      libvirt_servers dir data;
> diff --git a/input/input_ova.ml b/input/input_ova.ml
> index 0115f771cb..19c22d550e 100644
> --- a/input/input_ova.ml
> +++ b/input/input_ova.ml
> @@ -229,6 +229,8 @@ and error_missing_href href >    error (f_"-i
ova: OVF references file ?%s? which was not found in the OVA archive") href
>  
>  module OVA = struct
> +  let to_string options args = String.concat " " ("-i
ova" :: args)
> +
>    let setup dir options args >      ova_source dir options args
>  
> diff --git a/input/input_vcenter_https.ml b/input/input_vcenter_https.ml
> index 24ac927dda..bcefed16db 100644
> --- a/input/input_vcenter_https.ml
> +++ b/input/input_vcenter_https.ml
> @@ -117,6 +117,15 @@ let rec vcenter_https_source dir options args >   
source
>  
>  module VCenterHTTPS = struct
> +  let to_string options args > +    let xs = args in
> +    let xs > +      match options.input_conn with
> +      | Some ic -> ("-ic " ^ ic) :: xs
> +      | None -> xs in
> +    let xs = "-i libvirt" :: xs in
Huh, this was very non-intuitive. I thought "libvirt" here was an
error,
but it's not.
> +    String.concat " " xs
> +
>    let setup dir options args >      vcenter_https_source dir options
args
>  
> diff --git a/input/input_vddk.ml b/input/input_vddk.ml
> index 1cfb7f5ec3..b9a0b8bf5c 100644
> --- a/input/input_vddk.ml
> +++ b/input/input_vddk.ml
> @@ -193,6 +193,15 @@ and vddk_source dir options args >    source
>  
>  module VDDK = struct
> +  let to_string options args > +    let xs = "-it vddk" ::
args in
> +    let xs > +      match options.input_conn with
> +      | Some ic -> ("-ic " ^ ic) :: xs
> +      | None -> xs in
> +    let xs = "-i libvirt" :: xs in
> +    String.concat " " xs
> +
>    let setup dir options args >      vddk_source dir options args
Same here... I didn't realize the most frequently used transports for
accessing vmware were libvirt based...
>  
> diff --git a/input/input_vmx.ml b/input/input_vmx.ml
> index 9065e8571d..6e8948f9d5 100644
> --- a/input/input_vmx.ml
> +++ b/input/input_vmx.ml
> @@ -118,6 +118,8 @@ and absolute_path_from_other_file other_filename
filename >    else (Filename.dirname (absolute_path other_filename)) //
filename
>  
>  module VMX = struct
> +  let to_string options args = String.concat " " ("-i
vmx" :: args)
> +
>    let setup dir options args >      vmx_source dir options args
>  
> diff --git a/input/input_xen_ssh.ml b/input/input_xen_ssh.ml
> index cb8b1f9124..f18ac5cf40 100644
> --- a/input/input_xen_ssh.ml
> +++ b/input/input_xen_ssh.ml
> @@ -112,6 +112,15 @@ let rec xen_ssh_source dir options args >    source
>  
>  module XenSSH = struct
> +  let to_string options args > +    let xs = args in
> +    let xs > +      match options.input_conn with
> +      | Some ic -> ("-ic " ^ ic) :: xs
> +      | None -> xs in
> +    let xs = "-i libvirt" :: xs in
> +    String.concat " " xs
> +
>    let setup dir options args >      xen_ssh_source dir options args
>  
> diff --git a/output/output.ml b/output/output.ml
> index 101da82a70..659d20ac31 100644
> --- a/output/output.ml
> +++ b/output/output.ml
> @@ -38,6 +38,7 @@ type options = {
>  
>  module type OUTPUT = sig
>    type t
> +  val to_string : options -> string
>    val setup : string -> options -> Types.source -> t
>    val finalize : string -> options ->
>                   Types.source -> Types.inspect -> Types.target_meta
->
> diff --git a/output/output.mli b/output/output.mli
> index 03d71daf67..ced2216106 100644
> --- a/output/output.mli
> +++ b/output/output.mli
> @@ -30,6 +30,10 @@ module type OUTPUT = sig
>    type t
>    (** Opaque data used by the output mode. *)
>  
> +  val to_string : options -> string
> +  (** [to_string options] converts the destination to a printable
> +      string (for messages). *)
> +
>    val setup : string -> options -> Types.source -> t
>    (** [setup dir options source]
>  
> diff --git a/output/output_disk.ml b/output/output_disk.ml
> index eca3c727b7..386d031b46 100644
> --- a/output/output_disk.ml
> +++ b/output/output_disk.ml
> @@ -96,6 +96,12 @@ and disk_finalize dir source inspect target_meta
>  module Disk = struct
>    type t = unit
>  
> +  let to_string options > +    "-o disk" ^
> +      match options.output_storage with
> +      | Some os -> " -os " ^ os
> +      | None -> ""
> +
>    let setup dir options source >      if options.output_options
<> [] then
>        error (f_"no -oo (output options) are allowed here");
> diff --git a/output/output_glance.ml b/output/output_glance.ml
> index 0d7838dd38..85cbe58ea5 100644
> --- a/output/output_glance.ml
> +++ b/output/output_glance.ml
> @@ -122,6 +122,8 @@ and glance_finalize dir source inspect target_meta
output_format tmpdir >  module Glance = struct
>    type t = string
>  
> +  let to_string options = "-o glance"
> +
>    let setup dir options source >      if options.output_options
<> [] then
>        error (f_"no -oo (output options) are allowed here");
> diff --git a/output/output_json.ml b/output/output_json.ml
> index bb0cdfeb5a..88fb4778d4 100644
> --- a/output/output_json.ml
> +++ b/output/output_json.ml
> @@ -134,6 +134,12 @@ and json_path os output_name json_disks_pattern i >
module Json = struct
>    type t = unit
>  
> +  let to_string options > +    "-o json" ^
> +      match options.output_storage with
> +      | Some os -> " -os " ^ os
> +      | None -> ""
> +
>    let setup dir options source >      let data = json_parse_options
options in
>      let output_name = get_output_name options source in
I tried to understand here whether "-oo json-disks-pattern" should be
logged here; however, I can't tell the status of that option. The top of
this file indicates the option is still supported, but the bottom of the
file states the opposite ("no -oo (output options) are allowed here").
> diff --git a/output/output_libvirt.ml b/output/output_libvirt.ml
> index 52c4540130..20333363b7 100644
> --- a/output/output_libvirt.ml
> +++ b/output/output_libvirt.ml
> @@ -198,6 +198,12 @@ and target_features_of_capabilities_doc doc arch > 
module Libvirt_ = struct
>    type t = string * string
>  
> +  let to_string options > +    "-o libvirt" ^
> +      match options.output_storage with
> +      | Some os -> " -os " ^ os
> +      | None -> ""
> +
>    let setup dir options source >      if options.output_options
<> [] then
>        error (f_"no -oo (output options) are allowed here");
> diff --git a/output/output_null.ml b/output/output_null.ml
> index 34fbd6e148..56fb7ec63c 100644
> --- a/output/output_null.ml
> +++ b/output/output_null.ml
> @@ -76,6 +76,8 @@ and null_servers dir disks output_name >  module Null
= struct
>    type t = unit
>  
> +  let to_string options = "-o null"
> +
>    let setup dir options source >      if options.output_options
<> [] then
>        error (f_"no -oo (output options) are allowed here");
> diff --git a/output/output_openstack.ml b/output/output_openstack.ml
> index 334a1fc2ae..1798548dc3 100644
> --- a/output/output_openstack.ml
> +++ b/output/output_openstack.ml
> @@ -462,6 +462,8 @@ and iso_time >  module Openstack = struct
>    type t = string list
>  
> +  let to_string options = "-o openstack"
> +
>    let setup dir options source >      let data =
openstack_parse_options options in
>      let output_name = get_output_name options source in
No need to print "-oo server-id=SERVER" and the other optional -oo
options?
> diff --git a/output/output_qemu.ml b/output/output_qemu.ml
> index 0aac1eba2b..3d5d67820e 100644
> --- a/output/output_qemu.ml
> +++ b/output/output_qemu.ml
> @@ -315,6 +315,12 @@ and qemu_finalize dir source inspect target_meta
>  module QEMU = struct
>    type t = unit
>  
> +  let to_string options > +    "-o qemu" ^
> +      match options.output_storage with
> +      | Some os -> " -os " ^ os
> +      | None -> ""
> +
>    let setup dir options source >      let data = qemu_parse_options
options in
>      let output_name = get_output_name options source in
> diff --git a/output/output_rhv.ml b/output/output_rhv.ml
> index 6a67b7aa15..a386b9a58d 100644
> --- a/output/output_rhv.ml
> +++ b/output/output_rhv.ml
> @@ -266,6 +266,8 @@ and check_storage_domain domain_class os mp > 
module RHV = struct
>    type t = string * string * string * string list * string list * int64
list
>  
> +  let to_string options = "-o rhv"
> +
>    let setup dir options source >      if options.output_options
<> [] then
>        error (f_"no -oo (output options) are allowed here");
Bunch of -oo options possible here too I think -- I'm missing the
"organizing principle" behind what options are printed and what are
not.
> diff --git a/output/output_rhv_upload.ml b/output/output_rhv_upload.ml
> index 91e7be45bc..4d8dc1c135 100644
> --- a/output/output_rhv_upload.ml
> +++ b/output/output_rhv_upload.ml
> @@ -444,6 +444,15 @@ module RHVUpload = struct
>             JSON.field list * string option * string option *
>             string option * string
>  
> +  let to_string options > +    "-o rhv-upload" ^
> +      (match options.output_conn with
> +       | Some oc -> " -oc " ^ oc
> +       | None -> "") ^
> +      (match options.output_storage with
> +       | Some os -> " -os " ^ os
> +       | None -> "")
> +
>    let setup dir options source >      let data =
rhv_upload_parse_options options in
>      let output_name = get_output_name options source in
> diff --git a/output/output_vdsm.ml b/output/output_vdsm.ml
> index ce0d5b5e4b..676ecf0010 100644
> --- a/output/output_vdsm.ml
> +++ b/output/output_vdsm.ml
> @@ -212,6 +212,8 @@ and vdsm_finalize dir source inspect target_meta
>  module VDSM = struct
>    type t = string * string * int64 list
>  
> +  let to_string options = "-o vdsm"
> +
>    let setup dir options source >      let data = vdsm_parse_options
options in
>      let output_name = get_output_name options source in
> diff --git a/v2v/v2v.ml b/v2v/v2v.ml
> index 47e6e9371a..d74cc21f0a 100644
> --- a/v2v/v2v.ml
> +++ b/v2v/v2v.ml
> @@ -532,6 +532,8 @@ read the man page virt-v2v(1).
>    } in
>  
>    (* Start the input module (runs an NBD server in the background). *)
> +  message (f_"Setting up the source: %s")
> +    (Input_module.to_string input_options args);
>    let source = Input_module.setup tmpdir input_options args in
>  
>    (* If --print-source then print the source metadata and exit. *)
> @@ -548,6 +550,8 @@ read the man page virt-v2v(1).
>    unlink (tmpdir // "convert");
>  
>    (* Start the output module (runs an NBD server in the background). *)
> +  message (f_"Setting up the destination: %s")
> +    (Output_module.to_string output_options);
>    let output_t = Output_module.setup tmpdir output_options source in
>  
>    (* Debug the v2vdir. *)
> 
The code looks OK to me, but I'm not familiar enough with the various
input and output modules to really claim that the set of options printed
is -- or is not -- just right.

Reviewed-by: Laszlo Ersek <lersek at redhat.com>

Thanks
Laszlo