From 186c237ac1cb6f6830cfe2d08dfdcfdbdffab264 Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Mon, 6 Apr 2020 10:19:12 +0100

Subject: [PATCH] v2v: Allow large temporary directory to be set on a global

 basis.

Previously we placed large files in g#get_cachedir () (usually

/var/tmp).  However the problem is this ties the libguestfs appliance

and the virt-v2v overlay files to the same location.

When virt-v2v is run in a container, or any other situation where

local storage is limited, it's helpful to be able to put the overlay

files on an externally mounted PVC, which might be using NFS and

shared between containers.  But putting the libguestfs appliance on

NFS in a shared location is certainly not recommended.

This allows the two locations to be set separately:

  VIRT_V2V_TMPDIR - location of large temporary files, can use NFS

                    and may be shared

  LIBGUESTFS_CACHEDIR - location of libguestfs appliance

Another motivation for this patch is to allow more reliable cleanup of

large temporary files by an external process, as described in the

updated documentation.

Small temporary files are placed in $TMPDIR (usually /tmp).  I cleaned

up some existing code which used /var/tmp for small temporaries.

(cherry picked from commit 717b808bc5cb632778973eb000600e87eaf5c31a)

---

 docs/virt-v2v.pod        | 27 +++++++++++++++++++--------

 v2v/input_ova.ml         |  4 ++--

 v2v/input_vmx.ml         |  3 +--

 v2v/output_glance.ml     |  3 +--

 v2v/output_null.ml       |  3 +--

 v2v/output_rhv_upload.ml | 29 ++++++++++++++++-------------

 v2v/parse_ova.ml         |  6 ++----

 v2v/python_script.ml     | 12 +++---------

 v2v/python_script.mli    |  5 +----

 v2v/utils.ml             |  6 +++++-

 v2v/utils.mli            |  5 +++++

 v2v/v2v.ml               | 14 ++++++--------

 12 files changed, 62 insertions(+), 55 deletions(-)

diff --git a/docs/virt-v2v.pod b/docs/virt-v2v.pod

index 6f9f323e..af69d633 100644

--- a/docs/virt-v2v.pod

+++ b/docs/virt-v2v.pod

@@ -1172,8 +1172,8 @@ possible.

 =head3 Disk space

 Virt-v2v places potentially large temporary files in

-C<$LIBGUESTFS_CACHEDIR> (which is F if you don't set it).

-Using tmpfs is a bad idea.

+C<$VIRT_V2V_TMPDIR> (usually F, see also

+L</ENVIRONMENT VARIBLES> below).  Using tmpfs is a bad idea.

 For each guest disk, an overlay is stored temporarily.  This stores

 the changes made during conversion, and is used as a cache.  The

@@ -1186,12 +1186,12 @@ and output methods may use disk space, as outlined in the table below.

 =item I<-i ova>

 This temporarily places a full copy of the uncompressed source disks

-in C<$LIBGUESTFS_CACHEDIR> (or F).

+in C<$VIRT_V2V_TMPDIR> (or F).

 =item I<-o glance>

 This temporarily places a full copy of the output disks in

-C<$LIBGUESTFS_CACHEDIR> (or F).

+C<$VIRT_V2V_TMPDIR> (or F).

 =item I<-o local>

@@ -1311,7 +1311,7 @@ have at least 100 available inodes.

 =head3 Minimum free space check in the host

 You must have sufficient free space in the host directory used to

-store temporary overlays.  To find out

+store large temporary overlays.  To find out

 which directory this is, use:

  $ df -h "`guestfish get-cachedir`"

@@ -1319,9 +1319,12 @@ which directory this is, use:

  /dev/mapper/root   50G   40G  6.8G  86% /

 and look under the C<Avail> column.  Virt-v2v will refuse to do the

-conversion at all unless at least 1GB is available there.

+conversion at all unless at least 1GB is available there.  You can

+change the directory that virt-v2v uses by setting

+C<$VIRT_V2V_TMPDIR>.

-See also L</Resource requirements> above.

+See also L</Resource requirements> above and L</ENVIRONMENT VARIABLES>

+below.

 =head2 Running virt-v2v as root or non-root

@@ -1496,10 +1499,18 @@ conversion.

 =over 4

+=item C<VIRT_V2V_TMPDIR>

+

 =item C<LIBGUESTFS_CACHEDIR>

 Location of the temporary directory used for the potentially large

-temporary overlay file.  If not set, F is used.

+temporary overlay file.  If neither environment variable is set then

+F is used.

+

+To reliably ensure large temporary files are cleaned up (for example

+in case virt-v2v crashes) you should create a randomly named directory

+under F, set C<VIRT_V2V_TMPDIR> to point to this directory,

+then when virt-v2v exits remove the directory.

 See the L</Disk space> section above.

diff --git a/v2v/input_ova.ml b/v2v/input_ova.ml

index 5d3bece1..d78a5ce8 100644

--- a/v2v/input_ova.ml

+++ b/v2v/input_ova.ml

@@ -132,8 +132,8 @@ class input_ova ova = object

            (* The spec allows the file to be gzip-compressed, in

             * which case we must uncompress it into a temporary.

             *)

-           let temp_dir = (open_guestfs ())#get_cachedir () in

-           let new_filename = Filename.temp_file ~temp_dir "ova" ".vmdk" in

+           let new_filename =

+             Filename.temp_file ~temp_dir:Utils.large_tmpdir "ova" ".vmdk" in

            unlink_on_exit new_filename;

            let cmd =

              sprintf "zcat %s > %s" (quote filename) (quote new_filename) in

diff --git a/v2v/input_vmx.ml b/v2v/input_vmx.ml

index f1d143e9..7a7647e5 100644

--- a/v2v/input_vmx.ml

+++ b/v2v/input_vmx.ml

@@ -389,8 +389,7 @@ and find_nics vmx =

 class input_vmx input_password input_transport arg =

   let tmpdir =

-    let base_dir = (open_guestfs ())#get_cachedir () in

-    let t = Mkdtemp.temp_dir ~base_dir "vmx." in

+    let t = Mkdtemp.temp_dir "vmx." in

     rmdir_on_exit t;

     t in

 object

diff --git a/v2v/output_glance.ml b/v2v/output_glance.ml

index 0a9e9181..e8facd0a 100644

--- a/v2v/output_glance.ml

+++ b/v2v/output_glance.ml

@@ -33,8 +33,7 @@ class output_glance () =

    * to write to a temporary file.  XXX

    *)

   let tmpdir =

-    let base_dir = (open_guestfs ())#get_cachedir () in

-    let t = Mkdtemp.temp_dir ~base_dir "glance." in

+    let t = Mkdtemp.temp_dir ~base_dir:large_tmpdir "glance." in

     rmdir_on_exit t;

     t in

 object

diff --git a/v2v/output_null.ml b/v2v/output_null.ml

index 3528da50..edb749ea 100644

--- a/v2v/output_null.ml

+++ b/v2v/output_null.ml

@@ -75,8 +75,7 @@ class output_null =

    * the null-co device w/ a JSON URL.

    *)

   let tmpdir =

-    let base_dir = (open_guestfs ())#get_cachedir () in

-    let t = Mkdtemp.temp_dir ~base_dir "null." in

+    let t = Mkdtemp.temp_dir ~base_dir:large_tmpdir "null." in

     rmdir_on_exit t;

     t in

 object

diff --git a/v2v/output_rhv_upload.ml b/v2v/output_rhv_upload.ml

index 81896e53..913992d9 100644

--- a/v2v/output_rhv_upload.ml

+++ b/v2v/output_rhv_upload.ml

@@ -148,25 +148,28 @@ class output_rhv_upload output_alloc output_conn

                         rhv_options =

   (* Create a temporary directory which will be deleted on exit. *)

   let tmpdir =

-    let base_dir = (open_guestfs ())#get_cachedir () in

-    let t = Mkdtemp.temp_dir ~base_dir "rhvupload." in

+    let t = Mkdtemp.temp_dir "rhvupload." in

     rmdir_on_exit t;

     t in

   let diskid_file_of_id id = tmpdir // sprintf "diskid.%d" id in

   (* Create Python scripts for precheck, vmcheck, plugin and create VM. *)

-  let py_create = Python_script.create ~tmpdir in

-  let precheck_script = py_create ~name:"rhv-upload-precheck.py"

-                        Output_rhv_upload_precheck_source.code in

-  let vmcheck_script = py_create ~name:"rhv-upload-vmcheck.py"

-                       Output_rhv_upload_vmcheck_source.code in

-  let plugin_script = py_create ~name:"rhv-upload-plugin.py"

-                      Output_rhv_upload_plugin_source.code in

-  let createvm_script = py_create ~name:"rhv-upload-createvm.py"

-                        Output_rhv_upload_createvm_source.code in

-  let deletedisks_script = py_create ~name:"rhv-upload-deletedisks.py"

-                           Output_rhv_upload_deletedisks_source.code in

+  let precheck_script =

+    Python_script.create ~name:"rhv-upload-precheck.py"

+      Output_rhv_upload_precheck_source.code in

+  let vmcheck_script =

+    Python_script.create ~name:"rhv-upload-vmcheck.py"

+      Output_rhv_upload_vmcheck_source.code in

+  let plugin_script =

+    Python_script.create ~name:"rhv-upload-plugin.py"

+      Output_rhv_upload_plugin_source.code in

+  let createvm_script =

+    Python_script.create ~name:"rhv-upload-createvm.py"

+      Output_rhv_upload_createvm_source.code in

+  let deletedisks_script =

+    Python_script.create ~name:"rhv-upload-deletedisks.py"

+      Output_rhv_upload_deletedisks_source.code in

   (* JSON parameters which are invariant between disks. *)

   let json_params = [

diff --git a/v2v/parse_ova.ml b/v2v/parse_ova.ml

index 0b939ac4..568ac5fa 100644

--- a/v2v/parse_ova.ml

+++ b/v2v/parse_ova.ml

@@ -71,8 +71,7 @@ let rec parse_ova ova =

     if is_directory ova then ova, Directory

     else (

       let tmpdir =

-        let base_dir = (open_guestfs ())#get_cachedir () in

-        let t = Mkdtemp.temp_dir ~base_dir "ova." in

+        let t = Mkdtemp.temp_dir ~base_dir:large_tmpdir "ova." in

         rmdir_on_exit t;

         t in

@@ -221,8 +220,7 @@ and uncompress_head format file =

  *)

 and uncompressed_type format file =

   let head, headlen = uncompress_head format file in

-  let tmpfile, chan =

-    Filename.open_temp_file "ova.file." "" in

+  let tmpfile, chan = Filename.open_temp_file "ova.file." "" in

   output chan head 0 headlen;

   close_out chan;

   let ret = detect_file_type tmpfile in

diff --git a/v2v/python_script.ml b/v2v/python_script.ml

index b1ea8f9d..212c8e1b 100644

--- a/v2v/python_script.ml

+++ b/v2v/python_script.ml

@@ -31,15 +31,9 @@ type script = {

   path : string;                (* Path to script. *)

 }

-let create ?(name = "script.py") ?tmpdir code =

-  let tmpdir =

-    match tmpdir with

-    | None ->

-      let base_dir = (open_guestfs ())#get_cachedir () in

-      let t = Mkdtemp.temp_dir ~base_dir "v2v." in

-      rmdir_on_exit t;

-      t

-    | Some dir -> dir in

+let create ?(name = "script.py") code =

+  let tmpdir = Mkdtemp.temp_dir "v2v." in

+  rmdir_on_exit tmpdir;

   let path = tmpdir // name in

   with_open_out path (fun chan -> output_string chan code);

   { tmpdir; path }

diff --git a/v2v/python_script.mli b/v2v/python_script.mli

index 6bf77e34..fdf73514 100644

--- a/v2v/python_script.mli

+++ b/v2v/python_script.mli

@@ -20,14 +20,11 @@

 type script

-val create : ?name:string -> ?tmpdir:string -> string -> script

+val create : ?name:string -> string -> script

 (** Create a Python script object.

     The optional parameter [?name] is a hint for the name of the script.

-    The optional parameter [?tmpdir] is the temporary directory to use

-    (instead of creating a new one).

-

     The parameter is the Python code.  Usually this is

     [Some_source.code] where [some_source.ml] is generated from

     the Python file by [v2v/embed.sh] (see also [v2v/Makefile.am]). *)

diff --git a/v2v/utils.ml b/v2v/utils.ml

index c2940582..a6c359f0 100644

--- a/v2v/utils.ml

+++ b/v2v/utils.ml

@@ -24,6 +24,10 @@ open Std_utils

 open Tools_utils

 open Common_gettext.Gettext

+let large_tmpdir =

+  try Sys.getenv "VIRT_V2V_TMPDIR"

+  with Not_found -> (open_guestfs ())#get_cachedir ()

+

 (* Is SELinux enabled and enforcing on the host? *)

 let have_selinux =

   0 = Sys.command "getenforce 2>/dev/null | grep -isq Enforcing"

@@ -114,6 +118,7 @@ let qemu_img_supports_offset_and_size () =

    * file that has an offset and size.

    *)

   let tmp = Filename.temp_file "v2vqemuimgtst" ".img" in

+  unlink_on_exit tmp;

   Unix.truncate tmp 1024;

   let json = [

@@ -133,7 +138,6 @@ let qemu_img_supports_offset_and_size () =

             (if verbose () then "" else " 2>&1") in

   debug "%s" cmd;

   let r = 0 = Sys.command cmd in

-  Unix.unlink tmp;

   debug "qemu-img supports \"offset\" and \"size\" in json URLs: %b" r;

   r

diff --git a/v2v/utils.mli b/v2v/utils.mli

index 937e2b9b..d86ca507 100644

--- a/v2v/utils.mli

+++ b/v2v/utils.mli

@@ -18,6 +18,11 @@

 (** Utilities used in virt-v2v only. *)

+val large_tmpdir : string

+(** [VIRT_V2V_TMPDIR] or [/var/tmp].  Create all large temporary files

+    such as overlays in this directory.  Small temporary files can

+    use the default behaviour eg. of {!Filename.temp_file} *)

+

 val have_selinux : bool

 (** True if SELinux is enabled and enforcing on the host. *)

diff --git a/v2v/v2v.ml b/v2v/v2v.ml

index 73edff2c..a58ff433 100644

--- a/v2v/v2v.ml

+++ b/v2v/v2v.ml

@@ -264,8 +264,6 @@ and set_source_networks_and_bridges cmdline source =

   let nics = List.map (Networks.map cmdline.network_map) source.s_nics in

   { source with s_nics = nics }

-and overlay_dir = (open_guestfs ())#get_cachedir ()

-

 (* Conversion can fail or hang if there is insufficient free space in

  * the temporary directory used to store overlays on the host

  * (RHBZ#1316479).  Although only a few hundred MB is actually

@@ -273,12 +271,12 @@ and overlay_dir = (open_guestfs ())#get_cachedir ()

  * guestfs appliance which is also stored here.

  *)

 and check_host_free_space () =

-  let free_space = StatVFS.free_space (StatVFS.statvfs overlay_dir) in

-  debug "check_host_free_space: overlay_dir=%s free_space=%Ld"

-        overlay_dir free_space;

+  let free_space = StatVFS.free_space (StatVFS.statvfs large_tmpdir) in

+  debug "check_host_free_space: large_tmpdir=%s free_space=%Ld"

+        large_tmpdir free_space;

   if free_space < 1_073_741_824L then

     error (f_"insufficient free space in the conversion server temporary directory %s (%s).\n\nEither free up space in that directory, or set the LIBGUESTFS_CACHEDIR environment variable to point to another directory with more than 1GB of free space.\n\nSee also the virt-v2v(1) manual, section \"Minimum free space check in the host\".")

-          overlay_dir (human_size free_space)

+          large_tmpdir (human_size free_space)

 (* Create a qcow2 v3 overlay to protect the source image(s). *)

 and create_overlays source_disks =

@@ -286,7 +284,7 @@ and create_overlays source_disks =

   List.mapi (

     fun i ({ s_qemu_uri = qemu_uri; s_format = format } as source) ->

       let overlay_file =

-        Filename.temp_file ~temp_dir:overlay_dir "v2vovl" ".qcow2" in

+        Filename.temp_file ~temp_dir:large_tmpdir "v2vovl" ".qcow2" in

       unlink_on_exit overlay_file;

       (* There is a specific reason to use the newer qcow2 variant:

@@ -823,7 +821,7 @@ and preserve_overlays overlays src_name =

   List.iter (

     fun ov ->

       let saved_filename =

-        sprintf "%s/%s-%s.qcow2" overlay_dir src_name ov.ov_sd in

+        sprintf "%s/%s-%s.qcow2" large_tmpdir src_name ov.ov_sd in

       rename ov.ov_overlay_file saved_filename;

       info (f_"Overlay saved as %s [--debug-overlays]") saved_filename

   ) overlays

-- 

2.27.0