[Libguestfs] [v2v PATCH v2 4/4] convert_linux: install the QEMU guest agent with a firstboot script

[Laszlo Ersek]

Register a firstboot script, for installing the guest agent with the
guest's own package manager -- that is, "Guest_packages.install_command".

For installing the package, network connectivity is required. Check it
first with "nmcli" (also checking whether NetworkManager is running), then
with "systemd-networkd-wait-online" (dependent on systemd-networkd). Note
that NetworkManager and systemd-networkd are never supposed to be enabled
at the same time.

The source domain's SELinux policy may not allow our firstboot service to
execute the package's installation scripts (if any). For that reason,
temporarily disable SELinux around package installation.

After installation, register another script for launching the agent.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2028764
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---

Notes:
    v2:
    
    - drop the "pkg_mgmt" helper variable; replace the call to
      "g#inspect_get_package_management" with the already populated
      "inspect.i_package_management" [Rich]
    
    - replace "sleep 60" with an open-coded "nmcli + sleep" loop, plus
      systemd-networkd-wait-online [Rich]:
    
    > #!/bin/sh
    > if conn=$(nmcli networking connectivity); then
    >   tries=0
    >   while
    >     test $tries -lt 30 &&
    >     test full != "$conn"
    >   do
    >     sleep 1
    >     tries=$((tries + 1))
    >     conn=$(nmcli networking connectivity)
    >   done
    > elif systemctl -q is-active systemd-networkd; then
    >   /usr/lib/systemd/systemd-networkd-wait-online \
    >     -q --timeout=30
    > fi
    
    - refresh submodule checkout against now-upstream libguestfs-common
      commit 9e990f3e4530 ("mlcustomize: factor out pkg
      install/update/uninstall from guestfs-tools", 2022-06-09)

 convert/convert_linux.ml | 78 +++++++++++++++++++-
 common                   |  2 +-
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/convert/convert_linux.ml b/convert/convert_linux.ml
index 2ddbc07aa86a..59d143bdda4b 100644
--- a/convert/convert_linux.ml
+++ b/convert/convert_linux.ml
@@ -562,8 +562,82 @@ let convert (g : G.guestfs) source inspect keep_serial_console _ =
               name = qga_pkg
           ) inspect.i_apps in
         if not has_qemu_guest_agent then
-          (* FIXME -- install qemu-guest-agent here *)
-          ()
+          try
+            let inst_cmd = Guest_packages.install_command [qga_pkg]
+                             inspect.i_package_management in
+
+            (* Use only the portable filename character set in this. *)
+            let selinux_enforcing = "/root/virt-v2v-fb-selinux-enforcing"
+            and timeout = 30 in
+            let fbs =
+              Firstboot.add_firstboot_script g inspect.i_root
+            in
+            info (f_"The QEMU Guest Agent will be installed for this guest at \
+                     first boot.");
+
+            (* Wait for the network to come online in the guest (best effort).
+             *)
+            fbs "wait online"
+              (sprintf "#!/bin/sh\n\
+                        if conn=$(nmcli networking connectivity); then\n\
+                        \ \ tries=0\n\
+                        \ \ while\n\
+                        \ \ \ \ test $tries -lt %d &&\n\
+                        \ \ \ \ test full != \"$conn\"\n\
+                        \ \ do\n\
+                        \ \ \ \ sleep 1\n\
+                        \ \ \ \ tries=$((tries + 1))\n\
+                        \ \ \ \ conn=$(nmcli networking connectivity)\n\
+                        \ \ done\n\
+                        elif systemctl -q is-active systemd-networkd; then\n\
+                        \ \ /usr/lib/systemd/systemd-networkd-wait-online \\\n\
+                        \ \ \ \ -q --timeout=%d\n\
+                        fi\n" timeout timeout);
+
+            (* Disable SELinux temporarily around package installation. Refer to
+             * <https://bugzilla.redhat.com/show_bug.cgi?id=2028764#c7> and
+             * <https://bugzilla.redhat.com/show_bug.cgi?id=2028764#c8>.
+             *)
+            fbs "setenforce 0"
+              (sprintf "#!/bin/sh\n\
+                        rm -f %s\n\
+                        if command -v getenforce >/dev/null &&\n\
+                        \ \ test Enforcing = \"$(getenforce)\"\n\
+                        then\n\
+                        \ \ touch %s\n\
+                        \ \ setenforce 0\n\
+                        fi\n" selinux_enforcing selinux_enforcing);
+            fbs "install qga" inst_cmd;
+            fbs "setenforce restore"
+              (sprintf "#!/bin/sh\n\
+                        if test -f %s; then\n\
+                        \ \ setenforce 1\n\
+                        \ \ rm -f %s\n\
+                        fi\n" selinux_enforcing selinux_enforcing);
+
+            (* Start the agent now and at subsequent boots. The following
+             * commands should work on both sysvinit distros / distro versions
+             * (regardless of "/etc/rc.d/" vs. "/etc/init.d/" being the scheme
+             * in use) and systemd distros (via redirection to systemctl).
+             *
+             * On distros where the chkconfig command is redirected to
+             * systemctl, the chkconfig command is likely superfluous. That's
+             * because on systemd distros, the QGA package comes with such
+             * runtime dependencies / triggers that the presence of the
+             * virtio-serial port named "org.qemu.guest_agent.0" automatically
+             * starts the agent during (second and later) boots. However, even
+             * on such distros, the chkconfig command should do no harm.
+             *)
+            fbs "start qga"
+              (sprintf "#!/bin/sh\n\
+                        service %s start\n\
+                        chkconfig %s on\n" qga_pkg qga_pkg)
+          with
+          | Guest_packages.Unknown_package_manager msg
+          | Guest_packages.Unimplemented_package_manager msg ->
+            warning (f_"The QEMU Guest Agent will not be installed.  The \
+                        install command for package ‘%s’ could not be created: \
+                        %s.") qga_pkg msg
 
   and configure_kernel () =
     (* Previously this function would try to install kernels, but we
diff --git a/common b/common
index 48527b8768d7..9e990f3e4530 160000
--- a/common
+++ b/common
@@ -1 +1 @@
-Subproject commit 48527b8768d7e010552beb62500a46ad940bca9a
+Subproject commit 9e990f3e4530df3708d176bc50e0bc68cf07d3ff
-- 
2.19.1.3.g30247aa5d201