[pve-devel] [PATCH v2] add APT hook to prevent proxmox-ve removal

[Fabian Grünbichler]

since this happens quite regularly when users accidentally install
conflicting packages.

sample output:
$ apt remove pve-qemu-kvm
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libxml-libxml-perl proxmox-widget-toolkit pve-edk2-firmware pve-i18n pve-xtermjs
Use 'apt autoremove' to remove them.
The following packages will be REMOVED:
  proxmox-ve pve-container pve-ha-manager pve-ha-manager-dbgsym pve-manager pve-qemu-kvm qemu-server spiceterm
0 upgraded, 0 newly installed, 8 to remove and 0 not upgraded.
After this operation, 37.6 MB disk space will be freed.
Do you want to continue? [Y/n] y
W: (pve-apt-hook) !! WARNING !!
W: (pve-apt-hook) You are attempting to remove the meta-package 'proxmox-ve'!
W: (pve-apt-hook)
W: (pve-apt-hook) If you really you want to permanently remove 'proxmox-ve' from your system, run the following command
W: (pve-apt-hook)       touch '/please-remove-proxmox-ve'
W: (pve-apt-hook) and repeat your apt-get/apt invocation.
W: (pve-apt-hook)
W: (pve-apt-hook) If you are unsure why 'proxmox-ve' would be removed, please verify
W: (pve-apt-hook)       - your APT repository settings
W: (pve-apt-hook)       - that you are using 'apt-get dist-upgrade' or 'apt full-upgrade' to upgrade your system
E: Sub-process /usr/share/proxmox-ve/pve-apt-hook returned an error code (1)
E: Failure running script /usr/share/proxmox-ve/pve-apt-hook

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---
Changes since v1:
- remove $check_file if it exists, to restore default behaviour if proxmox-ve
  ever gets re-installed (thanks Thomas for the suggestion!)

 debian/apthook/10pveapthook |  4 +++
 debian/apthook/pve-apt-hook | 73 +++++++++++++++++++++++++++++++++++++++++++++
 debian/proxmox-ve.install   |  2 ++
 3 files changed, 79 insertions(+)
 create mode 100644 debian/apthook/10pveapthook
 create mode 100755 debian/apthook/pve-apt-hook

diff --git a/debian/apthook/10pveapthook b/debian/apthook/10pveapthook
new file mode 100644
index 0000000..b7ae649
--- /dev/null
+++ b/debian/apthook/10pveapthook
@@ -0,0 +1,4 @@
+DPkg::Pre-Install-Pkgs { "/usr/share/proxmox-ve/pve-apt-hook"; };
+DPkg::Tools::Options::/usr/share/proxmox-ve/pve-apt-hook "";
+DPkg::Tools::Options::/usr/share/proxmox-ve/pve-apt-hook::Version "2";
+DPkg::Tools::Options::/usr/share/proxmox-ve/pve-apt-hook::InfoFD "20";
diff --git a/debian/apthook/pve-apt-hook b/debian/apthook/pve-apt-hook
new file mode 100755
index 0000000..f925090
--- /dev/null
+++ b/debian/apthook/pve-apt-hook
@@ -0,0 +1,73 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use File::Basename;
+
+my $fd = $ENV{APT_HOOK_INFO_FD};
+my $check_file = '/please-remove-proxmox-ve';
+my $check_package = 'proxmox-ve';
+my $hook_name = basename($0);
+
+my $log = sub {
+  my ($line) = @_;
+  print "W: ($hook_name) $line";
+};
+
+if (!defined $fd || $fd == 0) {
+  $log->("APT_HOOK_INFO_FD not correctly defined, skipping apt-pve-hook checks\n");
+  exit 0;
+}
+
+open(my $fh, "<&=${fd}") or die "E: could not open APT_HOOK_INFO_FD (${fd}) - $!\n";
+
+my $cleanup = sub {
+  my ($rc) = @_;
+
+  close($fh);
+  exit $rc;
+};
+
+chomp (my $ver = <$fh>);
+if ($ver ne "VERSION 2") {
+  $log->("apt-pve-hook misconfigured, expecting hook protocol version 2\n");
+  $cleanup->(0);
+}
+
+my $blank;
+while (my $line = <$fh>) {
+  chomp $line;
+
+  if (!defined($blank)) {
+    $blank = 1 if !$line;
+    next;
+  }
+
+  my ($pkg, $old, $dir, $new, $action) = (split / /, $line, 5);
+  if (!defined($action)) {
+    $log->("apt-pve-hook encountered unexpected line: $line\n");
+    next;
+  }
+
+  if ($pkg eq 'proxmox-ve' && $action eq '**REMOVE**') {
+    if (-e $check_file) {
+      $log->("'$check_file' exists, proceeding with removal of package '${check_package}'\n");
+      unlink $check_file;
+    } else {
+      $log->("!! WARNING !!\n");
+      $log->("You are attempting to remove the meta-package '${check_package}'!\n");
+      $log->("\n");
+      $log->("If you really you want to permanently remove '${check_package}' from your system, run the following command\n");
+      $log->("\ttouch '${check_file}'\n");
+      $log->("and repeat your apt-get/apt invocation.\n");
+      $log->("\n");
+      $log->("If you are unsure why '$check_package' would be removed, please verify\n");
+      $log->("\t- your APT repository settings\n");
+      $log->("\t- that you are using 'apt-get dist-upgrade' or 'apt full-upgrade' to upgrade your system\n");
+      $cleanup->(1);
+    }
+  }
+}
+
+$cleanup->(0);
diff --git a/debian/proxmox-ve.install b/debian/proxmox-ve.install
index 6ac09f5..13d16c4 100644
--- a/debian/proxmox-ve.install
+++ b/debian/proxmox-ve.install
@@ -1 +1,3 @@
 debian/proxmox-ve-release-5.x.gpg etc/apt/trusted.gpg.d/
+debian/apthook/10pveapthook etc/apt/apt.conf.d/
+debian/apthook/pve-apt-hook usr/share/proxmox-ve/
-- 
2.14.2