[pve-devel] [PATCH zfsonlinux 4/4] Preserve /etc/zfs/zed.d configuration on upgrade

[Stoiko Ivanov]

From: Antonio Russo <antonio.e.russo at gmail.com>

Of the zedlet scripts shipped by upstream, a subset are enabled by
default, by creating symlinks in /etc/zfs/zed.d.  These symlinks are
shipped in the zfs-zed package.  dpkg, however, does not support
conffile handling of symlinks, and therefore any changes (removals) to
the symlinks are not preserved on package upgrade.

To address this policy violation, we:

 1. During package build, create a list of enabled-by-default zedlets,
    instead of creating symlinks.
 2. On package removal, identify all enabled-by-default zedlets whose
    symlinks do not exist (i.e., were removed by the user). This is done
    by creating "whiteout" links to /dev/null in their place).
 3. On package installation, create links to enabled-by-default zedlets
    UNLESS there is already a file there (i.e., abort if there is a
    whiteout link).
 4. We also clean up broken symlinks to removed zedlets at package
    postinst.

(cherry picked and adapted from 5cee380324d74e640d5dd7a360faba3994c8007f [0])

[0] https://salsa.debian.org/zfsonlinux-team/zfs.git

Signed-off-by: Stoiko Ivanov <s.ivanov at proxmox.com>
---
 .../0006-dont-symlink-zed-scripts.patch       | 12 +++++++++++
 debian/patches/series                         |  1 +
 debian/zfs-zed.postinst                       | 20 +++++++++++++++++++
 debian/zfs-zed.prerm                          | 16 +++++++++++++++
 4 files changed, 49 insertions(+)
 create mode 100644 debian/patches/0006-dont-symlink-zed-scripts.patch
 create mode 100644 debian/zfs-zed.postinst
 create mode 100644 debian/zfs-zed.prerm

diff --git a/debian/patches/0006-dont-symlink-zed-scripts.patch b/debian/patches/0006-dont-symlink-zed-scripts.patch
new file mode 100644
index 00000000..de995793
--- /dev/null
+++ b/debian/patches/0006-dont-symlink-zed-scripts.patch
@@ -0,0 +1,12 @@
+Description: track default symlinks, instead of symlinking
+Forwarded: no need
+--- a/cmd/zed/zed.d/Makefile.am
++++ b/cmd/zed/zed.d/Makefile.am
+@@ -52,6 +52,6 @@
+ 	for f in $(zedconfdefaults); do \
+ 	  test -f "$(DESTDIR)$(zedconfdir)/$${f}" -o \
+ 	       -L "$(DESTDIR)$(zedconfdir)/$${f}" || \
+-	    ln -s "$(zedexecdir)/$${f}" "$(DESTDIR)$(zedconfdir)"; \
++	    echo "$${f}" >> "$(DESTDIR)$(zedexecdir)/DEFAULT-ENABLED" ; \
+ 	done
+ 	chmod 0600 "$(DESTDIR)$(zedconfdir)/zed.rc"
diff --git a/debian/patches/series b/debian/patches/series
index 988c5a3b..8fe3840a 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -3,3 +3,4 @@
 0003-Fix-the-path-to-the-zed-binary-on-the-systemd-unit.patch
 0004-import-with-d-dev-disk-by-id-in-scan-service.patch
 0005-Enable-zed-emails.patch
+0006-dont-symlink-zed-scripts.patch
diff --git a/debian/zfs-zed.postinst b/debian/zfs-zed.postinst
new file mode 100644
index 00000000..93325438
--- /dev/null
+++ b/debian/zfs-zed.postinst
@@ -0,0 +1,20 @@
+#!/bin/sh
+set -e
+
+zedd="/usr/lib/zfs-linux/zed.d"
+etcd="/etc/zfs/zed.d"
+
+# enable all default zedlets that are not overridden
+while read -r file ; do
+    etcfile="${etcd}/${file}"
+    [ -e "${etcfile}" ] && continue
+    ln -s "${zedd}/${file}" "${etcfile}"
+done < "${zedd}/DEFAULT-ENABLED"
+
+# remove the overrides created in prerm
+find "${etcd}" -maxdepth 1 -lname '/dev/null' -delete
+# remove any dangling symlinks to old zedlets
+find "${etcd}" -maxdepth 1 -lname "${zedd}/*" -xtype l  -delete
+
+#DEBHELPER#
+
diff --git a/debian/zfs-zed.prerm b/debian/zfs-zed.prerm
new file mode 100644
index 00000000..fca0f4a7
--- /dev/null
+++ b/debian/zfs-zed.prerm
@@ -0,0 +1,16 @@
+#!/bin/sh
+set -e
+
+zedd="/usr/lib/zfs-linux/zed.d"
+etcd="/etc/zfs/zed.d"
+
+if [ "$1" != "failed-upgrade" ] && [ -d "${etcd}" ] && [ -d "${zedd}" ] ; then
+    while read -r file ; do
+        etcfile="${etcd}/${file}"
+        [ -e "${etcfile}" ] && continue
+        ln -s /dev/null "${etcfile}"
+    done < "${zedd}/DEFAULT-ENABLED"
+fi
+
+#DEBHELPER#
+
-- 
2.20.1