From f31595c13101a56578482198f4b6fe50c2e0cb13 Mon Sep 17 00:00:00 2001
From: Aleksandr Maus <aleksandr.maus@elastic.co>
Date: Fri, 29 Jul 2022 11:30:10 -0400
Subject: [PATCH 1/3] Fix RPM/DEB clean install

---
 .../templates/linux/postinstall.sh.tmpl       | 41 ++++++++++++-------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
index 083ebb91060..a115aa48c3d 100644
--- a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
+++ b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
@@ -1,18 +1,27 @@
 #!/usr/bin/env bash
 
-set -e
-
 symlink="/usr/share/elastic-agent/bin/elastic-agent"
-old_agent_dir="$( dirname "$(readlink -f -- "$symlink")" )"
+old_agent_dir=""
+
+# check if $symlink exists for the previous install
+if test -f "$symlink"; then
+    resolved_symlink="$(readlink -f -e -- "$symlink")"
+    # check if it is resolved to non empty string
+    if ! [ -z "$resolved_symlink" ]; then
+        old_agent_dir="$( dirname "$resolved_symlink" )"
+    fi
+fi
 
-commit_hash="{{ commit_short }}"
+set -e
 
-yml_path="$old_agent_dir/state.yml"
-enc_path="$old_agent_dir/state.enc"
+commit_hash="{{ commit_short }}"
 
-new_agent_dir="$( dirname "$old_agent_dir")/elastic-agent-$commit_hash"
+new_agent_dir="/var/lib/elastic-agent/data/elastic-agent-$commit_hash"
 
-if ! [[ "$old_agent_dir" -ef "$new_agent_dir" ]]; then
+# copy the state files if there was a previous agent install
+if ! [ -z "$old_agent_dir" ]; then
+    yml_path="$old_agent_dir/state.yml"
+    enc_path="$old_agent_dir/state.enc"
     echo "migrate state from $old_agent_dir to $new_agent_dir"
 
     if test -f "$yml_path"; then
@@ -24,15 +33,17 @@ if ! [[ "$old_agent_dir" -ef "$new_agent_dir" ]]; then
         echo "found "$enc_path", copy to "$new_agent_dir"."
         cp "$enc_path" "$new_agent_dir"
     fi
+fi
 
-    if test -f "$symlink"; then
-        echo "found symlink $symlink, unlink"
-        unlink "$symlink"
-    fi
-
-    echo "create symlink "$symlink" to "$new_agent_dir/elastic-agent""
-    ln -s "$new_agent_dir/elastic-agent" "$symlink"
+# delete symlink if exists
+if test -f "$symlink"; then
+    echo "found symlink $symlink, unlink"
+    unlink "$symlink"
 fi
 
+# create symlink to the new agent
+echo "create symlink "$symlink" to "$new_agent_dir/elastic-agent""
+ln -s "$new_agent_dir/elastic-agent" "$symlink"
+
 systemctl daemon-reload 2> /dev/null
 exit 0

From a1c04e54f66c875ac9ac8550ce9f6a058878af04 Mon Sep 17 00:00:00 2001
From: Aleksandr Maus <aleksandr.maus@elastic.co>
Date: Sun, 31 Jul 2022 22:55:19 -0400
Subject: [PATCH 2/3] Improve the post install script

* Do not try to copy the state files if the agent directory is the same,
  this causes the error.
* Check the existance of symlink instead of the file it is pointing to
  for the state file migration.
---
 .../packaging/templates/linux/postinstall.sh.tmpl     | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
index a115aa48c3d..8852a655a63 100644
--- a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
+++ b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
@@ -1,25 +1,26 @@
 #!/usr/bin/env bash
 
+set -e
+
 symlink="/usr/share/elastic-agent/bin/elastic-agent"
 old_agent_dir=""
 
 # check if $symlink exists for the previous install
-if test -f "$symlink"; then
-    resolved_symlink="$(readlink -f -e -- "$symlink")"
+# and derive the old agent directory
+if test -L "$symlink"; then
+    resolved_symlink="$(readlink -f -- "$symlink")"
     # check if it is resolved to non empty string
     if ! [ -z "$resolved_symlink" ]; then
         old_agent_dir="$( dirname "$resolved_symlink" )"
     fi
 fi
 
-set -e
-
 commit_hash="{{ commit_short }}"
 
 new_agent_dir="/var/lib/elastic-agent/data/elastic-agent-$commit_hash"
 
 # copy the state files if there was a previous agent install
-if ! [ -z "$old_agent_dir" ]; then
+if ! [ -z "$old_agent_dir" ] && ! [ "$old_agent_dir" -ef "$new_agent_dir" ]; then
     yml_path="$old_agent_dir/state.yml"
     enc_path="$old_agent_dir/state.enc"
     echo "migrate state from $old_agent_dir to $new_agent_dir"

From 924da80d4fbbce298813d4ff101e82a0ecb82317 Mon Sep 17 00:00:00 2001
From: Aleksandr Maus <aleksandr.maus@elastic.co>
Date: Mon, 1 Aug 2022 13:53:52 -0400
Subject: [PATCH 3/3] Update check for symlink existance for the cases where
 the symlink points to non-existent file

---
 dev-tools/packaging/templates/linux/postinstall.sh.tmpl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
index 8852a655a63..d96f21a8629 100644
--- a/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
+++ b/dev-tools/packaging/templates/linux/postinstall.sh.tmpl
@@ -37,7 +37,7 @@ if ! [ -z "$old_agent_dir" ] && ! [ "$old_agent_dir" -ef "$new_agent_dir" ]; the
 fi
 
 # delete symlink if exists
-if test -f "$symlink"; then
+if test -L "$symlink"; then
     echo "found symlink $symlink, unlink"
     unlink "$symlink"
 fi