Fix PHP binary detection in package post-install script (#2707)

package/post-install.sh

@@ -22,19 +22,23 @@ CUSTOM_INI_FILE_NAME='ddtrace-custom.ini'
 
 PATH="${PATH}:/usr/local/bin"
 
+function println() {
+    echo -e '###' "$@"
+}
+
 # We attempt in this order the following binary names:
-#    1. php
-#    2. php8 (some alpine versions install php 8.x from main repo to this binary)
-#    3. php7 (some alpine versions install php 7.x from main repo to this binary)
-#    4. php5 (some alpine versions install php 5.x from main repo to this binary)
-if [ -z "$DD_TRACE_PHP_BIN" ]; then
-    DD_TRACE_PHP_BIN=$(command -v php || true)
-fi
-if [ -z "$DD_TRACE_PHP_BIN" ]; then
-    DD_TRACE_PHP_BIN=$(command -v php8 || true)
-fi
+for name in php php8 php83 php82 php81 php80 php7 php74 php73 php72 php71 php70
+do
+    if [ -z "$DD_TRACE_PHP_BIN" ]; then
+        DD_TRACE_PHP_BIN=$(command -v "$name" || true)
+    else
+        break
+    fi
+done
+
 if [ -z "$DD_TRACE_PHP_BIN" ]; then
-    DD_TRACE_PHP_BIN=$(command -v php7 || true)
+    println 'Unable to locate PHP binary'
+    exit 0
 fi
 
 function invoke_php() {
@@ -46,10 +50,6 @@ function invoke_php() {
     $DD_TRACE_PHP_BIN -d memory_limit=128M "$*"
 }
 
-function println() {
-    echo -e '###' "$@"
-}
-
 function append_configuration_to_file() {
     tee -a "$@" <<EOF
 ; Autogenerated by the Datadog post-install.sh script