diff --git a/conf/.env b/conf/.env
index 7d7f328..93c632a 100644
--- a/conf/.env
+++ b/conf/.env
@@ -8,7 +8,7 @@ PORT=__PORT__
 DB_DIR=__FINALPATH__/distbin-db
 
 # The external URL
-EXTERNAL_URL=https://__DOMAIN_URI__/
+EXTERNAL_URL=https://__DOMAIN____PATH__/
 
 # The internal URL
 INTERNAL_URL=http://localhost:__PORT__/
diff --git a/scripts/change_url b/scripts/change_url
index ae7acac..e08ba3a 100644
--- a/scripts/change_url
+++ b/scripts/change_url
@@ -113,22 +113,10 @@ fi
 #=================================================
 ynh_script_progression --message="Modifying config file..."
 
-config="$final_path/.env"
-ynh_backup_if_checksum_is_different --file="$config"
+domain="$new_domain"
+path_url="$new_path"
 
-# Change the URL in the configuration file
-
-if [ "$new_path" == "/" ]
-then
-    new_domain_uri="$new_domain"
-else
-    new_domain_uri="$new_domain$new_path"
-fi
-
-ynh_replace_string --match_string="EXTERNAL_URL=.*" --replace_string="EXTERNAL_URL=https://$new_domain_uri/" --target_file="$config"
-
-# Recalculate and store the checksum of the file for the next upgrade.
-ynh_store_file_checksum --file="$config"
+ynh_add_config --template="../conf/.env" --destination="$final_path/.env"
 
 #=================================================
 # GENERIC FINALISATION
diff --git a/scripts/install b/scripts/install
index 2eb581e..dada785 100644
--- a/scripts/install
+++ b/scripts/install
@@ -7,6 +7,7 @@
 #=================================================
 
 source _common.sh
+source ynh_add_config
 source /usr/share/yunohost/helpers
 
 #=================================================
@@ -150,28 +151,7 @@ ynh_add_systemd_config
 #=================================================
 ynh_script_progression --message="Modifying a config file..."
 
-config="$final_path/.env"
-cp "../conf/.env" "$config"
-
-if [ "$path_url" == "/" ]
-then
-    domain_uri="$domain"
-else
-    domain_uri="$domain$path_url"
-fi
-
-ynh_replace_string --match_string="__NODEJS_PATH__" --replace_string="$nodejs_path" --target_file="$config"
-ynh_replace_string --match_string="__PORT__" --replace_string="$port" --target_file="$config"
-ynh_replace_string --match_string="__DOMAIN_URI__" --replace_string="$domain_uri" --target_file="$config"
-ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$config"
-
-#=================================================
-# STORE THE CONFIG FILE CHECKSUM
-#=================================================
-ynh_script_progression --message="Storing the config file checksum..."
-
-# Calculate and store the config file checksum into the app settings
-ynh_store_file_checksum --file="$config"
+ynh_add_config --template="../conf/.env" --destination="$final_path/.env"
 
 #=================================================
 # GENERIC FINALIZATION
diff --git a/scripts/upgrade b/scripts/upgrade
index 3c3b832..27f9195 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -7,6 +7,7 @@
 #=================================================
 
 source _common.sh
+source ynh_add_config
 source /usr/share/yunohost/helpers
 
 #=================================================
@@ -162,24 +163,7 @@ ynh_add_systemd_config
 #=================================================
 ynh_script_progression --message="Modifying config file..."
 
-config="$final_path/.env"
-ynh_backup_if_checksum_is_different --file="$config"
-cp -f "../conf/.env" "$config"
-
-if [ "$path_url" == "/" ]
-then
-    domain_uri="$domain"
-else
-    domain_uri="$domain$path_url"
-fi
-
-ynh_replace_string --match_string="__NODEJS_PATH__" --replace_string="$nodejs_path" --target_file="$config"
-ynh_replace_string --match_string="__PORT__" --replace_string="$port" --target_file="$config"
-ynh_replace_string --match_string="__DOMAIN_URI__" --replace_string="$domain_uri" --target_file="$config"
-ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$config"
-
-# Recalculate and store the checksum of the file for the next upgrade.
-ynh_store_file_checksum --file="$config"
+ynh_add_config --template="../conf/.env" --destination="$final_path/.env"
 
 #=================================================
 # GENERIC FINALIZATION
diff --git a/scripts/ynh_add_config b/scripts/ynh_add_config
new file mode 100644
index 0000000..e92e46f
--- /dev/null
+++ b/scripts/ynh_add_config
@@ -0,0 +1,137 @@
+#!/bin/bash
+
+# Create a dedicated config file from a template
+#
+# examples: 
+#    ynh_add_config --template=".env" --destination="$final_path/.env"
+#    ynh_add_config --template="../conf/.env" --destination="$final_path/.env"
+#    ynh_add_config --template="/etc/nginx/sites-available/default" --destination="etc/nginx/sites-available/mydomain.conf"
+#
+# usage: ynh_add_config --template="template" --destination="destination"
+# | arg: -t, --template=     - Template config file to use
+# | arg: -d, --destination=    - Destination of the config file
+#
+# The template can be by default the name of a file in the conf directory
+# of a YunoHost Package, a relative path or an absolute path
+# The helper will use the template $template to generate a config file
+# $destination by replacing the following keywords with global variables
+# that should be defined before calling this helper :
+#   __PATH__             by  $path_url
+#   __NAME__            by $app
+#   __NAMETOCHANGE__    by $app
+#   __USER__            by $app
+#   __FINALPATH__       by $final_path
+#   __PHPVERSION__      by $YNH_PHP_VERSION
+#
+# And any dynamic variables that should be defined before calling this helper like:
+#   __DOMAIN__   by $domain
+#   __APP__      by $app
+#   __VAR_1__    by $var_1
+#   __VAR_2__    by $var_2
+#
+# The helper will verify the checksum and backup the destination file
+# if it's different before applying the new template.
+# And it will calculate and store the destination file checksum
+# into the app settings when configuration is done.
+#
+#
+ynh_add_config () {
+    # Declare an array to define the options of this helper.
+    local legacy_args=tdv
+    local -A args_array=( [t]=template= [d]=destination= )
+    local template
+    local destination
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+    local template_path
+
+    if [ -f "../conf/$template" ]; then
+        template_path="../conf/$template"
+    elif [ -f "../settings/conf/$template" ]; then
+        template_path="../settings/conf/$template"
+    elif [ -f "$template" ]; then
+        template_path=$template
+    else
+        ynh_die --message="The provided template $template doesn't exist"
+    fi
+
+    ynh_backup_if_checksum_is_different --file="$destination"
+
+    cp "$template_path" "$destination"
+
+    ynh_replace_vars --file="$destination"
+
+    ynh_store_file_checksum --file="$destination"
+}
+
+# Replace variables in a file
+#
+# usage: ynh_replace_vars --file="file"
+# | arg: -f, --file=     - File where to replace variables
+#
+# The helper will replace the following keywords with global variables
+# that should be defined before calling this helper :
+#   __PATH__             by  $path_url
+#   __NAME__            by $app
+#   __NAMETOCHANGE__    by $app
+#   __USER__            by $app
+#   __FINALPATH__       by $final_path
+#   __PHPVERSION__      by $YNH_PHP_VERSION
+#
+# And any dynamic variables that should be defined before calling this helper like:
+#   __DOMAIN__   by $domain
+#   __APP__      by $app
+#   __VAR_1__    by $var_1
+#   __VAR_2__    by $var_2
+#
+#
+ynh_replace_vars () {
+    # Declare an array to define the options of this helper.
+    local legacy_args=f
+    local -A args_array=( [f]=file= )
+    local file
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+
+    # Replace specific YunoHost variables
+    if test -n "${path_url:-}"
+    then
+        # path_url_slash_less is path_url, or a blank value if path_url is only '/'
+        local path_url_slash_less=${path_url%/}
+        ynh_replace_string --match_string="__PATH__/" --replace_string="$path_url_slash_less/" --target_file="$file"
+        ynh_replace_string --match_string="__PATH__" --replace_string="$path_url" --target_file="$file"
+    fi
+    if test -n "${app:-}"; then
+        ynh_replace_string --match_string="__NAME__" --replace_string="$app" --target_file="$file"
+        ynh_replace_string --match_string="__NAMETOCHANGE__" --replace_string="$app" --target_file="$file"
+        ynh_replace_string --match_string="__USER__" --replace_string="$app" --target_file="$file"
+    fi
+    if test -n "${final_path:-}"; then
+        ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$file"
+    fi
+    if test -n "${YNH_PHP_VERSION:-}"; then
+        ynh_replace_string --match_string="__PHPVERSION__" --replace_string="$YNH_PHP_VERSION" --target_file="$file"
+    fi
+
+    # Replace othes variables
+
+    # List other unique (__ __) variables in $file
+    local uniques_vars=( $(grep -o '__[A-Z0-9_]*__' $file | sort --unique | sed "s@__\([^.]*\)__@\L\1@g" ))
+
+    # Do the replacement
+    local delimit=@
+    for one_var in "${uniques_vars[@]}"
+    do
+        # Validate that one_var is indeed defined
+        test -n "${!one_var:-}" || ynh_die --message="\$$one_var wasn't initialized when trying to replace __${one_var^^}__ in $file"
+        
+        # Escape delimiter in match/replace string
+        match_string="__${one_var^^}__"
+        match_string=${match_string//${delimit}/"\\${delimit}"}
+        replace_string="${!one_var}"
+        replace_string=${replace_string//${delimit}/"\\${delimit}"}
+        
+        # Actually replace (sed is used instead of ynh_replace_string to avoid triggering an epic amount of debug logs)
+        sed --in-place "s${delimit}${match_string}${delimit}${replace_string}${delimit}g" "$file"
+    done
+}