Handle edgecases gracefully

Yunohost templating doesn't like @__NAME____proxy because `reverseproxy__2__proxy` will evaluate __2__ to $2
or @__NAME__@proxy because ynh_replace_vars uses @ as sed delimiter
and ynh_replace_vars really hates multiline blocks... Using actual newlines in string produces a sed unclosed delimiter error,
while using \n gets them double escaped to some weird output that crashed nginx.

conf/nginx.conf

@@ -1,4 +1,4 @@
-location @__NAME____proxy {
+location @__NAME__--proxy {
   proxy_pass        __PROXY_PATH__;
   proxy_redirect    off;
   proxy_set_header  Host $host;
@@ -18,11 +18,9 @@ location @__NAME____proxy {
 }
 
 # Support relative URLs
-location = __PATH_URL__ {
+__REDIRECT_BLOCK__
-    return 302 __PATH_URL__/;
-}
 
-location __PATH_URL__/ {
+location __PATH_URL_SLASH__ {
     alias __ASSETS_PATH__;
-    try_files $uri @__NAME____proxy;
+    try_files $uri @__NAME__--proxy;
 }

scripts/_common.sh

@@ -3,8 +3,6 @@
 #   - plaintext http is only allowed to localhost (to avoid leaking credentials on the network)
 #   - http(s) destination is webroot, no additional component allowed (eg. http://localhost:1234/test is invalid)
 rp_validate_proxy_path() {
-    proxy_path="$1"
-
     if [[ ! $proxy_path =~ '^unix:/' ]]; then
         url_regex='^(http://(127\.[0-9]+\.[0-9]+\.[0-9]+|localhost)|https://.*)(:[0-9]+)?(/.*)?$'
         [[ ! $proxy_path =~ $url_regex ]] && ynh_die \
@@ -24,3 +22,33 @@ rp_validate_proxy_path() {
         fi
     fi
 }
+
+# Verify that the requested assets path is valid
+#   - is a local folder
+#   - ends with a /
+rp_validate_assets_path() {
+    if [[ "$assets_path" = "" ]]; then
+        assets_path="/dev/null"
+    else
+        if [ ! -d "$assets_path" ]; then
+            ynh_die "Requested assets path "$assets_path" does not exist" 1
+        fi
+
+        if [[ ! "$assets_path" =~ /$ ]]; then
+            # Append missing trailing /
+            assets_path=""${assets_path}"/"
+        fi
+    fi
+}
+
+# When the app is not in the webroot (path_url = /), need to add a redirect block
+# to app/ so relative URLs work
+rp_handle_webroot() {
+	if [[ "$path_url" = "/" ]]; then
+		path_url_slash="/"
+		redirect_block="# Not needed for webroot"
+	else
+		path_url_slash=""$path_url"/"
+		redirect_block="location = "$path_url" { return 302 "$path_url_slash"; }"
+	fi
+}

scripts/change_url

@@ -39,6 +39,16 @@ path_url="$new_path"
 domain="$old_domain"
 proxy_path="$(ynh_app_setting_get --app=$app --key=proxy_path)"
 assets_path="$(ynh_app_setting_get --app=$app --key=assets_path)"
+
+# Validate reverse proxy destination
+rp_validate_proxy_path
+
+# Validate assets_path
+rp_validate_assets_path
+
+# Special case for "/" path_url
+rp_handle_webroot
+
 ynh_add_nginx_config
 
 # Move file to new domain if domain has changed

scripts/install

@@ -26,7 +26,6 @@ domain=$YNH_APP_ARG_DOMAIN
 path_url=$YNH_APP_ARG_PATH
 proxy_path=$YNH_APP_ARG_PROXY_PATH
 assets_path=$YNH_APP_ARG_ASSETS_PATH
-[[ "$assets_path" = "" ]] && assets_path="/dev/null"
 is_public=$YNH_APP_ARG_IS_PUBLIC
 
 #=================================================
@@ -37,7 +36,13 @@ is_public=$YNH_APP_ARG_IS_PUBLIC
 ynh_webpath_register --app=$app --domain=$domain --path_url=$path_url
 
 # Validate reverse proxy destination
-rp_validate_proxy_path "$proxy_path"
+rp_validate_proxy_path
+
+# Validate assets_path
+rp_validate_assets_path
+
+# Special case for "/" path_url
+rp_handle_webroot
 
 # Save extra settings
 ynh_app_setting_set --app=$app --key=proxy_path --value=$proxy_path

scripts/upgrade

@@ -39,7 +39,13 @@ ynh_abort_if_errors
 #=================================================
 
 # Validate proxy destination
-rp_validate_proxy_path "$proxy_path"
+rp_validate_proxy_path
+
+# Validate assets_path
+rp_validate_assets_path
+
+# Special case for "/" path_url
+rp_handle_webroot
 
 # Configure nginx
 ynh_script_progression --message="Configuring NGINX web server..." --weight=1