Managing packages

Managing packages on engine side

To get access to the contents of murano packages, murano-engine queries murano-api. However, it is also possible to specify a list of directories that may contain packages locally. This option is useful to speed up debugging and development of packages and/or to save bandwidth between the API and the engine. If local directories are specified, they are examined before querying the API.

Local package directories

To define a list of directories where the engine would look for package files, set the load_packages_from option in the engine section of the murano.conf configuration file. This option can be set to a comma-separated list of directory paths. Whenever an engine needs to access a package, it would inspect these directories first, before accessing murano-api.

API package cache

If the package was not found in any of the load_packages_from directories, or if none were specified, then murano-engine queries API for package contents. Whenever murano-engine downloads a package from API, it stores and unpacks it locally. The engine uses the directory defined in the packages_cache option in the engine section of the murano.conf configuration file. If it is not used, a temporary directory is created.

The enable_packages_cache option in the same section defines whether the packages would persist on disk or not. When set to False, each package downloaded from API is stored in a separate directory, that will be deleted after the deployment (or action) is over. This means that every deployment or action execution needs to download all the packages it requires, regardless of any packages previously downloaded by the engine. When set to True (default), the engine shares downloaded packages between deployments and action executions. This means that packages persist on disk and have to be eventually deleted. Therefore, whenever the engine requires a package and that package is not found locally, the engine downloads the package. Afterwards, it checks all the previously cached packages with the same FQN and same version. If the cached package is not required by any ongoing deployment, it gets deleted. Otherwise, it stays on disk until a new version is downloaded.


On UNIX-based operating systems, murano uses fcntl for IPC locks that support both shared and exclusive locking. On Windows, msvcrt is used. It does not support shared file locks. Therefore, enabling package cache mechanism under Windows might result in performance decrease, since only one process would be able to use one package at the same time.