AppLauncher Runtime

A Runtime that launches Modules (Modules are a Silverline Framework concept) in containers or processes to run standalone python interpreters or WASM runtimes (instead of directly on WASM micro-processes).

The purpose of this runtime is two-fold: (i) allow container/based applications to be managed by Silverline and (2) prototype different aspects of Silverline runtimes.

Prerequisites

You need to have Python 3, Make, CURL and sha256sum installed. The Makefile creates a Python virtual environment that deals with installing all Python dependencies.

Quick Start

1. Clone the repository.
2. Edit conf/settings.yaml to match your system/preferences (namely the MQTT connection). Here is an example:

# logzero log level: CRITICAL (fewer messages), ERROR, WARNING, INFO, DEBUG (more messages)
loglevel: INFO 

# runtime settings
runtime:
  name: aruntime # runtime name
  #uuid: # leave blank to generate a new uuid; or set a fixed uuid value
  reg_attempts: 0 # 0 = infinite; keeps trying to register
  reg_timeout_seconds: 5 # interval between register attempts
  max_nmodules: 100 # maximum number of modules we support
  realm: realm # realm topic used

# mqtt settings (NOTE: username and password in conf/.secrets.yaml)
mqtt:
  host: broker.com # broker host
  port: 1883 # broker port
  ssl: true # use ssl connection (true/false)

# where/how we keep program files
repository:
  url: https://filestore-host/store # base url where to get download program files

# launcher config; what starts modules 
launcher:
  pipe_stdout: true # stdout/err piped to pubsub (true/false)

Note: If your MQTT broker requires a password:

1. Copy conf/.secrets-example.yaml to conf/.secrets.yaml

2. Edit conf/.secrets.yaml with the username and password. The format is as follows (do not delete the dynaconf_merge: true configuration)

   dynaconf_merge: true # merge with sonf/settings.yaml (required)
   mqtt:
     username: ausername
     password: apassword
   

3. Start the runtime using the run Makefile target: make run

You can install the dependencies manually and run the program directly with Python 3 if you do not want to install Make. Have a look at the Dockerfile to see how this is done.

Application Settings

User-facing settings are defined in conf/settings.yaml. This is what you will want to edit most of the time. Internal settings are kept in the conf/.appsettings.yaml, which will be more relevant if you wish to change internal runtime behavior.

Most settings are related to how modules are started using a module launcher. A module launcher is the implementation of a particular way of starting modules. For example, a module launcher can start python programs inside a container and instantiate a docker client to do so. Different launchers can be implemented. A module launcher factory (LauncherContext) instantiates launchers based on conf/.appsettings.yaml.

Container Images for Launchers

Launchers use custom images to startup modules. The containers folders has the build files for these images. The images created here are then used in the launcher.docker.image setting for the corresponding laucher config in conf/.appsettings.yaml.