⚡ Executa

Execution engine for executable documents

Install

npm install --global @stencila/executa

Use

All configuration options can be set, in descending order of priority, by:

• a command line argument e.g. --<value> <value>
• an environment variable prefixed with EXECUTA_ e.g. EXECUTA_<option>=<value>
• a .json or .ini configuration file, set using the --config option, or .executarc by default

Name	Description	Type	Validators	Default
debug	Display debug log data?	boolean		false
stdio	Start a stdio server.	boolean		false
vsock	Start a vsock server.1	`boolean	number`
tcp	Start a TCP server.2	`boolean	string`	pattern: `/^((tcp?://)?([^:/]+)(:(d+))?(/(.+))?)
http	Start a HTTP server.3	`boolean	string`	pattern: `/^((https?://)?([^:/]+)(:(d+))?(/(.+))?)
ws	Start a WebSocket server.4	`boolean	string`	pattern: `/^((wss?://)?([^:/]+)(:(d+))?(/(.+))?)
timeout	Duration of inactivity after which the process should stop.5	number		0
timelimit	Maximum duration for the process.6	number		0
peers	List of peer addresses.7	string[]		["stdio://*"]
queueLength	Maximum length of the request queue.8	number	minimum: 0	1000
queueInterval	Interval between attempts to reduce request queue.9	number	exclusiveMinimum: 0	1
queueStale	Duration after which a request is removed from queue.10	number	exclusiveMinimum: 0	3600

1. If a number, it will be used as the port number. If true, the default Vsock port 6000 will be used.
2. If a string, it will be parsed and used as the address of the TCP server. If true, the default TCP address tcp://127.0.0.1:7000 will be used.
3. If a string, it will be parsed and used as the address of the HTTP server. If true, the default HTTP address http://127.0.0.1:8000 will be used.
4. If a string, it will be parsed and used as the address of the WebSocket server. If true, the default WebSocket address ws://127.0.0.1:9000 will be used.
5. Seconds. Zero means no timeout.
6. Seconds. Zero means no time limit.
7. Each string in this list is parsed as an address to a peer executor. e.g. https://123.45.67.89/, docker://image
8. When queue reaches this length, subsequent requests will fail with an error response to client.
9. Seconds.
10. Seconds. Client will be notified when a request is removed.

Develop

Testing with the REPL

There is an interactive REPL that can be used with the both query and execute CLI commands e.g.

npm run cli -- execute --repl --debug

Testing in the browser

1. Serve Executa over HTTP (to provide static HTML) and WebSocket (to provide JSON RPC):

   npm run cli:dev -- serve --http --ws

The :dev suffix to cli uses ts-node-dev which will restart the process when any source files change.

2. Visit http://localhost:8000 in your browser and play around with the <stencila-code-chunk> WebComponent that is connected to the Executa WebSocket that you just started.

Debug inspecting

There is a NPM script, cli:debug, that can be useful for debugging the CLI, for example, from within VSCode (which will auto attach to the Node process), e.g.

npm run cli:debug -- serve --http

The :debug suffix to cli enables the Node debug inspector so you can use your favorite IDE to attach to the CLI and step through the code.

FAQ

Why is @types/ws a production dependency?

This package has several dependents e.g @stencila/basha. If @types/ws is not installed as a production dependency, when you try to build dependent packages, you get the error "Cannot find type definition file for 'ws'.". By having it as a production dependency here, each dependent package does not have to install it as a development dependency.