Channel

Channels are how the proxy sends inputs to and receives outputs from interfaces in the subject system. For example:

channels:
  db:
    type: stream
    command: psql -q $DATABASE_URL
    format:
      type: sql
  api:
    type: exec
    format:
      type: template
      template: curl -sS -X {{method}} $API_BASE_URL{{path}}
  log:
    type: stream
    command: tail -F logs/app.log

#Output

A channel may produce outputs, which could be either:

• interactive, or explicitly caused by one input, e.g. a response to an HTTP request
• ambient, or having ambiguous causality, e.g. an application log line

In either case, every output is added to the log and may be included in a signal.

Interactive outputs always include an input_id foreign key to the input that caused it. Currently, these will only come from exec channels.

Ambient outputs come from stream channels. They may come from channels that take inputs, or from read-only channels.

#Primitive Types

A channel is represented as a discriminated union of primitive types:

• exec - runs each input as a command in a one-off sub-shell
• stream - sends each input to the stdin of a command in a sub-shell

Defines how it will transform an input prior to sending it to the system. If no format is specified, the input's JSON-encoded data will be sent.

There are two supported type: