Read CE from stdin, or file given by --from option #30
Description
Summary
Introduce the --from option for build and send commands, which a user can use to load CE from a file. The option defaults to -, which means the STDIN. Introduce the --from-format option as well, which defaults to json.
Description
The send and build commands may read the STDIN by default and expect there an event in JSON format.
This creates a nice and clean Unix-friendly flow:
$ kn event build --field a.b.c=foo | kn event send --to event-display
User might change that behavior with a new --from option:
$ kn event build --field a.b.c=foo -o json > event.json
# and later
$ kn event send --from event.json --to event-display
By adding the new --from option to the build sub-command as well, we could remove the event building options from send sub-command and keep nice and easy flow even for complex things (also with detecting tty on stdin/stdout we can automatically use json format instead of human-readable format):
$ kn event build --field a.b.c=foo
| some-ce-modifing-command
| kn event build --field a.d=bar
| kn event send --to pod:event-sender
(The above example will build a basic CE with a.b.c=foo data, pass it to some command in JSON format, then add a.d=bar fields, and finally send it to K8s pod called event-sender)
Original description by @rhuss:
For users who don't know the CE spec very well, it feels strange to specify the payload of an event with
--field event.data=something(also too long). Also we should allow to pick up the date from a file (which is not needed for other fields).So from a UX pov I propose to introduce something like a
--dataand--data-fromoption.