feat(snap): use updated environment variable injection

[MonicaisHer]

For details on the new scheme for setting environment variables, please refer to edgexfoundry/edgex-go#3986.
Signed-off-by: Mengyi Wang [email protected]

If your build fails due to your commit message not passing the build checks, please review the guidelines here: https://github.com/edgexfoundry/device-gpio/blob/main/.github/Contributing.md

PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?) N/A - they are in the imported module Add tests for snap config options canonical/edgex-snap-testing#53
• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
• I have opened a PR for the related docs change (if not, why?)

Testing Instructions

1. Set up:

snap install edgexfoundry --edge
snap install edgex-device-gpio --channel=edge/pr-25

2. Enable config and set a global config value:

$ snap set edgex-device-gpio config-enabled=true
$ snap set edgex-device-gpio config.service-startupmsg="testing injection"
$ snap start edgex-device-gpio
Started.

$ snap logs -n=all edgex-device-gpio | grep "testing"
2022-04-26T10:49:02+02:00 edgex-device-gpio.device-gpio[1745709]: level=INFO ts=2022-04-26T08:49:02.091648727Z app=device-gpio source=variables.go:352 msg="Variables override of 'Service.StartupMsg' by environment variable: SERVICE_STARTUPMSG=testing injection"
2022-04-26T10:49:02+02:00 edgex-device-gpio.device-gpio[1745709]: level=INFO ts=2022-04-26T08:49:02.102824925Z app=device-gpio source=message.go:55 msg="testing injection"

3. Set a app-specific value:

$ snap set edgex-device-gpio apps.device-gpio.config.service-port=11111
$ snap restart edgex-device-gpio
Restarted.

$ snap logs -n=all edgex-device-gpio | grep "11111"
2022-04-22T11:47:19+02:00 edgex-device-gpio.device-gpio[1257533]: level=INFO ts=2022-04-22T09:47:19.125348038Z app=device-gpio source=variables.go:352 msg="Variables override of 'Service.Port' by environment variable: SERVICE_PORT=11111"
2022-04-22T11:47:19+02:00 edgex-device-gpio.device-gpio[1257533]: level=INFO ts=2022-04-22T09:47:19.126726662Z app=device-gpio source=httpserver.go:123 msg="Web server starting (localhost:11111)"

New Dependency Instructions (If applicable)

[MonicaisHer]

This PR will be ready for review, once the new hook has been tagged and imported by this PR.

[MonicaisHer]

@farshidtz Please review, thank you.

[farshidtz]

Thanks. Works as expected:

$ snap install edgex-device-gpio --channel=edge/pr-25
edgex-device-gpio (edge/pr-25) 2.0.0-dev.2 from Canonical✓ installed

# validate error handling
$ snap set edgex-device-gpio config.service-startupmsg="testing injection"
error: cannot perform the following tasks:
- Run configure hook of "edgex-device-gpio" snap (run hook "configure": 
-----
edgex-device-gpio.configure: could not process options: 'config.' and 'apps.' options are allowed only when config-enabled is true.

WARNING: Setting config-enabled=true will unset existing 'env.' options and ignore future sets!!
-----)

$ snap set edgex-device-gpio config-enabled=true
$ snap set edgex-device-gpio config.service.startupmsg="testing injection"
error: cannot perform the following tasks:
- Run configure hook of "edgex-device-gpio" snap (run hook "configure": edgex-device-gpio.configure: could not process options: error converting config key to environment variable key: config key must not contain dots: service.startupmsg)

Test:

$ snap set edgex-device-gpio config-enabled=true
$ snap set edgex-device-gpio config.service-startupmsg="testing injection"
$ snap start edgex-device-gpio
Started.
farshid:~$ snap logs -n=all edgex-device-gpio | grep "testing"
2022-04-26T11:31:20+02:00 edgex-device-gpio.device-gpio[52529]: level=INFO ts=2022-04-26T09:31:20.979233295Z app=device-gpio source=variables.go:352 msg="Variables override of 'Service.StartupMsg' by environment variable: SERVICE_STARTUPMSG=testing injection"
2022-04-26T11:31:21+02:00 edgex-device-gpio.device-gpio[52529]: level=INFO ts=2022-04-26T09:31:21.003927272Z app=device-gpio source=message.go:55 msg="testing injection"

$ snap set edgex-device-gpio apps.device-gpio.config.service-port=11111
$ snap restart edgex-device-gpio
Restarted.
$ snap logs -n=all edgex-device-gpio | grep "11111"
2022-04-26T11:31:39+02:00 edgex-device-gpio.device-gpio[52702]: level=INFO ts=2022-04-26T09:31:39.678107294Z app=device-gpio source=variables.go:352 msg="Variables override of 'Service.Port' by environment variable: SERVICE_PORT=11111"
2022-04-26T11:31:39+02:00 edgex-device-gpio.device-gpio[52702]: level=INFO ts=2022-04-26T09:31:39.680475727Z app=device-gpio source=httpserver.go:123 msg="Web server starting (localhost:11111)"
2022-04-26T11:31:39+02:00 edgex-device-gpio.device-gpio[52702]: level=ERROR ts=2022-04-26T09:31:39.681485921Z app=device-gpio source=httpserver.go:135 msg="Web server failed: listen tcp 127.0.0.1:11111: bind: address already in use"


$ cat /var/snap/edgex-device-gpio/current/config/device-gpio/res/device-gpio.env 
export SERVICE_STARTUPMSG="testing injection"
export SERVICE_PORT="11111"