feat(snap): add support for env var injection

[farshidtz]

For details on the new scheme for setting environment variables, please refer to edgexfoundry/edgex-go#3986.

Signed-off-by: Farshid Tavakolizadeh [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/app-rfid-llrp-inventory/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?): 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-snmp --channel=edge/pr-160

2. Enable config and set a global config value:

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

$ snap start edgex-device-snmp
Started.

$ snap logs -n=all edgex-device-snmp | grep "testing"
2022-04-26T10:33:16+02:00 edgex-device-snmp.device-snmp[41697]: ++ export 'SERVICE_STARTUPMSG=testing injection'
2022-04-26T10:33:16+02:00 edgex-device-snmp.device-snmp[41697]: ++ SERVICE_STARTUPMSG='testing injection'
2022-04-26T10:33:16+02:00 edgex-device-snmp.device-snmp[41697]: level=INFO ts=2022-04-26T08:33:16.892242677Z app=device-snmp source=variables.go:352 msg="Variables override of 'Service.StartupMsg' by environment variable: SERVICE_STARTUPMSG=testing injection"
2022-04-26T10:33:16+02:00 edgex-device-snmp.device-snmp[41697]: level=INFO ts=2022-04-26T08:33:16.942854875Z app=device-snmp source=message.go:55 msg="testing injection"

3. Set a app-specific value:

$ snap set edgex-device-snmp apps.device-snmp.config.service-port=11111

$ snap restart edgex-device-snmp
Restarted.

$ snap logs -n=all edgex-device-snmp | grep "11111"
2022-04-26T10:14:12+02:00 edgex-device-snmp.device-snmp[33387]: ++ export SERVICE_PORT=11111
2022-04-26T10:14:12+02:00 edgex-device-snmp.device-snmp[33387]: ++ SERVICE_PORT=11111
2022-04-26T10:14:12+02:00 edgex-device-snmp.device-snmp[33387]: level=INFO ts=2022-04-26T08:14:12.464790178Z app=device-snmp source=variables.go:352 msg="Variables override of 'Service.Port' by environment variable: SERVICE_PORT=11111"
2022-04-26T10:14:12+02:00 edgex-device-snmp.device-snmp[33387]: level=INFO ts=2022-04-26T08:14:12.515347747Z app=device-snmp source=httpserver.go:123 msg="Web server starting (localhost:11111)"

New Dependency Instructions (If applicable)

[codecov-commenter]

Codecov Report

Merging #160 (982e461) into main (6b046bf) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##            main    #160   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files          2       2           
  Lines        200     200           
=====================================
  Misses       200     200           

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[farshidtz]

@MonicaisHer please review.

[MonicaisHer]

@farshidtz Thank you. It works as expected.

Validate error handling:

$ snap set edgex-device-snmp config.service-startupmsg="testing injection"
error: cannot perform the following tasks:
- Run configure hook of "edgex-device-snmp" snap (run hook "configure": 
-----
edgex-device-snmp.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-snmp config-enabled=true
$ snap set edgex-device-snmp config.service.startupmsg="testing injection"
error: cannot perform the following tasks:
- Run configure hook of "edgex-device-snmp" snap (run hook "configure": edgex-device-snmp.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-snmp config.service-startupmsg="testing injection"
$ snap start edgex-device-snmp
Started.

$ snap logs -n=all edgex-device-snmp | grep "testing"
2022-04-26T11:47:03+02:00 edgex-device-snmp.device-snmp[1762787]: ++ export 'SERVICE_STARTUPMSG=testing injection'
2022-04-26T11:47:03+02:00 edgex-device-snmp.device-snmp[1762787]: ++ SERVICE_STARTUPMSG='testing injection'
2022-04-26T11:47:04+02:00 edgex-device-snmp.device-snmp[1762787]: level=INFO ts=2022-04-26T09:47:04.323706439Z app=device-snmp source=variables.go:352 msg="Variables override of 'Service.StartupMsg' by environment variable: SERVICE_STARTUPMSG=testing injection"
2022-04-26T11:47:04+02:00 edgex-device-snmp.device-snmp[1762787]: level=INFO ts=2022-04-26T09:47:04.36831019Z app=device-snmp source=message.go:55 msg="testing injection"

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

$ snap logs -n=all edgex-device-snmp | grep "11111"
2022-04-26T11:47:39+02:00 edgex-device-snmp.device-snmp[1763017]: ++ export SERVICE_PORT=11111
2022-04-26T11:47:39+02:00 edgex-device-snmp.device-snmp[1763017]: ++ SERVICE_PORT=11111
2022-04-26T11:47:39+02:00 edgex-device-snmp.device-snmp[1763017]: level=INFO ts=2022-04-26T09:47:39.10975401Z app=device-snmp source=variables.go:352 msg="Variables override of 'Service.Port' by environment variable: SERVICE_PORT=11111"
2022-04-26T11:47:39+02:00 edgex-device-snmp.device-snmp[1763017]: level=INFO ts=2022-04-26T09:47:39.135056084Z app=device-snmp source=httpserver.go:123 msg="Web server starting (localhost:11111)"