fix: erroneous warning about prop overwrite

[craigpastro]

This PR

When adding flagdProperties to the context in preparation for evaluation return a new context so that it doesn't affect any references to the current context.

Without this change:

$ make run
make run-flagd
cd flagd; go run main.go start -f file:../config/samples/example_flags.flagd.json

                 ______   __       ________   _______    ______      
                /_____/\ /_/\     /_______/\ /______/\  /_____/\     
                \::::_\/_\:\ \    \::: _  \ \\::::__\/__\:::_ \ \    
                 \:\/___/\\:\ \    \::(_)  \ \\:\ /____/\\:\ \ \ \   
                  \:::._\/ \:\ \____\:: __  \ \\:\\_  _\/ \:\ \ \ \  
                   \:\ \    \:\/___/\\:.\ \  \ \\:\_\ \ \  \:\/.:| | 
                    \_\/     \_____\/ \__\/\__\/ \_____\/   \____/_/ 

2023-09-18T19:16:39.581-0700    info    cmd/start.go:117        flagd version: dev (HEAD), built at: unknown    {"component": "start"}
2023-09-18T19:16:39.581-0700    info    file/filepath_sync.go:37        Starting filepath sync notifier {"component": "sync", "sync": "filepath"}
2023-09-18T19:16:39.582-0700    info    flag-evaluation/connect_service.go:203  metrics and probes listening at 8014    {"component": "service"}
2023-09-18T19:16:39.582-0700    info    file/filepath_sync.go:66        watching filepath: ../config/samples/example_flags.flagd.json       {"component": "sync", "sync": "filepath"}
2023-09-18T19:16:39.582-0700    info    flag-evaluation/connect_service.go:183  Flag Evaluation listening at [::]:8013  {"component": "service"}
2023-09-18T19:16:41.258-0700    warn    eval/json_evaluator.go:368      overwriting $flagd properties in the context    {"component": "evaluator", "evaluator": "json"}
2023-09-18T19:16:41.259-0700    warn    eval/json_evaluator.go:368      overwriting $flagd properties in the context    {"component": "evaluator", "evaluator": "json"}
2023-09-18T19:16:41.259-0700    warn    eval/legacy_fractional_evaluation.go:35 fractionalEvaluation is deprecated, please use fractional, see: https://flagd.dev/concepts/#migrating-from-legacy-fractionalevaluation
2023-09-18T19:16:41.259-0700    warn    eval/json_evaluator.go:368      overwriting $flagd properties in the context    {"component": "evaluator", "evaluator": "json"}

With this change:

$ make run
make run-flagd
cd flagd; go run main.go start -f file:../config/samples/example_flags.flagd.json

                 ______   __       ________   _______    ______      
                /_____/\ /_/\     /_______/\ /______/\  /_____/\     
                \::::_\/_\:\ \    \::: _  \ \\::::__\/__\:::_ \ \    
                 \:\/___/\\:\ \    \::(_)  \ \\:\ /____/\\:\ \ \ \   
                  \:::._\/ \:\ \____\:: __  \ \\:\\_  _\/ \:\ \ \ \  
                   \:\ \    \:\/___/\\:.\ \  \ \\:\_\ \ \  \:\/.:| | 
                    \_\/     \_____\/ \__\/\__\/ \_____\/   \____/_/ 

2023-09-18T19:20:29.011-0700    info    cmd/start.go:117        flagd version: dev (HEAD), built at: unknown    {"component": "start"}
2023-09-18T19:20:29.012-0700    info    file/filepath_sync.go:37        Starting filepath sync notifier {"component": "sync", "sync": "filepath"}
2023-09-18T19:20:29.013-0700    info    flag-evaluation/connect_service.go:203  metrics and probes listening at 8014    {"component": "service"}
2023-09-18T19:20:29.013-0700    info    flag-evaluation/connect_service.go:183  Flag Evaluation listening at [::]:8013  {"component": "service"}
2023-09-18T19:20:29.014-0700    info    file/filepath_sync.go:66        watching filepath: ../config/samples/example_flags.flagd.json       {"component": "sync", "sync": "filepath"}
2023-09-18T19:20:32.784-0700    warn    eval/legacy_fractional_evaluation.go:35 fractionalEvaluation is deprecated, please use fractional, see: https://flagd.dev/concepts/#migrating-from-legacy-fractionalevaluation

Both logs were triggered by the request in the bug report:

$ curl -X POST "http://localhost:8013/schema.v1.Service/ResolveAll" \
  -d '{"context":{}}' -H "Content-Type: application/json"

Related Issues

Fixes #923.

Notes

Follow-up Tasks

How to test

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[codecov]

Codecov Report

Merging #924 (79fa5dc) into main (e1e7ca0) will decrease coverage by 0.09%.
Report is 1 commits behind head on main.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##             main     #924      +/-   ##
==========================================
- Coverage   72.71%   72.62%   -0.09%     
==========================================
  Files          28       28              
  Lines        2855     2857       +2     
==========================================
- Hits         2076     2075       -1     
- Misses        683      685       +2     
- Partials       96       97       +1     

Files Changed	Coverage Δ
core/pkg/eval/json_evaluator.go	84.69% <80.00%> (-0.93%)	⬇️

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[beeme1mr]

Awesome, thanks! 😃

[toddbaert]

LGTM!