Gokart Feature Discussion: What's read_environ()

Discussed in OSS gokart
https://github.com/m3dev/gokart/pull/272

Transcript

1. Gokart Feature Discussion
   What's read_environ()
   

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2. Let’s use luigi-style ${envvar}
   

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3. OK. But why gokart works without special interpolation???
   

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4. Default values of ALL sections!!!
   

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5. So？
   (cfg.ini)
   [foo]
   BAR=%(ENV)s
   [TaskOnKart]
   [foo]
   BAR=%(ENV)s
   ENV=foo
   [TaskOnKart]
   ENV=foo
   [foo]
   BAR=foo
   ENV=foo
   [TaskOnKart]
   ENV=foo
   basic variable
   interpolation
   envvars to
   default
   ENV=foo CONFIG=cfg.ini
   python main.py
   

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6. Problems
   Sideeffect
   ● [TaskOnKart] ENV=foo is not intended arguments
   ○ Creating [s3] section triggers errors by inserting ALL envvars from your env to s3client
   ● Although some products use this sideeffect (backward compatibility problem)
   ○
   COMMON_PARAM=3 python main.py
   [TaskA]
   a=1
   [TaskB]
   b=2
   TaskA(a=1, common_param=3)
   TaskB(b=2, common_param=3)
   

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7. Conclusion
   Though this breaks backward compatibility, this much less readable.
   So let’s reconstruct this.
   How much backward compatibility will be broken?
   ● poor: retain current
   ● better: not default, but %(envvar)s works
   ○ current PR
   ● best: just use ${envvar}
   

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