Add process_env provider

[kevbook]

Related Issues

#116

Description

Add process_env provider. Load the environment variables from the parent process as needed.

Example Config

providers:
  process_env:
    env_sync:

    env:
      ETC_DSN:

Checklist

• Tests
• Documentation
• Linting

[kaplanelad]

@kevbook overall looks good! thank you.

I have few main points

1. Move env_sync which get all the env var to disable by default and (less secure) and explain how to enable it.
2. When using env section, the key should be a teller key and the value should be what teller need to pick.
3. Please add test in process_env_test.go

[kaplanelad]

How can I disable to use env_sync which bring me all the environment variable? Should i comment env_sync section?

If yes, I think this should be the default in pkg/wizard_template.go with a comment description that this way that, bring all environment variables is less secure, and it is better to pick only what you need.

WDYT?

[kevbook]

This makes sense.

How do you feel about not having an env_sync: option? Firstly, it's same as carry_env, and secondly, that's not the intention of the provider really. @kaplanelad

[kaplanelad]

I think we can keep it for some usecases. but in default we can commented it out or totally remove it from the default config.
Sound good?

[kaplanelad]

Suggested change

	return nil
	return fmt.Errorf("%s does not implement delete mapping yet", a.Name())

[kaplanelad]

please changed the delete to deleteMapping

[kaplanelad]

Suggested change

	return nil
	return fmt.Errorf("%s does not implement putMapping yet", a.Name())

[kaplanelad]

See my comment in README.md file.

[kaplanelad]

From my understanding, this setup get the value ETC_DSN from env var
for example

$ export ETC_DSN=teller-value
$ teller yaml
ETC_DSN: teller-value

It will be better if we also allow the user to control the key name.
for example
the key under env should be the teller key, and the value is the name of the env key that we want to pick up.
.teller config:
.teller config:

providers:

  process_env:
    env:
       TELLER-KEY: ETC_DSN

Execute teller:

$ export ETC_DSN=teller-value
$ teller yaml
TELLER-KEY:: teller-value

[kevbook]

Yes, it'll use field to be consistent with other providers. So:

process_env:
  env:
    GH_USERNAME: # will use this field
    GH_TOKEN:
      field: TOKEN # will use this field to map to GH_TOKEN

[kaplanelad]

Hey @kevbook,
Just summarize the open issues in this PR:

1. remove env_sync from the config example meaning by default the env_sync will not generate when running teller new. but pkg/providers/process_env.go keep the GetMapping function to support env_sync in some usecases
2. Return errors (not nil) in places that we not implement the logic (see my change in suggestions), you also need to import fmt see your CI results
3. Add process_env_test.go

thanks for your help

[kevbook]

I've updated the code, wizard_template and the README with usage.

I don't really write go, so I am not sure how tests can be written. But I can take a stab at process_env_test.go if you'd like to review the code.

[kaplanelad]

Thanks @kevbook for this PR