hub: fix typo in apisecret lookup

[sanderpick]

Fixes apiSecret key lookup from the viper config.

There are three ways to leverage config values:

1. Flags

hub --apiKey=<key> --apiSecret=<secret> threads ls

2. Config file

api: api.hub.textile.io:443
apiKey: <key>
apiSecret: <secret>
org: <org> // not required

hub threads ls

3. Environment vars

env HUB_APIKEY=<key> HUB_APISECRET=<secret> hub threads ls

Viper lowercases config keys when binding to env vars, e.g., the var for api secret is HUB_APISECRET, not HUB_API_SECRET.

This is confusing because in other program configs we are mapping flags to nested config value. Here's an example from hubd:

"addrApi": {
    Key:      "addr.api",
    DefValue: "/ip4/127.0.0.1/tcp/3006",
},

That will map to an env var of HUB_ADDR_API due to the use of . in Key. We could update the hub CLI to use nested config values, or just provide better document for the env vars. Personally, I like the use of a single level (not nested) config file for hub, but open to opinions.

[asutula]

Thanks for the clarification. That is confusing for sure. I'm surprised viper doesn't have an option to go camelCase to UPPER_SNAKE_CASE.

[sanderpick]

If camelcase mapped to _, you could create an indeterminate situation with a config like the following:

apiSecret: <secret>
api
  secret: <secret>

Both of those entries would map to the env var HUB_API_SECRET, whereas now the first one gets mapped to HUB_APISECRET.

[asutula]

There is a Viper property called EnvKeyReplacer that could be useful here. Need to think about it more.

[sanderpick]

Yep, we're using it: https://github.com/textileio/textile/blob/master/cmd/config.go#L81

The thing is, you can't map camelcase since Viper removes uppercases. We could move to underscores in the config or nested values:

api: ...
api_key: ...
api_secret: ...

or

api:
  multi_addr: ...
  key: ...
  secret: ...