Add support for defining encryption key

[thevilledev]

Adds a CLI flag for defining encryption keys to Consul configuration. This is a non-breaking change as encrypt key uses an empty string as a default value.

[josh-padnick]

Thank you for submitting this PR! As it's been about 4 weeks since we're responding, I'll go ahead and commit these changes to your branch as a PR there so you can easily add them here.

[josh-padnick]

Let's use a var name like encrypt_key so users don't confuse this with a boolean.

[josh-padnick]

My concern with this line is that if we add any additional vars in the future and $encrypt is empty, the Bash function will ignore $encrypt entirely and the function arguments won't be passed to the correct argument position. Therefore, we need a null equivalent in Bash, but since Bash doesn't give us one, we should define a readonly var at the top like this:

readonly EMPTY_VAL="__EMPTY__"

Then we replace

local encrypt=""

with

local encrypt="$EMPTY_VAL"

Finally, we can update the code as follows:

# old
local encrypt_config=""
if [[ "$encrypt" != "" ]]; then
  encrypt_config="\"encrypt\": \"$encrypt\","
fi

...

   "ui": true,
   $encrypt_config,

...

# new
if [[ "$encrypt" == "$EMPTY_VAL" ]]; then
  encrypt=""
fi

...

   "ui": true,
   "encrypt": "$encrypt",

...

[josh-padnick]

Alright, just uploaded the changes and manually validated so we're good now. Merging!