#9970 feature: Support Docker-like environment variable interpolation Issue created by edgarrmondragon Feature scope CLI (options, error messages, logging, etc.) Description This would allow users and plugin developers submitting a new plugin to the Hub to use an environment variable as the default value if present, without forcing them to always set it. From the Docker docs:

Interpolation syntax

Interpolation is applied for unquoted and double-quoted values. Both braced (${VAR}) and unbraced ($VAR) expressions are supported.

For braced expressions, the following formats are supported:

• Direct substitution

•

${VAR}

-> value of

VAR

• Default value

•

${VAR:-default}

-> value of

VAR

if set and non-empty, otherwise

default

•

${VAR-default}

-> value of VAR if set, otherwise

default

• Required value

•

${VAR:?error}

-> value of

VAR

if set and non-empty, otherwise exit with error

•

${VAR?error}

-> value of

VAR

if set, otherwise exit with error

• Alternative value

•

${VAR:+replacement}

->

replacement

if

VAR

is set and non-empty, otherwise empty

•

${VAR+replacement}

->

replacement

if VAR is set, otherwise empty

For more information, see Interpolation in the Compose Specification.

meltano/meltano