bash associative array in .yml definition

[zrml]

it might be totally my fault,
but a couple of fairly obvious syntax to retrieve a passed-in array is failing with an "Invalid interpolation format" error.

In the doc it says that arrays are supported. In my case, being tricky, I need to make use of the associative array (bash > v4)

Any hope for me?
thank you

[aanand]

Arrays are not supported. Which document are you looking at?

[zrml]

https://docs.docker.com/compose/compose-file/

search for "array"

Thanks @aanand
that's a great shame and forces me in a very uncomfortable position in my company...

[zrml]

thinking about it: you have access to the shell environment so you can see it all, I guess:
Can I ask for an enhancement request?

[aanand]

OK, I think we're talking about different things. What that document states is that YAML values for build.args, environment and labels can be either arrays or dictionaries. That means that you can specify a set of e.g. environment variables for the container in two ways:

# as an array
environment:
  - FOO=hello
  - BAR=world

# as a dictionary
environment:
  FOO: hello
  BAR: world

Environment variable interpolation, however, necessarily deals with strings, because environment variables can only be strings. This is true of all command-line tools, not just Compose. For example, env can't see Bash variables that aren't strings:

$ FOO=hello
$ export FOO
$ env | grep FOO
FOO=hello

$ FOO=(1 2 3)
$ export FOO
$ env | grep FOO
(no output)

It's therefore not possible for Compose to understand Bash associative arrays.

[zrml]

1. OK, got the interpretation of array in the doc: it refers to the YML definition. Thanks
2. you stand correct that arrays (even normal integer based, like your example) are not exported.
   we'll have to wait for bash v.5 :-)
   thank you @aanand