Although you’re not using it exactly (missing space after colon), I’m not sure manual is right.
The dash in front (see your LinuxServer example) in environment passes the rest to Docker.
Reportedly the value after the = becomes the value, so don’t put any extra characters there.
Without dash in front, you make a YAML mapping, with colon space between key and value.
Duplicati manual does both (which is unusual), and I see someone saying you can’t do both:
Parsing of key-value build args in docker-compose not working #2661
you’re trying to use a “map” (
key: value) inside a list (starting with-)
is what I’d say about the Duplicati manual. Regardless, here are some other commentaries:
environment in dockerdocs showing map syntax and array syntax.
Collections in YAML spec talking about dash-space Sequence versus colon-space Mapping.
Environment variable assignment in Docker Compose - colon way says they both work, but
Why does the YAML spec mandate a space after the colon? says why the space is required.
I suppose instead of turning colon to equal, you could turn it to colon space to see if it works.