The use of duplicate YAML merge keys (<<) is now rejected from latest docker-compose spec.
It fails with the following syntax error due to go/yaml/v3 update:
$ docker-compose --project-name myidp -f docker-compose-ref.yml up -d
parsing ./docker-compose-ref.yml: yaml: unmarshal errors:
line 32: mapping key "<<" already defined at line 31
line 55: mapping key "<<" already defined at line 54
goyaml/v3 does not support repeated anchors (due to internal storage using << as key during parsing) but allows use of multi-values in anchors.
The use of duplicate YAML merge keys
(<<)
is now rejected from latest docker-compose spec.It fails with the following syntax error due to go/yaml/v3 update:
References: