how do nested anchor works in yaml? - yaml

Question

I have the following yaml file, and after following some other anchor tutorials, this looks like it should work, but passing it through some yaml validators, it doesn't:
echo_baz: &echo_baz
- run:
name: echo baz
command: echo baz
jobs:
myjobs:
steps:
- mystep
- run:
name: echo foo
command: echo foo
<<: *echo_baz
- run:
name: echo bar
command: echo bar
using the yamllint tool:
13:7 error syntax error: expected <block end>, but found '?' (syntax)
using http://www.yamllint.com/ gives me
(): did not find expected '-' indicator while parsing a block collection at line 9 column 7
I keep staring and I don't find anything wrong with it.

Answer 1

Looking at the the merge spec, you need to merge into a map, not a sequence, so keep the sequence indicator ("-") in the content part and define the anchor just in terms of its keys.
echo_baz: &echo_baz
run:
name: echo baz
command: echo baz
jobs:
myjobs:
steps:
- mystep
- run:
name: echo foo
command: echo foo
- <<: *echo_baz
- run:
name: echo bar
command: echo bar
Produces:
{
"echo_baz": {
"run": {
"name": "echo baz",
"command": "echo baz"
}
},
"jobs": {
"myjobs": {
"steps": [
"mystep",
{
"run": {
"name": "echo foo",
"command": "echo foo"
}
},
{
"run": {
"name": "echo baz",
"command": "echo baz"
}
},
{
"run": {
"name": "echo bar",
"command": "echo bar"
}
}
]
}
}
}