This is the input:

- hostname: rk089-s11
  compute: false
  control: true
  master: false
- hostname: rk090-s11
  compute: false
  control: true
  master: true

I am trying to get this output:

- hostname: rk089-s11
  role: control
- hostname: rk090-s11
  role: control,master

I tried this:

yq -r '.[] |
[
    {
    "hostname": .hostname,
    "role": (
        ( ( pute == true ) | "compute," ) +
        ( ( .control == true ) | "control," ) +
        ( ( .master == true ) | "master," )
    )
    }
]'|sed 's/,$//'

but I only got this