I'm running into what feels like a weird issue. Brief background: I have a tool that loads config info via YAML and hands the config to a variety of plugins, whose YAML layouts differ. As such, I find myself using map[string]interface{} in the YAML Unmarshal-ing. But when one of the map values is a slice, it appears to get mangled and refuse to type convert back.

Here's a slimmed down example:

package main

import (
    "fmt"

    "gopkg.in/yaml.v2"
)

var data = `
data:
- foo
- bar
- baz
`

type doc struct {
    Data interface{}
}

func main() {
    d := doc{}
    err := yaml.Unmarshal([]byte(data), &d)
    if err != nil {
        panic(err)
    }

    data, ok := d.Data.([]string)
    if !ok {
        fmt.Println("Things are not ok")
        return
    }

    fmt.Printf("%+v\n", data)
    fmt.Printf("%+v\n", data[0])
}

Which returns the following:

❯ go run main.go
Things are not ok

Am I missing some adjustment when Unmarshalling that's causing my YAML list to be mangled?