Issues with formats other than YAML

[prarit]

I've been trying a few different config formats to see how they differ. For example,

package main 
import (
    "fmt"
    "log"

    "github.com/spf13/viper"
)     

func main() {
    viper.SetConfigType("hcl")

    viper.AddConfigPath(".")
    viper.SetConfigName("example.hcl")

    err := viper.ReadInConfig()
    if err != nil {
            log.Fatal(err)
    }

    fmt.Println("host.address =", viper.GetString("host.address"))
    fmt.Println("host.port =", viper.GetString("host.port"))
    viper.Reset()
}

with config file ./example.hcl as

"host" = {
 "address" = "localhost"
 "port" = "5799" 
}   

The output is empty:

host.address = 
host.port =

If I try this with ./example.yaml (and make the two hcl to yaml changes in the code) everything works:

{
"host": {
    "address": "localhost",
    "port": 5799
  }
}

Is this a bug or is there some nature of using HCL/TOML/etc. that I'm missing? FWIW only YAML appears to work properly when embedded this way. If I use a simple HCL file of (and, again, make appropriate code changes)

 "address" = "localhost"
 "port" = "5799" 

then the address and port values are output correctly.

[prarit]

FWIW. A TOML file also fails:

[host]
   address = localhost
   port = 5799

[sagikazarmark]

First things first: viper.SetConfigName("example.hcl") is not entirely correct. It should be viper.SetConfigName("example"). If you want to set a file path directly, use SetConfigFile.

To be honest, I'm not really familiar with HCL (other than using it in terraform), but looking at your example, it seems your snippet is translated into this:

map[string]interface{}{
    "host":[]map[string]interface{}{
        map[string]interface{}{
            "address": "localhost",
            "port": 5799,
        },
    },
}

Notice that the value of host is actually a slice (as also pointed out in the linked issue). This seems to be HCL specific. I'm not entirely sure how to fix this. The test cases are also not very good for HCL. :\

You can get the original value using log.Print(viper.Get("host").([]map[string]interface{})[0]["address"]), but that's just awful.

I'd recommend choosing another format, until it's sorted out.

As for TOML: your example is invalid: you need to quote strings:

[host]
address = "localhost"
port = 5799

Also, make sure to properly set the config name and type. TOML works just fine for me with the above example.

Let me know if it helps.

[AutomationD]

@spf13 hey, I wanted to check-in and see if this is simply a lower-priority item, or there is some fundamental issue that prevents this to get fixed?

Thanks!

[sagikazarmark]

@AutomationD please see my answer above.

TL;DR HCL (or at least the implementation) is fundamentally broken and will be removed from Viper 2.

[AutomationD]

@sagikazarmark Hey, thanks for your response. So I'm curious what is stopping us to ensure the traversal is done considering the extra slice in-between maps?

[sagikazarmark]

I wouldn't want to add that kind of behavior to the config lookup, just to handle the quirks of HCL when it's not actually a popular option.

Once encoding/decoding is properly factored out from the Viper core, I don't mind doing any additional steps to make up for HCL's weird behavior. See #1167.

[AutomationD]

Good point. Thanks! What would be the top preferred formats to use with viper right now?

[sagikazarmark]

Yaml or json both work quite well.

[AutomationD]

Where do you see TOML in this list? would it be kept as a first-class citizen?

[sagikazarmark]

I think so.