This field cannot be set - Terraform custom provider - terraform

Question

I am newbie for creating the custom provider to terraform. I am trying to get some values from tf files. But I am gettings some errors.
Error: "tags": this field cannot be set
Here is my sample code
main.tf
# This is required for Terraform 0.13+
terraform {
required_providers {
example = {
version = "~> 1.0.0"
source = "example.com/sd/example"
}
}
}
resource "example_server" "my-server" {
address = "1.2.3.4"
sensitive_map {
key = "foo"
value = "dddd"
}
tags = {
env = "development"
name = "example tag"
}
}
Here is my resource provider file.
func resourceServer() *schema.Resource {
return &schema.Resource{
Create: resourceServerCreate,
Read: resourceServerRead,
Update: resourceServerUpdate,
Delete: resourceServerDelete,
Schema: map[string]*schema.Schema{
"address": &schema.Schema{
Type: schema.TypeString,
Required: true,
},
"tags": {
Type: schema.TypeMap,
Elem: &schema.Schema{
Type: schema.TypeString,
},
},
},
}
}
func resourceServerCreate(d *schema.ResourceData, m interface{}) error {
logs.Info("Creating word")
address := d.Get("address").(string)
// tags := d.Get("tags").(interface{})
// keyval := tags.(map[string]interface{})
d.SetId(address)
log.Printf("[WARN] No Server found: %s", d.Id())
f, err := os.OpenFile("/home/sdfd/Desktop/123.txt", os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
if err != nil {
panic(err)
}
defer f.Close()
tmps := d.Get("tags").(map[string]interface{})
address += tmps["env"].(string)
address += tmps["name"].(string)
if _, err = f.WriteString(address); err != nil {
panic(err)
}
return nil
}
I am not able to find the exact error. Logs also not printing in the terminal. Could anyone help to resolve this problem?
Thanks in advance

Answer 1

A schema.Schema object used to define an attribute or nested block must always have at least one of Required: true, Optional: true, or Computed: true set.
Required and Optional both indicate that the argument is one that can be set in the configuration. Since you've set neither of them for tags, the SDK is rejecting attempts to set tags in the configuration.
Computed indicates that the provider itself will be the one to decide the value. This can either be used alone or in conjunction with Optional. If you set both Optional and Computed then that means that the provider will provide its own value if (and only if) the user leaves it unset in the configuration.
Since it seems like your intent here is for tags to be set by the user in the configuration, I think the answer here would be to mark it as Optional:
"tags": {
Type: schema.TypeMap,
Elem: &schema.Schema{
Type: schema.TypeString,
},
Optional: true,
},
The above means that it may be set in the configuration, but the user isn't required to set it. If the user doesn't set it then your provider code will see it as the built-in default placeholder value for a map, which is an empty map.