The new D() syntax (preview)

This experimental syntax selects providers directly using their entry names in creds.json. The legacy NewRegistrar, NewDnsProvider, and DnsProvider helpers remain supported.

Before:

var REG_GANDI = NewRegistrar("gandi_main");
var DSP_GANDI = NewDnsProvider("gandi_main");

D("example.com", REG_GANDI, DnsProvider(DSP_GANDI),
    A("@", "192.0.2.1")
);

After:

D("example.com",
    REGISTRAR("gandi_main"),
    SERVICE("gandi_main"),
    A("@", "192.0.2.1")
);

REGISTRAR() must immediately follow the domain name. It may also appear in DEFAULTS(); an explicit registrar overrides that default. It accepts only the credential entry name, with no metadata.

SERVICE(name, maxNS, configMetadata) takes an optional nameserver limit and optional metadata. Omit maxNS to use all nameservers, use 0 to use none, or use ALL_NS (equal to -1) when supplying metadata without a limit.

Moving provider metadata

Before:

var DSP_GANDI = NewDnsProvider("gandi_main", {setting: "value"});
var REG_GANDI = NewRegistrar("gandi_main");

D("example.com", REG_GANDI, DnsProvider(DSP_GANDI),
    A("@", "192.0.2.1")
);

After:

D("example.com",
    REGISTRAR("gandi_main"),
    SERVICE("gandi_main", ALL_NS, {setting: "value"}),
    A("@", "192.0.2.1")
);

Metadata may be any JSON value and must follow maxNS. Declare it only once per domain and credential entry. Remove the metadata-bearing NewDnsProvider() declaration when moving metadata to SERVICE(): keeping both is an error even if their values match. Different domains may use different metadata for the same credential entry.

Substitutions

Before	After
D(name, REG, ...)	D(name, REGISTRAR("credEntry"), ...)
DnsProvider(DSP)	SERVICE("credEntry")
DnsProvider(DSP, maxNS)	SERVICE("credEntry", maxNS)
NewDnsProvider("credEntry", metadata)	Move metadata to SERVICE("credEntry", ALL_NS, metadata) for each domain.
NewRegistrar(...) / NewDnsProvider(...) variables	Remove declarations once all their uses are converted.
Experimental PROVIDER("credEntry") and DNS_SERVICE(...) from v5.3.0	Remove the declaration; use the entry name directly with REGISTRAR / SERVICE. Move PROVIDER metadata to each SERVICE.

Leave creds.json unchanged, with provider TYPE values there. Empty or missing credential files still supply the default none and bind entries. These modifiers also work in DEFAULTS() and D_EXTEND(); an explicit REGISTRAR in D_EXTEND() must likewise follow the domain name.

Feedback needed

The v5.3.0 syntax was experimental; PROVIDER and DNS_SERVICE have been replaced. Please test this revision and share feedback.

Compare dnscontrol preview before and after conversion. The output should be the same. Report problems or confusing conversions with your DNSControl version, provider type, and a minimal example without credentials.