When DNSControl interacts with a provider, any API keys, credentials, or other configuration parameters required are stored in creds.json. The file contains a set of key/value pairs for each configuration. That is, since a provider can be used multiple times with different credentials, the file contains a section for each set of credentials.

Here's a sample file:

  "cloudflare_tal": {
    "apikey": "REDACTED",
    "apiuser": "REDACTED"
  "inside": {
    "TYPE": "BIND",
    "directory": "inzones",
    "filenameformat": "db_%T%?_%D"
  "hexonet": {
    "TYPE": "HEXONET",
    "apilogin": "$HEXONET_APILOGIN",
    "apipassword": "$HEXONET_APIPASSWORD",
    "debugmode": "$HEXONET_DEBUGMODE",
    "domain": "$HEXONET_DOMAIN"


  • Primary keys: (e.g. cloudflare_tal, inside, hexonet)

    • ...refer to the first parameter in the NewRegistrar() or NewDnsProvider() functions in a dnsconfig.js file.

    • ...may include any printable character except colon (:)

    • Convention: all lower case, usually the name of the provider or the username at the provider or both.

  • Subkeys: (e.g. apikey, apiuser and etc.)

    • ...are whatever the provider specifies.

    • ...can be credentials, secrets, or configuration settings. In the above examples the inside setting is configuration parameters for the BIND provider, not credentials.

    • A missing subkey is not an error. The value is the empty string.

  • Values:

    • ...may include any JSON string value including the empty string.

    • If a subkey starts with $, it is taken as an env variable. In the above example, $HEXONET_APILOGIN would be replaced by the value of the environment variable HEXONET_APILOGIN or the empty string if no such environment variable exists.

New in v3.16

The special subkey "TYPE" is used to indicate the provider type (NONE, CLOUDFLAREAPI, GCLOUD, etc).

Prior to v3.16, the provider type is specified as the second argument to NewRegistrar() and NewDnsProvider() in dnsconfig.js or as a command-line argument in tools such as dnscontrol get-zones.

Starting in v3.16, NewRegistrar(), and NewDnsProvider() no longer require the provider type to be specified. It may be specified for backwards compatibility, but a warning will be generated with a suggestion of how to upgrade to the 4.0 format. Likewise, command-line tools no longer require the provider type to be specified, but for backwards compatibility one may specify - since the parameter is positional.

In 4.0, DNSControl will require the "TYPE" subkey in each creds.json entry. Command line tools will have a backwards-incompatible change to remove the provider-type as a positional argument. Prior to 4.0, the various commands will output warnings and suggestions to avoid compatibility issues during the transition.

Error messages


Message: WARNING: For future compatibility, add this entry creds.json:...

Message: WARNING: For future compatibility, update the ... entry in creds.json by adding:...

These messages indicates that this provider is not mentioned in creds.json. In v4.0 all providers used in dnsconfig.js will require an entry in creds.json.

For a smooth transition, please update your creds.json file now.

Here is the minimal entry required:

  "entryName": {
    "TYPE": "FILL_IN"


Message: INFO: In dnsconfig.js New*(..., ...) can be simplified to New*(...)

This message indicates that the same provider name is specified in dnsconfig.js and creds.json and offers a suggestion for reducing the redundancy.

The fix is to update dnsconfig.js as suggested in the error. Usually this is to simply remove the second parameter to the function.


-var REG_THING = NewRegistrar("thing", "THING");
+var REG_THING = NewRegistrar("thing");
-var REG_THING = NewRegistrar("thing", "THING", { settings: "value" } );
+var REG_THING = NewRegistrar("thing", { settings: "value" } );
-var DNS_MYGANDI = NewDnsProvider("mygandi", "GANDI_V5");
+var DNS_MYGANDI = NewDnsProvider("mygandi");
-var DNS_MYGANDI = NewDnsProvider("mygandi", "GANDI_V5", { settings: "value" } );
+var DNS_MYGANDI = NewDnsProvider("mygandi", { settings: "value" } );

Starting with v3.16 use of an OLD format will trigger warnings with suggestions on how to adopt the NEW format.

Starting with v4.0 support for the OLD format may be reported as an error.

Please adopt the NEW format when your installation has eliminated any use of DNSControl pre-3.16.


Message: ERROR: Mismatch found! creds.json entry ... has ... set to ... but dnsconfig.js specifies New*(..., ...)

This indicates that the provider type specified in creds.json does not match the one specified in dnsconfig.js or on the command line.

The fix is to change one to match the other.


Message: ERROR: creds.json entry ... is missing ...: ...

However no TYPE subkey was found in an entry in creds.json. In 3.16 forward, it is required if new-style NewRegistrar() or NewDnsProvider() was used. In 4.0 this is required.

The fix is to add a TYPE subkey to the creds.json entry.


Message: ERROR: creds.json entry ... has invalid ... value ...

This indicates that the type - was specified in a TYPE value in creds.json. There is no provider named - therefore that is invalid. Perhaps you meant to specify a - on a command-line tool?

The fix is to change the TYPE subkey entry in creds.json from - to a valid service provider identifier, as listed in the service provider list.

Using a different file name

The --creds flag allows you to specify a different file name.

  • Normally the file is read as a JSON file.

  • Do not end the filename with .yaml or .yml as some day we hope to support YAML.

  • Rather than specifying a file, you can specify a program or shell command to be run. The output of the program/command must be valid JSON and will be read the same way.

    • If the name begins with !, the remainder of the name is taken to be a shell command or program to be run.

    • If the name is a file that is executable (chmod +x bit), it is taken as the command to be run (Linux/MacOS only).

    • Exceptions: The x bit is not checked if the filename ends with .yaml, .yml or .json.

Example commands

Following commands would execute a program/script:

dnscontrol preview --creds !./
dnscontrol preview --creds ./
dnscontrol preview --creds
dnscontrol preview --creds !
dnscontrol preview --creds !/some/absolute/path/
dnscontrol preview --creds /some/absolute/path/

Following commands would execute a shell command:

dnscontrol preview --creds '!op inject -i creds.json.tpl'

This example requires the 1Password command-line tool but works with any shell command that returns a properly formatted creds.json. In this case, the 1Password CLI is used to inject the secrets from a 1Password vault, rather than storing them in environment variables. An example of a template file containing Linode and Cloudflare API credentials is available here: creds.json.

  "bind": {
    "TYPE": "BIND"
  "cloudflare": {
    "apitoken": "op://Secrets/Cloudflare DNSControl/credential",
    "accountid": "op://Secrets/Cloudflare DNSControl/username"
  "linode": {
    "TYPE": "LINODE",
    "token": "op://Secrets/Linode DNSControl/credential"

Don't store creds.json in a Git repo!

Do NOT store creds.json (or any secrets!) in a Git repository. That is not secure.

For example, storing the creds.json at the top of this document would be horribly insecure. Anyone with access to your Git repository or the history will know your apiuser is REDACTED. Removing secrets accidentally stored in Git is very difficult because you'll need to rewrite the repo history.

A better way is to use environment variables as in the hexonet example above. Use secure means to distribute the names and values of the environment variables.

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