Writing a new DNS provider is a relatively straightforward process. You essentially need to implement the providers.DNSServiceProvider interface. and the system takes care of the rest.
Please do note that if you submit a new provider you will be assigned bugs related to the provider in the future (unless you designate someone else as the maintainer). More details here.
I’ll ignore all the small stuff and get to the point.
GetDomainCorrections() function is the workhorse
of the provider. It is what gets called by
How does a provider’s
GetDomainCorrections() function work?
The goal of
GetDomainCorrections() is to return a list of
corrections. Each correction is a text string describing the change
(“Delete CNAME record foo”) and a function that, if called, will
make the change (i.e. call the API and delete record foo). Preview
mode simply prints the text strings.
dnscontrol push prints the
strings and calls the functions. Because of how Go’s functions work,
the function will have everything it needs to make the change.
Pretty cool, eh?
So how does
First, some terminology: The DNS records specified in the dnsconfig.js file are called the “desired” records. The DNS records stored at the DNS service provider are called the “existing” records.
Every provider does the same basic process. The function
GetDomainCorrections() is called with a list of the desired DNS
dc.Records). It then contacts the provider’s API and
gathers the existing records. It converts the existing records into
a list of
Now that it has the desired and existing records in the appropriate
differ.IncrementalDiff(existingRecords) is called and
does all the hard work of understanding the DNS records and figuring
out what changes need to be made. It generates lists of adds,
deletes, and changes.
GetDomainCorrections() then generates the list of
and returns. DNSControl takes care of the rest.
So, what does all this mean?
It basically means that writing a provider is as simple as writing
code that (1) downloads the existing records, (2) converts each
models.RecordConfig, (3) write functions that perform
adds, changes, and deletions.
If you are new to Go, there are plenty of providers you can copy from. In fact, many non-Go programmers have learned Go by contributing to DNSControl.
Oh, and what if the API simply requires that the entire zonefile be uploaded
every time? We still generate the text descriptions of the changes (so that
dnscontrol preview looks nice) but the functions are just no-ops, except
for one that uploads the new zonefile.
Now that you understand the general process, here are the details.
A provider can be a DnsProvider, a Registrar, or both. We recommend you write the DnsProvider first, release it, and then write the Registrar if needed.
If you have any questions, please discuss them in the Github issue related to the request for this provider. Please let us know what was confusing so we can update this document with advice for future authors (or even better, update this document yourself.)
Pick a similar provider as your base. Providers basically fall into three general categories:
All providers use the “diff” module to detect differences. It takes two zones and returns records that are unchanged, created, deleted, and modified. The zone providers use the information to print a human-readable list of what is being changed, but upload the entire new zone. The incremental providers use the differences to update individual records or recordsets.
Create a directory for the provider called
name is all lowercase and represents the commonly-used name for
The main driver should be called
The API abstraction is usually in a separate file (often called
Edit providers/_all/all.go. Add the provider list so DNSControl knows it exists.
Implement all the calls in providers.DNSServiceProvider interface..
GetDomainCorrections is a bit interesting. It returns
a list of corrections to be made. These are in the form of functions
that DNSControl can call to actually make the corrections.
Make sure the existing unit tests work. Add unit tests for any complex algorithms in the new code.
Run the unit tests with this command:
cd dnscontrol go test ./...
This is the most important kind of testing when adding a new provider. Integration tests use a test account and a real domain.
For example, this will run the tests using BIND:
cd dnscontrol/integrationTest go test -v -verbose -provider BIND
(BIND is a good place to start since it doesn’t require any API keys.)
This will run the tests on Amazon AWS Route53:
export R53_DOMAIN=dnscontroltest-r53.com # Use a test domain. export R53_KEY_ID='CHANGE_TO_THE_ID' export R53_KEY='CHANGE_TO_THE_KEY' go test -v -verbose -provider ROUTE53
docs/_providers/PROVIDERNAME.md: Use one of the other files in that directory as a base.
At this point you can submit a PR.
Actually you can submit the PR even earlier if you just want feedback, input, or have questions. This is just a good stopping place to submit a PR if you haven’t already.
Some DNS providers have features that others do not. For example some support the SRV record. A provider announces what it can do using the capabilities system.
If a provider doesn’t advertise a particular capability, the integration test system skips the appropriate tests. Therefore you might want to initially develop the provider with no particular capabilities advertised and code until all the integration tests work. Then enable capabilities one at a time to finish off the project.
Don’t feel obligated to implement everything at once. In fact, we’d prefer a few small PRs than one big one. Focus on getting the basic provider working well before adding these extras.
Operational features have names like
providers.CanUseAlias. The list of optional “capabilities” are
in the file
dnscontrol/providers/providers.go (look for
Capabilities are processed early by DNSControl. For example if a provider doesn’t support SRV records, DNSControl will error out when parsing dnscontrol.js rather than waiting until the API fails at the very end.
Enable optional capabilities in the nameProvider.go file and run the integration tests to see what works and what doesn’t. Fix any bugs and repeat, repeat, repeat until you have all the capabilities you want to implement.
FYI: If a provider’s capabilities changes, run
go generate to update
Run “go vet” and “golint” and clean up any errors found.
go vet ./... golint ./...
go vet from the newest release of Go.
If golint isn’t installed on your machine:
go get -u golang.org/x/lint/golint
See docs/release-engineering.md for tips about managing modules and checking for outdated dependencies.
Here are some last-minute things to check before you submit your PR.