dns-api-go

• dns-api-go
• Installation
  • Source Installation go <= 1.11
  • Source installation go >= 1.12
• Rate Limiting
• Metrics
• Docker deployment
• Heroku deployment
• Notes
• Hacking
• Production Deployment
• Github Setup

This is a golang port of the old perl-based DNS-API.org site.

• Still allows the same lookups.
• Still has rate-limiting.

Installation

There are two ways to install this project from source, which depend on the version of the go version you're using.

If you don't have a golang environment configured you should be able to download a binary release from the github project.

Source Installation go <= 1.11

If you're using go before 1.11 then the following command should fetch/update overseer, and install it upon your system:

 cd $GOPATH

go get -u -v github.com/skx/dns-api-go

dns-api-go -h

Source installation go >= 1.12

If you're using a more recent version of go (which is highly recommended), you need to clone to a directory which is not present upon your GOPATH:

git clone https://github.com/skx/dns-api-go
cd dns-api-go
go install

Rate Limiting

The server has support for rate-limiting, you can enable this by passing the address of a redis server to the binary:

$ dns-api-go  -redis-server localhost:6379

If this flag is not present then rate-limiting will be disabled. If a client makes too many requests they will be returned a HTTP 429 status-code. Each request made will return a series of headers prefixed with X-RateLimit to allow clients to see how many requests they have made, and have remaining.

Metrics

If you have a graphite-host you can point the environmental-variable METRICS at it. This will then receive metrics:

• Counts of DNS-queries by type.
• Count of success/failure responses.
• System-metrics.
  • via golang-metrics

Docker deployment

If you've cloned this repository you'll notice there is an existing Dockerfile which can be used to build a container. Create your image like so:

skx@frodo ~/go/src/github.com/skx/dns-api-go $ docker build -t dns-api:latest .
Sending build context to Docker daemon  301.1kB
Step 1/10 : FROM alpine
latest: Pulling from library/alpine
..
..
Step 10/10 : ENTRYPOINT ["/root/dns-api-go", "-host","0.0.0.0" , "-port 3001" ]
..
Successfully built

Once you have your container you can launch it like so:

 $ docker run -d -p 9999:9999/tcp dns-api:latest

And test it via:

 $ curl http://localhost:9999/txt/steve.fi

Deploying with a redis image too, to allow rate-limiting, is left as an exercise.

Heroku deployment

Get into the cloned git repository ($GOPATH/src/github.com/skx/dns-api-go) and run:

$ heroku create
$ git push heroku master

Notes

• The main page dynamically includes the domain-name under which it was reached, so we can deploy it automatically even on other sites.
• PTR (reverse-DNS) requests must be submitted in reverse-format, for example:
  • https://dns-api.org/ptr/100.183.9.176.in-addr.arpa.
  • https://dns-api.org/ptr/0.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.3.8.0.6.1.5.1.0.8.f.4.0.1.0.a.2.ip6.arpa.

Hacking

If you alter the template-files beneath data/ you will need to rebuild the static.go file before those changes will become visible. (i.e. They are pre-processed and included inline in our generated binary, rather than being read at run-time.)

You'll need to install the implant tool.

Now you can regenerate the static.go file using that:

 $ implant -input data/ -output static.go

And rebuild the main binary:

 $ go build .

Production Deployment

Surprisingly hosting this service publicly results in a ton of:

• Bandwidth usage.
• Support requests.

The former I tried to handle via cloudflare, but caching DNS data means the service doesn't run in a useful way, as you might expect.

To avoid further support-request and abuse complaints I'm taking the main service dns-api.org offline - unless people pay. The code here will always be open, and available for use though.

The current codebase will serve a "We're retired - unless you pay" message if the file /tmp/retired exists. This will be checked every 30 seconds or so.

API-key support will be added shortly, in #11.

Github Setup

This repository is configured to run tests upon every commit, and when pull-requests are created/updated. The testing is carried out via .github/run-tests.sh which is used by the github-action-tester action.

Releases are automated in a similar fashion via .github/build, and the github-action-publish-binaries action.

from https://github.com/skx/dns-api-go