In fact, a Custom Answer Configuration structure does not have any strict rules. Below, we just describe the recommended structure, that, in our opinion, is the best one for a Custom Answer Script. So feel free to use your own approach, experiment and invent.
A typical Custom Answer has three 'sections':
// configuration
const configuration = {
...
};
// functions
const someFunction = () => ... ;
...
function anotherFunction() {
...
};
...
// onRequest
function onRequest(req: IRequest, res: IResponse) {
...
};- configuration - here you place a
configurationobject, it can define providers with some properties, useful sets of data, default properties etc. For example:
const configuration = {
providers: [
{
providerName: ('belugacdn' as TCDNProvider), // CDN Provider alias
cname: 'www.foo.com', // cname to pick as a result
padding: 0, // additional bonus or penalty
countries: (['UA'] as TCountry[]) // countries to apply additional rules
},
{
providerName: ('ovh-cdn' as TCDNProvider),
cname: 'www.bar.com', // in most cases it is your Answer
padding: 0,
continents: (['NA', 'EU'] as TContinent[]) // to apply additional rules
},
{
providerName: ('cloudflare' as TCDNProvider),
cname: 'www.baz.com',
padding: 0,
asns: [12345, 54321] // ASN Numbers to apply additional rules
},
{
providerName: ('fastly' as TCDNProvider),
cname: 'www.foo-bar.com',
padding: 0,
except_countries: (['CN'] as TCountry[]) // Exception for rules
},
{
providerName: ('some-expensive-cdn' as TCDNProvider), // example!
cname: 'www.expensiveanswer.com',
padding: 100, // the penalty - will show what is it for below
except_countries: (['CN'] as TCountry[]) // Exception for rules
},
...
{
providerName: ('does-not-exist' as TCDNProvider)
whatever: 'some value', //
you: ['Y','O','U'],
want_to_have: 1000,
here: { here: 'now' }
}
],
defaultTtl: 20, // The DNS TTL to be applied to DNS responses in seconds.
geoDefault: false,
asnOverride: false, // Set to `true` to enable the asn override feature
defaultProvider: ('fastly' as TCDNProvider),
...
nyNiceProperty: 'anything'
...
}- functions - if you need additional funcs- that is the right place to put those:
/**
* Pick index of lowest number in array of numbers
*/
const getLowest = (array: number[]): number => array.indexOf(Math.min(...array));
...- onRequest - The
MainCustom Answers function we operate with.
function onRequest(req: IRequest, res: IResponse) {
let resultAnswer;
// Logic goes here
...
// Prepare response
res.setCNAMERecord(resultAnswer ? resultAnswer : defaultAnswer);
res.setTTL(defaultTtl);
return;
}As we have mentioned, feel free to implement your own structure and solutions. The only the must is onRequest(req: IRequest, res: IResponse) (Main function) usage.
The Case: A customer uses 2+ CDN providers. A user is directed to the CDN that is available at a given point in time. If both CDNs are available the decision is based on weight. Go to the Use Case
The Case: A customer uses 2+ nodes, monitored by PerfOps Monitoring Feature. A user is directed to the node that has the best Monitor Uptime at a given point in time. If both Monitors are down returns random answer. Go to the Use Case
The Case: A customer uses 2+ CDN providers. Their user is simply balanced to the better performing one. Go to the Use Case
The Case: User has different providers for 2 regions - using 1 CDN for the USA and another CDN for the rest of the world. Go to the Use Case
The Case: User has different CDN provider for each continent, we need to set corresponding answer or fallback if continent is not determined. Go to the Use Case
The Case: One of the most popular cases: select the CDN with the best performance for visitor's country.. Go to the Use Case
The Case: A customer keeps his answers-for-countries information as JSON at some remote source, wants to retrieve it and use for balancing. Go to the Use Case