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Allow older clients to download old maps data from Backblaze archive

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Signed-off-by: Alexander Borsuk <me@alex.bio>
This commit is contained in:
Alexander Borsuk 2021-11-11 13:47:27 +01:00
parent 773dceb447
commit 0c8b818eb1
1 changed files with 45 additions and 18 deletions
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63
src/index.ts
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@ -1,9 +1,39 @@
export {};
export { };
const SERVER = {
backblaze: 'https://cdn-us1.organicmaps.app/', // BackBlaze + CloudFlare (US-West) unmetered.
uk1: 'https://cdn-uk1.organicmaps.app/', // Mythic Beasts VPS (London, UK) 200TB/mo.
nl1: 'https://cdn-nl1.organicmaps.app/', // Mythic Beasts VPS (Amsterdam, NL) 200TB/mo.
planet: 'https://cdn.organicmaps.app/', // Hetzner BareMetal (Falkenstein, Germany) unmetered
pl1: 'https://cdn-pl1.organicmaps.app/', // OVH VPS (Warsaw, Poland) unmetered
fi1: 'https://cdn-fi1.organicmaps.app/', // Hetzner Cloud (Helsinki, Finland), 20TB/mo
de1: 'https://cdn-eu2.organicmaps.app/', // Hetzner Cloud (Falkenstein, Germany), 20TB/mo
};
// Main entry point.
addEventListener('fetch', (event) => {
event.respondWith(handleRequest(event.request).catch((err) => new Response(err.stack, { status: 500 })));
});
// Starting from September release, our clients have 'X-OM-DataVersion' header with the value
// of their current maps data version, for example, "211022" (October 22, 2021).
// It is lowercased by Cloudflare.
// Returns 0 if data version is absent or invalid, or a valid integer version.
function extractDataVersion(request: Request): Number {
const strDataVersion = request.headers.get('x-om-dataversion');
if (strDataVersion) {
const dataVersion = parseInt(strDataVersion);
if (!Number.isNaN(dataVersion) && dataVersion >= 210000 && dataVersion <= 500000)
return dataVersion;
}
return 0;
}
// TODO: Implement automated version checks from this metaserver script.
// It should check by cron if actual files are really available on all servers.
const LAST_AVAILABLE_VERSION = 210825;
const BEFORE_LAST_AVAILABLE_VERSION = 211002;
async function handleRequest(request: Request) {
const { pathname } = new URL(request.url);
@ -12,25 +42,22 @@ async function handleRequest(request: Request) {
case '/resources': // Public for resources.
case '/servers': { // Private for map files.
let servers;
switch (request.cf?.continent) {
const dataVersion = extractDataVersion(request);
if (dataVersion < LAST_AVAILABLE_VERSION) {
// Old maps versions are available only on BackBlaze.
servers = [SERVER.backblaze];
} else if (dataVersion < BEFORE_LAST_AVAILABLE_VERSION) {
// Some servers have one additional version available.
servers = [SERVER.uk1, SERVER.nl1, SERVER.backblaze];
} else switch (request.cf?.continent) {
// See https://developers.cloudflare.com/firewall/cf-firewall-language/fields for a list of all continents.
case 'NA': // North America
servers = [
'https://cdn-us1.organicmaps.app/', // BackBlaze US-West + CF, unmetered
'https://cdn-uk1.organicmaps.app/', // Mythic Beasts, 200TB
'https://cdn-nl1.organicmaps.app/', // Mythic Beasts, 200TB
'https://cdn.organicmaps.app/', // Hetzner BareMetal DE unmetered
];
case 'SA': // South America
case 'OC': // Oceania
servers = [SERVER.backblaze, SERVER.uk1, SERVER.nl1, SERVER.planet];
break;
default:
// Everything else
servers = [
'https://cdn-pl1.organicmaps.app/', // OVH PL, unmetered
'https://cdn-fi1.organicmaps.app/', // Hetzner Cloud FI, 20TB
'https://cdn-uk1.organicmaps.app/', // Mythic Beasts, 200TB
'https://cdn-nl1.organicmaps.app/', // Mythic Beasts, 200TB
'https://cdn-eu2.organicmaps.app/', // Hetzner Cloud DE, 20TB
'https://cdn.organicmaps.app/', // Hetzner BareMetal DE unmetered
];
default: // Every other continent + Tor networks.
servers = [SERVER.planet, SERVER.pl1, SERVER.uk1, SERVER.nl1, SERVER.fi1, SERVER.de1];
}
return new Response(JSON.stringify(servers), {
headers: { 'Content-Type': 'application/json' },