move cache to lua to minimise number of requests

docker/nginx/conf.d/server.dnslink.conf

@@ -1,3 +1,5 @@
+lua_shared_dict dnslink 10m;
+
 server {
     listen 80 default_server;
     listen [::]:80 default_server;

docker/nginx/conf.d/server/server.dnslink

@@ -5,6 +5,10 @@ location / {
     set $path $uri;
 
     rewrite_by_lua_block {
+        local cache = ngx.shared.dnslink
+        local cache_value = cache:get(ngx.var.host)
+
+        if cache_value == nil then
             local httpc = require("resty.http").new()
 
             -- 10.10.10.55 points to dnslink-api service (alias not available when using resty-http)
@@ -27,6 +31,12 @@ location / {
                 ngx.var.skylink = res.body
             end
 
+            local cache_ttl = 300 -- 5 minutes cache expire time
+            cache:set(ngx.var.host, ngx.var.skylink, cache_ttl)
+        else
+            ngx.var.skylink = cache_value
+        end
+
         ngx.var.skylink_v1 = ngx.var.skylink
         ngx.var.skylink_v2 = ngx.var.skylink
     }

packages/dnslink-api/package.json

@@ -5,8 +5,7 @@
   "license": "SEE LICENSE IN LICENSE.md",
   "dependencies": {
     "express": "^4.17.1",
-    "is-valid-domain": "^0.1.2",
+    "is-valid-domain": "^0.1.2"
-    "node-cache": "^5.1.2"
   },
   "devDependencies": {
     "prettier": "^2.4.1"

packages/dnslink-api/src/index.js

@@ -1,14 +1,11 @@
 const dns = require("dns");
 const express = require("express");
-const NodeCache = require("node-cache");
 const isValidDomain = require("is-valid-domain");
 
 const host = process.env.DNSLINK_API_HOSTNAME || "0.0.0.0";
 const port = Number(process.env.DNSLINK_API_PORT) || 3100;
-const cacheTTL = Number(process.env.DNSLINK_API_CACHE_TTL) || 300; // default to 5 minutes
 
 const server = express();
-const cache = new NodeCache({ stdTTL: cacheTTL });
 
 const dnslinkNamespace = "skynet-ns";
 const dnslinkRegExp = new RegExp(`^dnslink=/${dnslinkNamespace}/.+$`);
@@ -23,10 +20,6 @@ server.get("/dnslink/:name", async (req, res) => {
     return failure(`"${req.params.name}" is not a valid domain`);
   }
 
-  if (cache.has(req.params.name)) {
-    return success(cache.get(req.params.name));
-  }
-
   const lookup = `_dnslink.${req.params.name}`;
 
   dns.resolveTxt(lookup, (error, records) => {
@@ -65,8 +58,6 @@ server.get("/dnslink/:name", async (req, res) => {
 
     const skylink = matchSkylink[1];
 
-    cache.set(req.params.name, skylink);
-
     console.log(`${req.params.name} => ${skylink}`);
 
     return success(skylink);

packages/dnslink-api/yarn.lock

@@ -36,11 +36,6 @@ bytes@3.1.0:
   resolved "https://registry.yarnpkg.com/bytes/-/bytes-3.1.0.tgz#f6cf7933a360e0588fa9fde85651cdc7f805d1f6"
   integrity sha512-zauLjrfCG+xvoyaqLoV8bLVXXNGC4JqlxFCutSDWA6fJrTo2ZuvLYTqZ7aHBLZSMOopbzwv8f+wZcVzfVTI2Dg==
 
-clone@2.x:
-  version "2.1.2"
-  resolved "https://registry.yarnpkg.com/clone/-/clone-2.1.2.tgz#1b7f4b9f591f1e8f83670401600345a02887435f"
-  integrity sha1-G39Ln1kfHo+DZwQBYANFoCiHQ18=
-
 content-disposition@0.5.3:
   version "0.5.3"
   resolved "https://registry.yarnpkg.com/content-disposition/-/content-disposition-0.5.3.tgz#e130caf7e7279087c5616c2007d0485698984fbd"
@@ -257,13 +252,6 @@ negotiator@0.6.2:
   resolved "https://registry.yarnpkg.com/negotiator/-/negotiator-0.6.2.tgz#feacf7ccf525a77ae9634436a64883ffeca346fb"
   integrity sha512-hZXc7K2e+PgeI1eDBe/10Ard4ekbfrrqG8Ep+8Jmf4JID2bNg7NvCPOZN+kfF574pFQI7mum2AUqDidoKqcTOw==
 
-node-cache@^5.1.2:
-  version "5.1.2"
-  resolved "https://registry.yarnpkg.com/node-cache/-/node-cache-5.1.2.tgz#f264dc2ccad0a780e76253a694e9fd0ed19c398d"
-  integrity sha512-t1QzWwnk4sjLWaQAS8CHgOJ+RAfmHpxFWmc36IWTiWHQfs0w5JDMBS1b1ZxQteo0vVVuWJvIUKHDkkeK7vIGCg==
-  dependencies:
-    clone "2.x"
-
 on-finished@~2.3.0:
   version "2.3.0"
   resolved "https://registry.yarnpkg.com/on-finished/-/on-finished-2.3.0.tgz#20f1336481b083cd75337992a16971aa2d906947"