From 87e9bb3af7002cd70fcda48c4001690e4bda68a2 Mon Sep 17 00:00:00 2001
From: Thomas Droxler <thomas.droxler@gmail.com>
Date: Tue, 11 Aug 2026 11:08:45 +0200
Subject: [PATCH] Add `Cache-Control` header for charts and infos

Resolves: #670
---
 .../resources/explorer-backend-openapi.json   | 64 +++++++++++++++++++
 .../alephium/explorer/api/BaseEndpoint.scala  |  3 +
 .../explorer/api/ChartsEndpoints.scala        |  3 +
 .../explorer/api/InfosEndpoints.scala         |  3 +
 4 files changed, 73 insertions(+)

diff --git a/app/src/main/resources/explorer-backend-openapi.json b/app/src/main/resources/explorer-backend-openapi.json
index 139c4c96d..b5937a98c 100644
--- a/app/src/main/resources/explorer-backend-openapi.json
+++ b/app/src/main/resources/explorer-backend-openapi.json
@@ -5560,6 +5560,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "application/json": {
                 "schema": {
@@ -6072,6 +6080,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "text/plain": {
                 "schema": {
@@ -6172,6 +6188,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "text/plain": {
                 "schema": {
@@ -6272,6 +6296,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "text/plain": {
                 "schema": {
@@ -6372,6 +6404,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "text/plain": {
                 "schema": {
@@ -7000,6 +7040,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "application/json": {
                 "schema": {
@@ -7146,6 +7194,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "application/json": {
                 "schema": {
@@ -7290,6 +7346,14 @@
         "responses": {
           "200": {
             "description": "Ok",
+            "headers": {
+              "Cache-Control": {
+                "required": true,
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
             "content": {
               "application/json": {
                 "schema": {
diff --git a/app/src/main/scala/org/alephium/explorer/api/BaseEndpoint.scala b/app/src/main/scala/org/alephium/explorer/api/BaseEndpoint.scala
index 727eb7d6f..4abadb683 100644
--- a/app/src/main/scala/org/alephium/explorer/api/BaseEndpoint.scala
+++ b/app/src/main/scala/org/alephium/explorer/api/BaseEndpoint.scala
@@ -43,6 +43,9 @@ trait BaseEndpoint extends ErrorExamples with TapirCodecs with TapirSchemasLike
         )
       )
 
+  def cacheControl(maxAgeSeconds: Int): EndpointIO.FixedHeader[Unit] =
+    header("Cache-Control", s"public, max-age=$maxAgeSeconds")
+
   def arrayBody[T](tpe: String, maxSize: Int)(implicit
       examples: List[Example[ArraySeq[T]]],
       rw: ReadWriter[ArraySeq[T]],
diff --git a/app/src/main/scala/org/alephium/explorer/api/ChartsEndpoints.scala b/app/src/main/scala/org/alephium/explorer/api/ChartsEndpoints.scala
index 50b887856..055cd4c35 100644
--- a/app/src/main/scala/org/alephium/explorer/api/ChartsEndpoints.scala
+++ b/app/src/main/scala/org/alephium/explorer/api/ChartsEndpoints.scala
@@ -18,10 +18,13 @@ trait ChartsEndpoints extends BaseEndpoint with QueryParams {
 
   val intervalTypes: String = IntervalType.all.dropRight(1).map(_.string).mkString(", ")
 
+  private val chartCacheMaxAgeSeconds = 60
+
   private val chartsEndpoint =
     baseEndpoint
       .tag("Charts")
       .in("charts")
+      .out(cacheControl(chartCacheMaxAgeSeconds))
 
   val getHashrates: BaseEndpoint[(TimeInterval, IntervalType), ArraySeq[Hashrate]] =
     chartsEndpoint.get
diff --git a/app/src/main/scala/org/alephium/explorer/api/InfosEndpoints.scala b/app/src/main/scala/org/alephium/explorer/api/InfosEndpoints.scala
index 366bb7625..6cd86c66e 100644
--- a/app/src/main/scala/org/alephium/explorer/api/InfosEndpoints.scala
+++ b/app/src/main/scala/org/alephium/explorer/api/InfosEndpoints.scala
@@ -22,9 +22,12 @@ trait InfosEndpoints extends BaseEndpoint with QueryParams {
       .tag("Infos")
       .in("infos")
 
+  private val infoCacheMaxAgeSeconds = 30
+
   private val supplyEndpoint =
     infosEndpoint
       .in("supply")
+      .out(cacheControl(infoCacheMaxAgeSeconds))
 
   val getInfos: BaseEndpoint[Unit, ExplorerInfo] =
     infosEndpoint.get