From f10b60398910d10176ce35a6bb90acde2a6f2f09 Mon Sep 17 00:00:00 2001
From: Paul Schnetzinger <p.schnetzinger@haelsi.at>
Date: Mon, 20 Jul 2026 14:11:44 +0200
Subject: [PATCH] feat: add cache-from/cache-to passthrough to
 build-push-action

Lets consumers wire external build caches (e.g. GitHub Actions cache,
registry cache) through to docker/build-push-action, which already
supports cache-from/cache-to natively. Without this the composite
action forces every build to start cold, since GitHub-hosted runners
are fresh VMs per job and local buildx cache never persists across
runs regardless of builder lifecycle.

Backward compatible: both inputs default to empty string, matching
existing optional-input behavior in this action.
---
 README.md  |  2 ++
 action.yml | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/README.md b/README.md
index 46f9cfa..a1180de 100644
--- a/README.md
+++ b/README.md
@@ -120,6 +120,8 @@ context|The build context directory (the directory containing your Dockerfile an
 dockerfile|Filename of the Dockerfile within the context that you set.| |`./Dockerfile`
 platforms|Comma separated list of <a href="https://github.com/docker-library/official-images#architectures-other-than-amd64">platforms</a>.| |`linux/amd64`
 target|The target build stage to build.| |
+cache-from|List of external <a href="https://docs.docker.com/build/cache/backends/">cache sources</a> for the build (e.g., `type=gha`). Passed directly to `docker/build-push-action`.| |
+cache-to|List of <a href="https://docs.docker.com/build/cache/backends/">cache export destinations</a> for the build (e.g., `type=gha,mode=max`). Passed directly to `docker/build-push-action`.| |
 
 #### If you have more than one registry
 **🔀 Input Name**|**📚 Description**|**🛑 Required**|**👉 Default**
diff --git a/action.yml b/action.yml
index 195095f..42e5ec3 100644
--- a/action.yml
+++ b/action.yml
@@ -49,6 +49,14 @@ inputs:
     description: 'Comma separated list of platforms.'
     default: 'linux/amd64'
     required: false
+  cache-from:
+    description: 'List of external cache sources for the build (e.g., "type=gha"). Passed directly to docker/build-push-action.'
+    default: ''
+    required: false
+  cache-to:
+    description: 'List of cache export destinations for the build (e.g., "type=gha,mode=max"). Passed directly to docker/build-push-action.'
+    default: ''
+    required: false
 runs:
   using: 'composite'
   steps:
@@ -92,6 +100,8 @@ runs:
           push: true
           tags: ${{ inputs.tags }}
           target: ${{ inputs.target }}
+          cache-from: ${{ inputs.cache-from }}
+          cache-to: ${{ inputs.cache-to }}
 branding:
   icon: 'server'
   color: 'blue'