Build multiarch from same step

Author: bennettgoble

.github/workflows/ci.yaml

@@ -17,23 +17,12 @@ jobs:
   build:
     name: Build
     runs-on: [self-hosted, linux]
-    strategy:
-      matrix:
-        arch: [amd64, arm64]
-        include:
-          - arch: amd64
-            gomplate_sha256: 603539aac4e09f98a8ca5b6e5da0c21213221206dc7175a5644255c7a22b936d
-          - arch: arm64
-            gomplate_sha256: 3352ef521977ee39cdd406a9a7943d0b5f29772e5542995416bf093b90bbae2c
     needs: test
     steps:
       - uses: actions/checkout@v3
       - uses: secondlife/action-build-docker@v1
         with:
-          image: platform/nginx-proxy 
-          platforms: linux/${{ matrix.arch }}
+          image: /platform/nginx-proxy 
+          platforms: linux/amd64,linux/arm64
           promote: ${{ startsWith(github.ref, 'refs/tags/v') }}
           jfrog-token: ${{ secrets.SHARED_JFROG_TOKEN }}
-          build-args: |
-            GOMPLATE_ARCH=${{ matrix.arch }}
-            GOMPLATE_SHA256=${{ matrix.gomplate_sha256 }}

Dockerfile

@@ -1,15 +1,26 @@
 ############
-# Base 
+# Gomplate 
 ############
-ARG ARCH=
-FROM artifactory.secondlife.io/dockerhub/${ARCH}alpine:3 AS base
-ARG GOMPLATE_ARCH=amd64
-ARG GOMPLATE_SHA256=603539aac4e09f98a8ca5b6e5da0c21213221206dc7175a5644255c7a22b936d
+FROM artifactory.secondlife.io/dockerhub/alpine:3 AS gomplate 
+ARG TARGETPLATFORM=linux/amd64
 ARG GOMPLATE_VERSION=3.10.0
-ADD https://github.com/hairyhenderson/gomplate/releases/download/v${GOMPLATE_VERSION}/gomplate_linux-${GOMPLATE_ARCH}-slim /usr/local/bin/gomplate
-RUN echo "${GOMPLATE_SHA256}  /usr/local/bin/gomplate" | sha256sum -c \
-    && chmod +x /usr/local/bin/gomplate \
-    && apk add --no-cache \
+ARG GOMPLATE_AMD64_SHA256=603539aac4e09f98a8ca5b6e5da0c21213221206dc7175a5644255c7a22b936d
+ARG GOMPLATE_ARM64_SHA256=3352ef521977ee39cdd406a9a7943d0b5f29772e5542995416bf093b90bbae2c
+RUN apk add --no-cache curl bash
+SHELL ["/bin/bash", "-c"]
+RUN ARCH=${TARGETPLATFORM/linux\//} \
+    && curl -Lf https://github.com/hairyhenderson/gomplate/releases/download/v${GOMPLATE_VERSION}/gomplate_linux-${ARCH}-slim -o /tmp/gomplate \ 
+    && sha_envvar="GOMPLATE_${ARCH^^}_SHA256" \
+    && GOMPLATE_SHA256="${!sha_envvar}" \
+    && echo "${GOMPLATE_SHA256}  /tmp/gomplate" | sha256sum -c \
+    && chmod +x /tmp/gomplate
+
+############
+# Base 
+############
+FROM artifactory.secondlife.io/dockerhub/alpine:3 AS base
+COPY --from=gomplate /tmp/gomplate /usr/local/bin/
+RUN apk add --no-cache \
         bash \
         nginx \
         nginx-mod-http-headers-more