Add ARM and ARM64 support to flux GitHub Action

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

action/README.md

@@ -10,11 +10,21 @@ Usage:
         run: flux -v
 ```
 
-Note that this action can only be used on GitHub **Linux AMD64** runners.
 The latest stable version of the `flux` binary is downloaded from
 GitHub [releases](https://github.com/fluxcd/flux2/releases)
 and placed at `/usr/local/bin/flux`.
 
+Note that this action can only be used on GitHub **Linux** runners.
+You can change the arch (defaults to `amd64`) with:
+
+```yaml
+    steps:
+      - name: Setup Flux CLI
+        uses: fluxcd/flux2/action@main
+        with:
+          arch: arm64 # can be amd64, arm64 or arm
+```
+
 You can download a specific version with:
 
 ```yaml

action/action.yml

@@ -8,19 +8,24 @@ inputs:
   version:
     description: "Flux version e.g. 0.8.0 (defaults to latest stable release)"
     required: false
+  arch:
+    description: "arch can be amd64, arm64 or arm"
+    required: true
+    default: "amd64"
 runs:
   using: composite
   steps:
     - name: "Download flux binary to tmp"
       shell: bash
       run: |
+        ARCH=${{ inputs.arch }}
         VERSION=${{ inputs.version }}
 
         if [ -z $VERSION ]; then
           VERSION=$(curl https://api.github.com/repos/fluxcd/flux2/releases/latest -sL | grep tag_name | sed -E 's/.*"([^"]+)".*/\1/' | cut -c 2-)
         fi
 
-        BIN_URL="https://github.com/fluxcd/flux2/releases/download/v${VERSION}/flux_${VERSION}_linux_amd64.tar.gz"
+        BIN_URL="https://github.com/fluxcd/flux2/releases/download/v${VERSION}/flux_${VERSION}_linux_${ARCH}.tar.gz"
         curl -sL ${BIN_URL} -o /tmp/flux.tar.gz
         mkdir -p /tmp/flux
         tar -C /tmp/flux/ -zxvf /tmp/flux.tar.gz