Add support for multi-platform images

CHANGELOG.md

@@ -7,6 +7,10 @@ All notable changes will be documented in this file in accordance with
 
 ## \[2.0.0] - 2024-05-27
 
+### Added
+
+- Support for building multi-platform images via `platformsCsv` input
+
 ### Changed
 
 - Authentication configuration is now provided via `authConfig` (in the same format as dockers config.json) in order to ease usage for docker users.

README.md

@@ -32,6 +32,7 @@ op:
  # cacheDir: /default_cache
  # context: /default_context
  # contextIgnore: /default_context_ignore
+ # platformsCsv: ""
  outputs:
  image:
 ```

op.yml

@@ -36,6 +36,14 @@ inputs:
  instructions:
  file:
  description: build instructions in the format of a Containerfile/Dockerfile
+ platformsCsv:
+ string:
+ default: ''
+ description: |
+ Platforms the image will be built for in the form of comma separated [platform specifiers](https://github.com/containerd/containerd/blob/8686ededfc90076914c5238eb96c883ea093a8ba/platforms/platforms.go#L63)
+
+ e.g. 'linux/amd64,linux/arm64'
+
 outputs:
  image:
  dir:
@@ -61,6 +69,7 @@ run:
  --output type=oci,tar=false,dest=/image
  --import-cache type=local,src=/cacheDir
  --export-cache type=local,dest=/cacheDir,mode=max
+ --opt platform=$(platformsCsv)
  dirs:
  /buildContext: $(context)
  /cacheDir: $(cacheDir)