add support to override platform

Signed-off-by: Casey Lee <cplee@nektos.com>

cmd/input.go

@@ -12,6 +12,7 @@ type Input struct {
 	eventPath       string
 	reuseContainers bool
 	secrets         []string
+	platforms       []string
 	dryrun          bool
 	forcePull       bool
 	logOutput       bool

cmd/platforms.go

@@ -0,0 +1,25 @@
+package cmd
+
+import (
+	"strings"
+)
+
+func (i *Input) newPlatforms() map[string]string {
+	platforms := map[string]string{
+		"ubuntu-latest":  "ubuntu:18.04",
+		"ubuntu-18.04":   "ubuntu:18.04",
+		"ubuntu-16.04":   "ubuntu:16.04",
+		"windows-latest": "",
+		"windows-2019":   "",
+		"macos-latest":   "",
+		"macos-10.15":    "",
+	}
+
+	for _, p := range i.platforms {
+		pParts := strings.Split(p, "=")
+		if len(pParts) == 2 {
+			platforms[pParts[0]] = pParts[1]
+		}
+	}
+	return platforms
+}

cmd/root.go

@@ -31,6 +31,7 @@ func Execute(ctx context.Context, version string) {
 	rootCmd.Flags().BoolP("list", "l", false, "list workflows")
 	rootCmd.Flags().StringP("job", "j", "", "run job")
 	rootCmd.Flags().StringArrayVarP(&input.secrets, "secret", "s", []string{}, "secret to make available to actions with optional value (e.g. -s mysecret=foo or -s mysecret)")
+	rootCmd.Flags().StringArrayVarP(&input.platforms, "platform", "P", []string{}, "custom image to use per platform (e.g. -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04)")
 	rootCmd.Flags().BoolVarP(&input.reuseContainers, "reuse", "r", false, "reuse action containers to maintain state")
 	rootCmd.Flags().BoolVarP(&input.forcePull, "pull", "p", false, "pull docker image(s) if already present")
 	rootCmd.Flags().StringVarP(&input.eventPath, "eventpath", "e", "", "path to event JSON file")
@@ -98,6 +99,7 @@ func newRunCommand(ctx context.Context, input *Input) func(*cobra.Command, []str
 			Workdir:         input.Workdir(),
 			LogOutput:       input.logOutput,
 			Secrets:         newSecrets(input.secrets),
+			Platforms:       input.newPlatforms(),
 		}
 		runner, err := runner.New(config)
 		if err != nil {