use container image platform only on docker 1.41+ (#591)

Commit af5140f13e introduced support for
specifying a container image platform for cross-platform image building.

Unfortunately, attempting to execute a docker command that includes the
`--platform` flag against Docker daemons using API Version 1.40 and
before results in the following error:

```
"specify container image platform" requires API version 1.41, but the Docker daemon API version is 1.40
```

To allow `act` to be used on the 19.03 Docker CE and earlier versions,
this patch simply checks the Docker daemon API version and only
specifies platform specification when the daemon API version is 1.41 or
greater.

Fixes Issue #586

README.md

@@ -87,7 +87,7 @@ It will save that information to `~/.actrc`, please refer to [Configuration](#co
 ```none
   -a, --actor string                    user that triggered the event (default "nektos/act")
   -b, --bind                            bind working directory to container, rather than copy
-      --container-architecture string   Architecture which should be used to run containers, e.g.: linux/amd64. Defaults to linux/<your machine architecture> [linux/amd64]
+      --container-architecture string   Architecture which should be used to run containers, e.g.: linux/amd64. Defaults to linux/<your machine architecture> [linux/amd64]. Requires Docker server API Version 1.41+. Ignored on earlier Docker server platforms.
       --defaultbranch string            the name of the main branch
       --detect-event                    Use first event type from workflow as event that triggered the workflow
   -C, --directory string                working directory (default ".")

cmd/root.go

@@ -58,7 +58,7 @@ func Execute(ctx context.Context, version string) {
 	rootCmd.PersistentFlags().StringVarP(&input.secretfile, "secret-file", "", ".secrets", "file with list of secrets to read from (e.g. --secret-file .secrets)")
 	rootCmd.PersistentFlags().BoolVarP(&input.insecureSecrets, "insecure-secrets", "", false, "NOT RECOMMENDED! Doesn't hide secrets while printing logs.")
 	rootCmd.PersistentFlags().StringVarP(&input.envfile, "env-file", "", ".env", "environment file to read and use as env in the containers")
-	rootCmd.PersistentFlags().StringVarP(&input.containerArchitecture, "container-architecture", "", "", "Architecture which should be used to run containers, e.g.: linux/amd64. Defaults to linux/<your machine architecture> [linux/"+runtime.GOARCH+"]")
+	rootCmd.PersistentFlags().StringVarP(&input.containerArchitecture, "container-architecture", "", "", "Architecture which should be used to run containers, e.g.: linux/amd64. Defaults to linux/<your machine architecture> [linux/"+runtime.GOARCH+"]. Requires Docker server API Version 1.41+. Ignored on earlier Docker server platforms.")
 	rootCmd.SetArgs(args())
 
 	if err := rootCmd.Execute(); err != nil {

go.mod

@@ -4,6 +4,7 @@ go 1.14
 
 require (
 	github.com/AlecAivazis/survey/v2 v2.2.7
+	github.com/Masterminds/semver v1.5.0
 	github.com/MichaelTJones/walk v0.0.0-20161122175330-4748e29d5718 // indirect
 	github.com/andreaskoch/go-fswatch v1.0.0
 	github.com/containerd/containerd v1.4.1 // indirect

go.sum

@@ -93,6 +93,7 @@ github.com/Djarvur/go-err113 v0.0.0-20200410182137-af658d038157/go.mod h1:4UJr5H
 github.com/Djarvur/go-err113 v0.1.0/go.mod h1:4UJr5HIiMZrwgkSPdsjy2uOQExX/WEILpIrO9UPGuXs=
 github.com/GoogleCloudPlatform/cloudsql-proxy v0.0.0-20191009163259-e802c2cb94ae/go.mod h1:mjwGPas4yKduTyubHvD1Atl9r1rUq8DfVy+gkVvZ+oo=
 github.com/GoogleCloudPlatform/k8s-cloud-provider v0.0.0-20190822182118-27a4ced34534/go.mod h1:iroGtC8B3tQiqtds1l+mgk/BBOrxbqjH+eUfFQYRc14=
+github.com/Masterminds/semver v1.5.0 h1:H65muMkzWKEuNDnfl9d70GUjFniHKHRbFPGBuZ3QEww=
 github.com/Masterminds/semver v1.5.0/go.mod h1:MB6lktGJrhw8PrUyiEoblNEGEQ+RzHPF078ddwwvV3Y=
 github.com/Masterminds/semver/v3 v3.0.3/go.mod h1:VPu/7SZ7ePZ3QOrcuXROw5FAcLl4a0cBrbBpGY/8hQs=
 github.com/Masterminds/semver/v3 v3.1.0/go.mod h1:VPu/7SZ7ePZ3QOrcuXROw5FAcLl4a0cBrbBpGY/8hQs=

pkg/container/docker_run.go

@@ -26,6 +26,7 @@ import (
 	"github.com/docker/docker/pkg/stdcopy"
 	specs "github.com/opencontainers/image-spec/specs-go/v1"
 
+	"github.com/Masterminds/semver"
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/term"
@@ -77,6 +78,25 @@ func NewContainer(input *NewContainerInput) Container {
 	return cr
 }
 
+// supportsContainerImagePlatform returns true if the underlying Docker server
+// API version is 1.41 and beyond
+func supportsContainerImagePlatform(cli *client.Client) bool {
+	ctx := context.TODO()
+	logger := common.Logger(ctx)
+	ver, err := cli.ServerVersion(ctx)
+	if err != nil {
+		logger.Panicf("Failed to get Docker API Version: %s", err)
+		return false
+	}
+	sv, err := semver.NewVersion(ver.APIVersion)
+	if err != nil {
+		logger.Panicf("Failed to unmarshal Docker Version: %s", err)
+		return false
+	}
+	constraint, _ := semver.NewConstraint(">= 1.41")
+	return constraint.Check(sv)
+}
+
 func (cr *containerReference) Create() common.Executor {
 	return common.
 		NewDebugExecutor("%sdocker create image=%s platform=%s entrypoint=%+q cmd=%+q", logPrefix, cr.input.Image, cr.input.Platform, cr.input.Entrypoint, cr.input.Cmd).
@@ -272,22 +292,26 @@ func (cr *containerReference) create() common.Executor {
 			})
 		}
 
-		desiredPlatform := strings.SplitN(cr.input.Platform, `/`, 2)
+		var platSpecs *specs.Platform
+		if supportsContainerImagePlatform(cr.cli) {
+			desiredPlatform := strings.SplitN(cr.input.Platform, `/`, 2)
 
-		if len(desiredPlatform) != 2 {
-			logger.Panicf("Incorrect container platform option. %s is not a valid platform.", cr.input.Platform)
+			if len(desiredPlatform) != 2 {
+				logger.Panicf("Incorrect container platform option. %s is not a valid platform.", cr.input.Platform)
+			}
+
+			platSpecs = &specs.Platform{
+				Architecture: desiredPlatform[1],
+				OS:           desiredPlatform[0],
+			}
 		}
-
 		resp, err := cr.cli.ContainerCreate(ctx, config, &container.HostConfig{
 			Binds:       input.Binds,
 			Mounts:      mounts,
 			NetworkMode: container.NetworkMode(input.NetworkMode),
 			Privileged:  input.Privileged,
 			UsernsMode:  container.UsernsMode(input.UsernsMode),
-		}, nil, &specs.Platform{
-			Architecture: desiredPlatform[1],
-			OS:           desiredPlatform[0],
-		}, input.Name)
+		}, nil, platSpecs, input.Name)
 		if err != nil {
 			return errors.WithStack(err)
 		}