Fix S2I build with podman. (#1014)

Workaround a bug in podman:
containers/podman#13770

Signed-off-by: Matej Vasek <[email protected]>

s2i/builder.go

@@ -61,6 +61,10 @@ func (b *Builder) Build(ctx context.Context, f fn.Function) (err error) {
 	}
 	defer client.Close()
 
+	if isPodman(ctx, client) {
+		client = podmanDockerClient{client}
+	}
+
 	// Build Config
 	cfg := &api.Config{}
 	cfg.Quiet = !b.verbose

s2i/docker_client_wrapper.go

@@ -0,0 +1,62 @@
+package s2i
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/client"
+)
+
+// Wrapper to workaround https://github.com/containers/podman/issues/13770
+type podmanDockerClient struct {
+	client.CommonAPIClient
+}
+
+func (p podmanDockerClient) ContainerCommit(ctx context.Context, nameOrID string, opts types.ContainerCommitOptions) (types.IDResponse, error) {
+	if len(opts.Config.Cmd) > 0 {
+		bs, err := json.Marshal(opts.Config.Cmd)
+		if err != nil {
+			return types.IDResponse{}, err
+		}
+		opts.Changes = append(opts.Changes, "CMD "+string(bs))
+	}
+
+	if len(opts.Config.Entrypoint) > 0 {
+		bs, err := json.Marshal(opts.Config.Entrypoint)
+		if err != nil {
+			return types.IDResponse{}, err
+		}
+		opts.Changes = append(opts.Changes, "ENTRYPOINT "+string(bs))
+	}
+
+	if opts.Config.User != "" {
+		opts.Changes = append(opts.Changes, "USER "+opts.Config.User)
+	}
+
+	for _, e := range opts.Config.Env {
+		parts := strings.SplitN(e, "=", 2)
+		opts.Changes = append(opts.Changes, fmt.Sprintf("ENV %s=%q", parts[0], parts[1]))
+	}
+
+	for k, v := range opts.Config.Labels {
+		opts.Changes = append(opts.Changes, fmt.Sprintf("LABEL %q=%q", k, v))
+	}
+
+	return p.CommonAPIClient.ContainerCommit(ctx, nameOrID, opts)
+}
+
+func isPodman(ctx context.Context, cli client.CommonAPIClient) bool {
+	v, err := cli.ServerVersion(ctx)
+	if err != nil {
+		return false
+	}
+	for _, comp := range v.Components {
+		if comp.Name == "Podman Engine" {
+			return true
+		}
+	}
+	return false
+}