adds driver-opt arg as plugin parameter (#93)

#### 📖 Summary

Adds `--driver-opt` buildx arg as plugin parameter. This should make it possible to pass through proxy settings.

#### 📑 Test Plan

> 💡 Select your test plan for the code changes.

-  [x] CI pipeline tests
- Custom test
-  No test plan

##### Details / Justification

Manually tested on own instance behind corporate proxy:

![image](/attachments/b65d981d-c9b8-4228-8e9c-61fa517d98b6)

Unfortunately  the `--build-arg` passthru seems not working

#### 📚 Additional Notes

- fixes #82
- still to do:
  - [x] update docs
  - [x] add usage example

> 💡NOTE: This is my first contribution in this codebase. Feedback and help is probably needed 😸

Reviewed-on: https://codeberg.org/woodpecker-plugins/docker-buildx/pulls/93
Reviewed-by: Patrick Schratz <pat-s@noreply.codeberg.org>
Co-authored-by: OCram85 <marco.blessing@googlemail.com>
Co-committed-by: OCram85 <marco.blessing@googlemail.com>

plugin/docker.go

@@ -41,6 +41,10 @@ func commandBuilder(daemon Daemon) *exec.Cmd {
 		args = append(args, "--config", buildkitConfig)
 	}
 
+	for _, driveropt := range daemon.BuildkitDriverOpt.Value() {
+		args = append(args, "--driver-opt", driveropt)
+	}
+	
 	return exec.Command(dockerExe, args...)
 }
 

plugin/docker_test.go

@@ -0,0 +1,72 @@
+package plugin
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/urfave/cli/v2"
+)
+
+func TestCommandBuilder(t *testing.T) {
+
+	tests := []struct {
+		Name      string
+		Daemon    Daemon
+		Input     string
+		WantedLen int
+		Skip      bool
+		Excuse	string
+	}{
+		{
+			Name:      "Single driver-opt value",
+			Daemon:    Daemon{},
+			Input:     "no_proxy=*.mydomain",
+			WantedLen: 1,
+		},
+		{
+			Name:      "Single driver-opt value with comma",
+			Input:     "no_proxy=.mydomain,.sub.domain.com",
+			WantedLen: 1,
+			Skip: true,
+			Excuse: "Can be enabled whenever #94 is fixed.",
+
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			if (test.Skip) {
+				t.Skip(fmt.Printf("%v skipped. %v", test.Name, test.Excuse))
+			}
+			// prepare test values to mock plugin call with settings
+			os.Setenv("PLUGIN_BUILDKIT_DRIVEROPT", test.Input)
+
+			// create dummy cli app to reproduce the issue
+			app := &cli.App{
+				Name:    "dummy App",
+				Usage:   "testing inputs",
+				Version: "0.0.1",
+				Flags: []cli.Flag{
+					&cli.StringSliceFlag{
+						Name:        "daemon.buildkit-driveropt",
+						EnvVars:     []string{"PLUGIN_BUILDKIT_DRIVEROPT"},
+						Usage:       "adds optional driver-ops args like 'env.http_proxy'",
+						Destination: &test.Daemon.BuildkitDriverOpt,
+					},
+				},
+				Action: nil,
+			}
+
+			// need to run the app to resolve the flags
+			_ = app.Run(nil)
+
+			// call the commandBuilder to prepare the cmd with its args
+			_ = commandBuilder(test.Daemon)
+
+			assert.Len(t, test.Daemon.BuildkitDriverOpt.Value(), test.WantedLen)
+		})
+	}
+
+}

plugin/impl.go

@@ -18,20 +18,21 @@ import (
 
 // Daemon defines Docker daemon parameters.
 type Daemon struct {
-	Registry       string          // Docker registry
-	Mirror         string          // Docker registry mirror
-	Insecure       bool            // Docker daemon enable insecure registries
-	StorageDriver  string          // Docker daemon storage driver
-	StoragePath    string          // Docker daemon storage path
-	Disabled       bool            // DOcker daemon is disabled (already running)
-	Debug          bool            // Docker daemon started in debug mode
-	Bip            string          // Docker daemon network bridge IP address
-	DNS            cli.StringSlice // Docker daemon dns server
-	DNSSearch      cli.StringSlice // Docker daemon dns search domain
-	MTU            string          // Docker daemon mtu setting
-	IPv6           bool            // Docker daemon IPv6 networking
-	Experimental   bool            // Docker daemon enable experimental mode
-	BuildkitConfig string          // Docker buildkit config
+	Registry          string          // Docker registry
+	Mirror            string          // Docker registry mirror
+	Insecure          bool            // Docker daemon enable insecure registries
+	StorageDriver     string          // Docker daemon storage driver
+	StoragePath       string          // Docker daemon storage path
+	Disabled          bool            // DOcker daemon is disabled (already running)
+	Debug             bool            // Docker daemon started in debug mode
+	Bip               string          // Docker daemon network bridge IP address
+	DNS               cli.StringSlice // Docker daemon dns server
+	DNSSearch         cli.StringSlice // Docker daemon dns search domain
+	MTU               string          // Docker daemon mtu setting
+	IPv6              bool            // Docker daemon IPv6 networking
+	Experimental      bool            // Docker daemon enable experimental mode
+	BuildkitConfig    string          // Docker buildkit config
+	BuildkitDriverOpt cli.StringSlice // Docker buildkit driveropt args
 }
 
 // Login defines Docker login parameters.