refactor: move act under internal

The runner is an application, not a library. `act/model` and
`act/exprparser` were the last packages anything outside this repository
consumed and they now live in actionslib, so nothing needs the rest of
`act` to be importable, and keeping it importable invites the coupling
that was just removed.

Import paths only, the files are unchanged.

Assisted-by: Codet:GPT-5.1-Codex

internal/act/container/docker_build.go

@@ -0,0 +1,128 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// Copyright 2020 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !(WITHOUT_DOCKER || !(linux || darwin || windows || netbsd))
+
+package container
+
+import (
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+
+	"gitea.com/gitea/runner/internal/act/common"
+
+	"github.com/moby/go-archive"
+	"github.com/moby/go-archive/compression"
+	"github.com/moby/moby/client"
+	"github.com/moby/patternmatcher"
+	"github.com/moby/patternmatcher/ignorefile"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// NewDockerBuildExecutor function to create a run executor for the container
+func NewDockerBuildExecutor(input NewDockerBuildExecutorInput) common.Executor {
+	return func(ctx context.Context) error {
+		logger := common.Logger(ctx)
+		if input.Platform != "" {
+			logger.Infof("docker build -t %s --platform %s %s", input.ImageTag, input.Platform, input.ContextDir)
+		} else {
+			logger.Infof("docker build -t %s %s", input.ImageTag, input.ContextDir)
+		}
+		if common.Dryrun(ctx) {
+			return nil
+		}
+
+		cli, err := GetDockerClient(ctx)
+		if err != nil {
+			return err
+		}
+		defer cli.Close()
+
+		logger.Debugf("Building image from '%v'", input.ContextDir)
+
+		tags := []string{input.ImageTag}
+		options := client.ImageBuildOptions{
+			Tags:        tags,
+			Remove:      true,
+			AuthConfigs: LoadDockerAuthConfigs(ctx),
+			Dockerfile:  input.Dockerfile,
+			BuildArgs:   input.BuildArgs,
+		}
+		platform, err := parsePlatform(input.Platform)
+		if err != nil {
+			return err
+		}
+		if platform != nil {
+			options.Platforms = []specs.Platform{*platform}
+		}
+		var buildContext io.ReadCloser
+		if input.BuildContext != nil {
+			buildContext = io.NopCloser(input.BuildContext)
+		} else {
+			buildContext, err = createBuildContext(ctx, input.ContextDir, input.Dockerfile)
+		}
+		if err != nil {
+			return err
+		}
+
+		defer buildContext.Close()
+
+		logger.Debugf("Creating image from context dir '%s' with tag '%s' and platform '%s'", input.ContextDir, input.ImageTag, input.Platform)
+		resp, err := cli.ImageBuild(ctx, buildContext, options)
+
+		err = logDockerResponse(logger, resp.Body, err != nil)
+		if err != nil {
+			return err
+		}
+		return nil
+	}
+}
+
+func createBuildContext(ctx context.Context, contextDir, relDockerfile string) (io.ReadCloser, error) {
+	common.Logger(ctx).Debugf("Creating archive for build context dir '%s' with relative dockerfile '%s'", contextDir, relDockerfile)
+
+	// And canonicalize dockerfile name to a platform-independent one
+	relDockerfile = filepath.ToSlash(relDockerfile)
+
+	f, err := os.Open(filepath.Join(contextDir, ".dockerignore"))
+	if err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+	defer f.Close()
+
+	var excludes []string
+	if err == nil {
+		excludes, err = ignorefile.ReadAll(f)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// If .dockerignore mentions .dockerignore or the Dockerfile
+	// then make sure we send both files over to the daemon
+	// because Dockerfile is, obviously, needed no matter what, and
+	// .dockerignore is needed to know if either one needs to be
+	// removed. The daemon will remove them for us, if needed, after it
+	// parses the Dockerfile. Ignore errors here, as they will have been
+	// caught by validateContextDirectory above.
+	includes := []string{"."}
+	keepThem1, _ := patternmatcher.Matches(".dockerignore", excludes)
+	keepThem2, _ := patternmatcher.Matches(relDockerfile, excludes)
+	if keepThem1 || keepThem2 {
+		includes = append(includes, ".dockerignore", relDockerfile)
+	}
+
+	buildCtx, err := archive.TarWithOptions(contextDir, &archive.TarOptions{
+		Compression:     compression.None,
+		ExcludePatterns: excludes,
+		IncludeFiles:    includes,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return buildCtx, nil
+}