refactor: drop logrus and other direct dependencies (#1319)

After https://gitea.com/gitea/runner/pulls/1304, logrus stayed only to forward logs from docker/cli and moby/go-archive. The runner used a small part of those: volume parsing, the build context tar, the `ssh://` connection and registry credentials. Own code that matches them replaces them, so logrus leaves the module graph. docker/cli stays for its logrus-free `opts` and `connhelper/ssh` packages.

Other dependencies that the standard library or existing ones cover go too: mergo, httprouter (replaced by `http.ServeMux`), retry-go, go-isatty, go-selinux, container-device-interface, gotest.tools and go-cmp (replaced by testify). The binary shrinks by 5%.

Behaviour differences:

1. An unreadable file in a build context is skipped with a warning, where go-archive left a truncated tar.
2. Build contexts no longer carry `security.capability` xattrs.
3. The cache and artifact servers answer HEAD on GET routes, and no longer redirect trailing slashes or answer OPTIONS.

*Written by Claude.*

---------

Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1319
Reviewed-by: bircni <[email protected]>
Reviewed-by: Lunny Xiao <[email protected]>
Co-authored-by: silverwind <[email protected]>

act/container/docker_ssh.go

@@ -0,0 +1,111 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build !(WITHOUT_DOCKER || !(linux || darwin || windows || netbsd))
+
+package container
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os/exec"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/docker/cli/cli/connhelper/ssh"
+)
+
+func sshArgs(daemonURL string) ([]string, error) {
+	spec, err := ssh.ParseURL(daemonURL)
+	if err != nil {
+		return nil, err
+	}
+	remote := []string{"docker", "system", "dial-stdio"}
+	if strings.Trim(spec.Path, "/") != "" {
+		remote = []string{"docker", "--host=unix://" + spec.Path, "system", "dial-stdio"}
+	}
+	return spec.Command([]string{"-o", "ConnectTimeout=30", "-T"}, remote...)
+}
+
+func dialCommand(name string, args ...string) (net.Conn, error) {
+	conn := &commandConn{cmd: exec.Command(name, args...)}
+	conn.cmd.SysProcAttr = sshSysProcAttr() // a session of its own like docker's, so a ProxyCommand never reads the runner's terminal: https://github.com/docker/cli/issues/1707
+	conn.cmd.Stderr = &conn.stderr
+	conn.cmd.WaitDelay = time.Second // a ProxyCommand child keeping stderr open would otherwise block Wait after ssh exits
+	conn.wait = sync.OnceValue(func() error {
+		if err := conn.cmd.Wait(); err != nil && !errors.Is(err, exec.ErrWaitDelay) {
+			return fmt.Errorf("%s: %w: %s", strings.Join(conn.cmd.Args, " "), err, strings.TrimSpace(conn.stderr.String()))
+		}
+		return nil
+	})
+	var err error
+	if conn.stdin, err = conn.cmd.StdinPipe(); err != nil {
+		return nil, err
+	}
+	if conn.stdout, err = conn.cmd.StdoutPipe(); err != nil {
+		return nil, err
+	}
+	return conn, conn.cmd.Start()
+}
+
+type commandConn struct {
+	cmd    *exec.Cmd
+	stdin  io.WriteCloser
+	stdout io.ReadCloser
+	stderr cappedBuffer
+	wait   func() error
+}
+
+func (c *commandConn) waitWithin(timeout time.Duration) error {
+	timer := time.AfterFunc(timeout, func() { _ = c.cmd.Process.Kill() })
+	defer timer.Stop()
+	return c.wait()
+}
+
+func (c *commandConn) Read(p []byte) (int, error) {
+	n, err := c.stdout.Read(p)
+	if errors.Is(err, io.EOF) {
+		if waitErr := c.waitWithin(10 * time.Second); waitErr != nil {
+			return n, waitErr
+		}
+	}
+	return n, err
+}
+
+func (c *commandConn) Write(p []byte) (int, error) { return c.stdin.Write(p) }
+
+// CloseWrite lets the daemon see the end of a hijacked stream, like a TCP half-close.
+func (c *commandConn) CloseWrite() error { return c.stdin.Close() }
+
+func (c *commandConn) Close() error {
+	_ = c.stdin.Close()
+	if c.cmd.Process.Signal(syscall.SIGTERM) != nil { // SIGTERM lets ssh take its ProxyCommand down, Windows only kills
+		_ = c.cmd.Process.Kill()
+	}
+	_ = c.waitWithin(3 * time.Second)
+	return nil
+}
+
+func (c *commandConn) LocalAddr() net.Addr { return &net.UnixAddr{Name: "stdio", Net: "unix"} }
+
+func (c *commandConn) RemoteAddr() net.Addr { return &net.UnixAddr{Name: "stdio", Net: "unix"} }
+
+func (c *commandConn) SetDeadline(_deadline time.Time) error { return nil }
+
+func (c *commandConn) SetReadDeadline(_deadline time.Time) error { return nil }
+
+func (c *commandConn) SetWriteDeadline(_deadline time.Time) error { return nil }
+
+type cappedBuffer struct{ bytes.Buffer }
+
+func (b *cappedBuffer) Write(p []byte) (int, error) {
+	if b.Len() > 4096 {
+		b.Reset()
+	}
+	return b.Buffer.Write(p)
+}