tidy up deployment output

deploy.go

@@ -1,15 +1,18 @@
 package main
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/sha1"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strings"
+	"unicode"
 
 	"github.com/pelletier/go-toml/v2"
 )
@@ -303,9 +306,26 @@ systemctl restart pb@%s
 
 func runSSHCommand(server, script string) error {
 	cmd := exec.Command("ssh", append(sshArgs(server), "bash", "--noprofile", "--norc", "-c", script)...)
-	cmd.Stdout = os.Stdout
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
 	cmd.Stderr = os.Stderr
-	return cmd.Run()
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+
+	done := make(chan error, 1)
+	go func() {
+		done <- filterEnvStream(stdoutPipe, os.Stdout)
+	}()
+
+	waitErr := cmd.Wait()
+	pipeErr := <-done
+	if waitErr != nil {
+		return waitErr
+	}
+	return pipeErr
 }
 
 func runSSHOutput(server, script string) (string, error) {
@@ -316,7 +336,8 @@ func runSSHOutput(server, script string) (string, error) {
 	if err := cmd.Run(); err != nil {
 		return "", err
 	}
-	return strings.TrimSpace(out.String()), nil
+	filtered := stripLeadingEnvLines(out.String())
+	return strings.TrimSpace(filtered), nil
 }
 
 func syncLocalDirectories(server, remoteBase string, dirs []string) error {
@@ -388,3 +409,75 @@ func closeSSHControlMaster(server string) {
 	args = append(args, "-O", "exit", fmt.Sprintf("root@%s", server))
 	_ = exec.Command("ssh", args...).Run()
 }
+
+func filterEnvStream(r io.Reader, w io.Writer) error {
+	scanner := bufio.NewScanner(r)
+	scanner.Buffer(make([]byte, 0, 64*1024), 2*1024*1024)
+	skipping := true
+	for scanner.Scan() {
+		line := scanner.Text()
+		if skipping && isEnvLine(line) {
+			continue
+		}
+		if skipping {
+			skipping = false
+		}
+		if _, err := fmt.Fprintln(w, line); err != nil {
+			return err
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func stripLeadingEnvLines(input string) string {
+	scanner := bufio.NewScanner(strings.NewReader(input))
+	scanner.Buffer(make([]byte, 0, 64*1024), 2*1024*1024)
+	skipping := true
+	var builder strings.Builder
+	addedLine := false
+	for scanner.Scan() {
+		line := scanner.Text()
+		if skipping && isEnvLine(line) {
+			continue
+		}
+		if skipping {
+			skipping = false
+		}
+		if addedLine {
+			builder.WriteByte('\n')
+		}
+		builder.WriteString(line)
+		addedLine = true
+	}
+	if err := scanner.Err(); err != nil {
+		return input
+	}
+	return builder.String()
+}
+
+func isEnvLine(line string) bool {
+	trimmed := strings.TrimSpace(line)
+	if trimmed == "" {
+		return true
+	}
+	idx := strings.IndexRune(trimmed, '=')
+	if idx <= 0 {
+		return false
+	}
+	key := trimmed[:idx]
+	for i, r := range key {
+		if i == 0 {
+			if r != '_' && !unicode.IsLetter(r) {
+				return false
+			}
+			continue
+		}
+		if r != '_' && !unicode.IsLetter(r) && !unicode.IsDigit(r) {
+			return false
+		}
+	}
+	return true
+}