feat: migrate environment variables to plugin properties

Standardize how environment variables are migrated to properties during
install triggers and migrate all remaining DOKKU_* config vars to their
appropriate plugin properties.

Adds a reusable MigrateConfigToProperties() function in the common
package with Transform callback and ListProperty support, plus a
migrate-config-to-property subcommand for the prop binary so shell
plugins can use the same code path.

Migrated variables and their new property owners:
- DOKKU_APP_PROXY_TYPE/DOKKU_PROXY_TYPE → proxy type
- DOKKU_DISABLE_PROXY → proxy disabled
- DOKKU_PROXY_PORT → ports proxy-port
- DOKKU_PROXY_SSL_PORT → ports proxy-ssl-port
- DOKKU_APP_RESTORE → ps restore
- DOKKU_SKIP_DEPLOY → ps skip-deploy
- DOKKU_START_CMD → ps start-cmd
- DOKKU_DOCKERFILE_START_CMD → ps dockerfile-start-cmd
- DOKKU_DISABLE_APP_AUTOCREATION → apps disable-autocreation
- DOKKU_APP_SHELL → scheduler shell
- DOKKU_SKIP_CLEANUP → builder skip-cleanup
- DOKKU_CHECKS_DISABLED → checks disabled
- DOKKU_CHECKS_SKIPPED → checks skipped
- DOKKU_CHECKS_WAIT → checks wait
- DOKKU_CHECKS_TIMEOUT → checks timeout
- DOKKU_CHECKS_ATTEMPTS → checks attempts
- DOKKU_DEFAULT_CHECKS_WAIT → checks default-wait
- DOKKU_SKIP_ALL_CHECKS → checks disabled (legacy)
- DOKKU_SKIP_DEFAULT_CHECKS → checks skipped (legacy)

Also refactors existing bespoke migration loops in scheduler, ports, ps,
builder, and nginx-vhosts plugins to use the standardized utility.

Removes DOKKU_PARALLEL_ARGUMENTS from documentation (unused in core).
Deprecates fn-migrate-config-to-property bash function.

closes #1558

plugins/scheduler/scheduler.go

@@ -4,10 +4,12 @@ var (
 	// DefaultProperties is a map of all valid scheduler properties with corresponding default property values
 	DefaultProperties = map[string]string{
 		"selected": "docker-local",
+		"shell":    "",
 	}
 
 	// GlobalProperties is a map of all valid global scheduler properties
 	GlobalProperties = map[string]bool{
 		"selected": true,
+		"shell":    true,
 	}
 )

plugins/scheduler/triggers.go

@@ -1,7 +1,6 @@
 package scheduler
 
 import (
-	"errors"
 	"fmt"
 
 	"github.com/dokku/dokku/plugins/common"
@@ -31,53 +30,19 @@ func TriggerInstall() error {
 		return fmt.Errorf("Unable to install the scheduler plugin: %s", err.Error())
 	}
 
-	apps, err := common.UnfilteredDokkuApps()
-	if err != nil && !errors.Is(err, common.NoAppsExist) {
-		return nil
-	}
-
-	results, _ := common.CallPlugnTrigger(common.PlugnTriggerInput{
-		Trigger: "config-get-global",
-		Args:    []string{"DOKKU_SCHEDULER"},
-	})
-	globalScheduler := results.StdoutContents()
-	if globalScheduler != "" {
-		common.LogVerboseQuiet(fmt.Sprintf("Setting scheduler property 'selected' to %v", globalScheduler))
-		if err := common.PropertyWrite("scheduler", "--global", "selected", globalScheduler); err != nil {
-			return err
-		}
-
-		_, err := common.CallPlugnTrigger(common.PlugnTriggerInput{
-			Trigger: "config-unset",
-			Args:    []string{"--global", "DOKKU_SCHEDULER"},
-		})
-		if err != nil {
-			common.LogWarn(err.Error())
-		}
-	}
-
-	for _, appName := range apps {
-		results, _ := common.CallPlugnTrigger(common.PlugnTriggerInput{
-			Trigger: "config-get",
-			Args:    []string{appName, "DOKKU_SCHEDULER"},
-		})
-		scheduler := results.StdoutContents()
-		if scheduler == "" {
-			continue
-		}
-
-		common.LogVerboseQuiet(fmt.Sprintf("Setting %s scheduler property 'selected' to %v", appName, scheduler))
-		if err := common.PropertyWrite("scheduler", appName, "selected", scheduler); err != nil {
-			return err
-		}
-
-		_, err := common.CallPlugnTrigger(common.PlugnTriggerInput{
-			Trigger: "config-unset",
-			Args:    []string{appName, "DOKKU_SCHEDULER"},
-		})
-		if err != nil {
-			common.LogWarn(err.Error())
-		}
+	if err := common.MigrateConfigToProperties("scheduler", []common.MigrateConfigEntry{
+		{
+			ConfigVar:       "DOKKU_SCHEDULER",
+			GlobalConfigVar: "DOKKU_SCHEDULER",
+			Property:        "selected",
+		},
+		{
+			ConfigVar:       "DOKKU_APP_SHELL",
+			GlobalConfigVar: "DOKKU_APP_SHELL",
+			Property:        "shell",
+		},
+	}); err != nil {
+		return err
 	}
 
 	return nil