Spring Boot Ssh Shell

Spring shell in spring boot application over ssh

For more information please visit spring shell website or 2.0.1 reference documentation.

• Getting started
• Commands
• Post processors
• Parameter providers
• Custom authentication
• Command helper
• Banner
• Listeners
• Session Manager
• Tests
• Samples
• Release notes

Getting started

Dependency

<dependency>
    <groupId>com.github.fonimus</groupId>
    <artifactId>ssh-shell-spring-boot-starter</artifactId>
</dependency>

Note: auto configuration SshShellAutoConfiguration (active by default) can be deactivated by property ssh.shell.enable=false.

It means that the ssh server won't start and the commands won't be scanned. Unfortunately the application will still load the spring-shell auto configuration classes and display a shell at startup (shell:>). You can disable them with following property:

spring:
  autoconfigure:
    exclude:
      - org.springframework.shell.jline.JLineShellAutoConfiguration
      - org.springframework.shell.SpringShellAutoConfiguration
      - org.springframework.shell.jcommander.JCommanderParameterResolverAutoConfiguration
      - org.springframework.shell.legacy.LegacyAdapterAutoConfiguration
      - org.springframework.shell.standard.StandardAPIAutoConfiguration
      - org.springframework.shell.standard.commands.StandardCommandsAutoConfiguration

Configuration

Please check class: SshShellProperties.java for more information

ssh:
  shell:
    enable: true
    # 'simple' or 'security'
    authentication: simple
    # if authentication set to 'security' the AuthenticationProvider bean name
    # if not specified and only one AuthenticationProvider bean is present in the context, it will be used 
    auth-provider-bean-name:
    # since 1.2.2, optional file containing authorized public keys (standard authorized_keys format, one key per line
    # starting with 'ssh-rsa'), takes precedence over authentication (simple or not)
    authorized-public-keys-file:
    # since 1.5.5, optional spring resource containing authorized public keys (file:, classpath: , etc)
    # note: in case of a non file resource, a temporary file is created with given content and deleted on process exit
    # this is due to ssh external library which only accepts file in api
    authorized-public-keys:
    # for ssh helper 'confirm' method
    confirmation-words:
    - y    
    - yes
    # since 1.4.0, set enable to false to disable following default commands
    commands:
      actuator:
        create: true
        enable: true
        restricted: true
        # empty by default
        excludes:
          - ...
        authorized-roles: 
          - ACTUATOR
      # since 1.4.0
      jmx: 
        create: true
        enable: true
        restricted: true
        authorized-roles: 
          - ADMIN
      system: 
        create: true
        enable: true
        restricted: true
        authorized-roles: 
          - ADMIN
      # since 1.4.0
      datasource: 
        create: true
        enable: true
        restricted: true
        authorized-roles: 
          - ADMIN
        excludes:
          - datasource-update
      postprocessors: 
        create: true
        enable: true
        restricted: false
      # since 1.3.0, command which allows you to list ssh sessions, and stop them
      manage-sessions:
        create: true
        enable: false
        restricted: true
        authorized-roles: 
          - ADMIN
      # since 1.5.0
      tasks:
        create: true
        enable: false
        restricted: true
        authorized-roles: 
          - ADMIN
    display-banner: true
    # to use ExtendedFileValueProviderTest instead of spring shell FileValueProvider for all File option parameters
    # if set to false, it still can be used via '@ShellOption(valueProvider = ExtendedFileValueProviderTest.class) File file'
    extended-file-provider: true
    history-file: <java.io.tmpdir>/sshShellHistory.log
    # since 1.3.0, set to false to have one file per user (<history-directory>/sshShellHistory-<user>.log)
    shared-history: true
    # since 1.3.0, only if shared-history is set to false
    history-directory: <java.io.tmpdir>
    host: 127.0.0.1
    host-key-file: <java.io.tmpdir>/hostKey.ser
    # displayed in log if generated
    password:
    port: 2222
    user: user
    prompt:
      # in enum: com.github.fonimus.ssh.shell.PromptColor (black, red, green, yellow, blue, magenta, cyan, white, bright)
      color: white
      text: 'shell>'
      local:
        # since 1.2.1, to let default local spring shell prompt when application starts
        enable: false

• Add spring-boot-starter-actuator dependency to get actuator commands

• Add spring-boot-starter-security dependency to configure ssh.shell.authentication=security with AuthenticationProvider

Default behavior

Some commands are disabled by default, it can be the whole group (like manage-sessions), or just one sub command (like datasource-update in group datasource).

To enable a group, set the enable property to true :

ssh:
  shell:
    commands:
      manage-sessions:
        enable: true
      datasource:
        excludes:

To un-exclude a sub command inside a group, set the excludes property to the new wanted array. To include all sub commands, set new empty array :

ssh:
  shell:
    commands:
      datasource:
        excludes:

Writing commands

You can write your command exactly the way you would do with spring shell (For more information please visit spring shell (website, reference documentation)

Instead of using org.springframework.shell.standard.ShellComponent annotation, you should use com.github.fonimus.ssh.shell.commands.SshShellComponent: it is just a conditional @ShellComponent with @ConditionalOnProperty on property ssh.shell.enable

Example:

import org.springframework.shell.standard.ShellCommandGroup;
import org.springframework.shell.standard.ShellMethod;

import com.github.fonimus.ssh.shell.commands.SshShellComponent;


@SshShellComponent
@ShellCommandGroup("Test Commands")
public class TestCommands {

	@ShellMethod("test command")	
	public String test() {
	  return "ok";
	}
}

Commands

All commands group can be deactivated by enable property :

ssh:
  shell:
    commands:
      <command>:
        enable: true

Sub commands in group can be also filtered by includes and excludes properties :

ssh:
  shell:
    commands:
      <command>:
        includes:
          - xxx
        excludes:
          - xxx

Actuator

If org.springframework.boot:spring-boot-starter-actuator dependency is present, actuator commands will be available.

Command availability is also bind to endpoint activation.

management:
  endpoint:
    audit:
      enabled: false

Tasks

Activated by default if you have @EnableScheduling, these commands allow you to interact with spring boot scheduled tasks :

• tasks-list : List scheduled tasks
• tasks-stop : Stop one or all scheduled tasks
• tasks-restart : Restart one or all scheduled tasks

Task scheduler

Based on spring documentation org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.setScheduler the task scheduler used for scheduled tasks will be :

If not specified, it will look for unique bean of type TaskScheduler, or with name taskScheduler. Otherwise a local single-threaded will be created.

The TasksCommand keep the same mechanism in order to be able to restart stopped scheduled tasks. It also provides a setTaskScheduler() in case you want to specify custom one.

Examples

Jmx

• jmx-info: Displays information about jmx mbean. Use -a option to query attribute values.
• jmx-invoke: Invoke operation on object name.
• jmx-list: List jmx mbeans.

System

• system-env: List system environment.
• system-properties: List system properties.
• system-threads: List jvm threads.

Datasource

• datasource-list: List available datasources
• datasource-properties: Datasource properties command. Executes 'show variables'
• datasource-query: Datasource query command.
• datasource-update: Datasource update command.

Post processors

• postprocessors: Display the available post processors

Post processors

Note: since 1.0.6

Post processors can be used with '|' (pipe character) followed by the name of the post processor and the parameters. Also, custom ones can be added.

Provided post processors

Save

This specific post processor takes the key character '>'.

Example: echo test > /path/to/file.txt

Pretty

This post processor, named pretty takes an object and apply jackson pretty writer.

Example: info | pretty

Json

This post processor, named json allows you to find a specific path within a json object.

Caution: you need to have a json string. You can apply pretty post processor before to do so.

Example: info | pretty | json /build/version

Grep

This post processor, named grep allows you to find specific patterns within a string.

Examples: info | grep boot,info | pretty | grep boot spring

Highlight

This post processor, named highlight allows you to highlight specific patterns within a string.

Examples: info | highlight boot,info | pretty | highlight boot spring

Custom

To register a new json result post processor, you need to implement interface PostProcessor

Then register it within a spring configuration.

Example:

@Bean
public PostProcessor quotePostProcessor() {
    return new PostProcessor<String>() {

        @Override
        public String getName() {
            return "quote";
        }

        @Override
        public String process(String result, List parameters) {
            return "'" + result + "'";
        }
    };
}

Parameter providers

Enum

Enumeration option parameters have auto completion by default.

File

Thanks to [ExtendedFileValueProvider.java](./starter/src/main/java/com/github/fonimus/ssh/shell/providers /ExtendedFileValueProvider.java) (or FileValueProvider is deactivated), auto completion is available for java.io.File option parameters.

Custom values

To enable auto completion for a parameter, declare a valueProvider class.

Note: the value provider has to be in the spring context.

...
@ShellOption(valueProvider = CustomValuesProvider.class) String message
...

@Component
class CustomValuesProvider
        extends ValueProviderSupport {

    private final static String[] VALUES = new String[]{
            "message1", "message2", "message3"
    };

    @Override
    public List<CompletionProposal> complete(MethodParameter parameter, CompletionContext completionContext, String[] hints) {
        return Arrays.stream(VALUES).map(CompletionProposal::new).collect(Collectors.toList());
    }
}

Custom authentication

Instead of setting user and password (or using generated one), you can implement your own SshShellAuthenticationProvider.

Auto configuration will create default implementation only if there is not an existing one in the spring context.

Example:

import com.github.fonimus.ssh.shell.SshShellAuthenticationProvider;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class CustomPasswordConfiguration {

    @Bean
    public SshShellAuthenticationProvider sshShellAuthenticationProvider() {
        return (user, pass, serverSession) -> user.equals(pass);
    }

}

Command helper

A com.github.fonimus.ssh.shell.SshShellHelper bean is provided in context to help for additional functionalities.

You can either autowire it or inject it in a constructor:

import com.github.fonimus.ssh.shell.SshShellHelper;

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;
	
	// or
	
	public DemoCommand(SshShellHelper helper){
		this.helper = helper;
	}
}

User interaction

Print output

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;

	@ShellMethod("Print command")	
	public String print() {
	    boolean success = ...;
	    helper.print("Some message");
	    helper.print("Some black message", PromptColor.BLACK);
	    helper.printSuccess("Some success message");
	    return success ? helper.getSuccess("Some returned success message") : helper.getColored("Some returned blue message", PromptColor.BLUE);
	}
}

Read input

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;

	@ShellMethod("Welcome command")	
	public String welcome() {
	    String name = helper.read("What's your name ?");
	    return "Hello, '" + name + "' !";
	}
}

Confirmation

Util confirm method displays confirmation message and returns true if response equals ignore case confirmation words.

Default confirmation words are [y, yes]:

You can specify if it is case sensitive and provide your own confirmation words.

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;

	@ShellMethod("Confirmation command")
	public String conf() {
	    return helper.confirm("Are you sure ?" [, true|false] [, "oui", "si", ...]) ? "Great ! Let's do it !" : "Such a shame ...";
	}
}

Table

A builder com.github.fonimus.ssh.shell.SimpleTableBuilder is available to quickly set up print table.

Quick example:

helper.renderTable(SimpleTable.builder()
    .column("col1")
    .column("col2")
    .column("col3")
    .column("col4")
    .line(Arrays.asList("line1 col1", "line1 col2", "line1 col3", "line1 col4"))
    .line(Arrays.asList("line2 col1", "line2 col2", "line2 col3", "line2 col4"))
    .line(Arrays.asList("line3 col1", "line3 col2", "line3 col3", "line3 col4"))
    .line(Arrays.asList("line4 col1", "line4 col2", "line4 col3", "line4 col4"))
    .line(Arrays.asList("line5 col1", "line5 col2", "line5 col3", "line5 col4"))
    .line(Arrays.asList("line6 col1", "line6 col2", "line6 col3", "line6 col4"))
.build());

Result :

┌──────────┬──────────┬──────────┬──────────┐
│   col1   │   col2   │   col3   │   col4   │
├──────────┼──────────┼──────────┼──────────┤
│line1 col1│line1 col2│line1 col3│line1 col4│
├──────────┼──────────┼──────────┼──────────┤
│line2 col1│line2 col2│line2 col3│line2 col4│
├──────────┼──────────┼──────────┼──────────┤
│line3 col1│line3 col2│line3 col3│line3 col4│
├──────────┼──────────┼──────────┼──────────┤
│line4 col1│line4 col2│line4 col3│line4 col4│
├──────────┼──────────┼──────────┼──────────┤
│line5 col1│line5 col2│line5 col3│line5 col4│
├──────────┼──────────┼──────────┼──────────┤
│line6 col1│line6 col2│line6 col3│line6 col4│
└──────────┴──────────┴──────────┴──────────┘

Interactive

Note: since 1.1.3

This method takes an interface to display lines at regular interval.

Every refresh delay (here 2 seconds), com.github.fonimus.ssh.shell.interactive.InteractiveInput.getLines is called.

This can be used to display progress, monitoring, etc.

The interactive builder, Interactive.java allows you to build your interactive command.

This builder can also take key bindings to make specific actions, whose can be made by the following builder: KeyBinding.java.

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;
	
	@ShellMethod("Interactive command")
	public void interactive() {
	    
        KeyBinding binding = KeyBinding.builder()
                .description("K binding example")
                .key("k").input(() -> LOGGER.info("In specific action triggered by key 'k' !")).build();

        Interactive interactive = Interactive.builder().input((size, currentDelay) -> {
            LOGGER.info("In interactive command for input...");
            List<AttributedString> lines = new ArrayList<>();
            AttributedStringBuilder sb = new AttributedStringBuilder(size.getColumns());

            sb.append("\nCurrent time", AttributedStyle.BOLD).append(" : ");
            sb.append(String.format("%8tT", new Date()));

            lines.add(sb.toAttributedString());

            SecureRandom sr = new SecureRandom();
            lines.add(new AttributedStringBuilder().append(helper.progress(sr.nextInt(100)),
                    AttributedStyle.DEFAULT.foreground(sr.nextInt(6) + 1)).toAttributedString());
            lines.add(AttributedString.fromAnsi(SshShellHelper.INTERACTIVE_LONG_MESSAGE + "\n"));

            return lines;
        }).binding(binding).fullScreen(true|false).refreshDelay(5000).build();

        helper.interactive(interactive);
	}
}

Note: existing key bindings are:

• q: to quit interactive command and go back to shell
• +: to increase refresh delay by 1000 milliseconds
• -: to decrease refresh delay by 1000 milliseconds

Role check

If you are using AuthenticationProvider thanks to property ssh.shell.authentication=security, you can check that connected user has right authorities for command. The easiest way of doing it is thanks to ShellMethodAvailability functionality. Example:

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;

	@ShellMethod("Admin command")
	@ShellMethodAvailability("adminAvailability")
	public String admin() {
		return "Finally an administrator !!";
	}

	public Availability adminAvailability() {
		if (!helper.checkAuthorities(Collections.singletonList("ADMIN"))) {
			return Availability.unavailable("admin command is only for an admin users !");
		}
		return Availability.available();
	}
}

Retrieve spring security authentication

@SshShellComponent
public class DemoCommand {
	
	@Autowired
	private SshShellHelper helper;
	
	@ShellMethod("Authentication command")
	public SshAuthentication authentication() {
		return helper.getAuthentication();
	}
}

Banner

If a banner is found in spring context and display-banner is set to true, it will be used as welcome prompt message.

Listeners

An interface is provided in order to receive events on ssh sessions : com.github.fonimus.ssh.shell.listeners .SshShellListener.

Implement it and define a spring bean in order to receive events.

Example

@Bean
public SshShellListener sshShellListener() {
    return event -> LOGGER.info("[listener] event '{}' [id={}, ip={}]",
            event.getType(),
            event.getSession().getServerSession().getIoSession().getId(),
            event.getSession().getServerSession().getIoSession().getRemoteAddress());
}

Session Manager

Note: since 1.3.0`

A session manager bean is available and allows you to:

• list active sessions
• get information about one session
• stop a session

Note: you need to use @Lazy injection if you are using it in a command

Example

...
public MyCommand(@Lazy SshShellSessionManager sessionManager) {
    this.sessionManager = sessionManager;
}

@ShellMethod("My command")
public String myCommand() {
    sessionManager.listSessions();
    ...
}
...

Manage sessions commands

If activated ssh.shell.commands.manage-sessions.enable=true, the following commands are available :

• manage-sessions-info: Displays information about single session
• manage-sessions-list: Displays active sessions
• manage-sessions-stop: Stop single specific session

Tests

It can be annoying to load ssh server during spring boot tests. SshShellProperties class provides constants to easily deactivate the all ssh and spring shell auto configurations:

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE, properties = { "ssh.shell.port=2346",
		SshShellProperties.DISABLE_SSH_SHELL,
		SshShellProperties.DISABLE_SPRING_SHELL_AUTO_CONFIG
})
@ExtendWith(SpringExtension.class)
public class ApplicationTest {}

Samples

• Basic sample, no actuator, no security, no sessions

• Complete sample, actuator, security dependencies and configurations

Release notes

1.5.6

• Add Next execution column in task-list table

1.5.5

• Fix potential circular dependency for Windows users
• Fix classpath resource inside jar for authorized public keys file by using temporary file (ssh external library only accept files)

1.5.4

• authorizedPublicKeysFile becomes authorizedPublicKeys and is now a spring resource ; you can now use :
  • ssh.shell.authorized-public-keys=<spring-resource-path> (file:<path>, classpath:<path>, etc)
  • ssh.shell.authorized-public-keys-file=<file-path>

1.5.3

• Rewrite script command to be usable in background with result file (options added to default command)
• Add StoppableInteractiveInput to be able to stop the interactive mode with specific condition

1.5.2

• Add option to create group commands ssh.shell.commands.<command>.create, which is true by default. Setting a group command create property to false :
  • won't create the associated commands in spring context
  • won't display the associated commands in help
  • the associated commands won't be accessible in shell

1.5.1

• Add option for path (groups, components, etc) in health endpoint

1.5.0

• Add tasks commands :
  • tasks-list
  • tasks-stop
  • tasks-restart
• Rename commands :
  • system-env instead of jvm-env
  • system-properties instead of jvm-properties
  • system-threads instead of threads

1.4.2

• Rework commands properties (check configuration chapter) to add the following :
  • includes : to only include list of sub commands inside group (example: datasource-update in group datasource)
  • excludes : to excludes some sub commands inside group (example: datasource-update in group datasource)

1.4.1

• AnyOsFileValueProvider replaced by ExtendedFileValueProvider.java
  • Do not add space after directory proposal (allows following directories directly)
  • Supports Windows OS in addition to Unix
  • Can be deactivated by ssh.shell.extended-file-provider

1.4.0

• Bump to spring boot 2.3.3.RELEASE
• Bump to sshd 2.5.1
• Add method SshShellHelper#getSshEnvironment() to retrieve information about ssh environment
• Fixed start app failure in case of spring.main.lazy-initialization=true
• Fixed table rendering issue in SshShellHelper
• Add jmx commands :
  • jmx-list
  • jmx-info
  • jmx-invoke
• Add datasource commands
  • datasource-list
  • datasource-properties
  • datasource-query
  • datasource-update
• Add completion for post processors
• Rework commands properties (check configuration chapter)
  • default-commands becomes commands
  • Instead of just activation boolean, each command now has the following properties :
    • enable with default value set to true, except said otherwise in config
    • restricted with default value set to true, except said otherwise in config
    • authorizedRoles with default value initialized with ADMIN, except said otherwise in config
  • ssh.shell.actuator.* properties moved to ssh.shell.commands.actuator.*

1.3.0

• Bump to spring boot 2.3.0.RELEASE
• Add listeners mechanism
• Add session manager
  • Add possibility to activate manage-sessions-* commands`
• Add possibility to have history per user (ssh.shell.shared-history=false)

1.2.2

• Bump to sshd 2.4.0
• Add property ssh.shell.authorized-public-keys-file to specify authorized public keys to login via ssh. This file is a standard authorized_keys format (one key per line, starting with ssh-rsa)
• Add some methods in helper to help build table with com.github.fonimus.ssh.shell.SimpleTableBuilder

1.2.1

• Add property ssh.shell.prompt.local.enable (false by default) to let default local spring shell prompt when application starts

1.2.0

• Bump to spring boot 2.2.0.RELEASE
  • Audit and Http Trace actuator commands will be disabled by default, because endpoint will be by spring boot by default (check spring boot migration 2.2 for more info)
• Fix hanging terminal when unexpected runtime exception occurs

1.1.6

• Bump to spring boot 2.1.7.RELEASE
• Bump to sshd 2.3.0
• Add properties to exclude not wanted built-in commands
  • Via properties ssh.shell.default-commands.*

1.1.5

• Add threads, jvm-env and jvm-properties built-it commands

1.1.4

• AnyOsFileValueProvider.java replaces FileValueProvider (spring shell default) by default
  • Supports Windows OS in addition to Unix
  • Can be deactivated by ssh.shell.any-os-file-provider

1.1.3

• Remove static from SshShellHelper methods (getColored, getBackgroundColored)
• Add methods in SshShellHelper
  • terminalSize to get terminal columns and rows capabilities
  • progress to fill line with progress bar
    • [========> ]
  • interactive which takes an interface to display lines at regular interval
    • Check complete sample for a demo

1.1.2

• Fix option arguments with spaces, quotes, etc
• Update to spring boot 2.1.3
• Update to javadoc plugin 3.1.0
• Update to sshd 2.2.0

1.1.1

• Update to spring boot 2.1.0
  • Avoid overriding bean definitions as it is now disabled by default

1.1.0

• New artifact identifier: ssh-shell-spring-boot-starter -> maven central link

1.0.6

• Add new post processor
  • highlight
• Fix various issues where ssh.shell.enable=false makes application fail to start
• Add new @SshShellComponent

1.0.5

• Add post processor feature
  • pretty
  • grep
  • json
  • save
• Fix issue with terminal size which made autocomplete fail

1.0.4

• Make PrettyJsonResultHandler bean conditional on jackson ObjectMapper class
• Fix application start issue if banner is with configured with off mode

1.0.3

• Fix not working history
• Make history file location configurable
• Add authentication objects in ssh session context

1.0.2

• Add more user interactions in SshShellHelper

1.0.1

• Add spring security authentication provider for ssh connection
• Add spring security roles check
• Add user interactions (read, confirm)
• Bug fixes

1.0.0

• First stable release