SSH

Since Camel 2.10

Both producer and consumer are supported

The SSH component enables access to SSH servers such that you can send an SSH command, and process the response.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-ssh</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

ssh:[username[:password]@]host[:port][?options]

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The SSH component supports 17 options, which are listed below.

Name Description Default Type

failOnUnknownHost (common)

Specifies whether a connection to an unknown host should fail or not. This value is only checked when the property knownHosts is set.

false

boolean

knownHostsResource (common)

Sets the resource path for a known_hosts file.

String

timeout (common)

Sets the timeout in milliseconds to wait in establishing the remote SSH server connection. Defaults to 30000 milliseconds.

30000

long

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

pollCommand (consumer)

Sets the command string to send to the remote SSH server during every poll cycle. Only works with camel-ssh component being used as a consumer, i.e. from(ssh://…​) You may need to end your command with a newline, and that must be URL encoded %0A.

String

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

channelType (advanced)

Sets the channel type to pass to the Channel as part of command execution. Defaults to exec.

exec

String

configuration (advanced)

Component configuration.

SshConfiguration

shellPrompt (advanced)

Sets the shellPrompt to be dropped when response is read after command execution.

String

sleepForShellPrompt (advanced)

Sets the sleep period in milliseconds to wait reading response from shell prompt. Defaults to 100 milliseconds.

100

long

certResource (security)

Sets the resource path of the certificate to use for Authentication. Will use ResourceHelperKeyPairProvider to resolve file based certificate, and depends on keyType setting.

String

certResourcePassword (security)

Sets the password to use in loading certResource, if certResource is an encrypted key.

String

keyPairProvider (security)

Sets the KeyPairProvider reference to use when connecting using Certificates to the remote SSH Server.

KeyPairProvider

keyType (security)

Sets the key type to pass to the KeyPairProvider as part of authentication. KeyPairProvider.loadKey(…​) will be passed this value. From Camel 3.0.0 / 2.25.0, by default Camel will select the first available KeyPair that is loaded. Prior to this, a KeyType of 'ssh-rsa' was enforced by default.

String

password (security)

Sets the password to use in connecting to remote SSH server. Requires keyPairProvider to be set to null.

String

username (security)

Sets the username to use in logging into the remote SSH server.

String

Endpoint Options

The SSH endpoint is configured using URI syntax:

ssh:host:port

with the following path and query parameters:

Path Parameters (2 parameters)

Name Description Default Type

host (common)

Required Sets the hostname of the remote SSH server.

String

port (common)

Sets the port number for the remote SSH server.

22

int

Query Parameters (33 parameters)

Name Description Default Type

failOnUnknownHost (common)

Specifies whether a connection to an unknown host should fail or not. This value is only checked when the property knownHosts is set.

false

boolean

knownHostsResource (common)

Sets the resource path for a known_hosts file.

String

timeout (common)

Sets the timeout in milliseconds to wait in establishing the remote SSH server connection. Defaults to 30000 milliseconds.

30000

long

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

pollCommand (consumer)

Sets the command string to send to the remote SSH server during every poll cycle. Only works with camel-ssh component being used as a consumer, i.e. from(ssh://…​) You may need to end your command with a newline, and that must be URL encoded %0A.

String

sendEmptyMessageWhenIdle (consumer)

If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.

false

boolean

exceptionHandler (consumer (advanced))

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

  • InOptionalOut

ExchangePattern

pollStrategy (consumer (advanced))

A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel.

PollingConsumerPollStrategy

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

channelType (advanced)

Sets the channel type to pass to the Channel as part of command execution. Defaults to exec.

exec

String

shellPrompt (advanced)

Sets the shellPrompt to be dropped when response is read after command execution.

String

sleepForShellPrompt (advanced)

Sets the sleep period in milliseconds to wait reading response from shell prompt. Defaults to 100 milliseconds.

100

long

backoffErrorThreshold (scheduler)

The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.

int

backoffIdleThreshold (scheduler)

The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.

int

backoffMultiplier (scheduler)

To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured.

int

delay (scheduler)

Milliseconds before the next poll.

500

long

greedy (scheduler)

If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages.

false

boolean

initialDelay (scheduler)

Milliseconds before the first poll starts.

1000

long

repeatCount (scheduler)

Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever.

0

long

runLoggingLevel (scheduler)

The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that.

Enum values:

  • TRACE

  • DEBUG

  • INFO

  • WARN

  • ERROR

  • OFF

TRACE

LoggingLevel

scheduledExecutorService (scheduler)

Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool.

ScheduledExecutorService

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler.

none

Object

schedulerProperties (scheduler)

To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler.

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

Enum values:

  • NANOSECONDS

  • MICROSECONDS

  • MILLISECONDS

  • SECONDS

  • MINUTES

  • HOURS

  • DAYS

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details.

true

boolean

certResource (security)

Sets the resource path of the certificate to use for Authentication. Will use ResourceHelperKeyPairProvider to resolve file based certificate, and depends on keyType setting.

String

certResourcePassword (security)

Sets the password to use in loading certResource, if certResource is an encrypted key.

String

keyPairProvider (security)

Sets the KeyPairProvider reference to use when connecting using Certificates to the remote SSH Server.

KeyPairProvider

keyType (security)

Sets the key type to pass to the KeyPairProvider as part of authentication. KeyPairProvider.loadKey(…​) will be passed this value. From Camel 3.0.0 / 2.25.0, by default Camel will select the first available KeyPair that is loaded. Prior to this, a KeyType of 'ssh-rsa' was enforced by default.

String

password (security)

Sets the password to use in connecting to remote SSH server. Requires keyPairProvider to be set to null.

String

username (security)

Sets the username to use in logging into the remote SSH server.

String

Message Headers

The SSH component supports 4 message header(s), which is/are listed below:

Name Description Default Type

CamelSshUsername (common)

Constant: USERNAME_HEADER

The user name.

String

CamelSshPassword (common)

Constant: PASSWORD_HEADER

The password.

String

CamelSshStderr (common)

Constant: STDERR

The value of this header is a InputStream with the standard error stream of the executable.

InputStream

CamelSshExitValue (common)

Constant: EXIT_VALUE

The value of this header is the exit value that is returned, after the execution. By convention a non-zero status exit value indicates abnormal termination. Note that the exit value is OS dependent.

Integer

Usage as a Producer endpoint

When the SSH Component is used as a Producer (.to("ssh://…​")), it will send the message body as the command to execute on the remote SSH server.

Here is an example of this within the XML DSL. Note that the command has an XML encoded newline (&#10;).

<route id="camel-example-ssh-producer">
  <from uri="direct:exampleSshProducer"/>
  <setBody>
    <constant>features:list&#10;</constant>
  </setBody>
  <to uri="ssh://karaf:karaf@localhost:8101"/>
  <log message="${body}"/>
</route>

Authentication

The SSH Component can authenticate against the remote SSH server using one of two mechanisms: Public Key certificate or username/password. Configuring how the SSH Component does authentication is based on how and which options are set.

  1. First, it will look to see if the certResource option has been set, and if so, use it to locate the referenced Public Key certificate and use that for authentication.

  2. If certResource is not set, it will look to see if a keyPairProvider has been set, and if so, it will use that for certificate based authentication.

  3. If neither certResource nor keyPairProvider are set, it will use the username and password options for authentication. Even though the username and password are provided in the endpoint configuration and headers set with SshConstants.USERNAME_HEADER (CamelSshUsername) and SshConstants.PASSWORD_HEADER (CamelSshPassword), the endpoint configuration is surpassed and credentials set in the headers are used.

The following route fragment shows an SSH polling consumer using a certificate from the classpath.

In the XML DSL,

<route>
  <from uri="ssh://scott@localhost:8101?certResource=classpath:test_rsa&amp;useFixedDelay=true&amp;delay=5000&amp;pollCommand=features:list%0A"/>
  <log message="${body}"/>
</route>

In the Java DSL,

from("ssh://scott@localhost:8101?certResource=classpath:test_rsa&useFixedDelay=true&delay=5000&pollCommand=features:list%0A")
    .log("${body}");

An example of using Public Key authentication is provided in examples/camel-example-ssh-security.

Certificate Dependencies

You will need to add some additional runtime dependencies if you use certificate based authentication. You may need to use later versions depending what version of Camel you are using.

The component uses sshd-core library which is based on either bouncycastle or eddsa security providers. camel-ssh is picking explicitly bouncycastle as security provider.

<dependency>
  <groupId>org.apache.sshd</groupId>
  <artifactId>sshd-core</artifactId>
  <version>2.0.0</version>
</dependency>
<dependency>
  <groupId>org.bouncycastle</groupId>
  <artifactId>bcpg-jdk15on</artifactId>
  <version>1.65</version>
</dependency>
<dependency>
  <groupId>org.bouncycastle</groupId>
  <artifactId>bcpkix-jdk15on</artifactId>
  <version>1.65</version>
</dependency>

Spring Boot Auto-Configuration

When using ssh with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-ssh-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 18 options, which are listed below.

Name Description Default Type

camel.component.ssh.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.ssh.bridge-error-handler

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

Boolean

camel.component.ssh.cert-resource

Sets the resource path of the certificate to use for Authentication. Will use ResourceHelperKeyPairProvider to resolve file based certificate, and depends on keyType setting.

String

camel.component.ssh.cert-resource-password

Sets the password to use in loading certResource, if certResource is an encrypted key.

String

camel.component.ssh.channel-type

Sets the channel type to pass to the Channel as part of command execution. Defaults to exec.

exec

String

camel.component.ssh.configuration

Component configuration. The option is a org.apache.camel.component.ssh.SshConfiguration type.

SshConfiguration

camel.component.ssh.enabled

Whether to enable auto configuration of the ssh component. This is enabled by default.

Boolean

camel.component.ssh.fail-on-unknown-host

Specifies whether a connection to an unknown host should fail or not. This value is only checked when the property knownHosts is set.

false

Boolean

camel.component.ssh.key-pair-provider

Sets the KeyPairProvider reference to use when connecting using Certificates to the remote SSH Server. The option is a org.apache.sshd.common.keyprovider.KeyPairProvider type.

KeyPairProvider

camel.component.ssh.key-type

Sets the key type to pass to the KeyPairProvider as part of authentication. KeyPairProvider.loadKey(…​) will be passed this value. From Camel 3.0.0 / 2.25.0, by default Camel will select the first available KeyPair that is loaded. Prior to this, a KeyType of 'ssh-rsa' was enforced by default.

String

camel.component.ssh.known-hosts-resource

Sets the resource path for a known_hosts file.

String

camel.component.ssh.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.ssh.password

Sets the password to use in connecting to remote SSH server. Requires keyPairProvider to be set to null.

String

camel.component.ssh.poll-command

Sets the command string to send to the remote SSH server during every poll cycle. Only works with camel-ssh component being used as a consumer, i.e. from(ssh://…​) You may need to end your command with a newline, and that must be URL encoded %0A.

String

camel.component.ssh.shell-prompt

Sets the shellPrompt to be dropped when response is read after command execution.

String

camel.component.ssh.sleep-for-shell-prompt

Sets the sleep period in milliseconds to wait reading response from shell prompt. Defaults to 100 milliseconds.

100

Long

camel.component.ssh.timeout

Sets the timeout in milliseconds to wait in establishing the remote SSH server connection. Defaults to 30000 milliseconds.

30000

Long

camel.component.ssh.username

Sets the username to use in logging into the remote SSH server.

String
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