sihil / scala-ssh

Remote shell access via SSH for your Scala applications

scala-ssh is a Scala library providing remote shell access via SSH. It builds on sshj to provide the following features:

• Remote execution of one or more shell commands
• Access to stdin, stdout, stderr and exitcode of remote shell commands
• Authentication via password or public key
• Host key verification via known_hosts file or explicit fingerprint
• Convenient configuration of remote host properties via config file, resource or directly in code
• Scala-idiomatic API

Installation

The current release is 0.5.0, it's available from http://repo.spray.cc. If you use SBT you can pull in the scala-ssh artifacts with:

resolvers += "spray repo" at "http://repo.spray.cc"

libraryDependencies += "com.decodified" %% "scala-ssh" % "0.5.0"

sshj uses SLF4J for logging, so you might want to also add logback to your dependencies:

libraryDependencies += "ch.qos.logback" % "logback-classic" % "1.0.0"

Additionally, in many cases you will need the following two artifacts, which provide additional cypher and compression support:

libraryDependencies ++= Seq(
  "org.bouncycastle" % "bcprov-jdk16" % "1.46",
  "com.jcraft" % "jzlib" % "1.0.7"
)

Usage

The highest-level API element provided by scala-ssh is the SSH object. You use it like this:

SSH("example.com") { client =>
  client.exec("ls -a").right.map { result =>
    println("Result:\n" + result.stdOutAsString())
  }
}

This establishes an SSH connection to host example.com and gives you an SshClient instance that you can use to execute one or more commands on the host. SSH.apply has a second (optional) parameter of type HostConfigProvider, which is essentially a function returning a HostConfig instance for a given hostname. A HostConfig looks like this:

case class HostConfig(
  login: SshLogin,
  hostName: String = "",
  port: Int = 22,
  connectTimeout: Option[Int] = None,
  connectionTimeout: Option[Int] = None,
  commandTimeout: Option[Int] = None,
  useCompression: Boolean = false,
  hostKeyVerifier: HostKeyVerifier = ...,
  sshjConfig: Config = ...
)

It provides all the details required for properly establishing an SSH connection. If you don't provide an explicit HostConfigProvider the default one will be used. For every hostname you pass to the SSH.apply method this default HostConfigProvider expects a file ~/.scala-ssh/{hostname}, which contains the properties of a HostConfig in a simple config file format (see below for details). The HostResourceConfig object gives you alternative HostConfigProvider implementations that read the host config from JAR resources.

Host Config File Format

A host config file is a UTF8-encoded text file containing key = value pairs, one per line. Blank lines and lines starting with a # character are ignored. This is an example file:

# simple password-based config
login-type = password
username = bob
password = 123
command-timeout = 5000
enable-compression = yes

These key are defined:

• login-type: required, can be either password or keyfile

• host-name: optional, if not given the name of the config file is assumed to be the hostname

• port: optional, the default value is 22

• username: required

• password: required for login-type password, ignored otherwise

• keyfile: optionally specifies the location of the user keyfile to use with login-type keyfile, if not given the default files ~/.ssh/id_rsa and ~/.ssh/id_dsa are tried, ignored for login-type password

• passphrase: optionally specifies the passphrase for the keyfile, if not given the keyfile is assumed to be unencrypted, ignored for login-type password

• connect-timeout: optionally specifies the number of milli-seconds that a connection request has to succeed in before triggering a timeout error, default value is 'no timeout'

• connection-timeout: optionally specifies the number of milli-seconds that an idle connection is held open before being closed due due to idleness, default value is 'no timeout'

• commandTimeout: optionally specifies the number of milli-seconds that a pending response to an issued command is waited for before triggering a timeout error, default value is 'no timeout'

• use-compression: optionally adds zlib compression to preferred compression algorithms, there is no guarantee that it will be successfully negotiatied, requires jzlib on the classpath (see 'installation' chapter) above, default is 'no'

License

scala-ssh is licensed under APL 2.0.

Patch Policy

Feedback and contributions to the project, no matter what kind, are always very welcome. However, patches can only be accepted from their original author. Along with any patches, please state that the patch is your original work and that you license the work to the scala-ssh project under the project’s open source license.