Hosts

Hosts in Essh are SSH servers that you manage. Using hosts configuration, Essh dynamically generates SSH config, provides hook functions, classify the hosts by tags.

Example

host "web01.localhost" {
    -- SSH config properties.
    HostName = "192.168.0.11",
    Port = "22",
    User = "kohkimakimoto",
    -- ... And you can use all ssh_config options. see ssh_config(5)
    
    -- Essh config properties.
    description = "web01 development server",
    
    hidden = false,
    
    props = {
        aaa = "bbb",
        ccc = "ddd",
    },
    
    tags = {
        "web",
        "development",
    },
    
    hooks_before_connect = {
        "echo bar",
    },
}

Host is composed of two different kinds of properties. SSH Config Properties and Essh Config Properties.

SSH Config Properties

SSH config properties require that the first character is upper case. For instance HostName and Port. They are used to generate ssh_config. You can use all ssh options to these properties. see ssh_config(5).

Essh Config Properties

Essh config properties require that the first character is lower case. They are used for special purpose of Essh functions, not ssh_config.

All the properties of this type are listed below.

• description (string): Description of the host. This is used for displaying hosts list and zsh completion.

• hidden (boolean): If you set it true, zsh completion doesn’t show the host.

• hooks_before_connect (table): Hooks that fire before connect. This hook runs on local. The hook is defined as a Lua table. This table can have mulitple functions or strings. See the example:

  hooks_before_connect = {
      -- function
      function()
          print("foo")
      end,
  
      -- string (commands)
      "echo bar",
  
      -- If the function returns a string, Essh run the string as a command.
      function()
          return "echo foobar"
      end,
  }
  

  All hooks (includes hooks_after_connect, hooks_after_disconnect) implemented in Lua function runs on local.

  All hooks (includes hooks_after_connect, hooks_after_disconnect) only fire when your simply login with ssh. Hooks don’t fire in tasks and with --exec option.

• hooks_after_connect (table): Hooks that fire after connect. This hook runs on remote.

• hooks_after_disconnect (table): Hooks that fire after disconnect. This hook runs on local.

• tags (array table): Tags classifies hosts.

  tags = {
      "web",
      "production",
  }
  

  Tags mustn’t be duplicated with any host names.

• props (table): Props sets environment variables ESSH_HOST_PROPS_{KEY} when the host is used in tasks. The table key is modified to upper cased.

  props = {
      foo = "bar",
  }
  
  -- ESSH_HOST_PROPS_FOO=bar