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Definition of Ansible Expect

Ansible Expect command is a built-in Ansible module and comes default with the ansible installation and this module executes a command on the remote nodes and responds to the prompt that is provided with the response parameter and it can be useful for passing the arguments to the command. Although it uses a command parameter to run the command, it doesn’t use the shell or win_command to run the commands.

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Syntax:

Ansible Expect module uses the “command” parameter to run the command.

Ansible Expect module uses the “response” parameter to take the arguments for the input.

Other supported parameters:

chdir:

command: (Required)

The command module takes command to run.

creates:

It creates a file and if it already exists then this step won’t be executed.

echo:

Values: no (default) / yes

Whether or not to echo out your output string

responses: (required)

This parameter is to pass the series of strings or arguments to the input expected by the command parameter. You can pass the responses in the form of the string or the regex (Regular expression). If the response is a list, successive matches returns the successive responses.

timeout:

Value: 30 (Default)

Amount of the time in seconds to wait for the expected strings. Use null to disable the timeout.

How Expect works in Ansible?

Ansible “expect” command is the built-in command and installed by default with the ansible installation. The main purpose of this command to execute the command on the remote nodes using the “command” parameter and provide the required arguments to run the command using the “response” parameter.

When we use the command parameter, it doesn’t pass it through the shell but it is a separate command. If we need to specify the shell command or the cmd command then we need to specify the path of the cmd, shell, or the PowerShell to execute the command. For example, running PowerShell command will look like this,

C:WindowsSystem32WindowsPowerShellv1.0powershell.exe Read-host "Enter Username"

In the case of cmd, we can provide

C:WINDOWSsystem32cmd.exe yourcommand

Similarly, for the shell, we can provide,

When we pass the argument, we can provide the mapping of the string or the python regex in the response parameter. Case insensitive searches are indicated with a prefix of a “?i”

– response3

In the above example, the command will run from the path given, and then it responds with the series of the commands that we have provided in the responses section. In addition, you can add the various parameters to handle the errors, for example, if we need to fail the task when there are specific keywords in the output then we can use the failed_when parameter.

failed_when: condition

Examples

Let us discuss examples of Ansible Expect.

Example #1: Using the Expect command to change the MySQL database password

(?i)Enter password: “{{ mysql_password }}”

ansible-playbook expecttest.yml

The above playbook will set the MySQL password on the windows servers group.

Output:

Example #2: Expect the module to change the password on the Unix systems

(?i)password: “[email protected]$$w0rd”

The above playbook will change the password on the Unix system for the username called testusr.

Example #3: Expect a module example to install the DB server bypassing response.

ansible-playbook expecttest.yml

The above playbook will install the MySQL database with the different parameters provided and in addition

Output:

Example #4: Except module example to install the software on the windows system

ForceRestart: “yes”

The above playbook will install the software on the remote windows nodes, add the custom attributes, change the installation directory, and forcefully restart the system.

ansible-playbook expecttest.yml

Output:

Conclusion

Ansible “expect” parameter is helpful when the command requires some responses or the arguments like when we install software we need to provide certain responses like the path to install, accept software agreement, connection strings, etc which makes it easier to pass the responses that the command requires.