Fabric Module in Python

Linux users must do a variety of administrative and general duties regularly, such as reloading the apache server after making any changes, developing and deploying new applications, accessing certain log files, and so on. To do these operations regularly, SSH (Secure Shell) is necessary. Fabric is a useful Python module that works with SSH and the operating system to automate a variety of application development and administration activities. This command-line program is basic and straightforward to use. This article demonstrates how to install and utilize the fabric library in Python 3+.

It extends the APIs of Invoke (subprocess command execution and command-line features) and Paramiko (SSH protocol implementation), complementing and providing extra capabilities. The project's maintainer keeps a roadmap. Fabric's project information, such as the changelog and contribution requirements, is available on official website. The code documentation site, docs.fabfile.org, has extensive use and API documentation.

The paramiko is a library that allows you to do basic or lower-level ssh tasks. Fabric is a library that uses paramiko internally to execute various higher-level tasks (for ssh purposes). In a nutshell, if all you want to do is ssh, use paramiko; if you want to do a lot more, such as running a configuration, installing something on the server, or deploying code, use fabric script. It will make your life easier by requiring you to write fewer lines of code than if you used paramiko directly. (and don't worry, because paramiko is used internally by fabric).

Through an imported library, Paramiko simply provides an easy method to utilize SSH in Python. The fabric enables you to create a "fabfile" and perform various actions that are programmed into it. This may be anything you want it to be. For example, on my PC, I have a fabfile that links to the personal server, CDs into the proper directory, pull the git branch in, transfers different config files to the correct places (uwsgi, Nginx), and restarts the appropriate services. As a consequence, I can push the latest version of my site online with a single command on my local PC. The fabric also makes use of Paramiko as a dependency.

Now we know that the fabric library uses the paramiko module internally let us look at the paramiko module of the python library.

The creation of an SSHClient object is the first step in the high-level client API. Pass a socket (or socket-like object) to a Transport for more direct control, then use start server or start client to negotiate with the remote host as a server or client. As a client, you are responsible for verifying the server's host key and authenticating using a password or private key. (Paramiko handles key signature and verification, but you'll need to provide private keys and double-check that the content of a public key matches what you intended.) You, as the server, are in charge of determining which users, passwords, and keys to accept, as well as which channels to enable. After you've completed it, any party might ask for flow-controlled channels.

Now let us look at the code of the usage of the fabric module in Python::

Code::

Output:

nirnay@superbook:~$ python3 fabfile.py 
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
1
primary
All dirs listed successfully.
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
2
Enter the name of the directory that you want to create
mydir
mydir directory created successfully.
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
1
mydir
primary
All dirs listed successfully.
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
3
Enter the name of the directory to which you want to move
mydir
/home/client/Desktop/mydir
directory changed successfully
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
4
Enter the name of the directory in which you want to create files
mydir
Files were created successfully in the media directory.
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
5
Enter the name of the directory in which you want to list files
mydir
files1
files10
files11
files12
files13
files14
files15
files2
files3
files4
files5
files6
files7
files8
files9
Files are listed successfully in the mydir directory.
To move ahead with code execution enter [y] else [n]
y
Select any one of the fab operations you want to do::
1. To list all directories which are present.
2. To create a new directory.
3. To move to another directory.
4. To create files in a specific directory.
5. To list all the files inside a directory.
6. To display the files and dirs in tree mode.
7. To exit from the code execution.
6
.
|-- mydir
|   |-- files1
|   |-- files10
|   |-- files11
|   |-- files12
|   |-- files13
|   |-- files14
|   |-- files15
|   |-- files2
|   |-- files3
|   |-- files4
|   |-- files5
|   |-- files6
|   |-- files7
|   |-- files8
|   `-- files9
`-- primary

2 directories, 15 files
All dirs and files are listed successfully.
To move ahead with code execution enter [y] else [n]
n

Conclusion:

In the above-written code, we have used the fabric module of python to perform various operations on the remote site server these corporations are initiated from the client machine and every time a particular operation is triggered a secure connection between the remote site server and the client machine is established and after the successful establishment of the connection between the remote site server and the client machine with the use of fabric functions the specific operation is performed. the various operations which are performed are to list all the directories that are present inside a directory, to create a new directory, to list all the files that are present in a particular directory, to create new files a set of new files inside a directory, to change the current working directory of the code execution, and to list all the files and directories that are present inside a particular directory in a recursive manner that means the files or directories inside a directory which itself is present inside a directory are also listed in this method. And for all these operations there are separate functions that are written that perform the specified operation. In each method, first of all, a secure connection between the server-side and the client machine is established and for the establishment of the secure connection between the server and the client the inbuilt functions of the fabric module are used, once the connection is established the specified operation is performed for example if the user has selected to create a new directory inside a particular directory the user will be prompted to enter the name of the new directory that he wants to create, on entering the name of the directory which need to be created the create directory operation is performed and once the directory is successfully created similar message is prompted to the user. Similarly, if the user selects the option to list all the directories inside a particular directory the user is prompted to enter the name of the directory from which we want to list the children directories, on entering the name of the parent directory all the children directories present inside the directory are listed. Similarly whatever the option the user selects the user is asked for the relevant input if it is required and that particular operation is performed on the server and whatever the result is generated as the output is displayed to the user. so the user is prompted with the number of functions or options that are methods to perform different operations on the remote site server the user can select any one of them and perform the specific operation this options menu keeps on getting printed to perform various options if the user wants to exit the code execution he can select the last option with the help of which the user can exit the execution of the current code.

Advantages of Fabric Module in Python:

Now let us discuss some of the major advantages of the Fabric Module in Python that make it a very powerful and popular choice among the developers for automating a list of tasks that needs to be done repeatedly on the remote server that are prerequisites for various configurations of the applications.

• Given that Fabric is a Python library, any Python command (or method) and module can be used with it out of the box. Fabric's main value is its vast and superb interaction with SSH, which allows you to automate everything with simple scripts (i.e. fabfile.py). This section contains a list of Fabric tools (such as functions) that may be used to interface with environments where commands you express are executed.
• Deploying an application (whether it's a website, an API, or a server) usually entails starting from scratch (or from a snapshot), updating everything, downloading dependencies, setting up the file structure and permissions, and finally uploading your codebase - or downloading it using a version control system like Git. You'll probably have instructions that need to be run regularly during the development phase (ex: right before entering a deployment cycle).
• Being able to script these processes (both local and remote) in a logically ordered and - most importantly - programmable manner quickly becomes beneficial once you realize how much time is wasted repeatedly repeating the same steps, making everything error-prone in the process. Fabric comes to your rescue in the shape of a Python file that knows exactly what to do and where to do it.
• Things that appear mysterious will rapidly become familiar once you start working with your droplet (which is a fully virtualized server with complete management and access). It's only natural to expect some challenges as you launch your applications and begin dealing with their maintenance. However, as your application becomes more popular and things begin to expand, the necessity to manage several droplets and repeat everything ceases to be enjoyable.
• A single Fabric script (fabfile), as we indicated in the beginning, can be used to conduct activities on both the local machine and the distant system (s). Fabric offers the local operative the ability to run commands locally for this purpose.
• However, unlike run or sudo, there is no ability to interact with the output of local in the same way. The switch can be configured with the capture argument to capture or print either output. Local helpers, such as the lcd context manager (which sets the local working directory), are honored in the same manner as run (or sudo) honors the cd context manager.

So in this article, we have seen how we can use the fabric module in Python to connect to a remote server and perform various operations on that remote server, the main use case of the fabric module is seen in the scenarios where a system administrator or network controller needs to manage several client machines having different configurations and requirement throughout the organization in this scenario the network administrator for this system administrator can use the fabric module of the python to easily automate the job of installing and configuring various system configurations and setting files easily with the help of simple python code. Similarly, we have seen in this example how we can perform various operations on the remote site server easily just with the help of a simple python script. These functions can perform simple to simple as well as complex tasks.