final-project-01.md

Final Project 01: Building a Generic Network Client in Go

Concept:

Creating a reusable Go package that encapsulates different network interaction methods (SSH, NETCONF, gNMI) for a generic network device.

Challenge:

Create a networkclient package with an interface (e.g., NetworkDevice) and implementations for SR Linux using SSH and gNMI. The interface should define methods like GetHostname(), SetHostname(), GetInterfaceState().

Code Example (Conceptual, building on previous days):

// networkclient/device.go
package networkclient

import "fmt"

// NetworkDevice defines the interface for interacting with a network device.
type NetworkDevice interface {
    Connect() error
    Close() error
    GetHostname() (string, error)
    SetHostname(hostname string) error
    GetInterfaceState(ifaceName string) (string, error) // Simplified state
    // Add more methods as needed (e.g., GetConfig, SetConfig, Subscribe)
}

// SRLGNMIClient implements NetworkDevice for SR Linux via gNMI
type SRLGNMIClient struct {
    // gNMI client related fields
    Target   string
    Username string
    Password string
    // grpc.ClientConn and gpb.GNMIClient
}

func (c *SRLGNMIClient) Connect() error {
    // Implement gNMI connection logic 
    fmt.Printf("Connecting to %s via gNMI...\n", c.Target)
    return nil
}
func (c *SRLGNMIClient) Close() error {
    fmt.Println("Closing gNMI connection.")
    return nil
}
func (c *SRLGNMIClient) GetHostname() (string, error) {
    fmt.Println("Getting hostname via gNMI.")
    return "example-srl-gnmi", nil // Placeholder
}
func (c *SRLGNMIClient) SetHostname(hostname string) error {
    fmt.Printf("Setting hostname to %s via gNMI.\n", hostname)
    return nil
}
func (c *SRLGNMIClient) GetInterfaceState(ifaceName string) (string, error) {
    fmt.Printf("Getting state for %s via gNMI.\n", ifaceName)
    return "up", nil // Placeholder
}

// SRLSSHClient implements NetworkDevice for SR Linux via SSH
type SRLSSHClient struct {
    // SSH client related fields
    Target   string
    Username string
    Password string
    // golang.org/x/crypto/ssh.Client
}

func (c *SRLSSHClient) Connect() error {
    // Implement SSH connection logic from Day 7/8
    fmt.Printf("Connecting to %s via SSH...\n", c.Target)
    return nil
}
func (c *SRLSSHClient) Close() error {
    fmt.Println("Closing SSH connection.")
    return nil
}
func (c *SRLSSHClient) GetHostname() (string, error) {
    fmt.Println("Getting hostname via SSH.")
    return "example-srl-ssh", nil // Placeholder
}
func (c *SRLSSHClient) SetHostname(hostname string) error {
    fmt.Printf("Setting hostname to %s via SSH.\n", hostname)
    return nil
}
func (c *SRLSSHClient) GetInterfaceState(ifaceName string) (string, error) {
    fmt.Printf("Getting state for %s via SSH.\n", ifaceName)
    return "up", nil // Placeholder
}


// main.go
package main

import (
    "fmt"
    "log"
    "day18/networkclient" // Assuming module name is day18
)

func main() {
    // Using the gNMI client implementation
    gnmiClient := &networkclient.SRLGNMIClient{
        Target: "clab-srl-2-nodes-srl1:57400",
        Username: "admin",
        Password: "NokiaSrl1!",
    }
    if err := gnmiClient.Connect(); err != nil {
        log.Fatalf("Error connecting via gNMI: %v", err)
    }
    defer gnmiClient.Close()

    hostname, err := gnmiClient.GetHostname()
    if err != nil {
        log.Printf("Error getting hostname: %v", err)
    } else {
        fmt.Printf("Hostname (gNMI): %s\n", hostname)
    }
    gnmiClient.SetHostname("new-srl-gnmi-host")

    fmt.Println()

    // Using the SSH client implementation
    sshClient := &networkclient.SRLSSHClient{
        Target: "clab-srl-2-nodes-srl1:22",
        Username: "admin",
        Password: "NokiaSrl1!",
    }
    if err := sshClient.Connect(); err != nil {
        log.Fatalf("Error connecting via SSH: %v", err)
    }
    defer sshClient.Close()

    hostname, err = sshClient.GetHostname()
    if err != nil {
        log.Printf("Error getting hostname: %v", err)
    } else {
        fmt.Printf("Hostname (SSH): %s\n", hostname)
    }
    sshClient.SetHostname("new-srl-ssh-host")
}

Instructions:

1. Create a directory final.
2. Inside final, create a directory networkclient.
3. Save the first code block as networkclient/device.go.
4. Save the second code block as main.go in the day18 directory.
5. Run go mod init final.
6. Run go run main.go.

Assignment

• Create a working network client based on the given Code ** **The Connect, GetHostname, etc., methods are placeholders and need to be fully implemented using the SSH and gNMI libraries from previous challenges for a functional client