Python for network engineers
Published 17 September 2026
Most Python courses were written for people building software, and they teach network engineers the wrong half of the language. You do not need inheritance, decorators, or a sorting algorithm. You need to parse ugly text, fill in templates, and not break production. That list is short enough to learn in a fortnight.
What the job actually is
Nearly every network automation task is the same four steps: get text out of a device, turn it into data, make a decision, push text back. Everything else is detail.
That shape is why the usual "learn Python" path misleads. It spends weeks on class hierarchies you will never write and skips the things you will use on day one.
The six things that do the work
| Skill | Why it matters here |
|---|---|
| Strings, lists, dicts | Device output is text; everything you build turns it into dictionaries. Ninety per cent of the job. |
| Loops with error handling | You are running the same thing against 400 devices. Twelve will fail. The script must survive them. |
| Reading and writing YAML/JSON | Your inventory and your intended state live here, not in the script. |
| Jinja2 templating | Config generation. Variables in, configuration out. |
| A parsing library | TextFSM or a vendor's structured output. Do not write regex for show output. |
| Virtual environments | The difference between a script that runs anywhere and one that runs on your laptop only. |
What you can genuinely skip
- Object-oriented programming. You will consume classes
that others wrote. You will rarely write one. Understand what
.does and move on. - Algorithms and data structures. Nobody is asking you to balance a tree. You are looping over a list of switches.
- Async, threading, multiprocessing. Until you are waiting on hundreds of devices and the runtime genuinely hurts, this is premature. When it does hurt, the libraries already handle it.
- Web frameworks. A different job. Learn it if you want it, not because a course bundled it.
Regex is a trap, and there is a better way
The instinct is to regex show ip interface brief. It works on
your output, on your version, until the day a column shifts and the script
silently returns nothing, which reads as "no interfaces" rather than as an
error, and that is the dangerous kind of wrong.
Use a parser with templates other people maintain, or ask the device for structured output in the first place. Modern platforms will hand you JSON if you ask, and JSON does not move when a column does.
Regex still has a place: grabbing one value out of one line. It is a scalpel, not a parser.
The library shortlist
| Library | Use it for |
|---|---|
| Netmiko | SSH to network devices. The first thing most people learn, and rightly. |
| NAPALM | The same operations across vendors, with config diff and rollback. |
| Nornir | Inventory and concurrency in Python rather than YAML. |
| TextFSM / ntc-templates | Turning show output into dictionaries. |
| ncclient | NETCONF, when you have moved past screen-scraping. |
| Jinja2 | Config templates. Also what Ansible uses underneath. |
Learn Netmiko and Jinja2 first. They cover the majority of real tasks, and everything else makes more sense once you have felt why it exists.
The habits that separate a script from automation
- Read before you write. Your first fifty scripts should collect and report, not change anything. You build trust, and a read-only script that is wrong costs nothing.
- Make it idempotent. Running it twice must be the same as running it once. This single property is most of the difference between automation and a loop that types.
- Bound the blast radius. A device list, a dry-run switch, and a limit on how many devices one run may touch. The worst network outages of the automation era were one correct script applied confidently to everything.
- Keep credentials out of the file. Environment variables or a vault. Not the script, and not the repository.
- Version it. Git from the first script. You will want to know what changed and when, and so will the person after you.
Practising without risking anything
You do not need hardware. Containerlab and vendor images will give you a topology on a laptop, and a lab you can destroy is worth more than production you are afraid of. Practise the boring case: a device that times out, a login that fails, a command that returns nothing, because that is what breaks real runs.
Know what the output means before you parse it. A script that reads traceroute or a certificate chain is only as good as your reading of it. The traceroute asterisks piece covers a misreading that gets automated into alerting more often than any other.
Where AI fits, honestly
A model will write your first Netmiko script faster than you will, and it will write a plausible parser for output it has never seen. Both are useful and neither removes the need to read the result: the failure mode is confident, well-formatted code that is subtly wrong about your platform.
The engineers getting the most out of it are the ones who could have written it themselves and are simply faster. That is the argument for learning this at all, and it is covered further in will AI replace network engineers.