How to Convert YAML to CSV (3 Ways)

Published 2026-09-072 min readCopy link

Config lives in YAML, spreadsheets live in CSV. Sooner or later someone asks you for the Kubernetes inventory, the Docker Compose service list or the Ansible host vars as a spreadsheet. Here's how to get there without mangling the data.

Method 1: CLI Tools

Using transmute

$ cat services.yaml | qf --to csv
name,image,replicas
web,nginx:latest,3
api,node:20,2

qf auto-detects YAML on input, takes the top-level list of objects (or a named key containing one) and emits proper CSV headers. Nested maps are flattened with dot notation (resources.limits.cpu becomes its own column).

Using yq

$ yq -o=json eval services.yaml | jq -r '(.[0] | keys_unsorted) as $cols | $cols, .[] | [.[$cols[]]] | @csv'

There's no direct YAML→CSV path in yq, so this pipes through JSON and jq. It works, but it's two tools and a cryptic filter.

Method 2: Python (stdlib + PyYAML)

import yaml, csv, sys
data = yaml.safe_load(open("services.yaml"))
rows = data["services"] if isinstance(data, dict) else data
with open("out.csv", "w", newline="") as f:
    w = csv.DictWriter(f, fieldnames=rows[0].keys())
    w.writeheader()
    w.writerows(rows)

Fine for a one-off — but note it assumes flat rows. Nested values will serialize as Python dicts unless you flatten them first.

Method 3: Free Online Converter

Paste YAML into the browser converter and copy CSV out. It runs entirely client-side, so cluster names and internal hostnames never leave your machine.

The Hard Part: Lists of Lists

Reality check: YAML can express arbitrarily deep nesting; CSV is one flat table. Ports lists, volume mounts, environment maps — each needs a decision: join into one cell (8080|8443), repeat the parent row, or split into a second sheet. No tool makes that choice correctly for you, because it depends on what the reader wants.

• One-off: free web converter.
• Scripts/CI: Transmute CLI — pipe in, pipe out.
• Weekly spreadsheet requests: Transmute Desktop — $19 one-time.