Parse docker-compose.yml with yq to generate documentation - docker-compose

Question

I'm trying to parse my docker-compose file using yq (the go implementation from https://github.com/mikefarah/yq) to auto-generate a documentation using asciidoc.
My docker-compose.yml looks fairly simple and does nothing out of the ordinary:
---
version: "3.3"
services:
# prometheus metrics
node_exporter:
image: prom/node-exporter:latest
container_name: node_exporter
labels:
description: Prometheus exporter to monitor system metrics
restart: always
command:
- --path.rootfs=/host
pid: host
network_mode: host
# ports:
# - 9100:9100
# The network_mode: host tells docker to run the container as if it was running on the
# server itself, so all ports exports by the container will directly be mapped to the server.
volumes:
- /:/host:ro,rslave
- /etc/timezone:/etc/timezone:ro
# prometheus metrics
cadvisor:
image: gcr.io/cadvisor/cadvisor:latest
container_name: cadvisor
restart: always
expose:
- 9110
ports:
- 9110:8080
volumes:
- /:/rootfs:ro
- /var/run:/var/run:rw
- /sys:/sys:ro
- /var/lib/docker/:/var/lib/docker:ro
# Mange containers
portainer:
image: portainer/portainer-ce:alpine
container_name: portainer
command: -H unix:///var/run/docker.sock --admin-password-file /tmp/portainer_passwords
restart: always
ports:
- 9990:9000
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- portainer_data:/data
- ./assets/portainer.passwd:/tmp/portainer_passwords
- /etc/timezone:/etc/timezone:ro
volumes:
portainer_data:
I want some information for each service. Most important to me is the image. container name restart and ports. Plus maybe labels -> description which is a field I use for some documentation (what does the respective service actually do).
I don't know how I can get these fields for the respective service combined. When I run yq eval '.services.[] | .container_name, .services.[] | .image' $composeFile I first get 3 lines with the container name and then 3 lines with the image.
node_exporter
cadvisor
portainer
prom/node-exporter:latest
gcr.io/cadvisor/cadvisor:latest
portainer/portainer-ce:alpine
This result is not grouped by service. I'd prefer something like this:
node_exporter
prom/node-exporter:latest
cadvisor
gcr.io/cadvisor/cadvisor:latest
portainer
portainer/portainer-ce:alpine
Or since I want to generate asciidoc,the perfect solution would be this:
|node_exporter |prom/node-exporter:latest
|cadvisor |gcr.io/cadvisor/cadvisor:latest
|portainer |portainer/portainer-ce:alpine
This way I can generate the body of an asciidoc table with information on my services for my documentation.
Anyone got an idea how I can get yq to work as I indend?

Answer 1

Each .services.[] starts a new iteration. Do it once and extract all you need from there:
yq eval '.services.[] | "|" + .container_name + "| " + .image'
|node_exporter| prom/node-exporter:latest
|cadvisor| gcr.io/cadvisor/cadvisor:latest
|portainer| portainer/portainer-ce:alpine