Is there an easy way to generate a graph of Ansible role dependencies?

Question

Since version 1.3, Ansible has supported role dependencies to encourage reuse of role definitions. To audit and maintain larger orchestrations, it would be nice to have some way to easily generate a dependency graph of which roles depend on which other roles.

An example of dependency definitions might be roles/app_node/meta/main.yml:

---
dependencies:
  - { role: common, some_parameter: 3 }
  - { role: apache, port: 80 }
  - { role: postgres_client, 
      dbname: blarg, 
      other_parameter: 12 }

where roles/postgres_client/meta/main.yml might include something like

---
dependencies:
  - { role: postgres_common }
  - { role: stunnel, 
      client: yes,
      local_port: 5432
      remote_host: db_host
      remote_port: 15432 
    }

Such nested dependencies can get messy to maintain when the number of roles in an orchestration grows. I therefore wonder if anyone has found an easy way to generate a graph of such dependencies, either graphically (dot or neato?) or just as an indented text graph? Such a tool could help reduce the maintenance complexity.

score 4 · Accepted Answer · edited Jun 24 '16 at 07:08

4

The following python script worked for me:

#!/usr/bin/env python

import sys
import gv
from glob import glob
import yaml

g = gv.digraph('roles')

role_nodes = {}

def add_role(role):
    if role not in role_nodes:
        role_nodes[role] = gv.node(g, role)

def link_roles(dependent, depended):
    gv.edge(
        role_nodes[dependent_role],
        role_nodes[depended_role]
    )

for path in glob('roles/*/meta/main.yml'):
    dependent_role = path.split('/')[1]

    add_role(dependent_role)

    with open(path, 'r') as f:
        for dependency in yaml.load(f.read())['dependencies']:
            depended_role = dependency['role']

            add_role(depended_role)
            link_roles(dependent_role, depended_role)

gv.layout(g, 'dot')
gv.render(g, 'png', 'doc/ansible-roles.png')

edited Jun 24 '16 at 07:08

Ikar Pohorský

4,617
6
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answered Dec 03 '15 at 22:44

sebn

64
2

This answer could be improved by explaining _how_ it addresses the problem stated in the question. – Dec 03 '15 at 23:07
Running: "ImportError: No module named gv". pip install gv: "No distributions at all found for gv" – Travis Bear May 04 '16 at 16:03
2

@TravisBear The `gv` module is part of Graphviz, it is not distributed on PyPI. You can install it using the package manager of your linux distribution (apt, yum...). Package name may be something like `graphviz-python` or `python-graphviz`. – sebn May 08 '16 at 07:15
1

I've made an [alternative version](https://gist.github.com/sboisson/472c6af5c7e15bc24114b13f11456190) using [graphviz](https://pypi.org/project/graphviz/) python package – Le Hibou Jun 30 '20 at 11:29

score 1 · Answer 2 · answered May 16 '14 at 14:45

1

You can use Graphviz to do this like the ginas project has.

answered May 16 '14 at 14:45

ghr

647
4
16

score 0 · Answer 3 · edited Feb 04 '21 at 14:48

0

# install gv on ubuntu
sudo apt-get install python3-gv

edited Feb 04 '21 at 14:48

Suraj Rao

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answered Feb 04 '21 at 14:45

Mary Ciricean

84
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1

This answer could be improved by showing how `python-gv` answers OP's problem. – zkoza Feb 04 '21 at 20:48
I think this should actually just be added to sebn's answer. It seems to be the missing piece for most of those who don't get how to install `gv`. – Martin Thorsen Ranang Feb 04 '21 at 21:56

Is there an easy way to generate a graph of Ansible role dependencies?

3 Answers3