在Python中借用Jinja2模板时如何遍历YAML列表/字典项

Question

I seem to get stuck either with code or concept and need some help in iterating through YAML based dict/list while rendering Jinja2 Template in Python. I am a bit new in programming (3 weeks) so apologies in advance for any blunders.

For instance I have the following dictionary defined in YAML.

---
- hostname: R1
  interfaces:
    - name: f0/0
      description: This is FastEth 0/0 connected to R2 FastEth 0/0
    - name: f0/1
      description: This is FastEth 0/1 connected to Local Host Loopback
- hostname: R2
  interfaces:
    - name: f0/0
      description: This is FastEth 0/0 connected to R2 FastEth 0/0
    - name: f0/1
      description: This is FastEth 0/1 connected to Local Host Loopback

and the following is the Jinja Template I am rendering:

{% for iface in config.interfaces %}
int {{ config.name }}
description {{ config.description }}
{% endfor %}

.... I have two routers R1 and R2 on which I want to send the rendered configs based on their dictionaries only. I want to generate two config sets, one for each router. Hence I thought of doing this is Python but with no luck.

env = Environment(loader=FileSystemLoader('./templates'),trim_blocks=True)
with open('./YAML/configuration.yml') as _:
    config_commands_var = yaml.load(_)

for device in range(len(devices)):
    print "\nStart time: " + str(datetime.now())
    username = devices[device]['username']
    password = devices[device]['password']
    ip = devices[device]['ip']
    device_type = devices[device]['device_type']
    secret = devices[device]['secret']
    hostname = devices[device]['hostname']

    config_commands = template.render(config=config_commands_var)
    push_config_commands(username, password, ip, device_type, secret, config_commands)

Here "devices" is a list of dictionaries of devices. and "push_config_commands" function send list of commands at once to any device.

I hope to really get my problem solved here, so will appreciate any sort of help. Thanks in advance.

Answer 1

I think I got it working. However any suggestions are still welcomed.

Changed the YAML file as:

---
interfaces:
  R1:
    f0/0:
      description: This is FastEth 0/0 connected to R2 FastEth 0/0
    f0/1:
      description: This is FastEth 0/1 connected to Local Host Loopback
  R2:
    f0/0:
      description: This is FastEth 0/0 connected to R2 FastEth 0/0
    f0/1:
      description: This is FastEth 0/1 connected to Local Host Loopback

I changed the template as:

{% for iface in config %}
interface {{ iface }}
description {{ config[iface]['description'] }}
{% endfor %}

and while rendering I passed keys to look at:

config_commands = template.render(config=config_commands_var['interfaces'][hostname])

Any improvements are more than welcomed.

Thanks.