Parsing and Extracting from Junos Configurations - Python

Question

I am parsing Junos configurations stored in text files generated by RANCID. For convenience in my dev case, some of the interesting configuration hierarchies are stored in a variable in the script.

My specific requirement is to collect the physical interface, its associated units, and each unit's associated IPv4 & IPv6 IP addresses.

ChatGPT and I have worked it to some degree but I have hit a roadblock and I'm asking for help.

The current script nests a list into a nested dict of an outer dict. Outer: interfaces_physical Middle: interfaces_unit Inner list: ips / ip_address

The script is close but duplicates entries in output. I need to more tightly bind the physical, unit, and addresses with each other to prevent the duplication. I believe this is just a loop formatting issue, but I'm out of my depth. I appreciate any help you can offer.

Example Broken Output:

Interfaces {
    xe-0/0/8 {
        unit 4 {
                address 1.1.1.0/31;

    xe-0/0/8 {
        unit 4 {
                address 2.2.2.1/25;

Interfaces {
    irb {
        unit 10 {
                address 2.2.2.1/25;

    irb {
        unit 10 {
                address 5.5.5.1/26;

    irb {
        unit 10 {
                address 3.3.3.1/26;

---

#!/usr/bin/env python3
import re

config = """
interfaces {
    xe-0/0/8 {
        description "AGG BACKBONE: to asdf.fdas xe-0/0/17 | 10GE-13434 [PENDING]";
        vlan-tagging;
        mtu 9192;
        encapsulation flexible-ethernet-services;
        unit 4 {
            description "NAT64 to asdf.fdas xe-0/0/17 | NW | VLAN-3435 [PENDING]";
            vlan-id 4;
            family inet {
                mtu 9000;
                address 1.1.1.0/31;
            }
        }
    }
    irb {
        unit 10 {
            description "RACKLAN: DENV Racklan | VLAN-03827";
            family inet {
                address 2.2.2.1/25;
            }
        }
        unit 11 {
            description "Management | MANAGEMENT | MGMT | @SID@ [NO-MONITOR]";
            family inet {
                mtu 1500;
                address 5.5.5.1/26;
            }
        }
        unit 60 {
            description "Service Gateway | 1G-Service | default | @SID@ [NO-MONITOR]";
            family inet {
                address 3.3.3.1/26;
            }
        }
        unit 3903 {
            description "TIC_3903 | NWAVE | VLAN-04251";
            family inet {
                mtu 9000;
                filter {
                    input SAMPLE_AND_MIRROR_OUT_XCPT;
                    output SAMPLE_AND_MIRROR_OUT_XCPT;
                }
                address 4.4.4.2/31;
            }
            family inet6 {
                inactive: filter {
                    input MIRROR6;
                    output MIRROR6;
                }
                address 2610:0:0:1::1/64;
            }
        }
    }
    lo0 {
        unit 0 {
            family inet {
                filter {
                    input 20180626_LOOPBACK_IPV4;
                }
                address 5.5.5.1/32;
            }
            family iso {
                address 49.0002.0050.0500.5001.00;
            }
            family inet6 {
                filter {
                    input 20161130_LOOPBACK_IPV6;
                }
                address 2610:0:0::30/128;
            }
        }
    ae2 {
        apply-groups INTERFACE_LAG_DEFAULTS;
        description "asdf.asfd | LAG-04250";
        flexible-vlan-tagging;
        mtu 9192;
        encapsulation flexible-ethernet-services;
        unit 3903 {
            description "qwr.rewq | 3903 | VLAN-04251";
            encapsulation vlan-bridge;
            vlan-id 3903;
        }
        unit 3904 {
            description "qwer.rewq | 3904 | VLAN-04252";
            encapsulation vlan-bridge;
            vlan-id 3904;
        }
    }
    ae3 {
        description "qwer.zxcv | LAG-04672";
        mtu 9192;
        unit 0 {
            description "dfgh.asdf | default VLAN-04673";
            family inet {
                mtu 9000;
                address 10.174.4.21/30 {
                    arp 10.174.4.22 mac 00:01:02:03:04:08;
                }
            }
            family inet6 {
                mtu 9000;
                address fc00::3/127 {
                    ndp fc00::2 mac 00:01:02:03:04:08;
                }
            }
        }
    }
"""

interfaces_physical = re.compile(r"^\ {4}[gaxeli]r?[oetb].*$\n", re.MULTILINE)
interfaces_unit = re.compile(r"^\ {8}unit.*$\n", re.MULTILINE)
ip_address = re.compile(r"(^\ {16}address.*$\n)", re.MULTILINE)

interfaces = {}

for match in interfaces_physical.finditer(config):
    interface = match.group()
    interfaces[interface] = {}
    for match in interfaces_unit.finditer(config, match.start()):
        unit = match.group()
        ips = [m.group(1) for m in ip_address.finditer(config, match.start())]
        interfaces[interface][unit] = ips

for k1, v1 in interfaces.items():
    for k2, v2 in v1.items():
        for ipaddr in v2:
            print("{}{}{}".format(k1, k2, ipaddr))
    print("Interfaces {")