Topics which will be covered:
- preparation of Ansible files for config generation (Jinja2 template, playbook, inventory, files with variables)
- preparation of Docker container with Ansible installed
Prerequisites:- Docker container environment (Docker host needs to have Internet access)
Scenario for which configuration files will be generated:
Two datacenters are present:
- DatacenterA
- DatacenterB
Configuration which should be present on every device, regardless in which datacenter device is located:
- vlan 1 and vlan 2
- L2 interfaces ethernet3 and ethernet4 configured for tagged traffic ('switchport mode trunk' command)
Configuration specific to datacenter (every device in specific datacenter should have that settings applied):
- ntp server IP (10.10.10.10 for DatacenterA, 192.168.10.10 for DatacenterB)
- presence of specific vlan (vlan 10 in DatacenterA, vlan 20 in DatacenterB)
Configuration specific for each device:
- IP addresses on L3 interfaces
One device is present in each datacenter:
- DatacenterA_Device01
- DatacenterB_Device01
2. Files and folders
Directory and file structure which need to be prepared prior to building container:
| [test@localhost for_docker]$ tree -f -i . ./ansible_template ./ansible_template/Dockerfile ./ansible_template/src ./ansible_template/src/configs ./ansible_template/src/config_template.j2 ./ansible_template/src/generate_config_playbook.yaml ./ansible_template/src/group_vars ./ansible_template/src/group_vars/all ./ansible_template/src/group_vars/DatacenterA ./ansible_template/src/group_vars/DatacenterA/DatacenterA ./ansible_template/src/group_vars/DatacenterB ./ansible_template/src/group_vars/DatacenterB/DatacenterB ./ansible_template/src/host_vars ./ansible_template/src/host_vars/DatacenterA_Device01 ./ansible_template/src/host_vars/DatacenterB_Device01 ./ansible_template/src/inventory 7 directories, 9 files |
Content of file "Dockerfile" (file used for building container):
| [test@localhost ansible_template]$ cat Dockerfile FROM centos:centos7 RUN yum -y update; yum clean all RUN yum -y install epel-release; yum clean all RUN yum -y install gcc python python-devel python-pip openssh-clients ; yum clean all RUN pip install --upgrade pip RUN pip install ansible RUN mkdir /config_generation COPY ./src/ /config_generation/ WORKDIR config_generation CMD ["sleep","10000000"] |
Content of file "config_template.j2" (Jinja2 template used for building configuration file):
| [test@localhost src]$ cat config_template.j2 hostname {{ inventory_hostname }} ntp server {{ ntp_server }} {% for vlan in vlans %} vlan {{ vlan.id }} name {{ vlan.name }} {% endfor %} {% for vlan in common_vlans %} vlan {{ vlan.id }} name {{ vlan.name }} {% endfor %} {% for interface in L3_interfaces %} interface {{ interface.name }} description L3 interface address {{ interface.address }} {% endfor %} {% for interface in L2_tagged_interfaces %} interface {{ interface.name }} description L2 tagged interface, all vlans allowed switchport mode trunk {% endfor %} |
Content of file "generate_config_playbook.yaml" (Ansible playbook for building configuration file based on template):
| [test@localhost src]$ cat generate_config_playbook.yaml - name: Generate configuration from template hosts: all gather_facts: no connection: local tasks: - name: Config file generation example template: src: ./config_template.j2 dest: ./configs/{{ inventory_hostname}}_config.txt |
Content of file "inventory":
| [test@localhost src]$ cat inventory [all] DatacenterA_Device01 DatacenterB_Device01 [DatacenterA] DatacenterA_Device01 [DatacenterB] DatacenterB_Device01 |
Content of file "all" (variables common for every device regardless of datacenter):
| [test@localhost group_vars]$ cat all common_vlans: - id: 1 name: common vlan which is present in both datacenters - id: 2 name: common vlan which is present in both datacenters L2_tagged_interfaces: - name: ethernet3 - name: ethernet4 |
Content of file "DatacenterA" (variables for devices in DatacenterA):
| [test@localhost DatacenterA]$ cat DatacenterA ntp_server: 10.10.10.10 vlans: - id: 10 name: specific vlan for DatacenterA |
Content of file "DatacenterB" (variables for devices in DatacenterB):
| [test@localhost DatacenterB]$ cat DatacenterB ntp_server: 192.168.10.10 vlans: - id: 20 name: specific vlan for DatacenterB |
Content of file "DatacenterA_Device01" (variables for specific device DatacenterA_Device01):
| [test@localhost host_vars]$ cat DatacenterA_Device01 L3_interfaces: - name: ethernet1 address: 10.1.1.1 255.255.255.0 - name: ethernet2 address: 10.1.2.1 255.255.255.0 |
Content of file "DatacenterB_Device01" (variables for specific device DatacenterB_Device01):
| [test@localhost host_vars]$ cat DatacenterB_Device01 L3_interfaces: - name: ethernet1 address: 192.168.1.1 255.255.255.0 - name: ethernet2 address: 192.168.2.1 255.255.255.0 |
3. Preparing docker container
Next docker image with Ansible will be build. Command need to be executed from within prepared folder "ansible_template" .
sudo docker build -f Dockerfile -t "ansible_template" .
When docker image is ready, docker container can be launched:
sudo docker run -d -t ansible_template
Command for retrieving id of launched docker container:
sudo docker ps
Command for accessing shell of launched container (value of container_id, need to be retrieved using "sudo docker ps" command):
sudo docker exec -i -t container_id /bin/bash
Command for running ansible playbook from within prepared container (command need to be run from folder /config_generation, generated configuration files will be placed in folder /config_generation/configs )
ansible-playbook generate_config_playbook.yaml -i inventory
Example output:
Configuration generation:
Generated configuration file for device DatacenterA_Device01:
Generated configuration file for device DatacenterB_Device01:
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