Using Jinja Variable Data

Teflo uses Jinja2 template engine to be able to template variables within a scenario file. Teflo allows template variable data to be set as environmental variables as well as pass variable data via command line.

You can also store the variable data in a file and provide the file path in teflo.cfg

Here is an example scenario file using Jinja to template some variable data:

---

name: linchpin_vars_example
description: template example

provision:
  - name: db2_dummy
    provisioner: linchpin-wrapper
    groups: example
    credential: openstack
    resource_group_type: openstack
    resource_definitions:
      - name: {{ name | default('database') }}
        role: os_server
        flavor: {{ flavor | default('m1.small') }}
        image:  rhel-7.5-server-x86_64-released
        count: {{ count | default('1') }}
        keypair: test-keypair
        networks:
          - {{ networks | default('provider_net_ipv6_only') }}

The variable data can now be passed in one of three ways.

Raw JSON

You can pass in the data raw as a JSON dictionary

teflo run -s scenario.yml -t provision --vars-data '{"flavor": "m2.small", "name": "test"}'

teflo run -s scenario.yml -t provision --vars-data '{"flavor": "m2.small", "name": "test"}'
--vars-data '{"count": "2"}'

Variable File

You can pass in a variable file in yaml format defining the variable data you need. The variable file needs to be placed in the teflo workspace as var_file.yml or as yaml files under vars directory

User can also set var_file as a parameter in the defaults section of teflo.cfg. This way user can avoid passing variable data via command line at every run

Following is the precedence of how Teflo looks for variable data:

1. Via command line

2. defaults section of teflo.cfg

3. var_file.yml under the teflo workspace

4. yml files under the directory vars under teflo workspace

Below is an example of the contents of a variable file template_file.yaml.

---
flavor: m2.small
networks: provider_net_cci_5
name: test

You can pass in the variable file directly

teflo run -s scenario.yml -t provision --vars-data template_file.yml --vars-data '{"count": "2"}'

If using teflo.cfg this can be set as below. The var_file param can be a path to the variable file or path to the directory where the variable file is stored. If Teflo identifies it a directory then recursively it looks for all files with .yml or .yaml extension within that directory.

[defaults]
var_file=~/template_file.yml

[defaults]
var_file=~/var_dir

The above example will look like

teflo run -s scenario.yml -t provision

Directory with multiple .yml files

You can pass in a directory path containing multiple .yml files. The code will look for files ending with ‘.yml’

teflo run -s scenario.yml -t provision --vars-data ~/files_dir
--vars-data '{"count": "2", "key": "val"}'

Nested Variable Usage

Currently teflo supports nested variable using any of above methods

Note: The nested variable can only be string after parsing

For example:

A nested variable can look like below:

1. nested_var: “hello”

2. nested_var: {{ hey }}

3. nested_var: “hello{{ hey }}”

You can

1. Use multiple layer nested vars

   name: {{ hello }}
   hello: {{ world }}
   world: {{ Hey }}
   Hey: "I'm a developer"
   

2. Use multiple nested variables inside one filed

   name: "{{ hello }} {{ world }}"
   hello: "asd"
   world: {{ Hey }}
   Hey: "I'm a developer"
   

3. Use nested variable in a list or dict

   name:
       Tom: {{ TomName }}
       Jack: {{ JackName }}
   TomName: "Tom Biden"
   JackName: "Jack Chen"
   adress:
       - {{ street }}
       - {{ city }}
       - {{ state }}
   street: "Boston Street"
   city: "Boston"
   state: "Massachusetts"
   

Note

TEFLO_DATA_FOLDER , TEFLO_RESULTS_FOLDER and TEFLO_WORKSPACE are TEFLO

environmental variables that are made available during a teflo run, which can be used in scripts and playbooks. They provide the absolute path for teflo’s data folder, results folder and workspace respectively