Ansible variable inside variable.

 Lets assume there is a json with following structure

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
{
    "dev":{
      "app_1":{
          "key":"element",
          "value":"somevalue"
      },
      "app_2":{
          "key":"element",
          "value":"somevalue"
      }  
    },
    "test":{
        "app_1":{
          "key":"element",
          "value":"somevalue"
      },
      "app_2":{
          "key":"element",
          "value":"somevalue"
      }  
    },
    "production":{
        "app_1":{
          "key":"element",
          "value":"somevalue"
      },
      "app_2":{
          "key":"element",
          "value":"somevalue"
      }  
    }
}

From this json we have to extract values using the Ansible. As you see "key" and "value" fields are constant and we have variable environment ("dev", "app", "production") and app name ("app_1", "app_2")

We have an Ansible playbook where we have "Environment" and "Application Name" as part of arguments, where we have to read the respective values from the above JSON.

Let's assume that JSON is downloaded from somewhere. In this sample, we are saving ourselves from that complexity. 


- name: My Play
  vars:
    ENVIRONMENT: '{{ environment}} '
    APP_NAME: '{{ app }}'
  tasks:  
    - name: 'My Play - Variable defination and validation'
      block: 
        - name: downaloading Environment data file and setting data into variable
          set_fact:
             my_json_data: "somehow get the data"  
        - name: "Read data from JSON"
          set_fact:
             key_name: "{{ my_json_data[ENVIRONMENT][APP_NAME].key }}"
             value: "{{ my_json_data[ENVIRONMENT][APP_NAME].value}}"
        - name: Print
          debug:
            msg: '{{key_name}} --- {{ value }}'

We see that to fetch information from JSON file we have to mention "my_json_data" which itself is a variable. If we try to concatenate the variable, it gets converted into a string and cannot be used, to fetch data from JSON. 

The best way to solve this problem is {{ my_json_data[ENVIRONMENT][APP_NAME].key }}


Comments

Post a Comment

Popular posts from this blog

Caused by: java.sql.SQLTimeoutException: ORA-01013: user requested cancel of current operation

Many times we encounter this error and think that there might be some JPA issue or network issue. However, the error is pretty explicit in its nature, but still not clear to ring the bell very first time. As the error says there is a timeout, and since Oracle is saying, we shall accept it. Another clue is "user requested cancel of current operation". This means that the connection was closed by the application server not the database server, hence it can be safely concluded that application has configured timeouts on transactions at its end. However, if you feel that this transaction should have been concluded within the application server limits, your doubt might be true. This problem can arise in case there is a lock on the record being updated by JPA or lock on the table in which JPA is attempting to insert. The lock is most probably being held by some other application, and since application server configuration is on aggressive SLA, the transaction is waiting its
Read more

HashiCorp Vault Integration with Ansible Etower using approle

Image
HashiCorp Vault is  a secrets management tool specifically designed to control access to sensitive credentials in a low-trust environment . It can be used to store sensitive values and at the same time dynamically generate access for specific services/applications on lease.  Integrating the vault with Ansible Etower provides robust and secure automation. Following is the step-by-step guide for the integration. Enable key-value secret engine in Hashi Vault (also known as "kv" engine). Let's call the engine, the "kv" engine. Create a secret inside "kv". A secret can be a collection of key-value pairs or a JSON for nested structure.            Lets assume that secrets are stored as JSON  in the format   { "my_app":{ "service_account_name": "some_service", "service_account_password": "some_password" } } Create a secret policy defining what can be done with the above-defined secret. Create an
Read more

utility to extract date from text with java

Image
A date pattern recognition algorithm to not only identify date pattern but also fetches probable date in Java date format. This algorithm is very fast and lightweight. The processing time is linear and all dates are identified in a single pass. Algorithm resolves date using tree traverse mechanism. Tree data structures are custom created to build supported date, time and month patterns. Following Trees are used (Note: ^ sign denotes complete pattern) DATE PATTERN TREE Month Pattern Tree (Jan and January both are valid, identified using ^ sign) Time pattern (Identified as suffix to Date, $ sign indicates SPACE character) Tree structures are used in the following algorithm.  Date Part Identification algorithm flowchart Time part identification algorithm flowchart These flow charts are self-explanatory in most part. --> sign is used to denote next match in respective tree structures. The algorithm also acknowledges multipl
Read more