title: Overwrite a nested list element using jsonnet
body: <p><strong>I have the following json</strong></p>
  
  <pre><code>{
      "namespace": "monitoring",
      "name": "alok",
      "spec": {
          "replicas": 1,
          "template": {
              "metadata": "aaa",
              "spec": {
                  "containers": [
                      {
                          "image": "practodev/test:test",
                          "env": [
                              {
                                  "name":"GF_SERVER_HTTP_PORT",
                                  "value":"3000"
                              },
                              {
                                  "name":"GF_SERVER_HTTPS_PORT",
                                  "value":"443"
                              },
                          ]
                      }
                  ]
              }
          }
      }
  }
  </code></pre>
  
  <p><strong>How do I add <code>deployment_env.json</code> using jsonnet?</strong></p>
  
  <pre><code>{
      "env": [
          {
              "name":"GF_AUTH_DISABLE_LOGIN_FORM",
              "value":"false"
          },
          {
              "name":"GF_AUTH_BASIC_ENABLED",
              "value":"false"
          },
  
      ]
  }
  </code></pre>
  
  <p>I need to add it under spec.template.containers[0].env = deployment_env.json</p>
  
  <p>I wrote the below jsonnet to do that. It appends a new element. But i need to change the existing 0th container element in the json. <strong>Please suggest how to do it.</strong></p>
  
  <pre><code>local grafana_envs = (import 'custom_grafana/deployment_env.json');
  local grafanaDeployment = (import 'nested.json') + {
      spec+: {
          template+: {
              spec+: {
                  containers+: [{
                      envs: grafana_envs.env,
                  }]
              }
          }
      },
  };
  grafanaDeployment 
  </code></pre>