Using Jsonnet with Express Gateway configuration

gateway.config.jsonnet

/*
  Run:
    $ HTTPBIN_URL=https://httpbin.org jsonnet -V HTTPBIN_URL \
    -o ./config/gateway.config.json \
    ./config/gateway.config.jsonnet
*/

{
  http: {
    port: 8080
  },
  admin: {
    port: 9876,
    hostname: "localhost"
  },
  apiEndpoints: {
    api: {
      host: "localhost",
      paths: "/ip"
    }
  },
  serviceEndpoints: {
    httpbin: {
      url: std.extVar("HTTPBIN_URL")
    }
  },
  policies: [
    "proxy"
  ],
  pipelines: {
    default: {
      apiEndpoints: [
        "api"
      ],
      policies: [
        {
          proxy: [
            {
              action: {
                serviceEndpoint: "httpbin",
                changeOrigin: true
              }
            }
          ]
        }
      ]
    }
  }
}