websocket #473
Description
websocket
I'm working on below sample code, how to use websockets on Google App Engine Flexible Environment with java.
as it mentions in the doc, in order to use websockets on App Engine, we need to connect directly to application instance using the instance's public external IP. This IP can be obtained from the metadata server.
but looks like I'm getting below 403 error when I'm trying to access metadata server
java.io.IOException: Server returned HTTP response code: 403 for URL: http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/access-configs/0/external-ip
Sorry, It's working now, forgot to add Metadata-Flavor header in the request
still, it's worth having spring-websocket sample code, who want to use jGAE with spring websocket
Sample Code
Firewall rule
gcloud compute firewall-rules create default-allow-websockets \
--allow tcp:65080 \
--target-tags websocket \
--description "Allow websocket traffic on port 65080"
app.yaml
runtime: java
env: flex
runtime_config: # Optional
jdk: openjdk8
server: jetty9
handlers:
- url: /.*
script: this field is required, but ignored
secure: optional # always never optional # Require HTTPS
manual_scaling:
instances: 1
network:
forwarded_ports:
- 65080
instance_tag: websocket
private static final int DEFAULT_PORT = 65080;
private static final String NETWORK_INTERFACE_METADATA_URL = "http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/access-configs/0/" + "external-ip";
private String getHostname() throws IOException {
String hostname = "localhost";
// if (SystemProperty.environment.value().equals(SystemProperty.Environment.Value.Production)) {
URL url = new URL(NETWORK_INTERFACE_METADATA_URL);
HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setRequestProperty("Metadata-Flavor", "Google");
// httpUrlConnection.setRequestProperty("X-Google-Metadata-Request", "true");
InputStream in = httpUrlConnection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String result, line = reader.readLine();
result = line;
while ((line = reader.readLine()) != null) {
result += line;
}
hostname = result;
// }
return hostname;
}
/**
* @return a Websocket URL of this server.
* @throws IOException when failed to get the external IP address from the metadata server.
*/
public String getWebSocketURL() throws IOException {
return "ws://" + getHostname() + ":" + this.getPort() + "/";
}