If you are checking health and serving content on the same port, you can set your health check --proxy-header to match your load balancer setting. This tutorial uses port for health checking and serving content.
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If you are using different ports, you can set this for your health check or not, as appropriate. Health checks determine which instances can receive new connections. Health check probes to your load balanced instances come from addresses in the ranges These are IP address ranges that the load balancer uses to connect to backend instances. Your firewall rules must allow these connections on the relevant port. See the Health Checks page for details on health checks. You can enable connection draining on backend services to ensure minimal interruption to your users when an instance that is serving traffic is terminated, removed manually, or removed by an autoscaler.
To learn more about connection draining, read the Enabling Connection Draining documentation. This is because TCP Proxy Load Balancing is implemented at the edge of the Google Cloud and firewall rules are implemented on instances in the datacenter. Because port is a restricted port for many browsers, you must use a tool such as curl to test your load balancer. If you cannot reach your pages by using curl , the rest of this section offers some troubleshooting steps.
Temporarily set a firewall rule that allows you to access your instances individually, then try to load a page from a specific instance. If your instances are not accessible by this method, make sure that your software is running correctly. If your instances are accessible individually, make sure your load balancer firewall rule is correct.
When you're sure the instances are working, remove the "from anywhere" firewall rule. Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.
For details, see our Site Policies. Last updated September 4, Google Cloud. Send feedback. Overview This example demonstrates setting up global TCP Proxy Load Balancing for a simple service that exists in two regions: us-central1 and us-east1. In this example, you configure the following: Four instances distributed between two regions Instance groups, which contain the instances A health check for verifying instance health A backend service, which monitors the instances and prevents them from exceeding configured usage The target TCP proxy An external static IPv4 address and forwarding rule that sends user traffic to the proxy An external static IPv6 address and forwarding rule that sends user traffic to the proxy A firewall rule that allows traffic from the load balancer and health checker to reach the instances After the load balancer is configured, you test the configuration.
Configuring instances and instance groups This section shows how to create simple instance groups, add instances to them, then add those instances to a backend service with a health check. Configuring instances For testing purposes, install Apache on four instances, two in each of two instance groups. Go to the VM instances page Click Create instance. Set Name to ig-us-central Set the Region to us-central1. Set the Zone to us-central1-b.
Click Management, security, disks, networking, sole tenancy to reveal advanced settings. Under Management , click Networking and populate the Tags field with tcp-lb. Click Create. Go to the Instance groups page Click Create instance group. Set the Name to us-ig1. Click Specify port name mapping. Set Port name to tcp Set Port numbers to Under Group type , select Unmanaged instance group. Under VM instances , select ig-us-central and ig-us-central Leave the other settings as they are. Repeat the steps, but set the following values: Name : us-ig2 Region : us-east1 Zone : us-east1-b Port name : tcp Port numbers : Instances : ig-us-east and ig-us-east Create the us-ig2 instance group.
Go to the Load balancing page Click Create load balancer. Under TCP load balancing , click Start configuration. Set Multiple regions or single region to Multiple regions. Click Continue.
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Set the Name to my-tcp-lb. Click Backend configuration. The Name of the backend service appears as my-tcp-lb.
Set Protocol to TCP. Under New backend , select instance group us-ig1. In the Instance group has a named port dialog, click Use existing port name.
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Leave other settings as they are. Click Add backend. Port numbers Within a server, it is possible for more than one user process to use TCP at the same time. To identify the data associated with each process, port numbers are used. Port numbers are bit, and numbers up to are possible, although in practice only a small subset of these numbers are commonly used. A URL normally locates an existing resource on the Internet.
A URL is used when a Web client makes a request to a server for a resource. Status codes and reason phrases In the HTTP response that is sent to a client, the status code, which is a three-digit number, is accompanied by a reason phrase also known as status text that summarizes the meaning of the code. Along with the HTTP version of the response, these items are placed in the first line of the response, which is therefore known as the status line. Escaped and unescaped data To assist with the correct transmission and interpretation of an HTTP request, there are restrictions on the use of certain characters within a URL.
These characters must be converted to a safe format when the request is transmitted. Forms are used by Web applications to allow end users to provide data to be sent to the server. Chunked transfer-coding Chunked transfer-coding, also known as chunking, involves transferring the body of a message as a series of chunks, each with its own chunk size header.