brief introduction

This scenario is designed to support you to migrate from HAProxy to Envoy Proxy. It will help you apply any previous experience and understanding of HAProxy to Envoy.

You will learn how to:

• Configure Envoy proxy server configuration and settings.
• Configure the Envoy agent to proxy traffic to external services.
• Configure access and error logs.

At the end of the scenario, you will learn about the core Envoy Proxy functionality and how to migrate existing HAProxy scripts to the platform.

HAProxy example

You can view the sample HA proxy configuration haproxy.cfg in the editor by opening.

global
        log /dev/log    local0
        log /dev/log    local1 notice
        user haproxy
        group haproxy
        daemon

defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull

frontend localnodes
    bind *:8080
    mode http
    default_backend nodes

backend nodes
    mode http
    balance roundrobin
    option forwardfor
    server web01 172.18.0.3:80 check
    server web02 172.18.0.4:80 check

HA agent configuration usually has four key elements:

• Configure HA proxy server, log structure and process wide security and performance adjustments, which will affect HAProxy at a low level. This is defined globally in all instances. See the global section haproxy.cfg in.
• The configuration defaults apply to all frontend and backend sections after it. See the defaults section in haproxy.cfg.
• Configure the HA agent to accept incoming requests. This section defines the IP addresses and ports that clients can connect to. See haproxy.cfg in the frontend section of.
• Configure where traffic is handled. It defines a set of servers that will be load balanced and distributed to process requests. See the backend section in haproxy.cfg.

Not all configurations are applicable to envoy agents, and some aspects are not required due to different architectures and decisions. Envoy Proxy has four key types and supports the core infrastructure provided by HA Proxy. The core is:

• Listeners: they define how the Envoy agent accepts incoming requests. Currently, Envoy Proxy only supports TCP based listeners. After the connection is established, it is passed to a set of filters for processing.
• Filters: they are part of a pipeline architecture that can handle inbound and outbound data. This feature enables filters, such as Gzip, which compresses data before sending it to the client.
• Routes: they forward traffic to the desired destination, defined as clusters.
• Clusters: they define the destination endpoint and configuration settings for traffic.

We will use these four components to create the envoy agent configuration to match the defined ha agent configuration. Envoy has always focused on API s and dynamic configuration. In this case, the configuration will use the static, hard coded resources defined by the HA agent.

Frontend Configuration

In the HTTP configuration block, the HA agent configures the listening port 8080, and all traffic is processed by the back-end node.

frontend localnodes
    bind *:8080
    mode http
    default_backend nodes

In Envoy Proxy, this concept is handled by Listeners.

Envoy Listeners

The configured Envoy binding is defined as Listeners. Each listener can define a port and a series of filters, routes and clusters that respond on the port. In this case, a listener bound to port 8080 is defined.
Envoy Proxy is configured using YAML notation. If you are not familiar with this notation, you can view it link.

static_resources:
  listeners:
  - name: listener_0
    address:
      socket_address: { address: 0.0.0.0, port_value: 8080 }

In the next step, you will find the routing and cluster configuration that will handle the traffic.

Backend Configuration

The backend configuration defines the load balancer configuration to handle incoming traffic. In this configuration example, two nodes are defined in a circular fashion.

backend nodes
    mode http
    balance roundrobin
    option forwardfor
    server web01 172.18.0.3:80 check
    server web02 172.18.0.4:80 check

In Envoy, this function is handled by creating filters and clusters.

Envoy Filters and Clusters

For static configurations, filters define how incoming requests are handled. In this case, we define a filter that matches all flows. When a request matching the defined domain and route is issued, the traffic is forwarded to the cluster. This is equivalent to the upstream configuration:

filter_chains:
- filters:
  - name: envoy.http_connection_manager
    config:
      codec_type: auto
      stat_prefix: ingress_http
      route_config:
        name: local_route
        virtual_hosts:
        - name: backend
          domains:
            - "*"
          routes:
          - match:
              prefix: "/"
            route:
              cluster: nodes
      http_filters:
      - name: envoy.router

Name envoy.http_connection_manager is a built-in filter in envy proxy. Other filters include Redis, Mongo and TCP. You can find the complete list in the document.

The filter controls how Envoy matches incoming HTTP requests and which cluster should process them. The cluster controls which servers are handling traffic and load balancing configurations, such as loops.

clusters:
- name: nodes
  connect_timeout: 0.25s
  type: STRICT_DNS
  dns_lookup_family: V4_ONLY
  lb_policy: ROUND_ROBIN
  hosts: [
    { socket_address: { address: 172.18.0.3, port_value: 80 }},
    { socket_address: { address: 172.18.0.4, port_value: 80 }}
  ]