Enable gzip compression for an ASM ingress gateway - Alibaba Cloud Service Mesh

HTTP responses from backend services often contain compressible text content such as HTML, JSON, and CSS. Without compression, the ingress gateway forwards these responses at full size, which increases bandwidth costs and slows client load times. Gzip compression on the ASM ingress gateway compresses eligible responses before they reach the client, reducing response sizes and improving transfer speed.

How it works

When a client sends an HTTP request with the Accept-Encoding: gzip header, the ingress gateway compresses the response body before returning it. The gateway compresses a response only when all of the following conditions are met:

The request includes Accept-Encoding: gzip (or *).
The response Content-Type matches one of the types specified in compression.content_type.
The response is not already compressed (no existing Content-Encoding header).

If remove_accept_encoding_header is set to true, the gateway strips the Accept-Encoding header before forwarding the request upstream. This prevents the upstream service from compressing the response on its own, keeping the gateway as the single point of compression.

Prerequisites

A cluster is added to the ASM instance. See Add a cluster to an ASM instance.
An ingress gateway is deployed. See Create an ingress gateway.
A sample application is deployed in the Container Service for Kubernetes (ACK) cluster, with a virtual service and Istio gateway routing traffic through the ASM ingress gateway. If you do not have an existing application, see Set up a sample application.
An Internet Content Provider (ICP) filing is obtained for a domain name if you want to use one.

Configure gzip compression

Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
On the Mesh Management page, find the target ASM instance. Click the instance name or click Manage in the Actions column.
In the left-side navigation pane, choose ASM Gateways > Ingress Gateway.
On the Ingress Gateway page, find the target ingress gateway and click YAML.

In the Edit dialog box, add the following compression block to the YAML and click OK.

   compression:
     content_type:
       - text/html
     enabled: true
     gzip:
       memory_level: 9
     remove_accept_encoding_header: true

Configuration reference

The table below describes the compression fields. For all ingress gateway fields, see Create and manage an ingress gateway by using the Kubernetes API.

Field	Description
`compression.enabled`	Specifies whether to enable data compression for the ingress gateway service.
`compression.content_type`	The Content-Type values eligible for compression. Only responses with a matching `Content-Type` header are compressed.
`compression.gzip.memory_level`	The amount of internal memory used for compression. Higher values use more memory but can produce better compression.
`compression.remove_accept_encoding_header`	Whether to strip the `Accept-Encoding` header before forwarding requests to the upstream service. Set to `true` to prevent the upstream from double-compressing responses.

Note: Specify multiple content types to compress a wider range of responses. Common types include text/html, application/json, application/javascript, text/css, text/plain, and application/xml.

Verify compression

After you configure compression, confirm that the ingress gateway returns gzip-compressed responses.

Get the external IP address of the ingress gateway.
1. Log on to the ACK console. In the left-side navigation pane, click Clusters.
2. On the Clusters page, click the cluster name. In the left-side navigation pane, choose Network > Services.
3. On the Services page, select istio-system from the Namespace drop-down list. Find istio_ingressgateway and note the IP address for port 80 in the External IP column.
Send a request with the Accept-Encoding: gzip header and check the response headers. Replace <ingress-gateway-ip> with the external IP address from step 1.
```
   curl -s -o /dev/null -D - -H "Accept-Encoding: gzip" http://<ingress-gateway-ip>/
```
Check the output. If the response includes content-encoding: gzip, compression is working.
```
   HTTP/1.1 200 OK
   content-encoding: gzip
   content-type: text/html
   ...
```
If the content-encoding header is absent, verify the following:
- The request includes the Accept-Encoding: gzip header.
- The response Content-Type matches a type listed in compression.content_type.
- compression.enabled is set to true.
- The response is not already compressed by the upstream service. If remove_accept_encoding_header is false, the upstream may have applied its own compression, and the gateway skips re-compression.
Alternatively, open Chrome DevTools (More tools > Developer tools), navigate to the ingress gateway IP address, and look for content-encoding: gzip in the Response Headers section of the Network tab.

Set up a sample application (optional)

If you do not have an existing application behind the ingress gateway, deploy a sample NGINX application with the required Istio gateway and virtual service.

Step 1: Deploy the NGINX application

Create a file named nginx.yaml with the following content and apply it to the ACK cluster.

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
        sidecarset-injected: "true"
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  ports:
    - name: http
      port: 80
      protocol: TCP
      targetPort: 80
  selector:
    app: nginx
  type: ClusterIP

kubectl apply -f nginx.yaml

Step 2: Create the Istio gateway and virtual service

In the ASM console, navigate to the details page of your ASM instance.
In the left-side navigation pane, choose ASM Gateways > Gateway. Click Create from YAML.

Select a namespace, paste the following YAML, and click Create.

   apiVersion: networking.istio.io/v1beta1
   kind: Gateway
   metadata:
     name: nginx-gateway
     namespace: default
   spec:
     selector:
       istio: ingressgateway
     servers:
       - hosts:
           - '*'
         port:
           name: http
           number: 80
           protocol: HTTP

In the left-side navigation pane, choose Traffic Management Center > VirtualService. Click Create from YAML.

Select a namespace, paste the following YAML, and click Create.

   apiVersion: networking.istio.io/v1beta1
   kind: VirtualService
   metadata:
     name: nginx
     namespace: default
   spec:
     gateways:
       - nginx-gateway
     hosts:
       - '*'
     http:
       - match:
           - uri:
               exact: /
         route:
           - destination:
               host: nginx
               port:
                 number: 80

After the gateway and virtual service are created, return to Configure gzip compression to enable compression on the ingress gateway.

What's next

Create and manage an ingress gateway by using the Kubernetes API -- full reference for ingress gateway YAML fields.