Use an egress traffic policy to manage egress traffic - Alibaba Cloud Service Mesh

ASM instances of version 1.16.4 and later allow you to use CustomResourceDefinition (CRD) fields to define an egress traffic policy. This topic describes how to use an egress traffic policy to manage egress traffic.

Background

Implementation principle

ASM supports egress traffic management by creating multiple resources such as ServiceEntry, VirtualService, Gateway, and Destination, and ensuring that these resources are interconnected. Upon completion of the configuration, it achieves transparent redirection of traffic to the egress gateway, which then forwards it to external services.

These configurations are complex and require a deep understanding of the relevant fields, making them prone to errors. To lower the threshold for egress traffic configuration, ASM introduces the ASMEgressTrafficPolicy resource.

ASMEgressTrafficPolicy abstracts and simplifies egress traffic configuration. Instead of manually configuring resources like ServiceEntry, VirtualService, Gateway, and Destination, you only need to add some necessary configurations to achieve transparent redirection of traffic to the egress gateway and send it to external services through HTTP/HTTPS protocols.

Since ASMEgressTrafficPolicy simplifies native resources of ASM, it may not meet some of your advanced needs (such as proportional routing of egress traffic, initiating mTLS from the egress gateway, and others). If you need to use advanced features, such as adding custom configurations, see Configure an egress gateway to route all outbound traffic in ASM.

Feature introduction

ASM provides a unified way to connect, manage, and protect communication between applications. Unlike IP-based methods, ASM uses an application-centric approach without requiring modifications to existing application code. ASMEgressTrafficPolicy defines how to manage and access external traffic through the egress gateway. By combining the ASM egress gateway and AuthorizationPolicy, you can more flexibly control egress traffic. Dingtalk_20230411112608

The traffic paths in this example can be categorized into two types:

1. Communication between sidecar proxies and between sidecar proxies and gateways: By default, mutual Transport Layer Security (mTLS) is enabled for the communication, and certificates are managed by ASM.

2. Communication between applications and sidecar proxies and between gateways and external services:

a. To ensure that advanced Layer 7 capabilities of ASM can function properly, applications and sidecar proxies communicate in plaintext as much as possible. In this way, sidecar proxies can obtain Layer 7 information of the traffic and support more advanced features. Due to some special reasons, if applications must send HTTPS requests directly, only Layer 4 capabilities of ASM can be used.

b. You can configure the communication protocol between an egress gateway and an external service, either plaintext or HTTPS.

Prerequisites

An ASM instance of a commercial edition (Enterprise Edition or Ultimate Edition) is created. The version of the instance is 1.16.4 or later. For more information, see Create an ASM instance. For information about upgrading an instance, see Upgrade an ASM instance.
Automatic sidecar injection is enabled for the default namespace. For more information, see Enable automatic sidecar proxy injection.

Preparations

1. Set an egress traffic policy for the ASM instance

Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose Data Plane Component Management > Sidecar Proxy Setting.
On the global tab, click Outbound Traffic Policy, click REGISTRY_ONLY on the right of External Access Policy, and click Update Settings.

2. Create a namespace

Create the istio-egress namespace. For more information, see Manage global namespaces.
On the Global namespace page, click Sync Automatic Sidecar Injection to Kubernetes Cluster to sync the namespace to the ACK cluster managed by the ASM instance.

3. Create an egress gateway

Create an egress gateway named egressgateway-a in ASM, set Port Mapping to HTTP 80, HTTPS 443, and HTTPS 444, and enable Support two-way TLS authentication. For more information, see Create an egress gateway.

Ensure that the spec field in the generated YAML file contains the following content. If not, add such content:

spec:
  podLabels:
    security.istio.io/tlsMode: istio

4. Create services

Create a namespace named mytest for the ASM instance and enable automatic sidecar proxy injection. For more information, see Manage global namespaces.

In the ACK cluster, deploy the sleep-a service in the mytest namespace and deploy the NGINX service in the default namespace.

Create a file named test.yaml and copy the following content to the file:

Expand to view YAML file

apiVersion: v1
kind: Service
metadata:
  name: sleep-a
  namespace: mytest
  labels:
    app: sleep-a
    service: sleep-a
spec:
  ports:
  - port: 80
    name: http
  selector:
    app: sleep-a
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: sleep-a
  namespace: mytest
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sleep-a
  template:
    metadata:
      labels:
        app: sleep-a
    spec:
      terminationGracePeriodSeconds: 0
      containers:
      - name: sleep
        image: registry-cn-hangzhou.ack.aliyuncs.com/ack-demo/curl:asm-sleep
        command: ["/bin/sleep", "infinity"]
        imagePullPolicy: IfNotPresent
        volumeMounts:
        - mountPath: /etc/sleep/tls
          name: secret-volume
      volumes:
      - name: secret-volume
        secret:
          secretName: sleep-secret
          optional: true
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
  namespace: default
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: registry-cn-hangzhou.ack.aliyuncs.com/ack-demo/nginx:1.27.0
        imagePullPolicy: Always
        name: nginx
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30

In the ACK cluster, run the following command to deploy the sleep-a and NGINX services:
```
kubectl apply -f test.yaml
```

Run the following command to access http://www.httpbin.org through the sleep-a and NGINX services:

kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org

The output returns 502, indicating access failure.

Use the sleep-a service to access an external service over HTTP

Solution 1: Use HTTP plaintext for communication between the sidecar proxy and the egress gateway

This solution is not reasonable in a real environment. Currently, ASMEgressTrafficPolicy does not support using HTTP plaintext to access the egress gateway.

Traffic management is implemented in sidecar proxies on the client side and does not require egress gateways.
Observability does not rely on egress gateways.
Security capabilities depend on egress gateways. However, without mTLS, all authorization capabilities based on client identities are unavailable. In this case, egress gateways can only deny all requests indiscriminately.

(Recommended) Solution 2: Use mTLS for communication between the sidecar proxy and the egress gateway

Configure through the console

Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose ASM Gateways > Egress Gateway.
Click the gateway name to enter the Gateway overview page. Click Outbound Traffic Policy on the left. Configure parameters as shown in the following figure.
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Run the following command to access http://www.httpbin.org through the NGINX service in the default namespace:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
  The output returns 502, indicating that access to http://www.httpbin.org through the NGINX service fails.
2. Run the following command to access http://www.httpbin.org through the sleep-a service in the mytest namespace:
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
```
  The output returns 200 as expected.
3. On the Outbound Traffic Policy of Gateway page, click Clear Rules on the right to delete the ASMEgressTrafficPolicy configuration. Access http://www.httpbin.org again through the sleep-a service in the mytest namespace.
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
  The output returns 502, indicating that access to http://www.httpbin.org through the sleep-a service fails after the ASMEgressTrafficPolicy configuration is deleted.
The output indicates that the egress traffic policy takes effect.

Configure through kubectl

Create the egress-by-egressgateway.yaml file that contains the following content:

For more information about the fields, see CRD fields in an egress traffic policy.

apiVersion: istio.alibabacloud.com/v1
kind: ASMEgressTrafficPolicy
metadata:
  name: egress-by-egressgateway  # The format of this value is egress-by-{Name of the egress gateway}. This value corresponds to the name of the egress gateway.
  namespace: istio-egress         # This value is fixed to istio-egress.
spec:
  byEgressGateway:
    name: egressgateway
  egressRules:
  - from:
    - namespace: mytest
      workloadSelector:
        app: sleep-a
    to:
    - name: httpbin-service-http
      hosts:
      - www.httpbin.org  # The IP addresses of multiple domain names after DNS resolution must be the same.
      - httpbin.org      # The IP addresses of multiple domain names after DNS resolution must be the same.
      port:
        name: http
        number: 80
        protocol: HTTP
      byEgressGateway:
        port: 80        # Sidecar → 80 Gateway → 80 Service (httpbin.org)

In the ACK cluster, run the following command to create the ASMEgressTrafficPolicy resource:
```
kubectl apply -f egress-by-egressgateway.yaml
```
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Run the following command to access http://www.httpbin.org through the NGINX service in the default namespace:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
  The output returns 502, indicating that the NGINX service fails to access http://www.httpbin.org.
2. Run the following command to access http://www.httpbin.org through the sleep-a service in the mytest namespace.
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
```
  The output returns 200 as expected.
3. Run the following command to delete egress-by-egressgateway, and access http://www.httpbin.org again through the sleep-a service in the mytest namespace.
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
  The output returns 502, indicating that access to http://www.httpbin.org through the sleep-a service fails after the ASMEgressTrafficPolicy configuration is deleted.
The output indicates that the egress traffic policy takes effect.

Use the sleep-a service to access an external service over HTTPS

(Recommended) Solution 1: Use mTLS for communication between the sidecar proxy and the egress gateway

Configure through the console

Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose ASM Gateways > Egress Gateway.
Click the gateway name to enter the Gateway overview page and click Outbound Traffic Policy on the left. Configure parameters as shown in the following figure.
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Verify the sleep-a service in the mytest namespace.
  1. Run the following command to access http://www.httpbin.org through the sleep-a service:
```
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://httpbin.org
```
    The output returns 200, indicating successful access to http://www.httpbin.org through the sleep-a service.
  2. Run the following command to request the anything API of httpbin.org to verify whether the egress gateway upgrades the HTTP request to an HTTPS request:
```
kubectl -n mytest exec deployment/sleep-a -- sh -c "curl -s  http://httpbin.org/anything |grep url"
```
    Expected output:
```
"url": "https://httpbin.org/anything"
```
    You can see that the url field information starts with https, indicating that the egress gateway successfully upgrades the request to https and then forwards it to httpbin.org.
  3. Run the following command to access https://www.httpbin.org through the sleep-a service in the mytest namespace:
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
    The output returns 200, indicating successful access to https://www.httpbin.org through the sleep-a service.
2. Verify the NGINX service in the default namespace.
  1. Run the following command to access http://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the NGINX service fails.
  2. Run the following command to access https://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" https://www.httpbin.org
```
    The output shows that the request connection is refused, indicating that access to https://www.httpbin.org through the NGINX service fails.
  3. Run the following command to view the access logs of the sidecar proxy in the NGINX service workload and obtain the rejection reason:
```
 kubectl -n default  logs -f deployment/nginx -c istio-proxy   --tail=1 
```
    Expected output:
```
{"authority":"-","bytes_received":"0","bytes_sent":"0","downstream_local_address":"52.86.XX.XX:443","downstream_remote_address":"172.16.0.199:56748","duration":"0","istio_policy_status":"-","method":"-","path":"-","protocol":"-","request_id":"-","requested_server_name":"-","response_code":"0","response_flags":"UH","route_name":"-","start_time":"2023-04-11T02:00:07.409Z","trace_id":"-","upstream_cluster":"BlackHoleCluster","upstream_host":"-","upstream_local_address":"-","upstream_service_time":"-","upstream_transport_failure_reason":"-","user_agent":"-","x_forwarded_for":"-"}
```
    The expected output indicates that the request is forwarded to BlackHoleCluster, resulting in the connection being refused.
3. On the Outbound Traffic Policy of Gateway page, click Clear Rules on the right, and then access http://www.httpbin.org and https://www.httpbin.org again through the sleep-a service in the mytest namespace.
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
  When accessing http://www.httpbin.org, 502 is returned. When accessing https://www.httpbin.org, the request connection is refused. After deleting the ASMEgressTrafficPolicy configuration, access to both http://www.httpbin.org and https://www.httpbin.org through the sleep-a service is unsuccessful.
  The output indicates that the egress traffic policy takes effect.

Configure through kubectl

Update the egress-by-egressgateway.yaml file with the following content:

The spec field is updated to include the httpsUpgrade field and the definition for direct access to https://www.httpbin.org. For more information about the fields, see CRD fields in an egress traffic policy.

apiVersion: istio.alibabacloud.com/v1
kind: ASMEgressTrafficPolicy
metadata:
  name: egress-by-egressgateway  # The format of this value is egress-by-{Name of the egress gateway}. This value corresponds to the name of the egress gateway.
  namespace: istio-egress          # This value is fixed to istio-egress.
spec:
  byEgressGateway:
    name: egressgateway
  egressRules:
  - from:
     - namespace: mytest
       workloadSelector:
          app: sleep-a
    to:
    - name: httpbin-service-http
      hosts:
      - www.httpbin.org  # The IP addresses of multiple domain names after DNS resolution must be the same.
      - httpbin.org      # The IP addresses of multiple domain names after DNS resolution must be the same.
      port:
        name: http
        number: 80
        protocol: HTTP
      byEgressGateway:
        port: 80        # Sidecar → 80 Gateway → 80 Service (httpbin.org)
      httpsUpgrade:
        enabled: true   # If this value is set to false, the value of the port parameter under httpsUpgrade does not take effect.
        port: 443       # Sidecar → 80 Gateway → 443 Service (httpbin.org)

In the ACK cluster, run the following command to create the ASMEgressTrafficPolicy resource:
```
kubectl apply -f egress-by-egressgateway.yaml
```
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Verify the sleep-a service in the mytest namespace.
  1. Run the following command to access http://www.httpbin.org through the sleep-a service:
```
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://httpbin.org
```
    The output returns 200, indicating successful access to http://www.httpbin.org through the sleep-a service.
  2. Run the following command to request the anything API of httpbin.org to verify whether the egress gateway upgrades the HTTP request to an HTTPS request.
```
kubectl -n mytest exec deployment/sleep-a -- sh -c "curl -s  http://httpbin.org/anything |grep url"
```
    Expected output:
```
"url": "https://httpbin.org/anything"
```
    You can see that the url field information starts with https, indicating that the egress gateway successfully upgrades the request to https and then forwards it to httpbin.org.
  3. Run the following command to access https://www.httpbin.org through the sleep-a service in the mytest namespace:
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
    The output returns 200, indicating successful access to https://www.httpbin.org through the sleep-a service.
2. Verify the NGINX service in the default namespace.
  1. Run the following command to access http://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the NGINX service fails.
  2. Run the following command to access https://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" https://www.httpbin.org
```
    The output shows that the request connection is refused, indicating that access to https://www.httpbin.org through the NGINX service fails.
  3. Run the following command to view the access logs of the sidecar proxy in the NGINX service workload and obtain the rejection reason:
```
 kubectl -n default  logs -f deployment/nginx -c istio-proxy   --tail=1 
```
    Expected output:
```
{"authority":"-","bytes_received":"0","bytes_sent":"0","downstream_local_address":"52.86.XX.XX:443","downstream_remote_address":"172.16.0.199:56748","duration":"0","istio_policy_status":"-","method":"-","path":"-","protocol":"-","request_id":"-","requested_server_name":"-","response_code":"0","response_flags":"UH","route_name":"-","start_time":"2023-04-11T02:00:07.409Z","trace_id":"-","upstream_cluster":"BlackHoleCluster","upstream_host":"-","upstream_local_address":"-","upstream_service_time":"-","upstream_transport_failure_reason":"-","user_agent":"-","x_forwarded_for":"-"}
```
    The expected output indicates that the request is forwarded to BlackHoleCluster, resulting in the connection being refused.
3. Run the following command to delete egress-by-egressgateway, and then access http://www.httpbin.org and https://www.httpbin.org again through the sleep-a service in the mytest namespace:
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
  When accessing http://www.httpbin.org, 502 is returned. When accessing https://www.httpbin.org, the request connection is refused. After deleting the ASMEgressTrafficPolicy configuration, access to both http://www.httpbin.org and https://www.httpbin.org through the sleep-a service is unsuccessful.
The output indicates that the egress traffic policy takes effect.

Solution 2: Use HTTPS for communication between the sidecar proxy and the egress gateway

Configure through the console interface

Log on to the ASM console. In the left-side navigation pane, choose Service Mesh > Mesh Management.
On the Mesh Management page, click the name of the ASM instance. In the left-side navigation pane, choose ASM Gateways > Egress Gateway.
Click the gateway name to enter the Gateway overview page and click Outbound Traffic Policy on the left. Configure parameters as shown in the following figure.
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Verify the sleep-a service in the mytest namespace.
  1. Run the following command to access http://www.httpbin.org through the sleep-a service:
```
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the sleep-a service fails.
  2. Run the following command to access https://www.httpbin.org through the sleep-a service in the mytest namespace:
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
    The output returns 200, indicating successful access to https://www.httpbin.org through the sleep-a service.
2. Verify the NGINX service in the default namespace.
  1. Run the following command to access http://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the NGINX service fails.
  2. Run the following command to access https://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" https://www.httpbin.org
```
    The output shows that the request connection is refused, indicating that access to https://www.httpbin.org through the NGINX service fails.
  3. Run the following command to view the access logs of the sidecar proxy in the NGINX service workload and obtain the rejection reason:
```
 kubectl -n default  logs -f deployment/nginx -c istio-proxy   --tail=1 
```
    Expected output:
```
{"authority":"-","bytes_received":"0","bytes_sent":"0","downstream_local_address":"52.86.XX.XX:443","downstream_remote_address":"172.16.0.199:56748","duration":"0","istio_policy_status":"-","method":"-","path":"-","protocol":"-","request_id":"-","requested_server_name":"-","response_code":"0","response_flags":"UH","route_name":"-","start_time":"2023-04-11T02:00:07.409Z","trace_id":"-","upstream_cluster":"BlackHoleCluster","upstream_host":"-","upstream_local_address":"-","upstream_service_time":"-","upstream_transport_failure_reason":"-","user_agent":"-","x_forwarded_for":"-"}
```
    The expected output indicates that the request is forwarded to BlackHoleCluster, resulting in the connection being refused.
3. On the Outbound Traffic Policy of Gateway page, click Clear Rules on the right, and then access http://www.httpbin.org and https://www.httpbin.org again through the sleep-a service in the mytest namespace.
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
  When accessing http://www.httpbin.org, 502 is returned. When accessing https://www.httpbin.org, the request connection is refused. After deleting the ASMEgressTrafficPolicy configuration, access to both http://www.httpbin.org and https://www.httpbin.org through the sleep-a service is unsuccessful.
  The output indicates that the egress traffic policy takes effect.

Configure through kubectl

Update the egress-by-egressgateway.yaml file with the following content:

apiVersion: istio.alibabacloud.com/v1
kind: ASMEgressTrafficPolicy
metadata:
  name: egress-by-egressgateway  # The format of this value is egress-by-{Name of the egress gateway}. This value corresponds to the name of the egress gateway.
  namespace: istio-egress          # This value is fixed to istio-egress.
spec:
  byEgressGateway:
    name: egressgateway
  egressRules:
  - from:
     - namespace: mytest
       workloadSelector:
          app: sleep-a
    to:
    - name: httpbin-service-https
      hosts:
      - www.httpbin.org
      - httpbin.org
      port:
        name: https
        number: 443
        protocol: HTTPS
      byEgressGateway:
        port: 444   # HTTPS 444 port defined in step 3 of Preparations.

In the ACK cluster, run the following command to create the ASMEgressTrafficPolicy resource:
```
kubectl apply -f egress-by-egressgateway.yaml
```
Verify whether the ASMEgressTrafficPolicy configuration takes effect.
1. Verify the sleep-a service in the mytest namespace.
  1. Run the following command to access http://www.httpbin.org through the sleep-a service:
```
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n" http://httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the sleep-a service fails.
  2. Run the following command to access https://www.httpbin.org through the sleep-a service in the mytest namespace:
```
kubectl -n mytest exec deployment/sleep-a -- curl  -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
    The output returns 200, indicating successful access to https://www.httpbin.org through the sleep-a service.
2. Verify the NGINX service in the default namespace.
  1. Run the following command to access http://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" http://www.httpbin.org
```
    The output returns 502, indicating that access to http://www.httpbin.org through the NGINX service fails.
  2. Run the following command to access https://www.httpbin.org through the NGINX service:
```
kubectl -n default exec deployment/nginx -- curl -s -o /dev/null -w "%{http_code}\n" https://www.httpbin.org
```
    The output shows that the request connection is refused, indicating that access to https://www.httpbin.org through the NGINX service fails.
  3. Run the following command to view the access logs of the sidecar proxy in the NGINX service workload and obtain the rejection reason:
```
 kubectl -n default  logs -f deployment/nginx -c istio-proxy   --tail=1 
```
    Expected output:
```
{"authority":"-","bytes_received":"0","bytes_sent":"0","downstream_local_address":"52.86.XX.XX:443","downstream_remote_address":"172.16.0.199:56748","duration":"0","istio_policy_status":"-","method":"-","path":"-","protocol":"-","request_id":"-","requested_server_name":"-","response_code":"0","response_flags":"UH","route_name":"-","start_time":"2023-04-11T02:00:07.409Z","trace_id":"-","upstream_cluster":"BlackHoleCluster","upstream_host":"-","upstream_local_address":"-","upstream_service_time":"-","upstream_transport_failure_reason":"-","user_agent":"-","x_forwarded_for":"-"}
```
    The expected output indicates that the request is forwarded to BlackHoleCluster, resulting in the connection being refused.
3. Run the following command to delete egress-by-egressgateway, and then access http://www.httpbin.org and https://www.httpbin.org again through the sleep-a service in the mytest namespace:
```
kubectl -n istio-egress delete ASMEgressTrafficPolicy  egress-by-egressgateway
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  http://www.httpbin.org
kubectl -n mytest exec deployment/sleep-a -- curl -s -o /dev/null -w "%{http_code}\n"  https://www.httpbin.org
```
  When accessing http://www.httpbin.org, 502 is returned. When accessing https://www.httpbin.org, the request connection is refused. After deleting the ASMEgressTrafficPolicy configuration, access to both http://www.httpbin.org and https://www.httpbin.org through the sleep-a service is unsuccessful.
The output indicates that the egress traffic policy takes effect.

Related operations

Reject POST requests sent from a specified namespace

By using an egress gateway and an egress traffic policy, you can flexibly control outbound traffic in a cluster. In combination with an authorization policy, you can implement more fine-grained access control. For example, you can use the following policy to reject POST requests sent from the mytest namespace:

kind: AuthorizationPolicy
apiVersion: security.istio.io/v1beta1
metadata:
  name: sleep-a-egress-www-httpbin-org
  namespace: istio-system
spec:
  action: DENY
  rules:
    - to:
        - operation:
            hosts:
            - www.httpbin.org
            - httpbin.org
            methods:
              - POST
      from:
        - source:
            namespaces: ["mytest"]
  selector:
    matchLabels:
      istio: egressgateway-a

After applying the above configurations, when accessing www.httpbin.org through the sleep-a service using POST requests, RBAC: access is retured. GET requests to www.httpbin.org will not be affected.