如何使用Istio Service Mesh从Kubernetes集群中访问外部SMTP服务器

Question

我有一个kubernetes集群，其应用程序在Istio服务网格中运行。在一个应用程序中，我尝试使用SMTP发送电子邮件。如何设置Istio规则以允许我的应用程序使用我的外部SMTP服务器？

最初我收到异常“无法连接到SMTP主机：in-v3.mailjet.com，端口：587，响应：-1。”详细的here。访问这个网站后，我意识到我需要提供出口规则，我按照以下方式做了

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: mailjet
spec:
  hosts:
  - "in-v3.mailjet.com"
  location: MESH_EXTERNAL
  ports:
  - number: 587
    name: tls
    protocol: TLS
  resolution: DNS
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: mailjet
spec:
  hosts:
  - "*.mailjet.com"
  tls:
  - match:
    - port: 587
      sni_hosts:
      - "*.mailjet.com"
    route:
    - destination:
        host: "*.mailjet.com"
        port:
          number: 587
      weight: 100

我不再获得“无法连接到SMTP主机”异常，但我收到了SocketTieoutException

[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1487)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1378)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at java.lang.Thread.run(Thread.java:748)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55) Caused by: javax.mail.MessagingException: Exception reading response;
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)   nested exception is:
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  java.net.SocketTimeoutException: Read timed out
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:2460)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2187)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:740)
[0m[31m06:56:39,048 ERROR [stderr] (default task-55)  at javax.mail.Service.connect(Service.java:366)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at javax.mail.Service.connect(Service.java:246)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at javax.mail.Service.connect(Service.java:267)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at org.keycloak.email.DefaultEmailSenderProvider.send(DefaultEmailSenderProvider.java:138)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  ... 73 more
[0m[31m06:56:39,049 ERROR [stderr] (default task-55) Caused by: java.net.SocketTimeoutException: Read timed out
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.net.SocketInputStream.socketRead0(Native Method)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.net.SocketInputStream.read(SocketInputStream.java:171)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.net.SocketInputStream.read(SocketInputStream.java:141)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:126)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:106)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:2440)
[0m[31m06:56:39,049 ERROR [stderr] (default task-55)  ... 79 more
[0m[31m06:56:39,049 ERROR [org.keycloak.services.resources.admin.RealmAdminResource] (default task-55) Failed to send email
 javax.mail.MessagingException: Exception reading response;
  nested exception is:
        java.net.SocketTimeoutException: Read timed out

使用Istio服务网格在Kubernetes集群中成功发送电子邮件需要做什么？

Answer 1

在与[外部MySQL实例的网格外部服务条目]（https://istio.io/blog/2018/egress-tcp/#mesh-external-service-entry-for-an-external-mysql-instance）进行比较后，我设法使用TCP进行如下工作。我尝试使用IP地址的TLS，但这不起作用。如果我不必指定IP地址，那将是很好的

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: mailjet
spec:
  hosts:
  - in-v3.mailjet.com
  addresses:
  - 104.199.96.85/32
  ports:
  - name: tls
    number: 587
    protocol: tcp
  location: MESH_EXTERNAL
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: mailjet
spec:
  hosts:
  - in-v3.mailjet.com
  tcp:
  - match:
    - port: 587
    route:
    - destination:
        host: in-v3.mailjet.com
        port:
          number: 587 
---