4.2. 运行 ovnkube-trace

运行 ovn-trace 以模拟 OVN 逻辑网络内的数据包转发。

先决条件

已安装 OpenShift CLI（oc）。
使用具有 cluster-admin 权限的用户登陆到集群。
您已在本地主机上安装了 ovnkube-trace

示例：测试 DNS 解析是否适用于部署的 pod

本例演示了如何从部署的 pod 测试 DNS 解析到集群中运行的核心 DNS pod。

流程

输入以下命令在 default 命名空间中启动 web 服务：

oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80

$ oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80

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列出在 openshift-dns 命名空间中运行的 pod：

oc get pods -n openshift-dns

oc get pods -n openshift-dns

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输出示例

NAME                  READY   STATUS    RESTARTS   AGE
dns-default-8s42x     2/2     Running   0          5h8m
dns-default-mdw6r     2/2     Running   0          4h58m
dns-default-p8t5h     2/2     Running   0          4h58m
dns-default-rl6nk     2/2     Running   0          5h8m
dns-default-xbgqx     2/2     Running   0          5h8m
dns-default-zv8f6     2/2     Running   0          4h58m
node-resolver-62jjb   1/1     Running   0          5h8m
node-resolver-8z4cj   1/1     Running   0          4h59m
node-resolver-bq244   1/1     Running   0          5h8m
node-resolver-hc58n   1/1     Running   0          4h59m
node-resolver-lm6z4   1/1     Running   0          5h8m
node-resolver-zfx5k   1/1     Running   0          5h

NAME                  READY   STATUS    RESTARTS   AGE
dns-default-8s42x     2/2     Running   0          5h8m
dns-default-mdw6r     2/2     Running   0          4h58m
dns-default-p8t5h     2/2     Running   0          4h58m
dns-default-rl6nk     2/2     Running   0          5h8m
dns-default-xbgqx     2/2     Running   0          5h8m
dns-default-zv8f6     2/2     Running   0          4h58m
node-resolver-62jjb   1/1     Running   0          5h8m
node-resolver-8z4cj   1/1     Running   0          4h59m
node-resolver-bq244   1/1     Running   0          5h8m
node-resolver-hc58n   1/1     Running   0          4h59m
node-resolver-lm6z4   1/1     Running   0          5h8m
node-resolver-zfx5k   1/1     Running   0          5h

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运行以下 ovnkube-trace 命令来验证 DNS 解析是否正常工作：

./ovnkube-trace \
  -src-namespace default \
  -src web \
  -dst-namespace openshift-dns \
  -dst dns-default-p8t5h \
  -udp -dst-port 53 \
  -loglevel 0

$ ./ovnkube-trace \
  -src-namespace default \


  -src web \


  -dst-namespace openshift-dns \


  -dst dns-default-p8t5h \


  -udp -dst-port 53 \


  -loglevel 0

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1: 源 pod 的命名空间
2: 源 pod 名称
3: 目标 pod 的命名空间
4: 目标 pod 名称
5: 使用 udp 传输协议。端口 53 是 DNS 服务使用的端口。
6: 将日志级别设置为 0 (0 为 minimal，5 为 debug)

src&dst pod 在同一节点上放置时的输出示例

ovn-trace source pod to destination pod indicates success from web to dns-default-p8t5h
ovn-trace destination pod to source pod indicates success from dns-default-p8t5h to web
ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-p8t5h
ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-p8t5h to web
ovn-detrace source pod to destination pod indicates success from web to dns-default-p8t5h
ovn-detrace destination pod to source pod indicates success from dns-default-p8t5h to web

ovn-trace source pod to destination pod indicates success from web to dns-default-p8t5h
ovn-trace destination pod to source pod indicates success from dns-default-p8t5h to web
ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-p8t5h
ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-p8t5h to web
ovn-detrace source pod to destination pod indicates success from web to dns-default-p8t5h
ovn-detrace destination pod to source pod indicates success from dns-default-p8t5h to web

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src&dst pod 放置到另一个节点上时的输出示例

ovn-trace source pod to destination pod indicates success from web to dns-default-8s42x
ovn-trace (remote) source pod to destination pod indicates success from web to dns-default-8s42x
ovn-trace destination pod to source pod indicates success from dns-default-8s42x to web
ovn-trace (remote) destination pod to source pod indicates success from dns-default-8s42x to web
ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-8s42x
ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-8s42x to web
ovn-detrace source pod to destination pod indicates success from web to dns-default-8s42x
ovn-detrace destination pod to source pod indicates success from dns-default-8s42x to web

ovn-trace source pod to destination pod indicates success from web to dns-default-8s42x
ovn-trace (remote) source pod to destination pod indicates success from web to dns-default-8s42x
ovn-trace destination pod to source pod indicates success from dns-default-8s42x to web
ovn-trace (remote) destination pod to source pod indicates success from dns-default-8s42x to web
ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-8s42x
ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-8s42x to web
ovn-detrace source pod to destination pod indicates success from web to dns-default-8s42x
ovn-detrace destination pod to source pod indicates success from dns-default-8s42x to web

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ouput 表示从部署的 pod 到 DNS 端口的成功，也表示它已成功返回其他方向。因此，如果我的 Web pod 想要从核心 DNS 进行 dns 解析，则 UDP 端口 53 上支持双向流量。

例如，如果无法正常工作，并且您想要获取 ovn-trace、proto/trace 和 ovn-detrace 的 ovs-appctl，以及更多故障排除类型信息，将日志级别增加到 2，然后再次运行命令，如下所示：

./ovnkube-trace \
  -src-namespace default \
  -src web \
  -dst-namespace openshift-dns \
  -dst dns-default-467qw \
  -udp -dst-port 53 \
  -loglevel 2

$ ./ovnkube-trace \
  -src-namespace default \
  -src web \
  -dst-namespace openshift-dns \
  -dst dns-default-467qw \
  -udp -dst-port 53 \
  -loglevel 2

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这个日志级别的输出太大，无法在此处列出。在故障情况下，此命令的输出显示哪个流丢弃了该流量。例如，可以在不允许该流量的集群中配置 egress 或 ingress 网络策略。

示例：使用 debug 输出来验证配置的默认拒绝

本例演示了如何使用入口默认拒绝策略阻断流量的 debug 输出来识别。

流程

创建以下 YAML，以定义 deny-by-default 策略，以拒绝所有命名空间中的所有 pod 的入口流量。将 YAML 保存到 deny-by-default.yaml 文件中：

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: deny-by-default
  namespace: default
spec:
  podSelector: {}
  ingress: []

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: deny-by-default
  namespace: default
spec:
  podSelector: {}
  ingress: []

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输入以下命令应用策略：

oc apply -f deny-by-default.yaml

$ oc apply -f deny-by-default.yaml

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输出示例

networkpolicy.networking.k8s.io/deny-by-default created

networkpolicy.networking.k8s.io/deny-by-default created

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输入以下命令在 default 命名空间中启动 web 服务：

oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80

$ oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80

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运行以下命令来创建 prod 命名空间：
```
oc create namespace prod
```
```
$ oc create namespace prod
```
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运行以下命令来标记 prod 命名空间：
```
oc label namespace/prod purpose=production
```
```
$ oc label namespace/prod purpose=production
```
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运行以下命令，在 prod 命名空间中部署 alpine 镜像并启动 shell：

oc run test-6459 --namespace=prod --rm -i -t --image=alpine -- sh

$ oc run test-6459 --namespace=prod --rm -i -t --image=alpine -- sh

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打开另一个终端会话。

在这个新终端会话中，运行 ovn-trace 以验证在命名空间 prod 中运行的源 pod test-6459 与在 default 命名空间中的目标 pod 之间的通信失败：

./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 0

$ ./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 0

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输出示例

ovn-trace source pod to destination pod indicates failure from test-6459 to web

ovn-trace source pod to destination pod indicates failure from test-6459 to web

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运行以下命令，将日志级别增加到 2 以公开失败的原因：

./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 2

$ ./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 2

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输出示例

...
------------------------------------------------
 3. ls_out_acl_hint (northd.c:7454): !ct.new && ct.est && !ct.rpl && ct_mark.blocked == 0, priority 4, uuid 12efc456
    reg0[8] = 1;
    reg0[10] = 1;
    next;
 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 0, priority 500, uuid 69372c5d
    reg8[30..31] = 1;
    next(4);
 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 1, priority 500, uuid 2fa0af89
    reg8[30..31] = 2;
    next(4);
 4. ls_out_acl_eval (northd.c:7691): reg8[30..31] == 2 && reg0[10] == 1 && (outport == @a16982411286042166782_ingressDefaultDeny), priority 2000, uuid 447d0dab
    reg8[17] = 1;
    ct_commit { ct_mark.blocked = 1; }; 
    next;
...

...
------------------------------------------------
 3. ls_out_acl_hint (northd.c:7454): !ct.new && ct.est && !ct.rpl && ct_mark.blocked == 0, priority 4, uuid 12efc456
    reg0[8] = 1;
    reg0[10] = 1;
    next;
 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 0, priority 500, uuid 69372c5d
    reg8[30..31] = 1;
    next(4);
 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 1, priority 500, uuid 2fa0af89
    reg8[30..31] = 2;
    next(4);
 4. ls_out_acl_eval (northd.c:7691): reg8[30..31] == 2 && reg0[10] == 1 && (outport == @a16982411286042166782_ingressDefaultDeny), priority 2000, uuid 447d0dab
    reg8[17] = 1;
    ct_commit { ct_mark.blocked = 1; };


    next;
...

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1: 因为默认的 deny 策略被到位，所以入口流量会被阻止

创建一个策略，允许来自特定命名空间中所有 pod 的流量，其标签为 purpose=production。将 YAML 保存到 web-allow-prod.yaml 文件中：

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: web-allow-prod
  namespace: default
spec:
  podSelector:
    matchLabels:
      app: web
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          purpose: production

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: web-allow-prod
  namespace: default
spec:
  podSelector:
    matchLabels:
      app: web
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          purpose: production

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输入以下命令应用策略：
```
oc apply -f web-allow-prod.yaml
```
```
$ oc apply -f web-allow-prod.yaml
```
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输入以下命令运行 ovnkube-trace 来验证现在允许的流量：

./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 0

$ ./ovnkube-trace \
 -src-namespace prod \
 -src test-6459 \
 -dst-namespace default \
 -dst web \
 -tcp -dst-port 80 \
 -loglevel 0

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预期输出

ovn-trace source pod to destination pod indicates success from test-6459 to web
ovn-trace destination pod to source pod indicates success from web to test-6459
ovs-appctl ofproto/trace source pod to destination pod indicates success from test-6459 to web
ovs-appctl ofproto/trace destination pod to source pod indicates success from web to test-6459
ovn-detrace source pod to destination pod indicates success from test-6459 to web
ovn-detrace destination pod to source pod indicates success from web to test-6459

ovn-trace source pod to destination pod indicates success from test-6459 to web
ovn-trace destination pod to source pod indicates success from web to test-6459
ovs-appctl ofproto/trace source pod to destination pod indicates success from test-6459 to web
ovs-appctl ofproto/trace destination pod to source pod indicates success from web to test-6459
ovn-detrace source pod to destination pod indicates success from test-6459 to web
ovn-detrace destination pod to source pod indicates success from web to test-6459

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在在第 6 步中打开的 shell 中运行以下命令，以将 nginx 连接到 web-server：

 wget -qO- --timeout=2 http://web.default

 wget -qO- --timeout=2 http://web.default

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预期输出

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
  body {
    width: 35em;
    margin: 0 auto;
    font-family: Tahoma, Verdana, Arial, sans-serif;
  }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
  body {
    width: 35em;
    margin: 0 auto;
    font-family: Tahoma, Verdana, Arial, sans-serif;
  }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

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4.2. 运行 ovnkube-trace

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