netdns

concept

Fo this kind task, each kdoctor agent will send dns request to specified target, and get success rate and mean delay. It could specify success condition to tell the result succeed or fail. And, more detailed report will print to kdoctor agent stdout, or save to disc by kdoctor controller.

the following is the spec of netdns


cat <<EOF > netdns.yaml
apiVersion: kdoctor.io/v1beta1
kind: Netdns
metadata:
  name: testdns
spec:
  schedule:
    schedule: "1 1"
    roundNumber: 2
    roundTimeoutMinute: 1
  target:
    targetDns:
      testIPv4: true
      testIPv6: false
      serviceName: coredns
      serviceNamespace: kube-system
    targetUser:
      server: 172.18.0.1
      port: 53
  request:
    durationInSecond: 10
    qps: 20
    perRequestTimeoutInMS: 500
    domain: "kube-dns.kube-system.svc.cluster.local"
    protocol: udp
  expect:
    successRate: 1
    meanAccessDelayInMs: 10000
EOF

kubectl apply -f netdns.yaml

spec.schedule: set how to schedule the task.

roundNumber: how many rounds it should be to run this task

schedule: Support Linux crontab syntax for scheduling tasks, while also supporting simple writing. The first digit represents how long the task will start, and the second digit represents the interval time between each round of tasks, separated by spaces. Example: "1 2" indicates that the task will start in 1 minute, and the interval time between each round of tasks.

roundTimeoutMinute: the timeout in minute for each round, when the rask does not finish in time, it results to be failuire

sourceAgentNodeSelector [optional]: set the node label selector, then, the kdoctor agent who locates on these nodes will implement the task. If not set this field, all kdoctor agent will execute the task
spec.request: how each kdoctor agent should send the dns request

durationInSecond: for each round, the duration in second how long the dns request lasts

perRequestTimeoutInMS: timeout in ms for each dns request

qps: qps

domain： resolved domain
spec.target: set the target of dns request. it could not set targetUser and targetDns at the same time

targetUser [optional]: set an user-defined DNS server for the dns request
```
server: the address for dns server

port: the port for dns server
```
targetDns: [optional]: set cluster dns server for the dns request
```
testIPv4: test DNS server IPv4 address and request is type A.

testIPv6: test DNS server IPv6 address and request is type AAAA.

serviceName: Specify the name of the DNS to be tested
```
- serviceNamespace: Specify the namespace of the DNS to be tested
protocol: Specify request protocol,Optional value udp，tcp，tcp-tls,default udp.
spec.expect: define the success condition of the task result

meanAccessDelayInMs: mean access delay in MS, if the actual delay is bigger than this, it results to be failure

successRate: the success rate of all dns requests. Notice, when a dns response code is >=200 and < 400, it's treated as success. if the actual whole success rate is smaller than successRate, the task results to be failure

status: the status of the task doneRound: how many rounds have finished

expectedRound: how many rounds the task expect

finish: whether all rounds of this task have finished

lastRoundStatus: the result of last round

history: roundNumber: the round number

    status: the status of this round

    startTimeStamp: when this round begins

    endTimeStamp: when this round finally finished

    duration: how long the round spent

    deadLineTimeStamp: the time deadline of a round

    failedAgentNodeList: the node list where failed kdoctor agent locate

    notReportAgentNodeList: the node list where uknown kdoctor agent locate. This means these agents have problems.

    succeedAgentNodeList: the node list where successful kdoctor agent locate

example

test custom dns server by crontab


cat <<EOF > netdns1.yaml
apiVersion: kdoctor.io/v1beta1
kind: Netdns
metadata:
  name: testdns
spec:
  schedule:
    schedule: "*/1 * * * *"
    roundNumber: 2
    roundTimeoutMinute: 1
  target:
    targetUser:
      server: 172.18.0.1
      port: 53
  request:
    durationInSecond: 10
    qps: 10
    perRequestTimeoutInMS: 500
    domain: "baidu.com"
    protocol: udp
  expect:
    successRate: 1
    meanAccessDelayInMs: 1000
EOF

kubectl apply -f netdns1.yaml

test custom dns server by simple


cat <<EOF > netdns1.yaml
apiVersion: kdoctor.io/v1beta1
kind: Netdns
metadata:
  name: testdns
spec:
  schedule:
    schedule: "1 1"
    roundNumber: 2
    roundTimeoutMinute: 1
  target:
    protocol: udp
    targetUser:
      server: 172.18.0.1
      port: 53
  request:
    durationInSecond: 10
    qps: 10
    perRequestTimeoutInMS: 500
    domain: "baidu.com"
  expect:
    successRate: 1
    meanAccessDelayInMs: 1000
EOF

kubectl apply -f netdns1.yaml

test cluster dns server by crontab


cat <<EOF > netdns.yaml
apiVersion: kdoctor.io/v1beta1
kind: Netdns
metadata:
  name: testdns
spec:
  schedule:
    schedule: "*/1 * * * *"
    roundNumber: 2
    roundTimeoutMinute: 1
  target:
    targetDns:
      testIPv4: true
      testIPv6: false
      serviceNamespaceName: kube-system/kube-dns
    protocol: udp
  request:
    durationInSecond: 10
    qps: 20
    perRequestTimeoutInMS: 500
    domain: "kube-dns.kube-system.svc.cluster.local"
  expect:
    successRate: 1
    meanAccessDelayInMs: 10000
EOF

kubectl apply -f netdns.yaml

test cluster dns server by simple


cat <<EOF > netdns.yaml
apiVersion: kdoctor.io/v1beta1
kind: Netdns
metadata:
  name: testdns
spec:
  schedule:
    schedule: "1 1"
    roundNumber: 2
    roundTimeoutMinute: 1
  target:
    targetDns:
      testIPv4: true
      testIPv6: false
      serviceNamespaceName: kube-system/test-app
    protocol: udp
  request:
    durationInSecond: 10
    qps: 20
    perRequestTimeoutInMS: 500
    domain: "kube-dns.kube-system.svc.cluster.local"
  expect:
    successRate: 1
    meanAccessDelayInMs: 10000
EOF

kubectl apply -f netdns.yaml

report

when the kdoctor is not enabled to aggerate reports, all reports will be printed in the stdout of kdoctor agent. Use the following command to get its report

kubectl logs -n kube-system  kdoctor-agent-lwhtm | jq 'select( .TaskName=="netdns.testdns" )'

when the kdoctor is enabled to aggregate reports, all reports will be collected in the PVC or hostPath of kdoctor controller.

metric introduction

{
  "TaskName": "netdns.testdns",
  "TaskSpec": {
    "schedule": {
      "schedule": "1 1",
      "roundTimeoutMinute": 1,
      "roundNumber": 2
    },
    "target": {
      "protocol": "tcp"
    },
    "request": {
      "durationInSecond": 10,
      "qps": 20,
      "perRequestTimeoutInMS": 500,
      "domain": "kube-dns.kube-system.svc.cluster.local"
    },
    "success": {
      "successRate": 1,
      "meanAccessDelayInMs": 10000
    }
  },
  "RoundNumber": 1,
  "RoundResult": "succeed",
  "NodeName": "kdoctor-control-plane",
  "PodName": "kdoctor-agent-lwhtm",
  "FailedReason": "",
  "StartTimeStamp": "2023-04-27T07:07:32.032814878Z",
  "EndTimeStamp": "2023-04-27T07:07:32.070513569Z",
  "RoundDuraiton": "37.69869ms",
  "ReportType": "agent test report",
  "Detail": {}
}