今天我們來玩一下混沌工程的開源工具chaostoolkit 。

它的目標是提供一個免費，開放，社群驅動的工具集以及api。

官方原始碼連結：https://github.com/chaostoolkit/chaostoolkit

要想了解這個工具就必須知道混沌工程原則中提到的要點。如下所示：

記往這裡提到的第一個要點，建立穩態假設。

在執行這個工具之前，我們先來看一下它的架構。

簡單來解釋一下，就是ChaosToolkit通過Drivers來操作你的被測系統。

它的功能點包括如下部分：

下面我們把工具裝起來玩一下。

環境說明：CentOS7.8、k8s 1.19.5、示例應用

安裝python3

sudo yum install python3 python3-venv

安裝pipenv

gaolou@GaoMacPro ~ % pip3 install pipenv

安裝chaos-toolkit 的k8s擴充套件和報告模組

pip3 install -U chaostoolkit
pip3 install -U chaostoolkit-kubernetes
pip3 install -U chaostoolkit-reporting

如果你需要操作其他平臺，也可以安裝相應擴充套件。

建立虛擬環境

python3 -m venv .bundler
source .bundler/bin/activate

為了不影響其他環境，我們這裡用python的虛擬環境操作。

以上安裝過程是在k8s的master機器上執行的，如果你不是在k8s上安裝的，可以配置相應的k8s上下文，具體操作請參考：https://chaostoolkit.org/drivers/kubernetes/。

chaos discover 探索試驗

首先執行discover命令，chaostoolkit會根據./kube/config中的內容生成discovery.json檔案，這個檔案中會包括所有可以對k8s執行的操作集合。執行成功的結果如下：

(.bundler) [root@s5 chaostoolkit_scenarios]# chaos discover chaostoolkit-kubernetes
[2021-06-23 12:18:07 INFO] Attempting to download and install package 'chaostoolkit-kubernetes'
[2021-06-23 12:18:08 INFO] Package downloaded and installed in current environment
[2021-06-23 12:18:09 INFO] Discovering capabilities from chaostoolkit-kubernetes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.actions
[2021-06-23 12:18:09 INFO] Searching for probes in chaosk8s.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.deployment.actions
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.deployment.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.node.actions
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.node.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.pod.actions
[2021-06-23 12:18:09 INFO] Searching for probes in chaosk8s.pod.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.replicaset.actions
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.service.actions
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.service.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.statefulset.actions
[2021-06-23 12:18:09 INFO] Searching for probes in chaosk8s.statefulset.probes
[2021-06-23 12:18:09 INFO] Searching for actions in chaosk8s.crd.actions
[2021-06-23 12:18:09 INFO] Searching for probes in chaosk8s.crd.probes
[2021-06-23 12:18:09 INFO] Discovery outcome saved in ./discovery.json
(.bundler) [root@s5 chaostoolkit_scenarios]#

chaos init 生成試驗

執行初始化命令，可以根據提示建立一個混沌試驗。

(.bundler) [root@s5 chaostoolkit_scenarios]# chaos init
You are about to create an experiment.
This wizard will walk you through each step so that you can build
the best experiment for your needs.

An experiment is made up of three elements:
- a steady-state hypothesis [OPTIONAL]
- an experimental method
- a set of rollback activities [OPTIONAL]

Only the method is required. Also your experiment will
not run unless you define at least one activity (probe or action)
within it
Experiment's title: E2 #這裡是配置一個試驗名

A steady state hypothesis defines what 'normality' looks like in your system
The steady state hypothesis is a collection of conditions that are used,
at the beginning of an experiment, to decide if the system is in a recognised
'normal' state. The steady state conditions are then used again when your experiment
 is complete to detect where your system may have deviated in an interesting,
weakness-detecting way

Initially you may not know what your steady state hypothesis is
and so instead you might create an experiment without one
This is why the stead state hypothesis is optional.
Do you want to define a steady state hypothesis now? [y/N]: y # 建立穩態假說，請注意，這個是混沌工程中的重要概念，但是在其他的大部分混沌工具中都看不到這一步
Hypothesis's title: H2

You may now define probes that will determine
the steady-state of your system.
Add an activity
1) all_microservices_healthy
2) deployment_is_fully_available
3) deployment_is_not_fully_available
4) microservice_available_and_healthy
5) microservice_is_not_available
6) read_microservices_logs
7) service_endpoint_is_initialized
8) count_pods
9) pod_is_not_available
10) pods_in_conditions
11) pods_in_phase
12) pods_not_in_phase
13) read_pod_logs
14) statefulset_fully_available
15) statefulset_not_fully_available
16) get_cluster_custom_object
17) get_custom_object
18) list_cluster_custom_objects
19) list_custom_objects
Activity (0 to escape): 1 # 選擇穩態假說的判斷點，簡單來說，這裡就是建立一個預期結果

!!!DEPRECATED!!!
1) kill_microservice
2) remove_service_endpoint
Do you want to use this probe? [y/N]: y # 確定是否使用上面選擇的探針

A steady-state probe requires a tolerance value, within which
your system is in a reognised `normal` state.

What is the tolerance for this probe?: normal

You now need to fill the arguments for this activity. Default
values will be shown between brackets. You may simply press return
to use it or not set any value.
Argument's value for 'ns' [default]: chaosnamespace # 輸入k8s中要操作的名稱空間
Do you want to select another activity? [y/N]: y # 是否選擇一個的操作動作
Add an activity
1) all_microservices_healthy
2) deployment_is_fully_available
3) deployment_is_not_fully_available
1) kill_microservice
4) microservice_available_and_healthy
5) microservice_is_not_available
6) read_microservices_logs
7) service_endpoint_is_initialized
8) count_pods
9) pod_is_not_available
10) pods_in_conditions
11) pods_in_phase
12) pods_not_in_phase
13) read_pod_logs
14) statefulset_fully_available
15) statefulset_not_fully_available
16) get_cluster_custom_object
17) get_custom_object
18) list_cluster_custom_objects
19) list_custom_objects
Activity (0 to escape): 1 # 選擇具體的動作

!!!DEPRECATED!!!
Do you want to use this probe? [y/N]: y # 確定使用上面選擇的動作

You now need to fill the arguments for this activity. Default
values will be shown between brackets. You may simply press return
to use it or not set any value.
Argument's value for 'ns' [default]:
Do you want to select another activity? [y/N]: N # 是否要新增另一個試驗動作，這裡我不再添加了

An experiment's method contains actions and probes. Actions
vary real-world events in your system to determine if your
steady-state hypothesis is maintained when those events occur.

An experimental method can also contain probes to gather additional
information about your system as your method is executed.
Do you want to define an experimental method? [y/N]: y # 選擇一個試驗具體方法

Add an activity

1) kill_microservice

2) remove_service_endpoint

3) scale_microservice

4) start_microservice

5) all_microservices_healthy

6) deployment_is_fully_available

7) deployment_is_not_fully_available

8) microservice_available_and_healthy

9) microservice_is_not_available

10) read_microservices_logs

11) service_endpoint_is_initialized

12) create_deployment

13) delete_deployment

14) scale_deployment

15) deployment_available_and_healthy

16) deployment_fully_available

17) deployment_not_fully_available

18) cordon_node

19) create_node

20) delete_nodes

21) drain_nodes

22) uncordon_node

23) get_nodes

24) delete_pods

25) exec_in_pods

26) terminate_pods

27) count_pods

28) pod_is_not_available

29) pods_in_conditions

30) pods_in_phase

31) pods_not_in_phase

32) read_pod_logs

33) delete_replica_set

34) create_service_endpoint

35) delete_service

36) service_is_initialized

37) create_statefulset

38) remove_statefulset

39) scale_statefulset

40) statefulset_fully_available

41) statefulset_not_fully_available

42) create_cluster_custom_object

43) create_custom_object

44) delete_cluster_custom_object

45) delete_custom_object

46) patch_cluster_custom_object

47) patch_custom_object

48) replace_cluster_custom_object

49) replace_custom_object

50) get_cluster_custom_object

51) get_custom_object

52) list_cluster_custom_objects

53) list_custom_objects

Activity (0 to escape): 24 # 這裡我選擇第24個方法：刪除一個POD

!!!DEPRECATED!!!
Do you want to use this action? [y/N]: y # 確認選擇

You now need to fill the arguments for this activity. Default
values will be shown between brackets. You may simply press return
to use it or not set any value.

Argument's value for 'name': DeleteRedisPOD # 給這個方法命名

Argument's value for 'ns' [default]: chaosnamespace # 確定要操作的k8s名稱空間
Argument's value for 'label_selector' [name in ({name})]: app=redis # 輸入要操作物件的標籤，以便可以找到操作物件
Do you want to select another activity? [y/N]: N # 是否新增另一個動作，這裡我不再新增

An experiment may optionally define a set of remedial actions
that are used to rollback the system to a given state.

Do you want to add some rollbacks now? [y/N]: N # 是否添加回滾動作，這裡我是要刪除redis的POD，因為k8s會自動拉起來，所以我不用回滾動作

Experiment created and saved in './experiment.json' # 生成了試驗檔案

(.bundler) [root@s5 chaostoolkit_scenarios]#

Chaos Run 執行案例

(.bundler) [root@s5 chaostoolkit_scenarios]# chaos run experiment.json
[2021-06-28 23:03:23 INFO] Validating the experiment's syntax
[2021-06-28 23:03:24 INFO] Experiment looks valid
[2021-06-28 23:03:24 INFO] Running experiment: E2
[2021-06-28 23:03:24 INFO] Steady-state strategy: default
[2021-06-28 23:03:24 INFO] Rollbacks strategy: default
[2021-06-28 23:03:24 INFO] Steady state hypothesis: H2
[2021-06-28 23:03:24 INFO] Probe: all_microservices_healthy
[2021-06-28 23:03:24 WARNING] all_microservices_healthy function is DEPRECATED and will be removed in the next         releases, please use all_pods_healthy instead
[2021-06-28 23:03:24 INFO] Steady state hypothesis is met!
[2021-06-28 23:03:24 INFO] Playing your experiment's method now...
[2021-06-28 23:03:24 INFO] Action: delete_pods
[2021-06-28 23:03:24 INFO] Steady state hypothesis: H2
[2021-06-28 23:03:24 INFO] Probe: all_microservices_healthy
[2021-06-28 23:03:24 WARNING] all_microservices_healthy function is DEPRECATED and will be removed in the next         releases, please use all_pods_healthy instead
[2021-06-28 23:03:24 INFO] Steady state hypothesis is met!
[2021-06-28 23:03:24 INFO] Let's rollback...
[2021-06-28 23:03:24 INFO] No declared rollbacks, let's move on.
[2021-06-28 23:03:24 INFO] Experiment ended with status: completed
(.bundler) [root@s5 chaostoolkit_scenarios]#

檢查結果

執行試驗前：

[root@s5 ~]# kubectl get pods -n chaosnamespace -o wide

NAME                                   READY   STATUS    RESTARTS   AGE     IP               NODE   NOMINATED NODE   READINESS GATES

...........................

redis-master-b96c9795b-nqzmr           1/1     Running   0          3d9h    10.100.220.84    s6     <none>           <none>
redis-slave-6b8d456947-6r42k           1/1     Running   0          3d9h    10.100.220.86    s6     <none>           <none>
redis-slave-6b8d456947-z55m5           1/1     Running   0          3d9h    10.100.53.206    s7     <none>           <none>

執行試驗後：

[root@s5 ~]# kubectl get pods -n chaosnamespace -o wide

NAME                                   READY   STATUS              RESTARTS   AGE     IP               NODE   NOMINATED NODE   READINESS GATES

...............................

redis-master-b96c9795b-92rc6 0/1 ContainerCreating 0 3s <none> s6 <none> <none>

redis-master-b96c9795b-nqzmr           0/1     Terminating         0          3d9h    10.100.220.84    s6     <none>           <none>
redis-slave-6b8d456947-5m2xt           0/1     ContainerCreating   0          2s      <none>           s6     <none>           <none>
redis-slave-6b8d456947-6r42k           1/1     Terminating         0          3d9h    10.100.220.86    s6     <none>           <none>
redis-slave-6b8d456947-fj4xc           0/1     ContainerCreating   0          3s      <none>           s7     <none>           <none>
redis-slave-6b8d456947-z55m5           1/1     Terminating         0          3d9h    10.100.53.206    s7     <none>           <none>

POD完全啟動後：

[root@s5 ~]# kubectl get pods -n chaosnamespace -o wide

NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES

.......................

redis-master-b96c9795b-92rc6 1/1 Running 0 5m43s 10.100.220.89 s6 <none> <none>

redis-slave-6b8d456947-5m2xt 1/1 Running 0 5m42s 10.100.220.90 s6 <none> <none>

redis-slave-6b8d456947-fj4xc 1/1 Running 0 5m43s 10.100.53.211 s7 <none> <none>

[root@s5 ~]#

從上面的結果可以看到，試驗是執行成功的，幾個redisPOD都被殺掉並被k8s拉起來了。

今天我們就寫這一個試驗，你可以根據同樣的步驟去生成其他試驗。