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Newbie #11

Merged
merged 15 commits into from
Jan 3, 2018
116 changes: 85 additions & 31 deletions README.md
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## kube-monkey
kube-monkey is an implementation of [Netflix's Chaos Monkey](https://github.com/Netflix/chaosmonkey) for [Kubernetes](http://kubernetes.io/)
clusters. It randomly deletes Kubernetes pods in the cluster encouraging and validating the development of failure-resilient
services.
# kube-monkey
kube-monkey is an implementation of [Netflix's Chaos Monkey](https://github.com/Netflix/chaosmonkey) for [Kubernetes](http://kubernetes.io/) clusters. It randomly deletes Kubernetes pods in the cluster encouraging and validating the development of failure-resilient services.

--
---

kube-monkey runs at a pre-configured hour (`run_hour`, defaults to 8am) on weekdays, and builds a schedule of deployments that will face a random
Pod death sometime during the same day. The time-range during the day when the random pod Death might occur is configurable and defaults to 10am to 4pm.
Expand All @@ -15,16 +13,15 @@ The blacklist overrides the whitelist. The config will be populated with default

## Opting-In to Chaos

kube-monkey works on an opt-in model and will only schedule terminations for Deployments that have explicitly agreed
to have their pods terminated by kube-monkey.
kube-monkey works on an opt-in model and will only schedule terminations for k8 apps that have explicitly agreed to have their pods terminated by kube-monkey.

Opt-in is done by setting the following labels on a Kubernetes Deployment:
Opt-in is done by setting the following labels on a Kubernetes k8 app:

**`kube-monkey/enabled`**: Set to **`"enabled"`** to opt-in to kube-monkey
**`kube-monkey/mtbf`**: Mean time between failure (in days). For example, if set to **`"3"`**, the Deployment can expect to have a Pod
**`kube-monkey/mtbf`**: Mean time between failure (in days). For example, if set to **`"3"`**, the k8 app can expect to have a Pod
killed approximately every third weekday.
**`kube-monkey/identifier`**: A unique identifier for the deployment (eg. the deployment's name). This is used to identify the pods
that belong to a Deployment as Pods inherit labels from their Deployment.
**`kube-monkey/identifier`**: A unique identifier for the k8 app (eg. the k8 app's name). This is used to identify the pods
that belong to a k8 app as Pods inherit labels from their k8 app.
**`kube-monkey/kill-all`**: Set this label's value to `"kill-all"` if you want kube-monkey to kill ALL of your pods. Default behavior in the absence of this label is to kill only ONE pod. **Use this label carefully.**


Expand All @@ -42,70 +39,127 @@ spec:
metadata:
labels:
kube-monkey/enabled: enabled
kube-monkey/identifier: monkey-victim
kube-monkey/identifier: monkey-victim-pods
kube-monkey/mtbf: '2'
[... omitted ...]
```

For newer versions of kubernetes you may need to add the labels to the k8 app metadata as well.

```yaml
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: monkey-victim
namespace: app-namespace
labels:
kube-monkey/enabled: enabled
kube-monkey/identifier: monkey-victim
kube-monkey/mtbf: '2'
spec:
template:
metadata:
labels:
kube-monkey/enabled: enabled
kube-monkey/identifier: monkey-victim
[... omitted ...]
```

### Overriding the apiserver
#### Use cases:
* Since client-go does not support [cluster dns](https://github.com/kubernetes/client-go/blob/master/rest/config.go#L336) explicitly with a `// TODO: switch to using cluster DNS.` note in the code, you may need to override the apiserver.
* If you are running an unauthenticated system, you may need to force the http apiserver enpoint.

#### To override the apiserver specify in the config.toml file
```toml
[kubernetes]
host="https://your-apiserver-url.com"
```

## How kube-monkey works

#### Scheduling time
Scheduling happens once a day on Weekdays - this is when a schedule for terminations for the current day is generated.
During scheduling, kube-monkey will:
1. Generate a list of eligible deployments (deployments that have opted-in and are not blacklisted)
2. For each eligible deployment, flip a biased coin (bias determined by `kube-monkey/mtbf`) to determine if a pod for that deployment should be killed today
1. Generate a list of eligible k8 apps (k8 apps that have opted-in and are not blacklisted)
2. For each eligible k8 app, flip a biased coin (bias determined by `kube-monkey/mtbf`) to determine if a pod for that k8 app should be killed today
3. For each victim, calculate a random time when a pod will be killed

#### Termination time
This is the randomly generated time during the day when a victim Deployment will have a pod killed.
This is the randomly generated time during the day when a victim k8 app will have a pod killed.
At termination time, kube-monkey will:
1. Check if the deployment is still eligible (has not opted-out or been blacklisted since scheduling)
2. Get a list of running pods for the deployment
1. Check if the k8 app is still eligible (has not opted-out or been blacklisted since scheduling)
2. Get a list of running pods for the k8 app
3. Select one random pod and delete it

## Building

Clone the repository and build the container.

```
$ go get github.com/asobti/kube-monkey
$ cd $GOPATH/src/github.com/asobti/kube-monkey
$ make container
```bash
go get github.com/asobti/kube-monkey
cd $GOPATH/src/github.com/asobti/kube-monkey
make container
```

## Configuring
kube-monkey is configured by a toml file placed at `/etc/kube-monkey/config.toml`.
Configuration keys and descriptions can be found in [`config/param/param.go`](https://github.com/asobti/kube-monkey/blob/master/config/param/param.go)
kube-monkey is configured by a toml file placed at `/etc/kube-monkey/config.toml` and expects the configmap to exist before the kubemonkey deployment.

#### Example config file
Configuration keys and descriptions can be found in [`config/param/param.go`](https://github.com/asobti/kube-monkey/blob/master/config/param/param.go)

#### Example config.toml file
```toml
[kubemonkey]
dry_run = true # Terminations are only logged
run_hour = 8 # Run scheduling at 8am on weekdays
start_hour = 10 # Don't schedule any pod deaths before 10am
end_hour = 16 # Don't schedule any pod deaths after 4pm
blacklisted_namespaces = ["kube-system"] # Critical deployments live here
blacklisted_namespaces = ["kube-system"] # Critical apps live here
time_zone = "America/New_York" # Set tzdata timezone example. Note the field is time_zone not timezone
```

## Deploying

Run kube-monkey as a Deployment within the Kubernetes cluster, in a namespace that has permissions to kill Pods
in other namespaces (eg. `kube-system`).
1. First deploy the expected `kube-monkey-config-map` configmap in the namespace you intend to run kube-monkey in (for example, the `kube-system` namespace). Make sure to define the keyname as `config.toml`

> For example `kubectl create configmap km-config --from-file=config.toml=km-config.toml`

2. Run kube-monkey as a k8 app within the Kubernetes cluster, in a namespace that has permissions to kill Pods in other namespaces (eg. `kube-system`).

See dir [`examples/`](https://github.com/asobti/kube-monkey/tree/master/examples) for example Kubernetes yaml files.

## Logging

kube-monkey uses glog and supports all command-line features for glog. To specify a custom v level or a custom log directory on the pod, see `args: ["-v=5", "-log_dir=/path/to/custom/log"]` in the [example deployment file](https://github.com/asobti/kube-monkey/tree/master/examples/deployment.yaml)

> **Standardized glog levels `grep -r V\([0-9]\) *`**
>
> L0: None
>
> L1: Highest Level current status info and Errors with Terminations
>
> L2: Successful terminations
>
> L3: More detailed schedule status info
>
> L4: Debugging verbose schedule and config info
>
> L5: Auto-resolved inconsequential issues

More resources: See the [k8 logging page](https://kubernetes.io/docs/concepts/cluster-administration/logging/) suggesting [community conventions for logging severity](https://github.com/kubernetes/community/blob/master/contributors/devel/logging.md)

## Compatibility with Kubernetes

kube-monkey is built using v1.5 of [kubernetes/client-go](https://github.com/kubernetes/client-go). Refer to the
kube-monkey is built using v6.0 of [kubernetes/client-go](https://github.com/kubernetes/client-go). Refer to the
[Compatibility Matrix](https://github.com/kubernetes/client-go#compatibility-matrix) to see which
versions of Kubernetes are compatible.

## To do
## Ways to contribute

- Add tests
- Use a logging library like [glog](https://github.com/golang/glog)
- Add unit [tests](https://golang.org/pkg/testing/)
- Support more k8 types
- ~~deployments~~
- ~~statefulsets~~
- dameonsets
- etc