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advanced audit beta features
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@CaoShuFeng
CaoShuFeng committed Sep 5, 2017
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175 changes: 113 additions & 62 deletions docs/tasks/debug-application-cluster/audit.md
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Expand Up @@ -22,7 +22,7 @@ answer the following questions:
- from where was it initiated?
- to where was it going?

## Audit logs
## Legacy Audit

Kubernetes audit is part of [Kube-apiserver][kube-apiserver] logging all requests
processed by the server. Each audit log entry contains two lines:
Expand All @@ -37,8 +37,13 @@ Example output for `admin` user listing pods in the `default` namespace:
2017-03-21T03:57:09.108403639-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" response="200"
```

Note that this format changes when enabling the `AdvancedAuditing` feature discussed
later in this document.
Note that Kubernetes 1.8 has switched to use the advanced structured audit log by default.
To fallback to this legacy audit, disable the advanced auditing feature
using the `AdvancedAuditing` feature gate on the [kube-apiserver][kube-apiserver]:

```
--feature-gates=AdvancedAuditing=false
```

### Configuration

Expand All @@ -62,18 +67,12 @@ and `audit-log-maxage` options.
## Advanced audit

Kubernetes 1.7 expands auditing with experimental functionality such as event
filtering and a webhook for integration with external systems. The rest of this
document covers features that are __alpha__ and may change in backward incompatible
ways.
filtering and a webhook for integration with external systems. Kubernetes 1.8
upgrades the advanced audit feature to beta, and some backward incompatible changes
have been committed.

Enable the alpha auditing features using the `AdvancedAuditing` feature gate on
the [kube-apiserver][kube-apiserver]:

```
--feature-gates=AdvancedAuditing=true
```

`AdvancedAuditing`is customizable in two ways. Policy, which determines what's recorded,
`AdvancedAuditing` is customizable in two ways. Policy, which determines what's recorded,
and backends, which persist records. Backend implementations include logs files and
webhooks.

Expand Down Expand Up @@ -110,10 +109,17 @@ The policy file holds rules that determine the level of an event. Known audit le
When an event is processed, it's compared against the list of rules in order.
The first matching rule sets the audit level of the event. The audit policy is
defined by the [`audit.k8s.io` API group][audit-api].
Some new fields are supported in beta version, like `resourceNames` and `omitStages`.

In Kubernetes 1.8 `kind` and `apiVersion` along with `rules` __must__ be supplied to
the the audit policy file. A policy file with 0 rules, or a policy file doesn't provide
valid `apiVersion` and `kind` will be treated as illgal.

An example audit policy file:
Some example audit policy files:

```yaml
apiVersion: audit.k8s.io/v1beta1 #this is necessary in Kubernetes 1.8
kind: Policy
rules:
# Don't log watch requests by the "system:kube-proxy" on endpoints or services
- level: None
Expand Down Expand Up @@ -155,10 +161,46 @@ rules:
- level: Metadata
```
The next audit policy file shows new features Kubernetes 1.8:
```yaml
apiVersion: audit.k8s.io/v1beta1
kind: Policy
rules:
# Log pod changes at Request level
- level: Request
resources:
- group: ""
# Resource "pods" no longer matches requests to any subresource of pods,
# This behavior is consistent with the RBAC policy.
resources: ["pods"]
# Log "pods/log", "pods/status" at Metadata level
- level: Metadata
resources:
- group: ""
resources: ["pods/log", "pods/status"]

# Not log requests to a configmap called "controller-leader"
- level: None
resources:
- group: ""
resources: ["configmaps"]
resourceNames: ["controller-leader"]

# A catch-all rule to log all other requests at the Metadata level.
# For this rule we use "omitStages" to omit events at "ReqeustReceived" stage.
# events in this stage will not be sent to backend.
- level: Metadata
omitStages:
- "RequestReceived"
```
You can use a minimal audit policy file to log all requests at the `Metadata` level:

```yaml
# Log all requests at the Metadata level.
apiVersion: audit.k8s.io/v1beta1
kind: Policy
rules:
- level: Metadata
```
Expand All @@ -183,31 +225,34 @@ API can be found [here][audit-api] with more details about the exact fields capt
The behavior of the `--audit-log-path` flag changes when enabling the `AdvancedAuditing`
feature flag. This includes the cleanups discussed above, such as changes to the `method`
values and the introduction of a "stage" for each event. As before, the `id` field of
the log indicates which events were generated from the same request. With default legacy
the log indicates which events were generated from the same request. With default json
format, events are formatted as follows:

```
2017-06-15T21:50:50.259470834Z AUDIT: id="591e9fde-6a98-46f6-b7bc-ec8ef575696d" stage="RequestReceived" ip="10.2.1.3" method="update" user="system:serviceaccount:kube-system:default" groups="\"system:serviceaccounts\",\"system:serviceaccounts:kube-system\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="kube-system" uri="/api/v1/namespaces/kube-system/endpoints/kube-controller-manager" response="<deferred>"
2017-06-15T21:50:50.259470834Z AUDIT: id="591e9fde-6a98-46f6-b7bc-ec8ef575696d" stage="ResponseComplete" ip="10.2.1.3" method="update" user="system:serviceaccount:kube-system:default" groups="\"system:serviceaccounts\",\"system:serviceaccounts:kube-system\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="kube-system" uri="/api/v1/namespaces/kube-system/endpoints/kube-controller-manager" response="200"
{"kind":"Event","apiVersion":"audit.k8s.io/v1beta1","metadata":{"creationTimestamp":null},"level":"Metadata","timestamp":"2017-09-05T10:04:55Z","auditID":"77e58433-d345-40ac-b2d8-9866bd355cea","stage":"RequestReceived","requestURI":"/apis/rbac.authorization.k8s.io/v1/namespaces/default/roles","verb":"list","user":{"username":"kubecfg","groups":["system:masters","system:authenticated"]},"sourceIPs":["172.16.116.128"],"objectRef":{"resource":"roles","namespace":"default","apiGroup":"rbac.authorization.k8s.io","apiVersion":"v1"}}
{"kind":"Event","apiVersion":"audit.k8s.io/v1beta1","metadata":{"creationTimestamp":null},"level":"Metadata","timestamp":"2017-09-05T10:04:55Z","auditID":"77e58433-d345-40ac-b2d8-9866bd355cea","stage":"ResponseComplete","requestURI":"/apis/rbac.authorization.k8s.io/v1/namespaces/default/roles","verb":"list","user":{"username":"kubecfg","groups":["system:masters","system:authenticated"]},"sourceIPs":["172.16.116.128"],"objectRef":{"resource":"roles","namespace":"default","apiGroup":"rbac.authorization.k8s.io","apiVersion":"v1"},"responseStatus":{"metadata":{},"code":200}}
```

Logged events omit the request and response bodies. The `Request` and
`RequestResponse` levels are equivalent to `Metadata` for legacy format.
In alpha version, objectRef.apiVersion holds both the api group and version.
In beta version these were break out into objectRef.apiGroup and objectRef.apiVersion.

Since Kubernetes 1.8, structed json fromat is supported for log backend.
Use the following option to switch log to json format:
Since Kubernetes 1.8, structed json fromat is used for log backend by default.
Use the following option to switch log to legacy format:

```
--audit-log-format=json
--audit-log-format=legacy
```

With json format, events are formatted as follows:
With legacy format, events are formatted as follows:

```
{"kind":"Event","apiVersion":"audit.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"level":"Metadata","timestamp":"2017-07-12T11:02:43Z","auditID":"2e79f0c9-a941-45ae-a9ce-663a1b19ff14","stage":"RequestReceived","requestURI":"/api/v1/namespaces/default/pods","verb":"list","user":{"username":"kubecfg","groups":["system:masters","system:authenticated"]},"sourceIPs":["172.16.116.128"],"objectRef":{"resource":"pods","namespace":"default","apiVersion":"/v1"}}
{"kind":"Event","apiVersion":"audit.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"level":"Metadata","timestamp":"2017-07-12T11:02:43Z","auditID":"2e79f0c9-a941-45ae-a9ce-663a1b19ff14","stage":"ResponseComplete","requestURI":"/api/v1/namespaces/default/pods","verb":"list","user":{"username":"kubecfg","groups":["system:masters","system:authenticated"]},"sourceIPs":["172.16.116.128"],"objectRef":{"resource":"pods","namespace":"default","apiVersion":"/v1"},"responseStatus":{"metadata":{},"code":200}}
2017-09-05T06:08:19.885328047-04:00 AUDIT: id="c28a95ad-f9dd-47e1-a617-b6dc152db95f" stage="RequestReceived" ip="172.16.116.128" method="list" user="kubecfg" groups="\"system:masters\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="default" uri="/apis/rbac.authorization.k8s.io/v1/namespaces/default/roles" response="<deferred>"
2017-09-05T06:08:19.885328047-04:00 AUDIT: id="c28a95ad-f9dd-47e1-a617-b6dc152db95f" stage="ResponseComplete" ip="172.16.116.128" method="list" user="kubecfg" groups="\"system:masters\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="default" uri="/apis/rbac.authorization.k8s.io/v1/namespaces/default/roles" response="200"
```

Logged events omit the request and response bodies. The `Request` and
`RequestResponse` levels are equivalent to `Metadata` for legacy format.

#### Webhook backend

The audit webhook backend can be used to have [kube-apiserver][kube-apiserver]
Expand Down Expand Up @@ -255,41 +300,43 @@ Events are POSTed as a JSON serialized `EventList`. An example payload:
```json
{
"kind": "EventList",
"apiVersion": "audit.k8s.io/v1alpha1",
"items": [
{
"metadata": {
"creationTimestamp": null
},
"level": "Metadata",
"timestamp": "2017-06-15T23:07:40Z",
"auditID": "4faf711a-9094-400f-a876-d9188ceda548",
"stage": "ResponseComplete",
"requestURI": "/apis/rbac.authorization.k8s.io/v1beta1/namespaces/kube-public/rolebindings/system:controller:bootstrap-signer",
"verb": "get",
"user": {
"username": "system:apiserver",
"uid": "97a62906-e4d7-4048-8eda-4f0fb6ff8f1e",
"groups": [
"system:masters"
]
},
"sourceIPs": [
"127.0.0.1"
],
"objectRef": {
"resource": "rolebindings",
"namespace": "kube-public",
"name": "system:controller:bootstrap-signer",
"apiVersion": "rbac.authorization.k8s.io/v1beta1"
},
"responseStatus": {
"metadata": {},
"code": 200
}
}
]
"apiVersion": "audit.k8s.io/v1beta1",
"items": [
{
"auditID": "24f30caf-d7d4-45d5-b7bd-e7af300d7886",
"level": "Metadata",
"metadata": {
"creationTimestamp": null
},
"objectRef": {
"apiGroup": "rbac.authorization.k8s.io",
"apiVersion": "v1",
"name": "jane",
"namespace": "default",
"resource": "roles"
},
"requestURI": "/apis/rbac.authorization.k8s.io/v1/namespaces/default/roles/jane",
"responseStatus": {
"code": 200,
"metadata": {}
},
"sourceIPs": [
"172.16.116.128"
],
"stage": "ResponseComplete",
"timestamp": "2017-09-05T10:20:24Z",
"user": {
"groups": [
"system:masters",
"system:authenticated"
],
"username": "kubecfg"
},
"verb": "get"
}
],
"kind": "EventList",
"metadata": {}
}
```

Expand Down Expand Up @@ -422,9 +469,13 @@ Note that in addition to file output plugin, logstash has a variety of outputs t
let users route data where they want. For example, users can emit audit events to elasticsearch
plugin which supports full-text search and analytics.

[audit-api]: https://github.com/kubernetes/kubernetes/blob/v1.7.0-rc.1/staging/src/k8s.io/apiserver/pkg/apis/audit/v1alpha1/types.go
<!---
herf of audit-api is not right, because https://github.com/kubernetes/kubernetes/pull/49280 is not included in this tag.
Maybe it will show up in another tag, then I will update it.
-->
[audit-api]: https://github.com/kubernetes/kubernetes/blob/v1.8.0-beta.0/staging/src/k8s.io/apiserver/pkg/apis/audit/v1beta1/types.go
[kube-apiserver]: /docs/admin/kube-apiserver
[gce-audit-profile]: https://github.com/kubernetes/kubernetes/blob/v1.7.0/cluster/gce/gci/configure-helper.sh#L490
[gce-audit-profile]: https://github.com/kubernetes/kubernetes/blob/v1.8.0-beta.0/cluster/gce/gci/configure-helper.sh#L532
[fluentd]: http://www.fluentd.org/
[fluentd_install_doc]: http://docs.fluentd.org/v0.12/articles/quickstart#step1-installing-fluentd
[logstash]: https://www.elastic.co/products/logstash
Expand Down

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