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Change auditing docs page for 1.9 release (#6427)

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* Change auditing docs page for 1.9 release

Signed-off-by: Mik Vyatskov <vmik@google.com>

* Address review comments

Signed-off-by: Mik Vyatskov <vmik@google.com>

* Address review comments

Signed-off-by: Mik Vyatskov <vmik@google.com>

* Address review comments

Signed-off-by: Mik Vyatskov <vmik@google.com>

* Fix broken link

Signed-off-by: Mik Vyatskov <vmik@google.com>
This commit is contained in:
Mik Vyatskov
2017-12-07 21:46:36 +01:00
committed by Zach Corleissen
parent a6eb85887d
commit 07d84585ee
2 changed files with 162 additions and 300 deletions
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docs/tasks/debug-application-cluster/audit-policy.yaml
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@@ -0,0 +1,68 @@
apiVersion: audit.k8s.io/v1beta1 # This is required.
kind: Policy
# Don't generate audit events for all requests in RequestReceived stage.
omitStages:
- "RequestReceived"
rules:
# Log pod changes at RequestResponse level
- level: RequestResponse
resources:
- group: ""
# Resource "pods" doesn't match requests to any subresource of pods,
# which 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"]
# Don't log requests to a configmap called "controller-leader"
- level: None
resources:
- group: ""
resources: ["configmaps"]
resourceNames: ["controller-leader"]
# Don't log watch requests by the "system:kube-proxy" on endpoints or services
- level: None
users: ["system:kube-proxy"]
verbs: ["watch"]
resources:
- group: "" # core API group
resources: ["endpoints", "services"]
# Don't log authenticated requests to certain non-resource URL paths.
- level: None
userGroups: ["system:authenticated"]
nonResourceURLs:
- "/api*" # Wildcard matching.
- "/version"
# Log the request body of configmap changes in kube-system.
- level: Request
resources:
- group: "" # core API group
resources: ["configmaps"]
# This rule only applies to resources in the "kube-system" namespace.
# The empty string "" can be used to select non-namespaced resources.
namespaces: ["kube-system"]
# Log configmap and secret changes in all other namespaces at the Metadata level.
- level: Metadata
resources:
- group: "" # core API group
resources: ["secrets", "configmaps"]
# Log all other resources in core and extensions at the Request level.
- level: Request
resources:
- group: "" # core API group
- group: "extensions" # Version of group should NOT be included.
# A catch-all rule to log all other requests at the Metadata level.
- level: Metadata
# Long-running requests like watches that fall under this rule will not
# generate an audit event in RequestReceived.
omitStages:
- "RequestReceived"
docs/tasks/debug-application-cluster/audit.md
+94 -300
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@@ -9,7 +9,9 @@ title: Auditing
* TOC
{:toc}
Kubernetes Audit provides a security-relevant chronological set of records documenting
{% include feature-state-beta.md %}
Kubernetes auditing provides a security-relevant chronological set of records documenting
the sequence of activities that have affected system by individual users, administrators
or other components of the system. It allows cluster administrator to
answer the following questions:
@@ -22,178 +24,28 @@ answer the following questions:
- from where was it initiated?
- to where was it going?
## Legacy Audit
[Kube-apiserver][kube-apiserver] performs auditing. Each request on each stage
of its execution generates an event, which is then pre-processed according to
a certain policy and written to a backend. You can find more details about the
pipeline in the [design proposal][auditing-proposal].
Kubernetes audit is part of [Kube-apiserver][kube-apiserver] logging all requests
processed by the server. Each audit log entry contains two lines:
## Audit Policy
1. The request line containing a unique ID to match the response and request metadata, such as the source IP, requesting user, impersonation information, resource being requested, etc.
2. The response line containing a unique ID matching the request line and the response code.
Audit policy defines rules about what events should be recorded and what data
they should include. When an event is processed, it's compared against the list
of rules in order. The first matching rule sets the [audit level][auditing-level]
of the event. The audit policy object structure is defined in the
[`audit.k8s.io` API group][auditing-api].
Example output for `admin` user listing pods in the `default` namespace:
```
2017-03-21T03:57:09.106841886-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" ip="127.0.0.1" method="GET" user="admin" groups="\"system:masters\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="default" uri="/api/v1/namespaces/default/pods"
2017-03-21T03:57:09.108403639-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" response="200"
```
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
[Kube-apiserver][kube-apiserver] provides the following options which are responsible
for configuring where and how audit logs are handled:
- `audit-log-path` - enables the audit log pointing to a file where the requests are being logged to, '-' means standard out.
- `audit-log-maxage` - specifies maximum number of days to retain old audit log files based on the timestamp encoded in their filename.
- `audit-log-maxbackup` - specifies maximum number of old audit log files to retain.
- `audit-log-maxsize` - specifies maximum size in megabytes of the audit log file before it gets rotated. Defaults to 100MB.
If an audit log file already exists, Kubernetes appends new audit logs to that file.
Otherwise, Kubernetes creates an audit log file at the location you specified in
`audit-log-path`. If the audit log file exceeds the size you specify in `audit-log-maxsize`,
Kubernetes will rename the current log file by appending the current timestamp on
the file name (before the file extension) and create a new audit log file.
Kubernetes may delete old log files when creating a new log file; you can configure
how many files are retained and how old they can be by specifying the `audit-log-maxbackup`
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. Kubernetes 1.8
upgrades the advanced audit feature to beta, and some backward incompatible changes
have been committed.
`AdvancedAuditing` is customizable in two ways. Policy, which determines what's recorded,
and backends, which persist records. Backend implementations include logs files and
webhooks.
The structure of audit events changes when enabling the `AdvancedAuditing` feature
flag. This includes some cleanups, such as the `method` reflecting the verb evaluated
by the [authorization layer](/docs/admin/authorization/) instead of the [HTTP verb](/docs/admin/authorization/#determine-the-request-verb).
Also, instead of always generating two events per request, events are recorded with an associated "stage".
The known stages are:
- `RequestReceived` - The stage for events generated as soon as the audit handler receives the request.
- `ResponseStarted` - Once the response headers are sent, but before the response body is sent. This stage is only generated for long-running requests (e.g. watch).
- `ResponseComplete` - Once the response body has been completed.
- `Panic` - Events generated when a panic occurred.
### Audit Policy
Audit policy is a document defining rules about what events should be recorded.
The policy is passed to the [kube-apiserver][kube-apiserver] using the
`--audit-policy-file` flag.
```
--audit-policy-file=/etc/kubernetes/audit-policy.yaml
```
If `AdvancedAuditing` is enabled and this flag is omitted, no events are logged.
The policy file holds rules that determine the level of an event. Known audit levels are:
- `None` - don't log events that match this rule.
- `Metadata` - log request metadata (requesting user, timestamp, resource, verb, etc.) but not request or response body.
- `Request` - log event metadata and request body but not response body.
- `RequestResponse` - log event metadata, request and response bodies.
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 provided in
the audit policy file. A policy file with 0 rules, or a policy file that doesn't provide
a valid `apiVersion` and `kind` value will be treated as illgal.
You can pass a file with the policy to [kube-apiserver][kube-apiserver]
using the `--audit-policy-file` flag. If the flag is omitted, no events are logged.
__Note:__ `kind` and `apiVersion` fields along with `rules` __must__ be provided
in the audit policy file. A policy with no (0) rules, or a policy that doesn't
provide valid `apiVersion` and `kind` values is treated as illegal.
Some example audit policy files:
```yaml
apiVersion: audit.k8s.io/v1beta1 #this is required in Kubernetes 1.8
kind: Policy
rules:
# Don't log watch requests by the "system:kube-proxy" on endpoints or services
- level: None
users: ["system:kube-proxy"]
verbs: ["watch"]
resources:
- group: "" # core API group
resources: ["endpoints", "services"]
# Don't log authenticated requests to certain non-resource URL paths.
- level: None
userGroups: ["system:authenticated"]
nonResourceURLs:
- "/api*" # Wildcard matching.
- "/version"
# Log the request body of configmap changes in kube-system.
- level: Request
resources:
- group: "" # core API group
resources: ["configmaps"]
# This rule only applies to resources in the "kube-system" namespace.
# The empty string "" can be used to select non-namespaced resources.
namespaces: ["kube-system"]
# Log configmap and secret changes in all other namespaces at the Metadata level.
- level: Metadata
resources:
- group: "" # core API group
resources: ["secrets", "configmaps"]
# Log all other resources in core and extensions at the Request level.
- level: Request
resources:
- group: "" # core API group
- group: "extensions" # Version of group should NOT be included.
# A catch-all rule to log all other requests at the Metadata level.
- level: Metadata
```
The next audit policy file shows new features introduced in 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"]
# Don't 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"
```
{% include code.html language="yaml" file="audit-policy.yaml" ghlink="/docs/tasks/debug-application-cluster/audit-policy.yaml" %}
You can use a minimal audit policy file to log all requests at the `Metadata` level:
@@ -208,153 +60,51 @@ rules:
The [audit profile used by GCE][gce-audit-profile] should be used as reference by
admins constructing their own audit profiles.
### Audit backends
## Audit backends
Audit backends implement strategies for emitting events. The [kube-apiserver][kube-apiserver]
provides a logging and webhook backend.
Audit backends implement exporting audit events to an external storage.
[Kube-apiserver][kube-apiserver] out of the box provides two backends:
Each request to the API server can generate multiple events, one when the request is received,
another when the response is sent, and additional events for long running requests (such as
watches). The ID of events will be the same if they were generated from the same request.
- Log backend, which writes events to a disk
- Webhook backend, which sends events to an external API
The event format is defined by the `audit.k8s.io` API group. The `v1alpha1` format of this
API can be found [here][audit-api] with more details about the exact fields captured.
In both cases, audit events structure is defined by the API in the
`audit.k8s.io` API group. The current version of the API is
[`v1beta1`][auditing-api].
#### Log backend
### Log backend
The behavior of the `--audit-log-path` flag changes when enabling the `AdvancedAuditing`
feature flag. All generated events defined by `--audit-policy-file` are recorded in structured
json format:
Log backend writes audit events to a file in JSON format. You can configure
log audit backend using the following [kube-apiserver][kube-apiserver] flags:
```
{"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}}
```
- `--audit-log-path` specifies the log file path that log backend uses to write
audit events. Not specifying this flag disables log backend. `-` means standard out
- `--audit-log-maxage` defined the maximum number of days to retain old audit log files
- `--audit-log-maxbackup` defines the maximum number of audit log files to retain
- `--audit-log-maxsize` defines the maximum size in megabytes of the audit log file before it gets rotated
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.
### Webhook backend
Starting from Kubernetes 1.8, structured json format is used for log backend by default.
Use the following option to switch log to legacy format:
Webhook backend sends audit events to a remote API, which is assumed to be the
same API as [kube-apiserver][kube-apiserver] exposes. You can configure webhook
audit backend using the following kube-apiserver flags:
```
--audit-log-format=legacy
```
With legacy format, events are formatted as follows:
```
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. This legacy format
of advanced audit is different from the [Legacy Audit](# Legacy Audit) discussed above, such
as changes to the method values and the introduction of a "stage" for each event.
#### Webhook backend
The audit webhook backend can be used to have [kube-apiserver][kube-apiserver]
send audit events to a remote service. The webhook requires the `AdvancedAuditing`
feature flag and is configured using the following command line flags:
```
--audit-webhook-config-file=/etc/kubernetes/audit-webhook-kubeconfig
--audit-webhook-mode=batch
```
`audit-webhook-mode` controls buffering strategies used by the webhook. Known modes are:
- `batch` - buffer events and asynchronously send the set of events to the external service.
- `blocking` - block API server responses on sending each event to the external service.
- `--audit-webhook-config-file` specifies the path to a file with a webhook
configuration. Webhook configuration is effectively a [kubeconfig][kubeconfig].
- `--audit-webhook-mode` define the buffering strategy, one of the following:
- `batch` - buffer events and asynchronously send the set of events to the external service
This is the default
- `blocking` - block API server responses on sending each event to the external service
The webhook config file uses the kubeconfig format to specify the remote address of
the service and credentials used to connect to it.
```
# clusters refers to the remote service.
clusters:
- name: name-of-remote-audit-service
cluster:
certificate-authority: /path/to/ca.pem # CA for verifying the remote service.
server: https://audit.example.com/audit # URL of remote service to query. Must use 'https'.
## Log Collector Examples
# users refers to the API server's webhook configuration.
users:
- name: name-of-api-server
user:
client-certificate: /path/to/cert.pem # cert for the webhook plugin to use
client-key: /path/to/key.pem # key matching the cert
# kubeconfig files require a context. Provide one for the API server.
current-context: webhook
contexts:
- context:
cluster: name-of-remote-audit-service
user: name-of-api-sever
name: webhook
```
Events are POSTed as a JSON serialized `EventList`. An example payload:
```json
{
"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": {}
}
```
### Audit-Id
Audit-Id is a unique ID for each http request to kube-apiserver. The ID of events will be the
same if they were generated from the same request. Starting from Kubernetes 1.8, if an audit
event is generated for the request, kube-apiserver will respond with an Audit-Id in the HTTP header.
Note that for some special requests like `kubectl exec`, `kubectl attach`, kube-apiserver works
like a proxy, no Audit-Id will be returned even if audit events are recorded.
### Log Collector Examples
#### Use fluentd to collect and distribute audit events from log file
### Use fluentd to collect and distribute audit events from log file
[Fluentd][fluentd] is an open source data collector for unified logging layer.
In this example, we will use fluentd to split audit events by different namespaces.
Note that this example requries json format output support in Kubernetes 1.8.
1. install [fluentd, fluent-plugin-forest and fluent-plugin-rewrite-tag-filter][fluentd_install_doc] in the kube-apiserver node
1. create a config file for fluentd
@@ -412,7 +162,7 @@ Note that this example requries json format output support in Kubernetes 1.8.
--audit-policy-file=/etc/kubernetes/audit-policy.yaml --audit-log-path=/var/log/kube-audit --audit-log-format=json
1. check audits for different namespaces in /var/log/audit-*.log
#### Use logstash to collect and distribute audit events from webhook backend
### Use logstash to collect and distribute audit events from webhook backend
[Logstash][logstash] is an open source, server-side data processing tool. In this example,
we will use logstash to collect audit events from webhook backend, and save events of
@@ -477,9 +227,53 @@ 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/v1.8.0-beta.1/staging/src/k8s.io/apiserver/pkg/apis/audit/v1beta1/types.go
## Legacy Audit
__Note:__ Legacy Audit is deprecated and is disabled by default since Kubernetes 1.8.
To fallback to this legacy audit, disable the advanced auditing feature
using the `AdvancedAuditing` feature gate in [kube-apiserver][kube-apiserver]:
```
--feature-gates=AdvancedAuditing=false
```
In legacy format, each audit log entry contains two lines:
1. The request line containing a unique ID to match the response and request metadata, such as the source IP, requesting user, impersonation information, resource being requested, etc.
2. The response line containing a unique ID matching the request line and the response code.
Example output for `admin` user listing pods in the `default` namespace:
```
2017-03-21T03:57:09.106841886-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" ip="127.0.0.1" method="GET" user="admin" groups="\"system:masters\",\"system:authenticated\"" as="<self>" asgroups="<lookup>" namespace="default" uri="/api/v1/namespaces/default/pods"
2017-03-21T03:57:09.108403639-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" response="200"
```
### Configuration
[Kube-apiserver][kube-apiserver] provides the following options which are responsible
for configuring where and how audit logs are handled:
- `audit-log-path` - enables the audit log pointing to a file where the requests are being logged to, '-' means standard out.
- `audit-log-maxage` - specifies maximum number of days to retain old audit log files based on the timestamp encoded in their filename.
- `audit-log-maxbackup` - specifies maximum number of old audit log files to retain.
- `audit-log-maxsize` - specifies maximum size in megabytes of the audit log file before it gets rotated. Defaults to 100MB.
If an audit log file already exists, Kubernetes appends new audit logs to that file.
Otherwise, Kubernetes creates an audit log file at the location you specified in
`audit-log-path`. If the audit log file exceeds the size you specify in `audit-log-maxsize`,
Kubernetes will rename the current log file by appending the current timestamp on
the file name (before the file extension) and create a new audit log file.
Kubernetes may delete old log files when creating a new log file; you can configure
how many files are retained and how old they can be by specifying the `audit-log-maxbackup`
and `audit-log-maxage` options.
[kube-apiserver]: /docs/admin/kube-apiserver
[gce-audit-profile]: https://github.com/kubernetes/kubernetes/blob/v1.8.0-beta.0/cluster/gce/gci/configure-helper.sh#L532
[auditing-proposal]: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/auditing.md
[auditing-level]: https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/auditing.md#levels
[auditing-api]: https://github.com/kubernetes/kubernetes/blob/{{page.githubbranch}}/staging/src/k8s.io/apiserver/pkg/apis/audit/v1beta1/types.go
[gce-audit-profile]: https://github.com/kubernetes/kubernetes/blob/{{page.githubbranch}}/cluster/gce/gci/configure-helper.sh#L532
[kubeconfig]: https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/
[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