Routing your logs with Fluentd match directives
Note: This page describes routing logs with Fluentd. If you are using syslog-ng to route your log messages, see Routing your logs with syslog-ng.
The first step to process your logs is to select which logs go where. The Logging operator uses Kubernetes labels, namespaces and other metadata to separate different log flows.
Available routing metadata keys:
| Name | Type | Description | Empty |
|---|---|---|---|
| namespaces | []string | List of matching namespaces | All namespaces |
| labels | map[string]string | Key - Value pairs of labels | All labels |
| hosts | []string | List of matching hosts | All hosts |
| container_names | []string | List of matching containers (not Pods) | All containers |
Match statement
To select or exclude logs you can use the match statement. Match is a collection
of select and exclude expressions. In both expression you can use the labels
attribute to filter for pod’s labels. Moreover, in Cluster flow you can use namespaces
as a selecting or excluding criteria.
If you specify more than one label in a select or exclude expression, the labels have a logical AND connection between them. For example, an exclude expression with two labels excludes messages that have both labels. If you want an OR connection between labels, list them in separate expressions. For example, to exclude messages that have one of two specified labels, create a separate exclude expression for each label.
The select and exclude statements are evaluated in order!
Without at least one select criteria, no messages will be selected!
Flow:
kind: Flow
metadata:
name: flow-sample
spec:
match:
- exclude:
labels:
exclude-this: label
- select:
labels:
app: nginx
label/xxx: example
ClusterFlow:
kind: ClusterFlow
metadata:
name: flow-sample
spec:
match:
- exclude:
labels:
exclude-this: label
namespaces:
- developer
- select:
labels:
app: nginx
label/xxx: example
namespaces:
- production
- beta
Examples
Example 0. Select all logs
To select all logs, or if you only want to exclude some logs but retain others you need an empty select statement.
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-all
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- select: {}
Example 1. Select logs by label
Select logs with app: nginx labels from the namespace:
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-sample
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- select:
labels:
app: nginx
Example 2. Exclude logs by label
Exclude logs with app: nginx labels from the namespace
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-sample
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- exclude:
labels:
app: nginx
- select: {}
Example 3. Exclude and select logs by label
Select logs with app: nginx labels from the default namespace but exclude logs with env: dev labels
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-sample
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- exclude:
labels:
env: dev
- select:
labels:
app: nginx
Example 4. Exclude cluster logs by namespace
Select app: nginx from all namespaces except from dev and sandbox
apiVersion: logging.banzaicloud.io/v1beta1
kind: ClusterFlow
metadata:
name: clusterflow-sample
spec:
globalOutputRefs:
- forward-output-sample
match:
- exclude:
namespaces:
- dev
- sandbox
- select:
labels:
app: nginx
Example 5. Exclude and select cluster logs by namespace
Select app: nginx from all prod and infra namespaces but exclude cluster logs from dev, sandbox namespaces
apiVersion: logging.banzaicloud.io/v1beta1
kind: ClusterFlow
metadata:
name: clusterflow-sample
spec:
globalOutputRefs:
- forward-output-sample
match:
- exclude:
namespaces:
- dev
- sandbox
- select:
labels:
app: nginx
namespaces:
- prod
- infra
Example 6. Multiple labels - AND
Exclude logs that have both the app: nginx and app.kubernetes.io/instance: nginx-demo labels
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-sample
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- exclude:
labels:
app: nginx
app.kubernetes.io/instance: nginx-demo
- select: {}
Example 6. Multiple labels - OR
Exclude logs that have either the app: nginx or the app.kubernetes.io/instance: nginx-demo labels
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: flow-sample
namespace: default
spec:
localOutputRefs:
- forward-output-sample
match:
- exclude:
labels:
app: nginx
- exclude:
labels:
app.kubernetes.io/instance: nginx-demo
- select: {}