Alertmanager
AlertManager Resources
Configuring Alertmanager with webhooks and httpbin container with tshark sidecar as a consumer
Summary
The following describe a setup on OCP 3.11 with:
* a container running httpbin and a sidecar running tshark and filtering for incoming http requests and logging them
* configuration of Alertmanager so that it sends alerts via webhook to httpbin
* loading cluster with high number of pods
* analyzing generated alarms
Prerequisites
Make sure that ocntainers can run as any uid:
| # oc adm policy add-scc-to-user anyuid -z default
scc "anyuid" added to: ["system:serviceaccount:default:default"]
|
OpenShift httpbin with tshark sidecar
The following allows us to see any incoming requests to httpbin but to filter out httpbin's answers.
Prerequisites:
| # oc adm policy add-scc-to-user anyuid -z default
scc "anyuid" added to: ["system:serviceaccount:default:default"]
|
Create file httpbin.yaml:
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75 | apiVersion: route.openshift.io/v1
kind: Route
metadata:
labels:
app: httpbin-deploymentconfig
name: httpbin-service
spec:
host: httpbin.apps.akaris2.lab.pnq2.cee.redhat.com
port:
targetPort: 80
to:
kind: Service
name: httpbin-service
weight: 100
wildcardPolicy: None
---
apiVersion: v1
kind: Service
metadata:
name: httpbin-service
labels:
app: httpbin-deploymentconfig
spec:
selector:
app: httpbin-pod
ports:
- protocol: TCP
port: 80
targetPort: 80
---
apiVersion: v1
kind: DeploymentConfig
metadata:
name: httpbin-deploymentconfig
labels:
app: httpbin-deploymentconfig
spec:
replicas: 1
selector:
app: httpbin-pod
template:
metadata:
labels:
app: httpbin-pod
spec:
containers:
- name: tshark
image: danielguerra/alpine-tshark
command:
- "tshark"
- "-i"
- "eth0"
- "-Y"
- "http"
- "-V"
- "dst"
- "port"
- "80"
- name: httpbin
image: kennethreitz/httpbin
imagePullPolicy: Always
command:
- "gunicorn"
- "-b"
- "0.0.0.0:80"
- "httpbin:app"
- "-k"
- "gevent"
- "--capture-output"
- "--error-logfile"
- "-"
- "--access-logfile"
- "-"
- "--access-logformat"
- "'%(h)s %(t)s %(r)s %(s)s Host: %({Host}i)s} Header-i: %({Header}i)s Header-o: %({Header}o)s'"
|
Apply config:
Get the pod name and loolk at the pod's logs for container tshark:
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101 | [root@master-0 ~]# oc get pods -l app=httpbin-pod
NAME READY STATUS RESTARTS AGE
httpbin-deploymentconfig-8-tgmvn 2/2 Running 0 3m
[root@master-0 ~]# oc logs httpbin-deploymentconfig-8-tgmvn -c tshark -f
Capturing on 'eth0'
Frame 4: 535 bytes on wire (4280 bits), 535 bytes captured (4280 bits) on interface 0
Interface id: 0 (eth0)
Interface name: eth0
Encapsulation type: Ethernet (1)
Arrival Time: Mar 11, 2020 12:17:13.290037158 UTC
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1583929033.290037158 seconds
[Time delta from previous captured frame: 0.000002253 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 36.739477011 seconds]
Frame Number: 4
Frame Length: 535 bytes (4280 bits)
Capture Length: 535 bytes (4280 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:tcp:http:urlencoded-form]
Ethernet II, Src: 7a:9c:fa:d2:07:d8 (7a:9c:fa:d2:07:d8), Dst: 0a:58:0a:80:00:0c (0a:58:0a:80:00:0c)
Destination: 0a:58:0a:80:00:0c (0a:58:0a:80:00:0c)
Address: 0a:58:0a:80:00:0c (0a:58:0a:80:00:0c)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 7a:9c:fa:d2:07:d8 (7a:9c:fa:d2:07:d8)
Address: 7a:9c:fa:d2:07:d8 (7a:9c:fa:d2:07:d8)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 10.130.0.1, Dst: 10.128.0.12
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 521
Identification: 0xdfdf (57311)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 64
Protocol: TCP (6)
Header checksum: 0x4401 [validation disabled]
[Header checksum status: Unverified]
Source: 10.130.0.1
Destination: 10.128.0.12
Transmission Control Protocol, Src Port: 38288, Dst Port: 80, Seq: 1, Ack: 1, Len: 469
Source Port: 38288
Destination Port: 80
[Stream index: 1]
[TCP Segment Len: 469]
Sequence number: 1 (relative sequence number)
[Next sequence number: 470 (relative sequence number)]
Acknowledgment number: 1 (relative ack number)
1000 .... = Header Length: 32 bytes (8)
Flags: 0x018 (PSH, ACK)
000. .... .... = Reserved: Not set
...0 .... .... = Nonce: Not set
.... 0... .... = Congestion Window Reduced (CWR): Not set
.... .0.. .... = ECN-Echo: Not set
.... ..0. .... = Urgent: Not set
.... ...1 .... = Acknowledgment: Set
.... .... 1... = Push: Set
.... .... .0.. = Reset: Not set
.... .... ..0. = Syn: Not set
.... .... ...0 = Fin: Not set
[TCP Flags: ·······AP···]
Window size value: 221
[Calculated window size: 28288]
[Window size scaling factor: 128]
Checksum: 0xd9c6 [unverified]
[Checksum Status: Unverified]
Urgent pointer: 0
Options: (12 bytes), No-Operation (NOP), No-Operation (NOP), Timestamps
TCP Option - No-Operation (NOP)
Kind: No-Operation (1)
TCP Option - No-Operation (NOP)
Kind: No-Operation (1)
TCP Option - Timestamps: TSval 44637623, TSecr 44644920
Kind: Time Stamp Option (8)
Length: 10
Timestamp value: 44637623
Timestamp echo reply: 44644920
[SEQ/ACK analysis]
[iRTT: 0.001410475 seconds]
[Bytes in flight: 470]
[Bytes sent since last PSH flag: 469]
TCP payload (469 bytes)
Hypertext Transfer Protocol
POST /post HTTP/1.1\r\n
[Expert Info (Chat/Sequence): POST /post HTTP/1.1\r\n]
[POST /post HTTP/1.1\r\n]
[Severity level: Chat]
[Group: Sequence]
Request Method: POST
Request URI: /post
Request Version: HTTP/1.1
|
Configuring Alertmanager to send webhooks to httpbin pod
Prerequisites:
* https://docs.openshift.com/container-platform/3.11/install_config/prometheus_cluster_monitoring.html
In the following, replace myuser with the user who shall log into alertmanager:
| $ oc adm policy add-cluster-role-to-user cluster-monitoring-view myuser
cluster role "cluster-monitoring-view" added: "myuser"
|
We can use the above to tell alertmanager to use httpbin as its web hook:
| $ oc get routes -n openshift-monitoring
NAME HOST/PORT PATH SERVICES PORT TERMINATION WILDCARD
alertmanager-main alertmanager-main-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com alertmanager-main web reencrypt None
grafana grafana-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com grafana https reencrypt None
prometheus-k8s prometheus-k8s-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com prometheus-k8s web reencrypt None
|
Now, access:
| https://alertmanager-main-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com
|
The status page will show the current alertmanager configuration.
The following Red Hat knowledge base solution shows how to update the alertmanager config: https://access.redhat.com/solutions/3804781
Create file: ~/group_vars/OSEv3.yml:
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36 | openshift_cluster_monitoring_operator_alertmanager_config: |+
global:
resolve_timeout: 2m
route:
group_wait: 5s
group_interval: 10s
repeat_interval: 20s
receiver: default
routes:
- match:
alertname: DeadMansSwitch
repeat_interval: 30s
receiver: deadmansswitch
- match:
alertname: DeadMansSwitch
repeat_interval: 30s
receiver: wh
- match:
alertname: '*'
repeat_interval: 2m
receiver: wh
- match:
severity: critical
receiver: wh
- match:
severity: warning
receiver: wh
- match:
alertname: KubeAPILatencyHigh
receiver: wh
receivers:
- name: default
- name: deadmansswitch
- name: wh
webhook_configs:
- url: "http://httpbin.apps.akaris2.lab.pnq2.cee.redhat.com/anything"
|
And run:
| ansible-playbook -i hosts openshift-ansible/playbooks/openshift-monitoring/config.yml -e="openshift_cluster_monitoring_operator_install=true"
|
Verify:
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36 | $ oc get secret -n openshift-monitoring alertmanager-main -o yaml | awk '/alertmanager.yaml:/ {print $NF}' | base64 -d
global:
resolve_timeout: 2m
route:
group_wait: 5s
group_interval: 10s
repeat_interval: 20s
receiver: default
routes:
- match:
alertname: DeadMansSwitch
repeat_interval: 30s
receiver: deadmansswitch
- match:
alertname: DeadMansSwitch
repeat_interval: 30s
receiver: wh
- match:
alertname: '*'
repeat_interval: 2m
receiver: wh
- match:
severity: critical
receiver: wh
- match:
severity: warning
receiver: wh
- match:
alertname: KubeAPILatencyHigh
receiver: wh
receivers:
- name: default
- name: deadmansswitch
- name: wh
webhook_configs:
- url: "http://httpbin.apps.akaris2.lab.pnq2.cee.redhat.com/anything"
|
Restart pods:
| $ oc delete pods --selector=app=alertmanager -n openshift-monitoring
pod "alertmanager-main-0" deleted
pod "alertmanager-main-1" deleted
pod "alertmanager-main-2" deleted
|
And check in the web interface of alertmanager to make sure that the new configuration shows up.
Loading the cluster
An easy way to generate an alert in a small lab is to trigger alert KubeletTooManyPods. Go to prometheus and check its configuration:
| alert: KubeletTooManyPods
expr: kubelet_running_pod_count{job="kubelet"}
> 250 * 0.9
for: 15m
labels:
severity: warning
annotations:
message: Kubelet {{ $labels.instance }} is running {{ $value }} Pods, close to the
limit of 250.
|
Then, create the following busybox deployment with a number of pods that exceeds this number, e.g.:
busybox.yaml:
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23 | apiVersion: apps/v1
kind: Deployment
metadata:
name: busybox-deployment
labels:
app: busybox-deployment
spec:
replicas: 500
selector:
matchLabels:
app: busybox-pod
template:
metadata:
labels:
app: busybox-pod
spec:
containers:
- name: busybox
image: busybox
command:
- sleep
- infinity
imagePullPolicy: IfNotPresent
|
The cluster will need some time to create those pods and it'll take 15 minutes for the alarm to fire. So take a coffee and come back later. Once the alarm fires in prometheus, go to alertmanager and make sure that it shows there, too.
Among others, Alertmanager should show:
| alertname="KubeletTooManyPods"
16:06:32, 2020-03-11
message: Kubelet 10.74.176.204:10250 is running 250 Pods, close to the limit of 250.
severity="warning"
service="kubelet"prometheus="openshift-monitoring/k8s"namespace="kube-system"job="kubelet"instance="10.74.176.204:10250"endpoint="https-metrics"
|
Now, it's time to go back to the httpbin pod.
Monitoring incoming webhook reuests
Get the pod name:
| # oc get pods | grep httpbin
httpbin-deploymentconfig-8-8crvh 2/2 Running 0 1h
|
And check the logs of the tshark container which will show a verbose packet capture of HTTP with a destination port of 80 (so we are not capturing the response):
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290 | # oc logs httpbin-deploymentconfig-8-8crvh -c tshark | tail -n 400
(...)
Frame 1708: 5220 bytes on wire (41760 bits), 5220 bytes captured (41760 bits) on interface 0
Interface id: 0 (eth0)
Interface name: eth0
(...)
Ethernet II, Src: ... (...), Dst: ... (...)
(...)
Internet Protocol Version 4, Src: ..., Dst: ...
(...)
Transmission Control Protocol, Src Port: 41606, Dst Port: 80, Seq: 1, Ack: 1, Len: 5154
(...)
Hypertext Transfer Protocol
POST /anything HTTP/1.1\r\n
[Expert Info (Chat/Sequence): POST /anything HTTP/1.1\r\n]
[POST /anything HTTP/1.1\r\n]
[Severity level: Chat]
[Group: Sequence]
Request Method: POST
Request URI: /anything
Request Version: HTTP/1.1
User-Agent: Alertmanager/0.15.2\r\n
Content-Length: 4743\r\n
[Content length: 4743]
Content-Type: application/json\r\n
(...)
JavaScript Object Notation: application/json
Object
Member Key: receiver
String value: wh
Key: receiver
Member Key: status
String value: firing
Key: status
Member Key: alerts
Array
Object
Member Key: status
String value: firing
Key: status
Member Key: labels
Object
Member Key: alertname
String value: KubeDaemonSetRolloutStuck
Key: alertname
Member Key: cluster
String value: openshift.akaris2.lab.pnq2.cee.redhat.com
Key: cluster
Member Key: daemonset
String value: node-exporter
Key: daemonset
Member Key: endpoint
String value: https-main
Key: endpoint
Member Key: instance
String value: ...:8443
Key: instance
Member Key: job
String value: kube-state-metrics
Key: job
Member Key: namespace
String value: openshift-monitoring
Key: namespace
Member Key: pod
String value: kube-state-metrics-6f4c658bcc-v57b6
Key: pod
Member Key: prometheus
String value: openshift-monitoring/k8s
Key: prometheus
Member Key: service
String value: kube-state-metrics
Key: service
Member Key: severity
String value: critical
Key: severity
Key: labels
Member Key: annotations
Object
Member Key: message
String value: Only 66.66666666666666% of desired pods scheduled and ready for daemon set openshift-monitoring/node-exporter
Key: message
Key: annotations
Member Key: startsAt
String value: 2020-03-11T16:07:40.59085788Z
Key: startsAt
Member Key: endsAt
String value: 0001-01-01T00:00:00Z
Key: endsAt
Member Key: generatorURL
String value [truncated]: https://prometheus-k8s-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com/graph?g0.expr=kube_daemonset_status_number_ready%7Bjob%3D%22kube-state-metrics%22%2Cnamespace%3D~%22%28openshift-.%2A%7Ckube-.%2A%7C
Key: generatorURL
Object
Member Key: status
String value: firing
Key: status
Member Key: labels
Object
Member Key: alertname
String value: KubeDaemonSetRolloutStuck
Key: alertname
Member Key: cluster
String value: openshift.akaris2.lab.pnq2.cee.redhat.com
Key: cluster
Member Key: daemonset
String value: ovs
Key: daemonset
Member Key: endpoint
String value: https-main
Key: endpoint
Member Key: instance
String value: ...:8443
Key: instance
Member Key: job
String value: kube-state-metrics
Key: job
Member Key: namespace
String value: openshift-sdn
Key: namespace
Member Key: pod
String value: kube-state-metrics-6f4c658bcc-v57b6
Key: pod
Member Key: prometheus
String value: openshift-monitoring/k8s
Key: prometheus
Member Key: service
String value: kube-state-metrics
Key: service
Member Key: severity
String value: critical
Key: severity
Key: labels
Member Key: annotations
Object
Member Key: message
String value: Only 66.66666666666666% of desired pods scheduled and ready for daemon set openshift-sdn/ovs
Key: message
Key: annotations
Member Key: startsAt
String value: 2020-03-11T16:07:40.59085788Z
Key: startsAt
Member Key: endsAt
String value: 0001-01-01T00:00:00Z
Key: endsAt
Member Key: generatorURL
String value [truncated]: https://prometheus-k8s-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com/graph?g0.expr=kube_daemonset_status_number_ready%7Bjob%3D%22kube-state-metrics%22%2Cnamespace%3D~%22%28openshift-.%2A%7Ckube-.%2A%7C
Key: generatorURL
Object
Member Key: status
String value: firing
Key: status
Member Key: labels
Object
Member Key: alertname
String value: KubeDaemonSetRolloutStuck
Key: alertname
Member Key: cluster
String value: openshift.akaris2.lab.pnq2.cee.redhat.com
Key: cluster
Member Key: daemonset
String value: sdn
Key: daemonset
Member Key: endpoint
String value: https-main
Key: endpoint
Member Key: instance
String value: ...:8443
Key: instance
Member Key: job
String value: kube-state-metrics
Key: job
Member Key: namespace
String value: openshift-sdn
Key: namespace
Member Key: pod
String value: kube-state-metrics-6f4c658bcc-v57b6
Key: pod
Member Key: prometheus
String value: openshift-monitoring/k8s
Key: prometheus
Member Key: service
String value: kube-state-metrics
Key: service
Member Key: severity
String value: critical
Key: severity
Key: labels
Member Key: annotations
Object
Member Key: message
String value: Only 66.66666666666666% of desired pods scheduled and ready for daemon set openshift-sdn/sdn
Key: message
Key: annotations
Member Key: startsAt
String value: 2020-03-11T16:07:40.59085788Z
Key: startsAt
Member Key: endsAt
String value: 0001-01-01T00:00:00Z
Key: endsAt
Member Key: generatorURL
String value [truncated]: https://prometheus-k8s-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com/graph?g0.expr=kube_daemonset_status_number_ready%7Bjob%3D%22kube-state-metrics%22%2Cnamespace%3D~%22%28openshift-.%2A%7Ckube-.%2A%7C
Key: generatorURL
Object
Member Key: status
String value: firing
Key: status
Member Key: labels
Object
Member Key: alertname
String value: KubeDaemonSetRolloutStuck
Key: alertname
Member Key: cluster
String value: openshift.akaris2.lab.pnq2.cee.redhat.com
Key: cluster
Member Key: daemonset
String value: sync
Key: daemonset
Member Key: endpoint
String value: https-main
Key: endpoint
Member Key: instance
String value: ...:8443
Key: instance
Member Key: job
String value: kube-state-metrics
Key: job
Member Key: namespace
String value: openshift-node
Key: namespace
Member Key: pod
String value: kube-state-metrics-6f4c658bcc-v57b6
Key: pod
Member Key: prometheus
String value: openshift-monitoring/k8s
Key: prometheus
Member Key: service
String value: kube-state-metrics
Key: service
Member Key: severity
String value: critical
Key: severity
Key: labels
Member Key: annotations
Object
Member Key: message
String value: Only 66.66666666666666% of desired pods scheduled and ready for daemon set openshift-node/sync
Key: message
Key: annotations
Member Key: startsAt
String value: 2020-03-11T16:07:40.59085788Z
Key: startsAt
Member Key: endsAt
String value: 0001-01-01T00:00:00Z
Key: endsAt
Member Key: generatorURL
String value [truncated]: https://prometheus-k8s-openshift-monitoring.apps.akaris2.lab.pnq2.cee.redhat.com/graph?g0.expr=kube_daemonset_status_number_ready%7Bjob%3D%22kube-state-metrics%22%2Cnamespace%3D~%22%28openshift-.%2A%7Ckube-.%2A%7C
Key: generatorURL
Key: alerts
Member Key: groupLabels
Object
Key: groupLabels
Member Key: commonLabels
Object
Member Key: alertname
String value: KubeDaemonSetRolloutStuck
Key: alertname
Member Key: cluster
String value: openshift.akaris2.lab.pnq2.cee.redhat.com
Key: cluster
Member Key: endpoint
String value: https-main
Key: endpoint
Member Key: instance
String value: ...:8443
Key: instance
Member Key: job
String value: kube-state-metrics
Key: job
Member Key: pod
String value: kube-state-metrics-6f4c658bcc-v57b6
Key: pod
Member Key: prometheus
String value: openshift-monitoring/k8s
Key: prometheus
Member Key: service
String value: kube-state-metrics
Key: service
Member Key: severity
String value: critical
Key: severity
Key: commonLabels
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