Open Infrastructure

h1. The ungleich kubernetes infrastructure and ungleich kubernetes manual

{{toc}}

h2. Status

This document is **pre-production**.

This document is to become the ungleich kubernetes infrastructure overview as well as the ungleich kubernetes manual.

h2. k8s clusters

| Cluster            | Purpose/Setup     | Maintainer | Master(s)                     | argo                                                   | v4 http proxy | last verified |

| c0.k8s.ooo         | Dev               | -          | UNUSED                        |                                                        |               |    2021-10-05 |

| c1.k8s.ooo         | retired           |            | -                             |                                                        |               |    2022-03-15 |

| c2.k8s.ooo         | Dev p7 HW         | Nico       | server47 server53 server54    | "argo":https://argocd-server.argocd.svc.c2.k8s.ooo     |               |    2021-10-05 |

| c3.k8s.ooo         | retired           | -          | -                             |                                                        |               |    2021-10-05 |

| c4.k8s.ooo         | Dev2 p7 HW        | Jin-Guk    | server52 server53 server54    |                                                        |               |             - |

| c5.k8s.ooo         | retired           |            | -                             |                                                        |               |    2022-03-15 |

| c6.k8s.ooo         | Dev p6 VM Jin-Guk | Jin-Guk    |                               |                                                        |               |               |

| [[p5.k8s.ooo]]     | production        |            | server34 server36 server38    | "argo":https://argocd-server.argocd.svc.p5.k8s.ooo     | -             |               |

| [[p5-cow.k8s.ooo]] | production        | Nico       | server47 server51 server55    | "argo":https://argocd-server.argocd.svc.p5-cow.k8s.ooo |               |    2022-08-27 |

| [[p6.k8s.ooo]]     | production        |            | server67 server69 server71    | "argo":https://argocd-server.argocd.svc.p6.k8s.ooo     | 147.78.194.13 |    2021-10-05 |

| [[p6-cow.k8s.ooo]] | production        |            | server134 server135 server136 | "argo":https://argocd-server.argocd.svc.p6in10.k8s.ooo | ?             |    2023-05-17 |

| [[p10.k8s.ooo]]    | production        |            | server131 server132 server133 | "argo":https://argocd-server.argocd.svc.p10.k8s.ooo    | 147.78.194.12 |    2021-10-05 |

| [[k8s.ge.nau.so]]  | development       |            | server107 server108 server109 | "argo":https://argocd-server.argocd.svc.k8s.ge.nau.so  |               |               |

| [[dev.k8s.ooo]]    | development       |            | server110 server111 server112 | "argo":https://argocd-server.argocd.svc.dev.k8s.ooo    | -             |    2022-07-08 |

| [[r1r2p15k8sooo|r1.p15.k8s.ooo]] | production | Nico | server120 | | | 2022-10-30 |

| [[r1r2p15k8sooo|r2.p15.k8s.ooo]] | production | Nico | server121 | | | 2022-09-06 |

| [[r1r2p10k8sooo|r1.p10.k8s.ooo]] | production | Nico | server122 | | | 2022-10-30 |

| [[r1r2p10k8sooo|r2.p10.k8s.ooo]] | production | Nico | server123 | | | 2022-10-15 |

| [[r1r2p5k8sooo|r1.p5.k8s.ooo]] | production | Nico | server137 | | | 2022-10-30 |

| [[r1r2p5k8sooo|r2.p5.k8s.ooo]] | production | Nico | server138 | | | 2022-10-30 |

| [[r1r2p6k8sooo|r1.p6.k8s.ooo]] | production | Nico | server139 | | | 2022-10-30 |

| [[r1r2p6k8sooo|r2.p6.k8s.ooo]] | production | Nico | server140 | | | 2022-10-30 |

h2. General architecture and components overview

* All k8s clusters are IPv6 only

* We use BGP peering to propagate podcidr and serviceCidr networks to our infrastructure

* The main public testing repository is "ungleich-k8s":https://code.ungleich.ch/ungleich-public/ungleich-k8s

** Private configurations are found in the **k8s-config** repository

h3. Cluster types

| **Type/Feature**            | **Development**                | **Production**         |

| Min No. nodes               | 3 (1 master, 3 worker)         | 5 (3 master, 3 worker) |

| Recommended minimum         | 4 (dedicated master, 3 worker) | 8 (3 master, 5 worker) |

| Separation of control plane | optional                       | recommended            |

| Persistent storage          | required                       | required               |

| Number of storage monitors  | 3                              | 5                      |

h2. General k8s operations

h3. Cheat sheet / external great references

* "kubectl cheatsheet":https://kubernetes.io/docs/reference/kubectl/cheatsheet/

h3. Allowing to schedule work on the control plane / removing node taints

* Mostly for single node / test / development clusters

* Just remove the master taint as follows

<pre>

kubectl taint nodes --all node-role.kubernetes.io/master-

kubectl taint nodes --all node-role.kubernetes.io/control-plane-

</pre>

You can check the node taints using @kubectl describe node ...@

h3. Get the cluster admin.conf

* On the masters of each cluster you can find the file @/etc/kubernetes/admin.conf@

* To be able to administrate the cluster you can copy the admin.conf to your local machine

* Multi cluster debugging can very easy if you name the config ~/cX-admin.conf (see example below)

<pre>

% scp root@server47.place7.ungleich.ch:/etc/kubernetes/admin.conf ~/c2-admin.conf

% export KUBECONFIG=~/c2-admin.conf    

% kubectl get nodes

NAME       STATUS                     ROLES                  AGE   VERSION

server47   Ready                      control-plane,master   82d   v1.22.0

server48   Ready                      control-plane,master   82d   v1.22.0

server49   Ready                      <none>                 82d   v1.22.0

server50   Ready                      <none>                 82d   v1.22.0

server59   Ready                      control-plane,master   82d   v1.22.0

server60   Ready,SchedulingDisabled   <none>                 82d   v1.22.0

server61   Ready                      <none>                 82d   v1.22.0

server62   Ready                      <none>                 82d   v1.22.0               

</pre>

h3. Installing a new k8s cluster

* Decide on the cluster name (usually *cX.k8s.ooo*), X counting upwards

** Using pXX.k8s.ooo for production clusters of placeXX

* Use cdist to configure the nodes with requirements like crio

* Decide between single or multi node control plane setups (see below)

** Single control plane suitable for development clusters

Typical init procedure:

* Single control plane: @kubeadm init --config bootstrap/XXX/kubeadm.yaml@

* Multi control plane (HA): @kubeadm init --config bootstrap/XXX/kubeadm.yaml --upload-certs@

h3. Deleting a pod that is hanging in terminating state

<pre>

kubectl delete pod <PODNAME> --grace-period=0 --force --namespace <NAMESPACE>

</pre>

(from https://stackoverflow.com/questions/35453792/pods-stuck-in-terminating-status)

h3. Listing nodes of a cluster

<pre>

[15:05] bridge:~% kubectl get nodes

NAME       STATUS   ROLES                  AGE   VERSION

server22   Ready    <none>                 52d   v1.22.0

server23   Ready    <none>                 52d   v1.22.2

server24   Ready    <none>                 52d   v1.22.0

server25   Ready    <none>                 52d   v1.22.0

server26   Ready    <none>                 52d   v1.22.0

server27   Ready    <none>                 52d   v1.22.0

server63   Ready    control-plane,master   52d   v1.22.0

server64   Ready    <none>                 52d   v1.22.0

server65   Ready    control-plane,master   52d   v1.22.0

server66   Ready    <none>                 52d   v1.22.0

server83   Ready    control-plane,master   52d   v1.22.0

server84   Ready    <none>                 52d   v1.22.0

server85   Ready    <none>                 52d   v1.22.0

server86   Ready    <none>                 52d   v1.22.0

</pre>

h3. Removing / draining a node

Usually @kubectl drain server@ should do the job, but sometimes we need to be more aggressive:

<pre>

kubectl drain --delete-emptydir-data --ignore-daemonsets serverXX

</pre>

h3. Readding a node after draining

<pre>

kubectl uncordon serverXX

</pre>

h3. (Re-)joining worker nodes after creating the cluster

* We need to have an up-to-date token

* We use different join commands for the workers and control plane nodes

Generating the join command on an existing control plane node:

<pre>

kubeadm token create --print-join-command

</pre>

h3. (Re-)joining control plane nodes after creating the cluster

* We generate the token again

* We upload the certificates

* We need to combine/create the join command for the control plane node

Example session:

<pre>

% kubeadm token create --print-join-command

kubeadm join p10-api.k8s.ooo:6443 --token xmff4i.ABC --discovery-token-ca-cert-hash sha256:longhash 

% kubeadm init phase upload-certs --upload-certs

[upload-certs] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace

[upload-certs] Using certificate key:

CERTKEY

# Then we use these two outputs on the joining node:

kubeadm join p10-api.k8s.ooo:6443 --token xmff4i.ABC --discovery-token-ca-cert-hash sha256:longhash --control-plane --certificate-key CERTKEY

</pre>

Commands to be used on a control plane node:

<pre>

kubeadm token create --print-join-command

kubeadm init phase upload-certs --upload-certs

</pre>

Commands to be used on the joining node:

<pre>

JOINCOMMAND --control-plane --certificate-key CERTKEY

</pre>

SEE ALSO

* https://stackoverflow.com/questions/63936268/how-to-generate-kubeadm-token-for-secondary-control-plane-nodes

* https://blog.scottlowe.org/2019/08/15/reconstructing-the-join-command-for-kubeadm/

h3. How to fix etcd does not start when rejoining a kubernetes cluster as a control plane

If during the above step etcd does not come up, @kubeadm join@ can hang as follows:

<pre>

[control-plane] Creating static Pod manifest for "kube-apiserver"                                                              

[control-plane] Creating static Pod manifest for "kube-controller-manager"                                                     

[control-plane] Creating static Pod manifest for "kube-scheduler"                                                              

[check-etcd] Checking that the etcd cluster is healthy                                                                         

error execution phase check-etcd: etcd cluster is not healthy: failed to dial endpoint https://[2a0a:e5c0:10:1:225:b3ff:fe20:37

8a]:2379 with maintenance client: context deadline exceeded                                                                    

To see the stack trace of this error execute with --v=5 or higher         

</pre>

Then the problem is likely that the etcd server is still a member of the cluster. We first need to remove it from the etcd cluster and then the join works.

To fix this we do:

* Find a working etcd pod

* Find the etcd members / member list

* Remove the etcd member that we want to re-join the cluster

<pre>

# Find the etcd pods

kubectl -n kube-system get pods -l component=etcd,tier=control-plane

# Get the list of etcd servers with the member id 

kubectl exec -n kube-system -ti ETCDPODNAME -- etcdctl --endpoints '[::1]:2379' --cacert /etc/kubernetes/pki/etcd/ca.crt --cert  /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member list

# Remove the member

kubectl exec -n kube-system -ti ETCDPODNAME -- etcdctl --endpoints '[::1]:2379' --cacert /etc/kubernetes/pki/etcd/ca.crt --cert  /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member remove MEMBERID

</pre>

Sample session:

<pre>

[10:48] line:~% kubectl -n kube-system get pods -l component=etcd,tier=control-plane

NAME            READY   STATUS    RESTARTS     AGE

etcd-server63   1/1     Running   0            3m11s

etcd-server65   1/1     Running   3            7d2h

etcd-server83   1/1     Running   8 (6d ago)   7d2h

[10:48] line:~% kubectl exec -n kube-system -ti etcd-server65 -- etcdctl --endpoints '[::1]:2379' --cacert /etc/kubernetes/pki/etcd/ca.crt --cert  /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member list

356891cd676df6e4, started, server65, https://[2a0a:e5c0:10:1:225:b3ff:fe20:375c]:2380, https://[2a0a:e5c0:10:1:225:b3ff:fe20:375c]:2379, false

371b8a07185dee7e, started, server63, https://[2a0a:e5c0:10:1:225:b3ff:fe20:378a]:2380, https://[2a0a:e5c0:10:1:225:b3ff:fe20:378a]:2379, false

5942bc58307f8af9, started, server83, https://[2a0a:e5c0:10:1:3e4a:92ff:fe79:bb98]:2380, https://[2a0a:e5c0:10:1:3e4a:92ff:fe79:bb98]:2379, false

[10:48] line:~% kubectl exec -n kube-system -ti etcd-server65 -- etcdctl --endpoints '[::1]:2379' --cacert /etc/kubernetes/pki/etcd/ca.crt --cert  /etc/kubernetes/pki/etcd/server.crt --key /etc/kubernetes/pki/etcd/server.key member remove 371b8a07185dee7e

Member 371b8a07185dee7e removed from cluster e3c0805f592a8f77

</pre>

SEE ALSO

* We found the solution using https://stackoverflow.com/questions/67921552/re-installed-node-cannot-join-kubernetes-cluster

h3. Node labels (adding, showing, removing)

Listing the labels:

<pre>

kubectl get nodes --show-labels

</pre>

Adding labels:

<pre>

kubectl label nodes LIST-OF-NODES label1=value1 

</pre>

For instance:

<pre>

kubectl label nodes router2 router3 hosttype=router 

</pre>

Selecting nodes in pods:

<pre>

apiVersion: v1

kind: Pod

...

spec:

  nodeSelector:

    hosttype: router

</pre>

Removing labels by adding a minus at the end of the label name:

<pre>

kubectl label node <nodename> <labelname>-

</pre>

For instance:

<pre>

kubectl label nodes router2 router3 hosttype- 

</pre>

SEE ALSO

* https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes/

* https://stackoverflow.com/questions/34067979/how-to-delete-a-node-label-by-command-and-api

h3. Hardware Maintenance using ungleich-hardware

Use the following manifest and replace the HOST with the actual host:

<pre>

apiVersion: v1

kind: Pod

metadata:

  name: ungleich-hardware-HOST

spec:

  containers:

  - name: ungleich-hardware

    image: ungleich/ungleich-hardware:0.0.5

    args:

    - sleep

    - "1000000"

    volumeMounts:

      - mountPath: /dev

        name: dev

    securityContext:

      privileged: true

  nodeSelector:

    kubernetes.io/hostname: "HOST"

  volumes:

    - name: dev

      hostPath:

        path: /dev

</pre>

Also see: [[The_ungleich_hardware_maintenance_guide]]

h3. Triggering a cronjob / creating a job from a cronjob

To test a cronjob, we can create a job from a cronjob:

<pre>

kubectl create job --from=cronjob/volume2-daily-backup volume2-manual

</pre>

This creates a job volume2-manual based on the cronjob  volume2-daily

h3. su-ing into a user that has nologin shell set

Many times users are having nologin as their shell inside the container. To be able to execute maintenance commands within the

container, we can use @su -s /bin/sh@ like this:

<pre>

su -s /bin/sh -c '/path/to/your/script' testuser

</pre>

Found on https://serverfault.com/questions/351046/how-to-run-command-as-user-who-has-usr-sbin-nologin-as-shell

h3. How to print a secret value

Assuming you want the "password" item from a secret, use:

<pre>

kubectl get secret SECRETNAME -o jsonpath="{.data.password}" | base64 -d; echo "" 

</pre>

h3. How to upgrade a kubernetes cluster

h4. General

* Should be done every X months to stay up-to-date

** X probably something like 3-6

* kubeadm based clusters

* Needs specific kubeadm versions for upgrade

* Follow instructions on https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* Finding releases: https://github.com/kubernetes/kubernetes/tree/master/CHANGELOG

h4. Getting a specific kubeadm or kubelet version

<pre>

RELEASE=v1.22.17

RELEASE=v1.23.17

RELEASE=v1.24.9

RELEASE=v1.25.9

RELEASE=v1.26.6

RELEASE=v1.27.2

ARCH=amd64

curl -L --remote-name-all https://dl.k8s.io/release/${RELEASE}/bin/linux/${ARCH}/{kubeadm,kubelet}

chmod u+x kubeadm kubelet

</pre>

h4. Steps

* kubeadm upgrade plan

** On one control plane node

* kubeadm upgrade apply vXX.YY.ZZ

** On one control plane node

* kubeadm upgrade node

** On all other control plane nodes

** On all worker nodes afterwards

Repeat for all control planes nodes. The upgrade kubelet on all other nodes via package manager.

h4. Upgrading to 1.22.17

* https://v1-22.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* Need to create a kubeadm config map

* Done for p6 on 2023-10-04

h4. Upgrading to 1.23.17

* https://v1-23.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* No special notes

* Done for p6 on 2023-10-04

h4. Upgrading to 1.24.17

* https://v1-24.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* No special notes

* Done for p6 on 2023-10-04

h4. Upgrading to 1.25.14

* https://v1-24.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* No special notes

* Done for p6 on 2023-10-04

h4. Upgrading to 1.26.9

* https://v1-26.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* No special notes

* Done for p6 on 2023-10-04

h4. Upgrade to kubernetes 1.27

* https://v1-27.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

* kubelet will not start anymore

* reason: @"command failed" err="failed to parse kubelet flag: unknown flag: --container-runtime"@

* /var/lib/kubelet/kubeadm-flags.env contains that parameter

* remove it, start kubelet

h4. Upgrade to kubernetes 1.28

* https://v1-28.docs.kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

h4. Upgrade to crio 1.27: missing crun

Error message

<pre>

level=fatal msg="validating runtime config: runtime validation: \"crun\" not found in $PATH: exec: \"crun\": executable file not found in $PATH"

</pre>

Fix:

<pre>

apk add crun

</pre>

h2. Reference CNI

* Mainly "stupid", but effective plugins

* Main documentation on https://www.cni.dev/plugins/current/

* Plugins

** bridge

*** Can create the bridge on the host

*** But seems not to be able to add host interfaces to it as well

*** Has support for vlan tags

** vlan

*** creates vlan tagged sub interface on the host

*** "It's a 1:1 mapping (i.e. no bridge in between)":https://github.com/k8snetworkplumbingwg/multus-cni/issues/569

** host-device

*** moves the interface from the host into the container

*** very easy for physical connections to containers

** ipvlan

*** "virtualisation" of a host device

*** routing based on IP

*** Same MAC for everyone

*** Cannot reach the master interface

** maclvan

*** With mac addresses

*** Supports various modes (to be checked)

** ptp ("point to point")

*** Creates a host device and connects it to the container

** win*

*** Windows implementations

h2. Calico CNI

h3. Calico Installation

* We install "calico using helm":https://docs.projectcalico.org/getting-started/kubernetes/helm

* This has the following advantages:

** Easy to upgrade

** Does not require os to configure IPv6/dual stack settings as the tigera operator figures out things on its own

Usually plain calico can be installed directly using:

<pre>

VERSION=v3.25.0

helm repo add projectcalico https://docs.projectcalico.org/charts

helm repo update

helm upgrade --install --namespace tigera calico projectcalico/tigera-operator --version $VERSION --create-namespace

</pre>

* Check the tags on https://github.com/projectcalico/calico/tags for the latest release

h3. Installing calicoctl

* General installation instructions, including binary download: https://projectcalico.docs.tigera.io/maintenance/clis/calicoctl/install

To be able to manage and configure calico, we need to 

"install calicoctl (we choose the version as a pod)":https://docs.projectcalico.org/getting-started/clis/calicoctl/install#install-calicoctl-as-a-kubernetes-pod

<pre>

kubectl apply -f https://docs.projectcalico.org/manifests/calicoctl.yaml

</pre>

Or version specific:

<pre>

kubectl apply -f https://github.com/projectcalico/calico/blob/v3.20.4/manifests/calicoctl.yaml

# For 3.22

kubectl apply -f https://projectcalico.docs.tigera.io/archive/v3.22/manifests/calicoctl.yaml

</pre>

And making it easier accessible by alias:

<pre>

alias calicoctl="kubectl exec -i -n kube-system calicoctl -- /calicoctl"

</pre>

h3. Calico configuration

By default our k8s clusters "BGP peer":https://docs.projectcalico.org/networking/bgp

with an upstream router to propagate podcidr and servicecidr.

Default settings in our infrastructure:

* We use a full-mesh using the @nodeToNodeMeshEnabled: true@ option

* We keep the original next hop so that *only* the server with the pod is announcing it (instead of ecmp)

* We use private ASNs for k8s clusters

* We do *not* use any overlay

After installing calico and calicoctl the last step of the installation is usually:

<pre>

calicoctl create -f - < calico-bgp.yaml

</pre>

A sample BGP configuration:

<pre>

---

apiVersion: projectcalico.org/v3

kind: BGPConfiguration

metadata:

  name: default

spec:

  logSeverityScreen: Info

  nodeToNodeMeshEnabled: true

  asNumber: 65534

  serviceClusterIPs:

  - cidr: 2a0a:e5c0:10:3::/108

  serviceExternalIPs:

  - cidr: 2a0a:e5c0:10:3::/108

---

apiVersion: projectcalico.org/v3

kind: BGPPeer

metadata:

  name: router1-place10

spec:

  peerIP: 2a0a:e5c0:10:1::50

  asNumber: 213081

  keepOriginalNextHop: true

</pre>

h2. Cilium CNI (experimental)

h3. Status

*NO WORKING CILIUM CONFIGURATION FOR IPV6 only modes*

h3. Latest error

It seems cilium does not run on IPv6 only hosts:

<pre>

level=info msg="Validating configured node address ranges" subsys=daemon

level=fatal msg="postinit failed" error="external IPv4 node address could not be derived, please configure via --ipv4-node" subsys=daemon

level=info msg="Starting IP identity watcher" subsys=ipcache

</pre>

It crashes after that log entry

h3. BGP configuration

* The cilium-operator will not start without a correct configmap being present beforehand (see error message below)

* Creating the bgp config beforehand as a configmap is thus required.

The error one gets without the configmap present:

Pods are hanging with:

<pre>

cilium-bpqm6                       0/1     Init:0/4            0             9s

cilium-operator-5947d94f7f-5bmh2   0/1     ContainerCreating   0             9s

</pre>

The error message in the cilium-*perator is:

<pre>

Events:

  Type     Reason       Age                From               Message

  ----     ------       ----               ----               -------

  Normal   Scheduled    80s                default-scheduler  Successfully assigned kube-system/cilium-operator-5947d94f7f-lqcsp to server56

  Warning  FailedMount  16s (x8 over 80s)  kubelet            MountVolume.SetUp failed for volume "bgp-config-path" : configmap "bgp-config" not found

</pre>

A correct bgp config looks like this:

<pre>

apiVersion: v1

kind: ConfigMap

metadata:

  name: bgp-config

  namespace: kube-system

data:

  config.yaml: |

    peers:

      - peer-address: 2a0a:e5c0::46

        peer-asn: 209898

        my-asn: 65533

      - peer-address: 2a0a:e5c0::47

        peer-asn: 209898

        my-asn: 65533

    address-pools:

      - name: default

        protocol: bgp

        addresses:

          - 2a0a:e5c0:0:14::/64

</pre>

h3. Installation

Adding the repo

<pre>

helm repo add cilium https://helm.cilium.io/

helm repo update

</pre>

Installing + configuring cilium

<pre>

ipv6pool=2a0a:e5c0:0:14::/112

version=1.12.2

helm upgrade --install cilium cilium/cilium --version $version \

  --namespace kube-system \

  --set ipv4.enabled=false \

  --set ipv6.enabled=true \

  --set enableIPv6Masquerade=false \

  --set bgpControlPlane.enabled=true 

#  --set ipam.operator.clusterPoolIPv6PodCIDRList=$ipv6pool

# Old style bgp?

#   --set bgp.enabled=true --set bgp.announce.podCIDR=true \

# Show possible configuration options

helm show values cilium/cilium

</pre>

Using a /64 for ipam.operator.clusterPoolIPv6PodCIDRList fails with:

<pre>

level=fatal msg="Unable to init cluster-pool allocator" error="unable to initialize IPv6 allocator New CIDR set failed; the node CIDR size is too big" subsys=cilium-operator-generic

</pre>

See also https://github.com/cilium/cilium/issues/20756

Seems a /112 is actually working.

h3. Kernel modules

Cilium requires the following modules to be loaded on the host (not loaded by default):

<pre>

modprobe  ip6table_raw

modprobe  ip6table_filter

</pre>

h3. Interesting helm flags

* autoDirectNodeRoutes

* bgpControlPlane.enabled = true

h3. SEE ALSO

* https://docs.cilium.io/en/v1.12/helm-reference/

h2. Multus

* https://github.com/k8snetworkplumbingwg/multus-cni

* Installing a deployment w/ CRDs

<pre>

VERSION=v4.0.1

kubectl apply -f https://raw.githubusercontent.com/k8snetworkplumbingwg/multus-cni/${VERSION}/deployments/multus-daemonset-crio.yml

</pre>

h2. ArgoCD

h3. Argocd Installation

* See https://argo-cd.readthedocs.io/en/stable/

As there is no configuration management present yet, argocd is installed using

<pre>

kubectl create namespace argocd

# OR: latest stable

kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

# OR Specific Version

kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/v2.3.2/manifests/install.yaml

</pre>

h3. Get the argocd credentials

<pre>

kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d; echo ""

</pre>

h3. Accessing argocd

In regular IPv6 clusters:

* Navigate to https://argocd-server.argocd.CLUSTERDOMAIN

In legacy IPv4 clusters

<pre>

kubectl --namespace argocd port-forward svc/argocd-server 8080:80

</pre>

* Navigate to https://localhost:8080

h3. Using the argocd webhook to trigger changes

* To trigger changes post json https://argocd.example.com/api/webhook

h3. Deploying an application

* Applications are deployed via git towards gitea (code.ungleich.ch) and then pulled by argo

* Always include the *redmine-url* pointing to the (customer) ticket

** Also add the support-url if it exists

Application sample

<pre>

apiVersion: argoproj.io/v1alpha1

kind: Application

metadata:

  name: gitea-CUSTOMER

  namespace: argocd

spec:

  destination:

    namespace: default

    server: 'https://kubernetes.default.svc'

  source:

    path: apps/prod/gitea

    repoURL: 'https://code.ungleich.ch/ungleich-intern/k8s-config.git'

    targetRevision: HEAD

    helm:

      parameters:

        - name: storage.data.storageClass

          value: rook-ceph-block-hdd

        - name: storage.data.size

          value: 200Gi

        - name: storage.db.storageClass

          value: rook-ceph-block-ssd

        - name: storage.db.size

          value: 10Gi

        - name: storage.letsencrypt.storageClass

          value: rook-ceph-block-hdd

        - name: storage.letsencrypt.size

          value: 50Mi

        - name: letsencryptStaging

          value: 'no'

        - name: fqdn

          value: 'code.verua.online'

  project: default

  syncPolicy:

    automated:

      prune: true

      selfHeal: true

  info:

    - name: 'redmine-url'

      value: 'https://redmine.ungleich.ch/issues/ISSUEID'

    - name: 'support-url'

      value: 'https://support.ungleich.ch/Ticket/Display.html?id=TICKETID'

</pre>

h2. Helm related operations and conventions

We use helm charts extensively.

* In production, they are managed via argocd

* In development, helm chart can de developed and deployed manually using the helm utility.

h3. Installing a helm chart

One can use the usual pattern of

<pre>

helm install <releasename> <chartdirectory>

</pre>

However often you want to reinstall/update when testing helm charts. The following pattern is "better", because it allows you to reinstall, if it is already installed:

<pre>

helm upgrade --install <releasename> <chartdirectory>

</pre>

h3. Naming services and deployments in helm charts [Application labels]

* We always have {{ .Release.Name }} to identify the current "instance"

* Deployments:

** use @app: <what it is>@, f.i. @app: nginx@, @app: postgres@, ...

* See more about standard labels on

** https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/

** https://helm.sh/docs/chart_best_practices/labels/

h3. Show all versions of a helm chart

<pre>

helm search repo -l repo/chart

</pre>

For example:

<pre>

% helm search repo -l projectcalico/tigera-operator 

NAME                         	CHART VERSION	APP VERSION	DESCRIPTION                            

projectcalico/tigera-operator	v3.23.3      	v3.23.3    	Installs the Tigera operator for Calico

projectcalico/tigera-operator	v3.23.2      	v3.23.2    	Installs the Tigera operator for Calico

....

</pre>

h3. Show possible values of a chart

<pre>

helm show values <repo/chart>

</pre>

Example:

<pre>

helm show values ingress-nginx/ingress-nginx

</pre>

h3. Download a chart

For instance for checking it out locally. Use:

<pre>

helm pull <repo/chart>

</pre>

h2. Rook + Ceph

h3. Installation

* Usually directly via argocd

h3. Executing ceph commands

Using the ceph-tools pod as follows:

<pre>

kubectl exec -n rook-ceph -ti $(kubectl -n rook-ceph get pods -l app=rook-ceph-tools -o jsonpath='{.items[*].metadata.name}') -- ceph -s

</pre>

h3. Inspecting the logs of a specific server

<pre>

# Get the related pods

kubectl -n rook-ceph get pods -l app=rook-ceph-osd-prepare 

...

# Inspect the logs of a specific pod

kubectl -n rook-ceph logs -f rook-ceph-osd-prepare-server23--1-444qx

</pre>

h3. Inspecting the logs of the rook-ceph-operator

<pre>

kubectl -n rook-ceph logs -f -l app=rook-ceph-operator

</pre>

h3. Restarting the rook operator

<pre>

kubectl -n rook-ceph delete pods  -l app=rook-ceph-operator

</pre>

h3. Triggering server prepare / adding new osds

The rook-ceph-operator triggers/watches/creates pods to maintain hosts. To trigger a full "re scan", simply delete that pod:

<pre>

kubectl -n rook-ceph delete pods -l app=rook-ceph-operator

</pre>

This will cause all the @rook-ceph-osd-prepare-..@ jobs to be recreated and thus OSDs to be created, if new disks have been added.

h3. Removing an OSD

* See "Ceph OSD Management":https://rook.io/docs/rook/v1.7/ceph-osd-mgmt.html

* More specifically: https://github.com/rook/rook/blob/release-1.7/cluster/examples/kubernetes/ceph/osd-purge.yaml

* Then delete the related deployment

Set osd id in the osd-purge.yaml and apply it. OSD should be down before.

<pre>

apiVersion: batch/v1

kind: Job

metadata:

  name: rook-ceph-purge-osd

  namespace: rook-ceph # namespace:cluster

  labels:

    app: rook-ceph-purge-osd

spec:

  template:

    metadata:

      labels:

        app: rook-ceph-purge-osd

    spec:

      serviceAccountName: rook-ceph-purge-osd

      containers:

        - name: osd-removal

          image: rook/ceph:master

          # TODO: Insert the OSD ID in the last parameter that is to be removed

          # The OSD IDs are a comma-separated list. For example: "0" or "0,2".

          # If you want to preserve the OSD PVCs, set `--preserve-pvc true`.

          #

          # A --force-osd-removal option is available if the OSD should be destroyed even though the

          # removal could lead to data loss.

          args:

            - "ceph"

            - "osd"

            - "remove"

            - "--preserve-pvc"

            - "false"

            - "--force-osd-removal"

            - "false"

            - "--osd-ids"

            - "SETTHEOSDIDHERE"

          env:

            - name: POD_NAMESPACE

              valueFrom:

                fieldRef:

                  fieldPath: metadata.namespace

            - name: ROOK_MON_ENDPOINTS

              valueFrom:

                configMapKeyRef:

                  key: data

                  name: rook-ceph-mon-endpoints

            - name: ROOK_CEPH_USERNAME

              valueFrom:

                secretKeyRef:

                  key: ceph-username

                  name: rook-ceph-mon

            - name: ROOK_CEPH_SECRET

              valueFrom:

                secretKeyRef:

                  key: ceph-secret

                  name: rook-ceph-mon

            - name: ROOK_CONFIG_DIR

              value: /var/lib/rook

            - name: ROOK_CEPH_CONFIG_OVERRIDE

              value: /etc/rook/config/override.conf

            - name: ROOK_FSID

              valueFrom:

                secretKeyRef:

                  key: fsid

                  name: rook-ceph-mon

            - name: ROOK_LOG_LEVEL

              value: DEBUG

          volumeMounts:

            - mountPath: /etc/ceph

              name: ceph-conf-emptydir

            - mountPath: /var/lib/rook

              name: rook-config

      volumes:

        - emptyDir: {}

          name: ceph-conf-emptydir

        - emptyDir: {}

          name: rook-config

      restartPolicy: Never

</pre>

Deleting the deployment:

<pre>

[18:05] bridge:~% kubectl -n rook-ceph delete deployment rook-ceph-osd-6

deployment.apps "rook-ceph-osd-6" deleted

</pre>

h3. Placement of mons/osds/etc.

See https://rook.io/docs/rook/v1.11/CRDs/Cluster/ceph-cluster-crd/#placement-configuration-settings

h2. Ingress + Cert Manager

* We deploy "nginx-ingress":https://docs.nginx.com/nginx-ingress-controller/ to get an ingress

* we deploy "cert-manager":https://cert-manager.io/ to handle certificates

* We independently deploy @ClusterIssuer@ to allow the cert-manager app to deploy and the issuer to be created once the CRDs from cert manager are in place

h3. IPv4 reachability 

The ingress is by default IPv6 only. To make it reachable from the IPv4 world, get its IPv6 address and configure a NAT64 mapping in Jool.

Steps:

h4. Get the ingress IPv6 address

Use @kubectl -n ingress-nginx get svc ingress-nginx-controller -o jsonpath='{.spec.clusterIP}'; echo ''@

Example:

<pre>

kubectl -n ingress-nginx get svc ingress-nginx-controller -o jsonpath='{.spec.clusterIP}'; echo ''

2a0a:e5c0:10:1b::ce11

</pre>

h4. Add NAT64 mapping

* Update the __dcl_jool_siit cdist type

* Record the two IPs (IPv6 and IPv4)

* Configure all routers

h4. Add DNS record

To use the ingress capable as a CNAME destination, create an "ingress" DNS record, such as:

<pre>

; k8s ingress for dev

dev-ingress                 AAAA 2a0a:e5c0:10:1b::ce11

dev-ingress                 A 147.78.194.23

</pre> 

h4. Add supporting wildcard DNS

If you plan to add various sites under a specific domain, we can add a wildcard DNS entry, such as *.k8s-dev.django-hosting.ch:

<pre>

*.k8s-dev         CNAME dev-ingress.ungleich.ch.

</pre>

h2. Harbor

* We user "Harbor":https://goharbor.io/ as an image registry for our own images. Internal app reference: apps/prod/harbor.

* The admin password is in the password store, it is Harbor12345 by default

* At the moment harbor only authenticates against the internal ldap tree

h3. LDAP configuration

* The url needs to be ldaps://...

* uid = uid

* rest standard

h2. Monitoring / Prometheus

* Via "kube-prometheus":https://github.com/prometheus-operator/kube-prometheus/

Access via ...

* http://prometheus-k8s.monitoring.svc:9090

* http://grafana.monitoring.svc:3000

* http://alertmanager.monitoring.svc:9093

h3. Prometheus Options

* "helm/kube-prometheus-stack":https://github.com/prometheus-community/helm-charts/tree/main/charts/kube-prometheus-stack

** Includes dashboards and co.

* "manifest based kube-prometheus":https://github.com/prometheus-operator/kube-prometheus

** Includes dashboards and co.

* "Prometheus Operator (mainly CRD manifest":https://github.com/prometheus-operator/prometheus-operator

h3. Grafana default password

* If not changed: @prom-operator@

h2. Nextcloud

h3. How to get the nextcloud credentials 

* The initial username is set to "nextcloud"

* The password is autogenerated and saved in a kubernetes secret

<pre>

kubectl get secret RELEASENAME-nextcloud -o jsonpath="{.data.PASSWORD}" | base64 -d; echo "" 

</pre>

h3. How to fix "Access through untrusted domain"

* Nextcloud stores the initial domain configuration

* If the FQDN is changed, it will show the error message "Access through untrusted domain"

* To fix, edit /var/www/html/config/config.php and correct the domain

* Then delete the pods

h3. Running occ commands inside the nextcloud container

* Find the pod in the right namespace

Exec:

<pre>

su www-data -s /bin/sh -c ./occ

</pre>

* -s /bin/sh is needed as the default shell is set to /bin/false

h4. Rescanning files

* If files have been added without nextcloud's knowledge

<pre>

su www-data -s /bin/sh -c "./occ files:scan --all"

</pre>

h2. Infrastructure versions

h3. ungleich kubernetes infrastructure v5 (2021-10)

Clusters are configured / setup in this order:

* Bootstrap via kubeadm

* "Networking via calico + BGP (non ECMP) using helm":https://docs.projectcalico.org/getting-started/kubernetes/helm

* "ArgoCD for CD":https://argo-cd.readthedocs.io/en/stable/

** "rook for storage via argocd":https://rook.io/

** haproxy for in IPv6-cluster-IPv4-to-IPv6 proxy via argocd

** "kubernetes-secret-generator for in cluster secrets":https://github.com/mittwald/kubernetes-secret-generator

** "ungleich-certbot managing certs and nginx":https://hub.docker.com/repository/docker/ungleich/ungleich-certbot

h3. ungleich kubernetes infrastructure v4 (2021-09)

* rook is configured via manifests instead of using the rook-ceph-cluster helm chart

* The rook operator is still being installed via helm

h3. ungleich kubernetes infrastructure v3 (2021-07)

* rook is now installed via helm via argocd instead of directly via manifests

h3. ungleich kubernetes infrastructure v2 (2021-05)

* Replaced fluxv2 from ungleich k8s v1 with argocd

** argocd can apply helm templates directly without needing to go through Chart releases

* We are also using argoflow for build flows

* Planned to add "kaniko":https://github.com/GoogleContainerTools/kaniko for image building

h3. ungleich kubernetes infrastructure v1 (2021-01)

We are using the following components:

* "Calico as a CNI":https://www.projectcalico.org/ with BGP, IPv6 only, no encapsulation

** Needed for basic networking

* "kubernetes-secret-generator":https://github.com/mittwald/kubernetes-secret-generator for creating secrets

** Needed so that secrets are not stored in the git repository, but only in the cluster

* "ungleich-certbot":https://hub.docker.com/repository/docker/ungleich/ungleich-certbot

** Needed to get letsencrypt certificates for services

* "rook with ceph rbd + cephfs":https://rook.io/ for storage

** rbd for almost everything, *ReadWriteOnce*

** cephfs for smaller things, multi access *ReadWriteMany*

** Needed for providing persistent storage

* "flux v2":https://fluxcd.io/

** Needed to manage resources automatically