The services has to be running ------------------------------ Etcd: - etcd Node: - origin-node Master nodes: - origin-master-api - origin-master-controllers - origin-master is not running Required Services: - lvm2-lvmetad.socket - lvm2-lvmetad.service - docker - it may happen that service is alive according to systemd, but does not respond ('docker ps' timeouts) - NetworkManager - firewalld - dnsmasq - openvswitch Extra Services: - ssh - ntp - openvpn - ganesha (on master nodes, optional) Pods has to be running ---------------------- Kubernetes System - kube-service-catalog/apiserver - kube-service-catalog/controller-manager OpenShift Main Services - default/docker-registry - default/registry-console - default/router (3 replicas) - openshift-template-service-broker/api-server (daemonset, on all nodes) OpenShift Secondary Services - openshift-ansible-service-broker/asb - openshift-ansible-service-broker/asb-etcd GlusterFS - glusterfs-storage (daemonset, on all storage nodes) - glusterblock-storage-provisioner-dc - heketi-storage Metrics (openshift-infra): - hawkular-cassandra - hawkular-metrics - heapster Debugging ========= - Ensure system consistency as explained in 'consistency.txt' (incomplete) - Check current pod logs and possibly logs for last failed instance oc logs --tail=100 [-p] - dc/name or ds/name as well - Verify initialization steps (check if all volumes are mounted) oc describe - Security (SCC) problems are visible if replica controller is queried oc -n adei get rc/mysql-1 -o yaml - It worth looking the pod environment oc env po --list - It worth connecting running container with 'rsh' session and see running processes, internal logs, etc. The 'debug' session will start a new instance of the pod. - If try looking if corresponding pv/pvc are bound. Check logs for pv. * Even if 'pvc' is bound. The 'pv' may have problems with its backend. * Check logs here: /var/lib/origin/plugins/kubernetes.io/glusterfs/ - Another frequent problems is failing 'postStart' hook. Or 'livenessProbe'. As it immediately crashes it is not possible to connect. Remedies are: * Set larger initial delay to check the probe. * Try to remove hook and execute it using 'rsh'/'debug' - Determine node running the pod and check the host logs in '/var/log/messages' * Particularly logs of 'origin-master-controllers' are of interest - Check which docker images are actually downloaded on the node docker images network ======= - There is a NetworkManager script which should adjust /etc/resolv.conf to use local dnsmasq server. This is based on '/etc/NetworkManager/dispatcher.d/99-origin-dns.sh' which does not play well if OpenShift is running on non-default network interface. I provided a patched version, but it worth verifying * that nameserver is pointing to the host itself (but not localhost, this is important to allow running pods to use it) * that correct upstream nameservers are listed in '/etc/dnsmasq.d/origin-upstream-dns.conf' * that correct upstream nameservers are listed in '/etc/origin/node/resolv.conf' * In some cases, it was necessary to restart dnsmasq (but it could be also for different reasons) If script misbehaves, it is possible to call it manually like that DEVICE_IFACE="eth1" ./99-origin-dns.sh eth1 up etcd (and general operability) ==== - Few of this sevices may seem running accroding to 'systemctl', but actually misbehave. Then, it may be needed to restart them manually. I have noticed it with * lvm2-lvmetad.socket (pvscan will complain on problems) * node-origin * glusterd in container (just kill the misbehaving pod, it will be recreated) * etcd but BEWARE of too entusiastic restarting: - However, restarting etcd many times is BAD as it may trigger a severe problem with 'kube-service-catalog/apiserver'. The bug description is here https://github.com/kubernetes/kubernetes/issues/47131 - Due to problem mentioned above, all 'oc' queries are very slow. There is not proper solution suggested. But killing the 'kube-service-catalog/apiserver' helps for a while. The pod is restarted and response times are back in order. * Another way to see this problem is quering 'healthz' service which would tell that there is too many clients and, please, retry later. curl -k https://apiserver.kube-service-catalog.svc/healthz - On node crash, the etcd database may get corrupted. * There is no easy fix. Backup/restore is not working. * Easiest option is to remove the failed etcd from the cluster. etcdctl3 --endpoints="192.168.213.1:2379" member list etcdctl3 --endpoints="192.168.213.1:2379" member remove * Add it to [new_etcd] section in inventory and run openshift-etcd to scale-up etcd cluster. - There is a helth check provided by the cluster curl -k https://apiserver.kube-service-catalog.svc/healthz it may complain about etcd problems. It seems triggered by OpenShift upgrade. The real cause and remedy is unclear, but the installation is mostly working. Discussion is in docs/upgrade.txt - There is also a different etcd which is integral part of the ansible service broker: 'openshift-ansible-service-broker/asb-etcd'. If investigated with 'oc logs' it complains on: 2018-03-07 20:54:48.791735 I | embed: rejected connection from "127.0.0.1:43066" (error "tls: failed to verify client's certificate: x509: certificate signed by unknown authority", ServerName "") WARNING: 2018/03/07 20:54:48 Failed to dial 0.0.0.0:2379: connection error: desc = "transport: authentication handshake failed: remote error: tls: bad certificate"; please retry. Nevertheless, it seems working without much trouble. The error message seems caused by certificate verification code which introduced in etcd 3.2. There are multiple bug repports on the issue. pods (failed pods, rogue namespaces, etc...) ==== - OpenShift has numerous problems with clean-up resources after the pods. The problems are more likely to happen on the heavily loaded systems: cpu, io, interrputs, etc. * This may be indicated in the logs with various errors reporting inability to stop containers/processes, free network and storage resources. A few examples (not complete) dockerd-current: time="2019-09-30T18:46:12.298297013Z" level=warning msg="container kill failed because of 'container not found' or 'no such process': Cannot kill container 00a456097fcf8d70a0461f05813e5a1f547446dd10b3b43ebc1f0bb09e841d1b: rpc error: code = 2 desc = no such process" origin-node: W0930 18:46:11.286634 2497 util.go:87] Warning: Unmount skipped because path does not exist: /var/lib/origin/openshift.local.volumes/pods/6aecbed1-e3b2-11e9-bbd6-0cc47adef0e6/volumes/kubernetes.io~glusterfs/adei-tmp Error syncing pod 1ed138cd-e2fc-11e9-bbd6-0cc47adef0e6 ("adei-smartgrid-maintain-1569790800-pcmdp_adei(1ed138cd-e2fc-11e9-bbd6-0cc47adef0e6)"), skipping: failed to "CreatePodSandbox" for "adei-smartgrid-maintain-1569790800-pcmdp_adei(1ed138cd-e2fc-11e9-bbd6-0cc47adef0e6)" with CreatePodSandboxError: "CreatePodSandbox for pod \"adei-smartgrid-maintain-1569790800-pcmdp_adei(1ed138cd-e2fc-11e9-bbd6-0cc47adef0e6)\" failed: rpc error: code = 2 desc = NetworkPlugin cni failed to set up pod \"adei-smartgrid-maintain-1569790800-pcmdp_adei\" network: CNI request failed with status 400: 'failed to Statfs \"/proc/28826/ns/net\": no such file or directory\n'" * A more severe form is then PLEG (POD Lifecycle Event Generator) errors are reported: origin-node: I0925 07:52:00.422291 93115 kubelet.go:1796] skipping pod synchronization - [PLEG is not healthy: pleg was last seen active 3m0.448988393s ago; threshold is 3m0s] This indicates a severe delays in communication with docker daemon (can be checked with 'docker info') and may result in node marked temporarily NotReady causing 'pod' eviction. As pod eviction causes extensive load on the other nodes (which may also be affected of the same problem), the initial single-node issue may render all cluster unusable. * With mass evictions, the things could get even worse causing faults in etcd communication. This is reported like: etcd: lost the TCP streaming connection with peer 2696c5f68f35c672 (stream MsgApp v2 reader) * Apart from overloaded nodes (max cpu%, io, interrupts), PLEG issues can be caused by 1. Excessive amount of resident docker images on the node (see bellow) 2. This can cause and will be further amplified by the spurious interfaces on OpenVSwich (see bellow) x. Nuanced issues between kubelet, docker, logging, networking and so on, with remediation of the issue sometimes being brutal (restarting all nodes etc, depending on the case). https://github.com/kubernetes/kubernetes/issues/45419#issuecomment-496818225 * The problem is not bound to CronJobs, but having regular scheduled jobs make it presence significantly more visible. Furthermore, CronJobs especially scheduling fat containers, like ADEI, significantly add to the I/O load on the system and may cause more severe form. - After a while, the 'pods' schedulling may get more-and-more sluggish, in general or if assigned to a specific node. * The docker images are accumulating on the nodes over time. After a threshold it will start adding the latency to the operation of docker daemon, slow down the pod scheduling (on the affected nodes), and may cause other sever side effects. The problems will start appearing at around 500-1000 images accumulated at a specific node. With 2000-3000, it will get severe and almost unusable (3-5 minutes to start a pod). So, eventually the unused images should be cleaned oc adm prune images --keep-tag-revisions=3 --keep-younger-than=60m --confirm or alternatively per-node: docker rmi $(docker images --filter "dangling=true" -q --no-trunc) * Some images could be orphanned by OpenShift infrastructure (there was not a major number of orphaned images on KaaS yet). OpenShift supports 'hard' prunning to handle such images. https://docs.openshift.com/container-platform/3.7/admin_guide/pruning_resources.html * Even afterwards, a significant number of images may stay resident. There is two inter-related problems: 1. Docker infrastructure relies on the intermediate images. Consequently, very long Dockerfiles will create a LOT of images. 2. OpenShift keeps history of 'rc' which may refence several versions of old docker images. This will be not cleaned by the described approach. Furthermore, stopped containers lost by OpenShift infrastructure (see above) also prevent clean-up of the images Currenly, a dozen KDB pods produce about 200-300 images. In some cases, optimization of dockerfiles and, afterwards, a trough cleanup of old images may become necessity. The intermediate images can be found with 'docker images -a' (all images with as repository and the name), but there is no easy way to find pod populating them. One, but not very convinient is the following project (press F5 on startup): https://github.com/TomasTomecek/sen - In a more sever4 form, the 'pods' scheduling may fail all together on one (or more) of the nodes. After a long waiting, the 'oc logs' will report timeout. The 'oc describe' reports 'failed to create pod sandbox'. This can be caused by failure to clean-up after terminated pod properly. It causes rogue network interfaces to remain in OpenVSwitch fabric. * This can be determined by errors reported using 'ovs-vsctl show' or present in the log '/var/log/openvswitch/ovs-vswitchd.log' which may quickly grow over 100MB quickly. could not open network device vethb9de241f (No such device) * The work-around is to delete rogue interfaces with ovs-vsctl del-port br0 More info: ovs-ofctl -O OpenFlow13 show br0 ovs-ofctl -O OpenFlow13 dump-flows br0 This does not solve the problem, however. The new interfaces will get abandoned by OpenShift. * The issue is discussed here: https://bugzilla.redhat.com/show_bug.cgi?id=1518684 https://bugzilla.redhat.com/show_bug.cgi?id=1518912 - After crashes / upgrades some pods may end up in 'Error' state. This is quite often happen to * kube-service-catalog/controller-manager * openshift-template-service-broker/api-server Normally, they should be deleted. Then, OpenShift will auto-restart pods and they likely will run without problems. for name in $(oc get pods -n openshift-template-service-broker | grep Error | awk '{ print $1 }' ); do oc -n openshift-template-service-broker delete po $name; done for name in $(oc get pods -n kube-service-catalog | grep Error | awk '{ print $1 }' ); do oc -n kube-service-catalog delete po $name; done - Other pods will fail with 'ImagePullBackOff' after cluster crash. The problem is that ImageStreams populated by 'builds' will not be recreated automatically. By default OpenShift docker registry is stored on ephemeral disks and is lost on crash. The build should be re-executed manually. oc -n adei start-build adei - Furthermore, after long outtages the CronJobs will stop functioning. The reason can be found by analyzing '/var/log/messages' or specially systemctl status origin-master-controllers it will contain something like: 'Cannot determine if / needs to be started: Too many missed start time (> 100). Set or decrease .spec.startingDeadlineSeconds or check clock skew.' * The reason is that after 100 missed (or failed) launch periods it will stop trying to avoid excive load. The remedy is set 'startingDeadlineSeconds' which tells the system that if cronJob has failed to start in the allocated interval we stop trying until the next start period. Then, 100 is only counted the specified period. I.e. we should set period bellow the 'launch period / 100'. https://github.com/kubernetes/kubernetes/issues/45825 * The running CronJobs can be easily patched with oc -n adei patch cronjob/adei-autogen-update --patch '{ "spec": {"startingDeadlineSeconds": 120 }}' - Sometimes there is rogue namespaces in 'deleting' state. This is also hundreds of reasons, but mainly * Crash of both masters during population / destruction of OpenShift resources * Running of 'oc adm diagnostics' It is unclear how to remove them manually, but it seems if we run * OpenShift upgrade, the namespaces are gone (but there could be a bunch of new problems). * ... i don't know if install, etc. May cause the trouble... - There is also rogue pods (mainly due to some problems with unmounting lost storage) remaining "Deleting" state, etc. There are two possible situations: * The containers are actually already terminated, but OpenShift is not aware of it for some reason. * The containers are actually still running, but OpenShift is not able to terminate them for some reason. It is relatively easy to find out which is the case: * Finding the host running the failed pod with 'oc get pods -o wide' * Checking if associated containers are still running on the host with 'docker ps' The first case it relatively easy to handle, - one can simply enforce pod removal with oc delete --grace-period=0 --force In the second case we need * To actually stop containers before proceeding (enforcing will just leave them running forever). This can be done directly using 'docker' commands. * It also may be worth trying to clean associated resources. Check 'maintenace' documentation for details. - Permission problems will arise if non-KaaS namespace (using high range supplemental-group for GlusterFS mounts) is converted to KaaS (gid ranges within 1000 - 10,000 at the moment). The allowed gids should be configured in the namespace specification and the pods should be allowed to access files. Possible errors: unable to create pods: pods "mongodb-2-" is forbidden: no providers available to validate pod request Builds ====== - After changing storage for integrated docker registry, it may refuse builds with HTTP error 500. It is necessary to run: oadm policy reconcile-cluster-roles Storage ======= - Running a lot of pods may exhaust available storage. It worth checking if * There is enough Docker storage for containers (lvm) * There is enough Heketi storage for dynamic volumes (lvm) * The root file system on nodes still has space for logs, etc. Particularly there is a big problem for ansible-ran virtual machines. The system disk is stored under '/root/VirtualBox VMs' and is not cleaned/destroyed unlike second hard drive on 'vagrant destroy'. So, it should be cleaned manually. - Too many parallel mounts (above 500 per node) may cause systemd slow-down/crashes. It is indicated by the following messages in the log: E0926 09:29:50.744454 93115 mount_linux.go:172] Mount failed: exit status 1 Output: Failed to start transient scope unit: Connection timed out * Solution is unclear, there are some suggestions to use 'setsid' in place of 'systemd-run' to do mounting, but not clear how. Discussion: https://github.com/kubernetes/kubernetes/issues/79194 * Can we do some rate-limiting? - Problems with pvc's can be evaluated by running oc -n openshift-ansible-service-broker describe pvc etcd Furthermore it worth looking in the folder with volume logs. For each 'pv' it stores subdirectories with pods executed on this host which are mount this pod and holds the log for this pods. /var/lib/origin/plugins/kubernetes.io/glusterfs/ - Heketi is problematic. * Worth checking if topology is fine and running. heketi-cli -s http://heketi-storage-glusterfs.openshift.suren.me --user admin --secret "$(oc get secret heketi-storage-admin-secret -n glusterfs -o jsonpath='{.data.key}' | base64 -d)" - Furthermore, the heketi gluster volumes may be started, but with multiple bricks offline. This can be checked with gluster volume status detail * If not all bricks online, likely it is just enought to restart the volume gluster volume stop gluster volume start * This may break services depending on provisioned 'pv' like 'openshift-ansible-service-broker/asb-etcd' - If something gone wrong, heketi may end-up creating a bunch of new volumes, corrupt database, and crash refusing to start. Here is the recovery procedure. * Sometimes, it is still possible to start by setting 'HEKETI_IGNORE_STALE_OPERATIONS' environmental variable on the container. oc -n glusterfs env dc heketi-storage -e HEKETI_IGNORE_STALE_OPERATIONS=true * Even if it works, it does not solve the main issue with corruption. It is necessary to start a debugging pod for heketi (oc debug) export corrupted databased, fix it, and save back. Having database backup could save a lot of hussle to find that is amiss. heketi db export --dbfile heketi.db --jsonfile /tmp/q.json oc cp glusterfs/heketi-storage-3-jqlwm-debug:/tmp/q.json q.json cat q.json | python -m json.tool > q2.json ...... Fixing ..... oc cp q2.json glusterfs/heketi-storage-3-jqlwm-debug:/tmp/q2.json heketi db import --dbfile heketi2.db --jsonfile /tmp/q2.json cp heketi2.db /var/lib/heketi/heketi.db * If bunch of disks is created, there are still various left-overs. First, the Gluster volumes have to be cleaned. The idea is to compare 'vol_' prefixed volumes in Heketi and Gluster. And remove ones not present in heketi. There is the script in 'ands/scripts'. * There is LVM volumes left from Gluster (or even allocated, but not associated with Gluster for various failurs. so this clean-up is worth making independently). On each node we can easily find volumes created today lvdisplay -o name,time -S 'time since "2018-03-16"' or again we can compare lvm volumes which are used by Gluster bricks and which are not. The later ones should be cleaned up. Again there is the script. MySQL ===== - MySQL may stop replicating from the master. There is some kind of deadlock in multi-threaded SLAVE SQL. This can be seen by exexuting (which should show a lot of slave threads waiting on coordinator to provide load). SHOW PROCESSLIST; The remedy is to restart slave MySQL with 'slave_parallel_workers=0', give it a time to go, and then restart back in the standard multithreading mode. Administration ============== - Some management tasks may require to login on ipekatrin* nodes. Thereafter, the password-less execution of 'oc' may fail on master nodes complaining on invalid authentication token. To fix it, it is necessary to check /root/.kube/config and remove references on logged users keeping only 'system:admin/kaas-kit-edu:8443' alkso check listed contexts and current-context. Performance =========== - To find if OpenShift restricts the usage of system resources, we can 'rsh' to container and check cgroup limits in sysfs /sys/fs/cgroup/cpuset/cpuset.cpus /sys/fs/cgroup/memory/memory.limit_in_bytes Various ======= - IPMI may cause problems as well. Particularly, the mounted CDrom may start complaining. Easiest is just to remove it from the running system with echo 1 > /sys/block/sdd/device/delete