Troubleshooting etcd Nodes
This section contains commands and tips for troubleshooting nodes with the etcd role.
Checking if the etcd Container is Running
The container for etcd should have status Up. The duration shown after Up is the time the container has been running.
docker ps -a -f=name=etcd$
Example output:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
605a124503b9 rancher/coreos-etcd:v3.2.18 "/usr/local/bin/et..." 2 hours ago Up 2 hours etcd
etcd Container Logging
The logging of the container can contain information on what the problem could be.
docker logs etcd
| Log | Explanation |
|---|---|
health check for peer xxx could not connect: dial tcp IP:2380: getsockopt: connection refused | A connection to the address shown on port 2380 cannot be established. Check if the etcd container is running on the host with the address shown. |
xxx is starting a new election at term x | The etcd cluster has lost its quorum and is trying to establish a new leader. This can happen when the majority of the nodes running etcd go down/unreachable. |
connection error: desc = "transport: Error while dialing dial tcp 0.0.0.0:2379: i/o timeout"; Reconnecting to {0.0.0.0:2379 0 <nil>} | The host firewall is preventing network communication. |
rafthttp: request cluster ID mismatch | The node with the etcd instance logging rafthttp: request cluster ID mismatch is trying to join a cluster that has already been formed with another peer. The node should be removed from the cluster, and re-added. |
rafthttp: failed to find member | The cluster state (/var/lib/etcd) contains wrong information to join the cluster. The node should be removed from the cluster, the state directory should be cleaned and the node should be re-added. |
etcd Cluster and Connectivity Checks
The address where etcd is listening depends on the address configuration of the host etcd is running on. If an internal address is configured for the host etcd is running on, the endpoint for etcdctl needs to be specified explicitly. If any of the commands respond with Error: context deadline exceeded, the etcd instance is unhealthy (either quorum is lost or the instance is not correctly joined in the cluster)
Check etcd Members on all Nodes
Output should contain all the nodes with the etcd role and the output should be identical on all nodes.
Command:
docker exec etcd etcdctl member list
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list"
Example output:
xxx, started, etcd-xxx, https://IP:2380, https://IP:2379,https://IP:4001
xxx, started, etcd-xxx, https://IP:2380, https://IP:2379,https://IP:4001
xxx, started, etcd-xxx, https://IP:2380, https://IP:2379,https://IP:4001
Check Endpoint Status
The values for RAFT TERM should be equal and RAFT INDEX should be not be too far apart from each other.
Command:
docker exec -e ETCDCTL_ENDPOINTS=$(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") etcd etcdctl endpoint status --write-out table
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd etcdctl endpoint status --endpoints=$(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") --write-out table
Example output:
+-----------------+------------------+---------+---------+-----------+-----------+------------+
| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | RAFT TERM | RAFT INDEX |
+-----------------+------------------+---------+---------+-----------+-----------+------------+
| https://IP:2379 | 333ef673fc4add56 | 3.2.18 | 24 MB | false | 72 | 66887 |
| https://IP:2379 | 5feed52d940ce4cf | 3.2.18 | 24 MB | true | 72 | 66887 |
| https://IP:2379 | db6b3bdb559a848d | 3.2.18 | 25 MB | false | 72 | 66887 |
+-----------------+------------------+---------+---------+-----------+-----------+------------+
Check Endpoint Health
Command:
docker exec -e ETCDCTL_ENDPOINTS=$(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") etcd etcdctl endpoint health
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd etcdctl endpoint health --endpoints=$(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','")
Example output:
https://IP:2379 is healthy: successfully committed proposal: took = 2.113189ms
https://IP:2379 is healthy: successfully committed proposal: took = 2.649963ms
https://IP:2379 is healthy: successfully committed proposal: took = 2.451201ms
Check Connectivity on Port TCP/2379
Command:
for endpoint in $(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f5"); do
echo "Validating connection to ${endpoint}/health"
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -w "\n" --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) "${endpoint}/health"
done
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
for endpoint in $(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f5"); do
echo "Validating connection to ${endpoint}/health";
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -w "\n" --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) "${endpoint}/health"
done
Example output:
Validating connection to https://IP:2379/health
{"health": "true"}
Validating connection to https://IP:2379/health
{"health": "true"}
Validating connection to https://IP:2379/health
{"health": "true"}
Check Connectivity on Port TCP/2380
Command:
for endpoint in $(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f4"); do
echo "Validating connection to ${endpoint}/version";
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl --http1.1 -s -w "\n" --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) "${endpoint}/version"
done
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
for endpoint in $(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f4"); do
echo "Validating connection to ${endpoint}/version";
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl --http1.1 -s -w "\n" --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) "${endpoint}/version"
done
Example output:
Validating connection to https://IP:2380/version
{"etcdserver":"3.2.18","etcdcluster":"3.2.0"}
Validating connection to https://IP:2380/version
{"etcdserver":"3.2.18","etcdcluster":"3.2.0"}
Validating connection to https://IP:2380/version
{"etcdserver":"3.2.18","etcdcluster":"3.2.0"}
etcd Alarms
etcd will trigger alarms, for instance when it runs out of space.
Command:
docker exec etcd etcdctl alarm list
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT alarm list"
Example output when NOSPACE alarm is triggered:
memberID:x alarm:NOSPACE
memberID:x alarm:NOSPACE
memberID:x alarm:NOSPACE
etcd Space Errors
Related error messages are etcdserver: mvcc: database space exceeded or applying raft message exceeded backend quota. Alarm NOSPACE will be triggered.
Resolutions:
Compact the Keyspace
Command:
rev=$(docker exec etcd etcdctl endpoint status --write-out json | egrep -o '"revision":[0-9]*' | egrep -o '[0-9]*')
docker exec etcd etcdctl compact "$rev"
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
rev=$(docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT endpoint status --write-out json | egrep -o '\"revision\":[0-9]*' | egrep -o '[0-9]*'")
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT compact \"$rev\""
Example output:
compacted revision xxx
Defrag All etcd Members
Command:
docker exec -e ETCDCTL_ENDPOINTS=$(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") etcd etcdctl defrag
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd sh -c "etcdctl defrag --endpoints=$(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','")"
Example output:
Finished defragmenting etcd member[https://IP:2379]
Finished defragmenting etcd member[https://IP:2379]
Finished defragmenting etcd member[https://IP:2379]
Check Endpoint Status
Command:
docker exec -e ETCDCTL_ENDPOINTS=$(docker exec etcd /bin/sh -c "etcdctl member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") etcd etcdctl endpoint status --write-out table
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd sh -c "etcdctl endpoint status --endpoints=$(docker exec etcd /bin/sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT member list | cut -d, -f5 | sed -e 's/ //g' | paste -sd ','") --write-out table"
Example output:
+-----------------+------------------+---------+---------+-----------+-----------+------------+
| ENDPOINT | ID | VERSION | DB SIZE | IS LEADER | RAFT TERM | RAFT INDEX |
+-----------------+------------------+---------+---------+-----------+-----------+------------+
| https://IP:2379 | e973e4419737125 | 3.2.18 | 553 kB | false | 32 | 2449410 |
| https://IP:2379 | 4a509c997b26c206 | 3.2.18 | 553 kB | false | 32 | 2449410 |
| https://IP:2379 | b217e736575e9dd3 | 3.2.18 | 553 kB | true | 32 | 2449410 |
+-----------------+------------------+---------+---------+-----------+-----------+------------+
Disarm Alarm
After verifying that the DB size went down after compaction and defragmenting, the alarm needs to be disarmed for etcd to allow writes again.
Command:
docker exec etcd etcdctl alarm list
docker exec etcd etcdctl alarm disarm
docker exec etcd etcdctl alarm list
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT alarm list"
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT alarm disarm"
docker exec etcd sh -c "etcdctl --endpoints=\$ETCDCTL_ENDPOINT alarm list"
Example output:
docker exec etcd etcdctl alarm list
memberID:x alarm:NOSPACE
memberID:x alarm:NOSPACE
memberID:x alarm:NOSPACE
docker exec etcd etcdctl alarm disarm
docker exec etcd etcdctl alarm list
Log Level
The log level of etcd can be changed dynamically via the API. You can configure debug logging using the commands below.
Command:
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -XPUT -d '{"Level":"DEBUG"}' --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) $(docker exec etcd printenv ETCDCTL_ENDPOINTS)/config/local/log
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -XPUT -d '{"Level":"DEBUG"}' --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) $(docker exec etcd printenv ETCDCTL_ENDPOINT)/config/local/log
To reset the log level back to the default (INFO), you can use the following command.
Command:
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -XPUT -d '{"Level":"INFO"}' --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) $(docker exec etcd printenv ETCDCTL_ENDPOINTS)/config/local/log
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker run --net=host -v $(docker inspect kubelet --format '{{ range .Mounts }}{{ if eq .Destination "/etc/kubernetes" }}{{ .Source }}{{ end }}{{ end }}')/ssl:/etc/kubernetes/ssl:ro appropriate/curl -s -XPUT -d '{"Level":"INFO"}' --cacert $(docker exec etcd printenv ETCDCTL_CACERT) --cert $(docker exec etcd printenv ETCDCTL_CERT) --key $(docker exec etcd printenv ETCDCTL_KEY) $(docker exec etcd printenv ETCDCTL_ENDPOINT)/config/local/log
etcd Content
If you want to investigate the contents of your etcd, you can either watch streaming events or you can query etcd directly, see below for examples.
Watch Streaming Events
Command:
docker exec etcd etcdctl watch --prefix /registry
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd etcdctl --endpoints=\$ETCDCTL_ENDPOINT watch --prefix /registry
If you only want to see the affected keys (and not the binary data), you can append | grep -a ^/registry to the command to filter for keys only.
Query etcd Directly
Command:
docker exec etcd etcdctl get /registry --prefix=true --keys-only
Command when using etcd version lower than 3.3.x (Kubernetes 1.13.x and lower) and --internal-address was specified when adding the node:
docker exec etcd etcdctl --endpoints=\$ETCDCTL_ENDPOINT get /registry --prefix=true --keys-only
You can process the data to get a summary of count per key, using the command below:
docker exec etcd etcdctl get /registry --prefix=true --keys-only | grep -v ^$ | awk -F'/' '{ if ($3 ~ /cattle.io/) {h[$3"/"$4]++} else { h[$3]++ }} END { for(k in h) print h[k], k }' | sort -nr
Replacing Unhealthy etcd Nodes
When a node in your etcd cluster becomes unhealthy, the recommended approach is to fix or remove the failed or unhealthy node before adding a new etcd node to the cluster.