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Merge pull request #7 from tarosky/issue/6
Never use Init Container for unidempotent tasks Close #6.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,66 @@ | ||
| #!/bin/bash | ||
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| set -eux | ||
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| readonly namespace="$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace)" | ||
| readonly service_domain="_$SERVICE_PORT._tcp.$SERVICE.$namespace.svc.cluster.local" | ||
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| redis_info () { | ||
| set +e | ||
| timeout 10 redis-cli -h "$1" -a "$service_domain" info replication | ||
| set -e | ||
| } | ||
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| redis_info_role () { | ||
| echo "$1" | grep -e '^role:' | cut -d':' -f2 | tr -d '[:space:]' | ||
| } | ||
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| domain_ip () { | ||
| /opt/bin/dig-a "$1" | head -1 | awk -F' ' '{print $NF}' | ||
| } | ||
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| server_domains () { | ||
| /opt/bin/dig-srv "$1" | awk -F' ' '{print $NF}' | sed 's/\.$//g' | ||
| } | ||
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| run () { | ||
| # It's okay to fail during failover or other unpredictable states. | ||
| # This prevents from making things much worse. | ||
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| local -r servers="$(server_domains "$service_domain")" | ||
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| local master_ip='' | ||
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| local s | ||
| for s in $servers; do | ||
| local s_ip="$(domain_ip "$s")" | ||
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| if [ -z "$s_ip" ]; then | ||
| >&2 echo "Failed to resolve: $s" | ||
| continue | ||
| fi | ||
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| local i="$(redis_info "$s_ip")" | ||
| if [ -n "$i" ]; then | ||
| if [ "$(redis_info_role "$i")" = 'master' ]; then | ||
| master_ip="$s_ip" | ||
| fi | ||
| else | ||
| >&2 echo "Unable to get Replication INFO: $s ($s_ip)" | ||
| continue | ||
| fi | ||
| done | ||
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| if [ -z "$master_ip" ]; then | ||
| >&2 echo "Master not found." | ||
| exit 1 | ||
| fi | ||
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| cat /opt/sentinel.template.conf | \ | ||
| sed "s/%MASTER%/$master_ip/g" | \ | ||
| sed "s/%PASSWORD%/$service_domain/g" \ | ||
| > /opt/sentinel.conf | ||
| exec docker-entrypoint.sh redis-sentinel "$@" | ||
| } | ||
|
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| run "$@" |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,69 +1,8 @@ | ||
| #!/bin/bash | ||
|
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| set -e | ||
| set -u | ||
| set -x | ||
| set -eux | ||
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| readonly namespace="$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace)" | ||
| readonly service_domain="_$SERVICE_PORT._tcp.$SERVICE.$namespace.svc.cluster.local" | ||
|
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||
| redis_info () { | ||
| set +e | ||
| timeout 10 redis-cli -h "$1" -a "$service_domain" info replication | ||
| set -e | ||
| } | ||
|
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||
| redis_info_role () { | ||
| echo "$1" | grep -e '^role:' | cut -d':' -f2 | tr -d '[:space:]' | ||
| } | ||
|
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||
| domain_ip () { | ||
| dig +noall +answer a "$1" | head -1 | awk -F' ' '{print $NF}' | ||
| } | ||
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| server_domains () { | ||
| dig +noall +answer srv "$1" | awk -F' ' '{print $NF}' | sed 's/\.$//g' | ||
| } | ||
|
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| run () { | ||
| # It's okay to fail during failover or other unpredictable states. | ||
| # This prevents from making things much worse. | ||
|
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| local -r servers="$(server_domains "$service_domain")" | ||
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| local master_ip='' | ||
|
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| local s | ||
| for s in $servers; do | ||
| local s_ip="$(domain_ip "$s")" | ||
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| if [ -z "$s_ip" ]; then | ||
| >&2 echo "Failed to resolve: $s" | ||
| continue | ||
| fi | ||
|
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| local i="$(redis_info "$s_ip")" | ||
| if [ -n "$i" ]; then | ||
| if [ "$(redis_info_role "$i")" = 'master' ]; then | ||
| master_ip="$s_ip" | ||
| fi | ||
| else | ||
| >&2 echo "Unable to get Replication INFO: $s ($s_ip)" | ||
| continue | ||
| fi | ||
| done | ||
|
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| if [ -z "$master_ip" ]; then | ||
| >&2 echo "Master not found." | ||
| exit 1 | ||
| fi | ||
|
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| cp /sentinel.template.conf /opt/ | ||
| cat /sentinel.template.conf | \ | ||
| sed "s/%MASTER%/$master_ip/g" | \ | ||
| sed "s/%PASSWORD%/$service_domain/g" \ | ||
| > /opt/sentinel.conf | ||
| exit 0 | ||
| } | ||
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| run | ||
| mkdir -p /opt/bin | ||
| cp /dig-a /dig-srv /k8s-redis-ha-sentinel /opt/bin | ||
| cp /sentinel.template.conf /opt | ||
| chmod -R +x /opt/bin |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,135 @@ | ||
| #!/bin/bash | ||
|
|
||
| set -eux | ||
|
|
||
| readonly namespace="$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace)" | ||
| readonly service_domain="_$SERVICE_PORT._tcp.$SERVICE.$namespace.svc.cluster.local" | ||
| readonly sentinel_domain="_$SENTINEL_PORT._tcp.$SENTINEL.$namespace.svc.cluster.local" | ||
|
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||
| redis_info () { | ||
| set +e | ||
| timeout 10 redis-cli -h "$1" -a "$service_domain" info replication | ||
| set -e | ||
| } | ||
|
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| reset_sentinel () { | ||
| set +e | ||
| timeout 10 redis-cli -h "$1" -p 26379 sentinel reset mymaster | ||
| set -e | ||
| } | ||
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| redis_info_role () { | ||
| echo "$1" | grep -e '^role:' | cut -d':' -f2 | tr -d '[:space:]' | ||
| } | ||
|
|
||
| domain_ip () { | ||
| /opt/bin/dig-a "$1" | head -1 | awk -F' ' '{print $NF}' | ||
| } | ||
|
|
||
| server_domains () { | ||
| /opt/bin/dig-srv "$1" | awk -F' ' '{print $NF}' | sed 's/\.$//g' | ||
| } | ||
|
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| # At the end of the (succeeded) script, resetting all sentinels is necessary. | ||
| # This updates the list of supervised slaves. | ||
| # If this task is omitted, the number of "supervised" slaves continues to | ||
| # increase because sentinels are unable to recognize the recovered slave | ||
| # is the same slave as the dead one. | ||
| # Kubernetes may change Pod's IP address on restart. | ||
| reset_all_sentinels () { | ||
| local -r servers="$(server_domains "$sentinel_domain")" | ||
| local s | ||
| >&2 echo "Resetting all sentinels: $servers" | ||
| for s in $servers; do | ||
| local s_ip="$(domain_ip "$s")" | ||
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| if [ -z "$s_ip" ]; then | ||
| >&2 echo "Failed to resolve: $s" | ||
| continue | ||
| fi | ||
|
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| # Ignoring failed sentinels are allowed, since most of the sentinels are | ||
| # expected to be alive. | ||
| reset_sentinel "$s_ip" | ||
| done | ||
| } | ||
|
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| slave_priority () { | ||
| local -r no="$(echo "$(hostname)" | sed -e 's/^.\+-\([0-9]\+\)$/\1/g')" | ||
| local -r priority="$(((no + 1) * 10))" | ||
| echo "slave-priority $priority" | ||
| } | ||
|
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||
| # It's okay to fail during failover or other unpredictable states. | ||
| # This prevents from making things much worse. | ||
| run () { | ||
| cp /opt/redis.template.conf /opt/redis.conf | ||
|
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||
| # Domain name of the Service is also used as the password. | ||
| # In this case, password is just an ID to distinguish this replica set from | ||
| # other ones in the same Kubernetes cluster. | ||
| echo "masterauth $service_domain" >> /opt/redis.conf | ||
| echo "requirepass $service_domain" >> /opt/redis.conf | ||
|
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| # Replica with smaller number should be the preferred candidate for Master | ||
| # over ones with larger number. | ||
| # This is because replicas with larger number have higher chance of being | ||
| # removed by reducing the number of replica in a StatefulSet. | ||
| slave_priority >> /opt/redis.conf | ||
|
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| # Headless Service allows newly added Redis server to scan all working servers. | ||
| # This enables it to find if it is the first one. | ||
| local -r servers="$(server_domains "$service_domain")" | ||
| local -r my_host="$(hostname -f)" | ||
|
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| local master_ip='' | ||
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| local only_server=true | ||
| local s | ||
| for s in $servers; do | ||
| # My hostname must be excluded to handle restarts. | ||
| if [ "$s" = "$my_host" ]; then | ||
| continue | ||
| fi | ||
|
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| only_server=false | ||
|
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| local s_ip="$(domain_ip "$s")" | ||
|
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| if [ -z "$s_ip" ]; then | ||
| >&2 echo "Failed to resolve: $s" | ||
| continue | ||
| fi | ||
|
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| local i="$(redis_info "$s_ip")" | ||
| if [ -n "$i" ]; then | ||
| if [ "$(redis_info_role "$i")" = 'master' ]; then | ||
| master_ip="$s_ip" | ||
| fi | ||
| else | ||
| >&2 echo "Unable to get Replication INFO: $s ($s_ip)" | ||
| continue | ||
| fi | ||
| done | ||
|
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| if [ "$only_server" = true ]; then | ||
| # This is an exceptional case: if this is the first server to start in the | ||
| # replica, this must be run as Master. | ||
| # Otherwise the StatefulSet will be unable to start. | ||
| : | ||
| else | ||
| if [ -z "$master_ip" ]; then | ||
| >&2 echo "Unable to start because all servers are slave." | ||
| exit 1 | ||
| fi | ||
|
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| # Now the Master server has been found, this server will be launched as | ||
| # the slave of the Master. | ||
| echo "slaveof $master_ip 6379" >> /opt/redis.conf | ||
| fi | ||
|
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| reset_all_sentinels | ||
| exec docker-entrypoint.sh redis-server "$@" | ||
| } | ||
|
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| run "$@" |
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