Data Persistence

Dockerfile

@@ -3,12 +3,20 @@ MAINTAINER [email protected]
 
 RUN apt-get update && apt-get upgrade -y \
     && rm -rf /var/lib/apt/lists/*
-
-COPY scripts/ /docker-entrypoint-initdb.d/.
+
+COPY ["scripts/", "/docker-entrypoint-initdb.d/"]
+COPY ["bin/initialize.sh", "bin/preflight.sh", "bin/persistence-cleanup.sh", "/usr/local/bin/"]
+RUN chmod 755 /usr/local/bin/persistence-cleanup.sh; \
+    chmod 755 /usr/local/bin/initialize.sh; \
+    chmod 755 /usr/local/bin/preflight.sh; \
+    sed -i '/bin\/bash/a /usr/local/bin/initialize.sh' /usr/local/bin/docker-entrypoint.sh; \
+    sed -i '/exec "$@"/i /usr/local/bin/preflight.sh' /usr/local/bin/docker-entrypoint.sh
 
 # we need to touch and chown config files, since we cant write as mysql user
 RUN touch /etc/mysql/conf.d/galera.cnf \
+    touch /etc/mysql/conf.d/cust.cnf \
     && chown mysql.mysql /etc/mysql/conf.d/galera.cnf \
+    && chown mysql.mysql /etc/mysql/conf.d/cust.cnf \
     && chown mysql.mysql /docker-entrypoint-initdb.d/*.sql
 
 # we expose all Cluster related Ports
@@ -22,9 +30,8 @@ EXPOSE 3306 4444 4567 4568
 ENV GALERA_USER=galera \
     GALERA_PASS=galerapass \
     MAXSCALE_USER=maxscale \
-    MAXSCALE_PASS=maxscalepass \ 
+    MAXSCALE_PASS=maxscalepass \
     CLUSTER_NAME=docker_cluster \
     MYSQL_ALLOW_EMPTY_PASSWORD=1
-
-CMD ["mysqld"]
 
+CMD ["mysqld"]

README.md

@@ -112,4 +112,5 @@ The result should report the cluster up and running:
 	10.0.0.5           | 10.0.0.5        |  3306 |           0 | Master, Synced, Running
 	-------------------+-----------------+-------+-------------+--------------------
 
-
+### Data persistance
+If you need data persistance; Mount a volume to /data in the container (using --mount).  A subfolder of /data will be created for each container (by ip) and the mysql datadir will be redirected here. Ensure /data is owned by 999:999.

bin/initialize.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+echo "[mysqld]" > /etc/mysql/conf.d/cust.cnf
+
+#We check to see if /data folder exists.  Assume we need to change mariadb datadir if so (for data persistence).
+if [ -d "/data" ]; then
+
+  #Get the ip address for this container. There may be multiple.  We'll cross reference it with the $DB_SERVICE_NAME.
+  for interface in $(ip add|grep global|awk '{match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/); ip = substr($0,RSTART,RLENGTH); print ip}'); do
+	for swarm_service in $(getent hosts tasks.$DB_SERVICE_NAME|awk '{match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/); ip = substr($0,RSTART,RLENGTH); print ip}'); do
+	  if [ "$interface" == "$swarm_service" ]; then
+	    THIS_DB_SERVICE_IP=$interface
+      fi
+	done
+  done
+
+  #Set the data dir to /data + the IP of this container.
+  mkdir -p /data/$THIS_DB_SERVICE_IP
+  echo "datadir = /data/$THIS_DB_SERVICE_IP" >> /etc/mysql/conf.d/cust.cnf
+  #echo "socket = /data/$THIS_DB_SERVICE_IP/mysql.sock" >> /etc/mysql/conf.d/cust.cnf
+
+  #Cleanup - clean up data folders for nodes no longer in the cluster. Don't wait for this.
+  /usr/local/bin/persistence-cleanup.sh &
+fi

bin/persistence-cleanup.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+#Wait until the service is up and running on this host.
+healthcheck(){
+  /usr/local/bin/docker-healthcheck 2> /dev/null
+}
+count=0
+healthcheck
+while [ $? != 0 ]; do
+  sleep 1
+  ((count=count+1))
+  if [ "$count" -ge 100 ]; then
+    break
+  fi
+  healthcheck
+done
+
+
+/usr/local/bin/docker-healthcheck 2> /dev/null
+if [ $? -eq 0 ]; then
+  #If there is a /data/ip directory that doesn't match an active swarm cluster IP address, it should be cleaned up.
+  #Will only clean up a single such directory on a run.
+
+  #Get the ip address for this container. There may be multiple.  We'll cross reference it with the $DB_SERVICE_NAME.
+  for dir in `find /data -type d| awk '{match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/); ip = substr($0,RSTART,RLENGTH); print ip}'`; do
+    ip_match=0
+	for swarm_service in $(getent hosts tasks.$DB_SERVICE_NAME| awk '{match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/); ip = substr($0,RSTART,RLENGTH); print ip}'); do
+      if [ "$dir" == "$swarm_service" ]; then
+        ip_match=1
+      fi
+    done
+
+	#Delete this extra folder structure
+	if [ $dir ] && [ "$ip_match" != 1 ]; then
+	  echo "Removing stale persistence dir /data/$dir"
+	  rm -rf "/data/$dir"
+	  exit
+	fi
+  done
+fi

bin/preflight.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+# Check our configs
+# If a new container was launched with an old data volume the full docker-entrypoint.sh doesn't run.
+# The result is that galera.cnf is not created in the new container.
+
+#Check for galera.cnf
+if [ ! -s /etc/mysql/conf.d/galera.cnf ]; then
+  /docker-entrypoint-initdb.d/init_cluster_conf.sh
+fi

scripts/init_cluster_conf.sh

@@ -48,4 +48,4 @@ default-storage-engine = InnoDB
 innodb-doublewrite = 1 
 innodb-autoinc-lock-mode = 2 
 innodb-flush-log-at-trx-commit = 2 
-EOF
+EOF