Merge pull request #142 from motusllc/master

add support to replica mode for redis-sentinel to find the master

bitnami/redis/5.0/debian-9/Dockerfile

@@ -23,6 +23,9 @@ ENV ALLOW_EMPTY_PASSWORD="no" \
     REDIS_MASTER_PASSWORD="" \
     REDIS_MASTER_PASSWORD_FILE="" \
     REDIS_MASTER_PORT_NUMBER="6379" \
+    REDIS_SENTINEL_HOST="" \
+    REDIS_SENTINEL_MASTER_NAME="mymaster" \
+    REDIS_SENTINEL_PORT_NUMBER="26379" \
     REDIS_PASSWORD="" \
     REDIS_PASSWORD_FILE="" \
     REDIS_REPLICATION_MODE=""

bitnami/redis/5.0/debian-9/rootfs/libredis.sh

@@ -273,6 +273,11 @@ redis_configure_replication() {
             redis_conf_set masterauth "$REDIS_PASSWORD"
         fi
     elif [[ "$REDIS_REPLICATION_MODE" =~ ^(slave|replica)$ ]]; then
+        if [[ -n "$REDIS_SENTINEL_HOST" ]]; then
+            REDIS_SENTINEL_INFO=($(redis-cli -h $REDIS_SENTINEL_HOST -p $REDIS_SENTINEL_PORT_NUMBER sentinel get-master-addr-by-name $REDIS_SENTINEL_MASTER_NAME))
+            REDIS_MASTER_HOST=${REDIS_SENTINEL_INFO[0]}
+            REDIS_MASTER_PORT_NUMBER=${REDIS_SENTINEL_INFO[1]}
+        fi
         wait-for-port --host "$REDIS_MASTER_HOST" "$REDIS_MASTER_PORT_NUMBER"
         [[ -n "$REDIS_MASTER_PASSWORD" ]] && redis_conf_set masterauth "$REDIS_MASTER_PASSWORD"
         # Starting with Redis 5, use 'replicaof' instead of 'slaveof'. Maintaining both for backward compatibility

bitnami/redis/5.0/ol-7/Dockerfile

@@ -23,6 +23,9 @@ ENV ALLOW_EMPTY_PASSWORD="no" \
     REDIS_MASTER_PASSWORD="" \
     REDIS_MASTER_PASSWORD_FILE="" \
     REDIS_MASTER_PORT_NUMBER="6379" \
+    REDIS_SENTINEL_HOST="" \
+    REDIS_SENTINEL_MASTER_NAME="mymaster" \
+    REDIS_SENTINEL_PORT_NUMBER="26379" \
     REDIS_PASSWORD="" \
     REDIS_PASSWORD_FILE="" \
     REDIS_REPLICATION_MODE=""

bitnami/redis/5.0/ol-7/rootfs/libredis.sh

@@ -273,6 +273,11 @@ redis_configure_replication() {
             redis_conf_set masterauth "$REDIS_PASSWORD"
         fi
     elif [[ "$REDIS_REPLICATION_MODE" =~ ^(slave|replica)$ ]]; then
+        if [[ -n "$REDIS_SENTINEL_HOST" ]]; then
+            REDIS_SENTINEL_INFO=($(redis-cli -h $REDIS_SENTINEL_HOST -p $REDIS_SENTINEL_PORT_NUMBER sentinel get-master-addr-by-name $REDIS_SENTINEL_MASTER_NAME))
+            REDIS_MASTER_HOST=${REDIS_SENTINEL_INFO[0]}
+            REDIS_MASTER_PORT_NUMBER=${REDIS_SENTINEL_INFO[1]}
+        fi
         wait-for-port --host "$REDIS_MASTER_HOST" "$REDIS_MASTER_PORT_NUMBER"
         [[ -n "$REDIS_MASTER_PASSWORD" ]] && redis_conf_set masterauth "$REDIS_MASTER_PASSWORD"
         # Starting with Redis 5, use 'replicaof' instead of 'slaveof'. Maintaining both for backward compatibility

bitnami/redis/5.0/rhel-7/Dockerfile

@@ -23,6 +23,9 @@ ENV ALLOW_EMPTY_PASSWORD="no" \
     REDIS_MASTER_PASSWORD="" \
     REDIS_MASTER_PASSWORD_FILE="" \
     REDIS_MASTER_PORT_NUMBER="6379" \
+    REDIS_SENTINEL_HOST="" \
+    REDIS_SENTINEL_MASTER_NAME="mymaster" \
+    REDIS_SENTINEL_PORT_NUMBER="26379" \
     REDIS_PASSWORD="" \
     REDIS_PASSWORD_FILE="" \
     REDIS_REPLICATION_MODE=""

bitnami/redis/5.0/rhel-7/rootfs/libredis.sh

@@ -273,6 +273,11 @@ redis_configure_replication() {
             redis_conf_set masterauth "$REDIS_PASSWORD"
         fi
     elif [[ "$REDIS_REPLICATION_MODE" =~ ^(slave|replica)$ ]]; then
+        if [[ -n "$REDIS_SENTINEL_HOST" ]]; then
+            REDIS_SENTINEL_INFO=($(redis-cli -h $REDIS_SENTINEL_HOST -p $REDIS_SENTINEL_PORT_NUMBER sentinel get-master-addr-by-name $REDIS_SENTINEL_MASTER_NAME))
+            REDIS_MASTER_HOST=${REDIS_SENTINEL_INFO[0]}
+            REDIS_MASTER_PORT_NUMBER=${REDIS_SENTINEL_INFO[1]}
+        fi
         wait-for-port --host "$REDIS_MASTER_HOST" "$REDIS_MASTER_PORT_NUMBER"
         [[ -n "$REDIS_MASTER_PASSWORD" ]] && redis_conf_set masterauth "$REDIS_MASTER_PASSWORD"
         # Starting with Redis 5, use 'replicaof' instead of 'slaveof'. Maintaining both for backward compatibility

bitnami/redis/README.md

@@ -377,6 +377,26 @@ The above command scales up the number of replicas to `3`. You can scale down in
 
 > **Note**: You should not scale up/down the number of master nodes. Always have only one master node running.
 
+### Using redis-sentinel
+
+If you have redis-sentinel running, you can use it to find the current master by configuring the following environment variables:
+- REDIS_REPLICATION_MODE=slave (we only want to configure this when in slave mode)
+- REDIS_SENTINEL_HOST=<sentinel-hosts> (this would ideally be a round robin DNS hostname)
+- REDIS_SENTINEL_PORT=<port sentinel is listening on>
+
+What happens behind the scenes is at startup the sentinel gets queried for the current master IP and port, and sets the ```REDIS_MASTER_HOST``` and ```REDIS_MASTER_PORTNUMER``` with those values.
+
+```bash
+$ docker run --name redis-replica \
+  --link redis-master:master \
+  -e REDIS_REPLICATION_MODE=slave \
+  -e REDIS_SENTINEL_HOST=redis-sentinel \
+  -e REDIS_SENTINEL_PORT_NUMBER=26379 \
+  -e REDIS_SENTINEL_MASTER_NAME=mymaster \
+  -e REDIS_PASSWORD=password123 \
+  bitnami/redis:latest
+```
+
 ## Configuration file
 
 The image looks for configurations in `/opt/bitnami/redis/etc/redis.conf`. You can overwrite the `redis.conf` file using your own custom configuration file.