Importing cron, rsyslog & redis-cluster(wip) Dockerfiles

cron/Dockerfile

@@ -0,0 +1,7 @@
+FROM debian:stretch
+
+RUN apt update \
+        && apt install -y --no-install-recommends cron procps \
+        && rm -rf /var/lib/apt/lists/*
+
+CMD ["cron", "-f"]

redis-cluster/Dockerfile

@@ -0,0 +1,19 @@
+FROM redis:4.0
+
+COPY docker-entrypoint.sh /usr/local/bin/
+COPY sentinel.conf /usr/local/etc/redis/sentinel.conf
+
+
+ENV SENTINEL_QUORUM=2 \
+    SENTINEL_DOWN_AFTER=1000 \
+    SENTINEL_FAILOVER=1000 \
+    REDIS_MASTER_NAME=redismaster \
+    REDIS_MASTER=redis \
+    REDIS_SENTINEL_IP=redissentinel \
+    REDIS_SENTINEL_PORT=26379
+
+
+ENTRYPOINT ["docker-entrypoint.sh"]
+
+EXPOSE 6379
+CMD ["redis-server"]

redis-cluster/docker-entrypoint.sh

@@ -0,0 +1,107 @@
+#!/bin/sh
+set -e
+
+count_tasks() {
+    getent hosts tasks."$1" |wc -l
+}
+
+# Dirty hack to ensure that "getent hosts tasks.XXXX" will list us
+sleep 3
+
+
+## STARTING REDIS ##
+if [ "$1" = "redis-server" ]; then
+  echo "[DEBUG] PREPARING to start redis-server..."
+
+  # Check how many redis replicas are currently running...
+  if [ "$(count_tasks redis)" -gt 1 ]; then
+    # Other instances are running, we shall ask to one sentine who is master
+    echo "[DEBUG] Already one redis (or more) instance running, we'll ask the master IP to a sentinel and set ourself as slave..."
+
+    # TODO: sanity check : Manage the case where there's no sentinel ?
+
+    # Wait for a sentinel to be alive
+    until [ "$(redis-cli -h "$REDIS_SENTINEL_IP" -p "$REDIS_SENTINEL_PORT" ping)" = "PONG" ]; do
+      echo "$REDIS_SENTINEL_IP is unavailable - sleeping"
+      sleep 1
+    done
+
+    # Get current master IP
+    master_info=$(redis-cli -h "$REDIS_SENTINEL_IP" -p "$REDIS_SENTINEL_PORT" sentinel get-master-addr-by-name "$REDIS_MASTER_NAME")
+
+    # Ensure we have something from sentinel
+    until [ "$master_info" ]; do
+      echo "$REDIS_MASTER_NAME not found - sleeping"
+      sleep 1
+      master_info=$(redis-cli -h "$REDIS_SENTINEL_IP" -p "$REDIS_SENTINEL_PORT" sentinel get-master-addr-by-name "$REDIS_MASTER_NAME")
+    done
+
+    master_ip=$(echo $master_info | awk '{print $1}')
+    master_port=$(echo $master_info | awk '{print $2}')
+
+    echo "[DEBUG] STARTING redis as a SLAVE of $master_ip $master_port"
+    redis-server --slaveof $master_ip $master_port
+
+  else
+    # Only one redis - So we may be master? - TODO: Add sanity checks ?
+    # Like : Is there any sentinels ? What are they doing ?...
+    echo "[DEBUG] No other redis are running.... Starting redis as MASTER !!"
+    exec "$@"
+
+  fi
+
+
+## STARTING SENTINEL ##
+elif [ "$1" = "redis-sentinel" ]; then
+  echo "[DEBUG] PREPARING sentinel"
+
+  # Update config with ENV
+  sed -i "s/{{ SENTINEL_QUORUM }}/$SENTINEL_QUORUM/g" /usr/local/etc/redis/sentinel.conf
+  sed -i "s/{{ SENTINEL_DOWN_AFTER }}/$SENTINEL_DOWN_AFTER/g" /usr/local/etc/redis/sentinel.conf
+  sed -i "s/{{ SENTINEL_FAILOVER }}/$SENTINEL_FAILOVER/g" /usr/local/etc/redis/sentinel.conf
+  sed -i "s/{{ REDIS_MASTER_NAME }}/$REDIS_MASTER_NAME/g" /usr/local/etc/redis/sentinel.conf
+
+  # Check how many sentinels replicas are currently running...
+  if [ "$(count_tasks redissentinel)" -gt 1 ]; then
+    echo "[DEBUG] Already one (or more) sentinel instance running, we'll ask the master IP to a sentinel and set it as the master"
+
+    # Fetch sentiten
+    sentinel_ips=$(getent hosts tasks.redissentinel | awk '{print $1}');
+
+    for ip in $sentinel_ips; do
+      REDIS_IP=$(redis-cli -h "$ip" -p 26379 sentinel get-master-addr-by-name "$REDIS_MASTER_NAME" | head -1)
+      echo "[DEBUG] According to sentinel at $ip - Master_info is : $REDIS_IP"
+
+      if [ "$REDIS_IP" ]; then
+        break
+      fi
+    done
+
+
+    sed -i "s/{{ REDIS_IP }}/$REDIS_IP/g" /usr/local/etc/redis/sentinel.conf
+
+    echo "[DEBUG] Starting sentinel with redismaster as $REDIS_IP"
+    redis-server /usr/local/etc/redis/sentinel.conf --sentinel
+
+  else
+    # No other sentinels around.
+    echo "[DEBUG] No other sentinel running...."
+
+    # Is there redis instance running ?
+    if [ "$(count_tasks redis)" -gt 1 ]; then
+      # More than 1 redis running... Not so fun case to manage....
+      echo "[DEBUG] More than 1 redis running - Giving up...."
+
+    elif [ "$(count_tasks redis)" -eq 1 ]; then
+
+      echo "[DEBUG] Only one redis is runnig. Let's say its a master!"
+      REDIS_IP=$(getent hosts tasks.redis | awk '{print $1}');
+
+      sed -i "s/{{ REDIS_IP }}/$REDIS_IP/g" /usr/local/etc/redis/sentinel.conf
+      redis-server /usr/local/etc/redis/sentinel.conf --sentinel
+
+    else
+      echo "[DEBUG] No redis running... - Giving up...."
+    fi;
+  fi;
+fi;

redis-cluster/sentinel.conf

@@ -0,0 +1,8 @@
+port 26379
+
+dir /tmp
+
+sentinel monitor {{ REDIS_MASTER_NAME }} {{ REDIS_IP }} 6379 {{ SENTINEL_QUORUM }}
+sentinel down-after-milliseconds {{ REDIS_MASTER_NAME }} {{ SENTINEL_DOWN_AFTER }}
+sentinel parallel-syncs {{ REDIS_MASTER_NAME }} 1
+sentinel failover-timeout {{ REDIS_MASTER_NAME }} {{ SENTINEL_FAILOVER }}

rsyslog/Dockerfile

@@ -0,0 +1,17 @@
+FROM debian:stretch
+
+# procps is for debugging purpose only
+RUN apt-get update \
+        && apt-get install -y --no-install-recommends rsyslog procps \
+        && rm -rf /var/lib/apt/lists/*
+
+# Enable UDP syslog reception
+RUN sed -i 's/^#\(module(load="imudp")\)/\1/; s/^#\(input(type="imudp" port="514")\)/\1/' /etc/rsyslog.conf
+
+# Disable kernel logging support
+RUN sed -i 's/^module(load="imklog")/#&/' /etc/rsyslog.conf
+
+VOLUME /var/log/
+EXPOSE 514/udp
+
+CMD /usr/sbin/rsyslogd -n