Added auto memory configuration according to container memory limit

aleks-v-k · aleks-v-k · commit fba1496de7e8 · 2016-04-14T16:50:22.000+03:00
diff --git a/9.5/Dockerfile b/9.5/Dockerfile
@@ -52,6 +52,7 @@ ENV PGDATA /var/lib/postgresql/data
 VOLUME /var/lib/postgresql/data
 
 COPY docker-entrypoint.sh /
+COPY pg_auto_memory_config.sh /
 
 ENTRYPOINT ["/docker-entrypoint.sh"]
 
diff --git a/9.5/docker-entrypoint.sh b/9.5/docker-entrypoint.sh
@@ -93,6 +93,11 @@ if [ "$1" = 'postgres' ]; then
 		echo
 	fi
 
+    if [ ! -z "$PG_AUTO_MEMORY_CONFIG" ]; then
+        . /pg_auto_memory_config.sh "$PGDATA"
+    fi
+
+
 	exec gosu postgres "$@"
 fi
 
diff --git a/9.5/pg_auto_memory_config.sh b/9.5/pg_auto_memory_config.sh
@@ -0,0 +1,64 @@
+#!/bin/bash
+
+DATA_DIR="$1"
+CONFIG_FILE="$DATA_DIR/postgresql.conf"
+MEMORY_CONFIG_FILE=auto_memory_config.conf
+MEM_STAT_FILE=/sys/fs/cgroup/memory/memory.stat
+
+TOTAL_MEMORY=$(grep hierarchical_memory_limit $MEM_STAT_FILE|cut -d ' ' -f 2)
+
+# Always clean old memory config file, because the amount of memory may change
+# between container starts. Old config will be preserved in case of data
+# directory is mounted as some kind of persistent volume.
+echo '' > "$DATA_DIR/$MEMORY_CONFIG_FILE"
+
+if ! [[ "$TOTAL_MEMORY" =~ ^[0-9]+$ ]] ; then
+    echo "Failed to detect available memory size."
+    exit 1
+fi
+
+
+# In case when there is no limit set in the container, TOTAL_MEMORY will
+# contain very large value (9223372036854771712 or something like)
+total_host_memory=$(free -b | awk 'NR==2{print$2}')
+if (( $total_host_memory < $TOTAL_MEMORY )); then
+    echo "No memory limit set in the container. Skip auto configuration."
+    exit 0
+fi
+
+MEMORY_LIMIT_256M=$((256 * 1024 * 1024))
+MEMORY_LIMIT_512M=$((512 * 1024 * 1024))
+MEMORY_LIMIT_1G=$((1024 * 1024 * 1024))
+MEMORY_LIMIT_2G=$((2 * 1024 * 1024 * 1024))
+
+if (($TOTAL_MEMORY < $MEMORY_LIMIT_256M)); then
+    max_connections=20
+elif (($TOTAL_MEMORY < $MEMORY_LIMIT_512M)); then
+    max_connections=40
+elif (($TOTAL_MEMORY < $MEMORY_LIMIT_1G)); then
+    max_connections=60
+elif (($TOTAL_MEMORY < $MEMORY_LIMIT_2G)); then
+    max_connections=150
+else
+    max_connections=300
+fi
+
+shared_buffers=$(($TOTAL_MEMORY / 4))
+
+# Assume available memory for caching (OS + database). It is recommended to set
+# it from 1/2 to 3/4 of available memory.
+effective_cache_size=$(($TOTAL_MEMORY * 3 / 4))
+
+shared_buffers=$(($shared_buffers / (1024 * 1024)))MB
+effective_cache_size=$(($effective_cache_size / (1024 * 1024)))MB
+
+
+cat > "$DATA_DIR/$MEMORY_CONFIG_FILE" << EOF
+# Auto memory configuration.
+# TOTAL_MEMORY: $TOTAL_MEMORY
+max_connections = $max_connections
+shared_buffers = $shared_buffers
+effective_cache_size = $effective_cache_size
+EOF
+
+grep -Fq "$MEMORY_CONFIG_FILE" "$CONFIG_FILE" || echo "include = '$MEMORY_CONFIG_FILE'" >> "$CONFIG_FILE"
diff --git a/README.md b/README.md
@@ -1,3 +1,12 @@
+This is the fork of official image for postgres.
+The difference is an optional auto memory configuration feature:
+Define environment variable for the container *PG_AUTO_MEMORY_CONFIG=yes* and if
+there is a memory limit for the container, then will be created additional
+configuration file $PGDATA/auto_memory_config.conf.
+It defines *max_connections*, *shared_buffers*. *effective_cache_size*
+parameters according to memory limit in the container.
+
+
 # About this Repo
 
 This is the Git repo of the Docker [official image](https://docs.docker.com/docker-hub/official_repos/) for [postgres](https://registry.hub.docker.com/_/postgres/). See [the Docker Hub page](https://registry.hub.docker.com/_/postgres/) for the full readme on how to use this Docker image and for information regarding contributing and issues.
