Redis - Get Memory Usage and TTL of all keys | Devops Junction

In this article, I am going to share a shell script to help you get the TTL (time to live) and Memory Usage of all the keys available in Redis DB

Every tool/technology that we use in infrastructure comes with a certain cost of management.

Redis, a memory-intensive caching solution is no exception.

If we are not keeping track of what we are storing in Redis and how long we are storing it. Redis Memory usage will spike and it can bring your Production infrastructure down.

It can also burn your pocket and increase the Infrastructure costs. So it is always recommended to keep track of any data storage.

Whether it is long storage like DB or short storage like Redis Cache.

Now, To the objective.

A solution to get TTL  and Memory Usage of all the keys in Redis Database

I hope we are on the same page that how necessary it is to monitor the Redis database Keys and their size.

Of course, there are various solutions and integrated monitoring systems to monitor the TTL with configurable threshold alerts.

Now we are going to see a quick and easy solution to get TTL and Memory Usage of  all the keys in Redis DB

With no further ado, here is the script that uses some Shell commands and  redis-cli command-line tool

#!/bin/bash
# To Find Redis TTL and Memory Usage
# Author: Sarav AK

REDISHOST=my-redis-broker.0001.use1.cache.amazonaws.com
REDISPORT=6379
DBNO=4

KEYSLIST=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO keys  "*"|awk '{print $1}'`
echo "KEY TTL MEMORY_USAGE"
echo "----------------------------- – –  – – --"
while read LINE
do
    TTL=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO ttl "$LINE"`;
    MEMUSAGE=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO memory usage "$LINE"`;
    echo "$LINE $TTL $MEMUSAGE";
done <<< "$KEYSLIST"

 

Prerequisites

• You need to have the redis-cli tool installed in before executing this shell script
• Also Necessary access to Redis

 

How it works

• It first lists all the keys by connecting to Redis database using the provided connection information

  KEYSLIST=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO keys "*"|awk '{print $1}'`

• It passes the output of the previous command stored in KEYSLIST variable to a while loop where the following tasks are executed against each key
  • • Get the TTL ( Time to Live) value of each key using ttl command
    • Get the Memory Usage value of each key using memory usage command

  while read LINE 
  do 
      TTL=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO ttl "$LINE"`; 
      MEMUSAGE=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO memory usage "$LINE"`; 
      echo "$LINE $TTL $MEMUSAGE"; 
  done <<< "$KEYSLIST"

 

Where this can be used

This script can be used for All Redis deployments like Clustered or standalone

Can also be used in AWS Elastic Cache or any Managed Redis as well.

 

How to execute this script

Just copy the script and save it as *.sh file and make sure it has executable permission by giving

chmod a+x findmemttl-redis.sh

I have named my script as findmemttl-redis.sh you can rename it as you want

Now you can run the script

./findmemttl-redis.ssh

If you want some nice formatting and the values in separate columns. Execute the script with some awk like this

./findmemttl-redis.sh|awk '{ printf "%-50s %6s %s\n", $1, $2, $3 }'

If you have coloumn install you can use that instead of awk

 

How to write the output as CSV

If you want to write the output as CSV, All you have to do is to change the spaces to commas in the following line

echo "$LINE $TTL $MEMUSAGE";

Here is the modified script which writes the output as CSV ( Comma Separated Values)

#!/bin/bash
# To Find Redis TTL and Memory Usage
#

REDISHOST=my-broker-redis.use1.cache.amazonaws.com
REDISPORT=6379
DBNO=4

KEYSLIST=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO keys  "*"|awk '{print $1}'`
echo "KEY,TTL,MEMORY_USAGE"
while read LINE
do
    TTL=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO ttl "$LINE"`;
    MEMUSAGE=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO memory usage "$LINE"`;
    echo "$LINE,$TTL,$MEMUSAGE";
done <<< "$KEYSLIST"

You can run the script with output redirection to .csv file

./findmemttl-redis.ssh > output.csv

 

How to find the Non-Expiring Keys Redis

Sometimes you would not want all the keys, You might want only the Keys which do not have TTL configured.

In other words, Keys with no TTL set, The Non Expiring ones.

You can do that by adding a quick if condition into our script

#!/bin/bash
# To Find Redis TTL and Memory Usage
#

REDISHOST=my-redis-broker.use1.cache.amazonaws.com
REDISPORT=6379
DBNO=4

KEYSLIST=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO keys  "*"|awk '{print $1}'`
echo "KEY TTL MEMORY_USAGE"
echo "----------------------------- – –  – – -------------"
while read LINE
do
    TTL=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO ttl "$LINE"`;
    MEMUSAGE=`redis-cli -h $REDISHOST -p $REDISPORT -n $DBNO memory usage "$LINE"`;
    if [ $TTL -eq "-1" ]
    then
    	echo "$LINE $TTL $MEMUSAGE";
    fi
done <<< "$KEYSLIST"

Here we have added an IF statement to filter and print only the items which has a TTL value as -1

TTL -1 represents that the key is non-expiring or has no TTL value set for that key.

 

Cheers
Sarav AK

---