All databases produce logs - reams of information which can be dug through to get insight on how your database behaves. Historically, we've done that log splitting for you in the Compose dashboard. But as the number of databases we support has grown and the number of tools available to digest logs has expanded, we wanted to give more control to users.

That's why we're announcing a new downloadable log facility for Elasticsearch, Redis, PostgreSQL and RethinkDB deployments. You'll find the item for downloadable logs in the sidebar on your deployment view.

Selecting this will take you to a view of the last seven days of log files for that deployment, starting with yesterday's log files. Each database node of your deployment has a log file which can be downloaded and fed to whatever log analysis tool you want to use.

Accessing your Logfiles

How do I download a log? Just find the log you are interested in – they are grouped by day and then listed by capsule name and IP address for each database node. On the right hand side, the logs size and a download button is displayed. If no log was generated in the 24 hour period, the log size will be replaced by "empty" and there won't be a download button.

Capsule name? Each database node is allocated a capsule name and we're using that capsule name in the logs so you can differentiate between the nodes. You will find the capsule name also displayed with the IP address in your deployments overview here:

Where are the log files kept? We compress the log files and transfer them to our download provider each day, ready to be retrieved by you. We display the compressed file size as that's what you'll be downloading.

What's in the logs? That depends on which database is generating the log. We give you an unfiltered version of the logging from that node. The only thing we add to the log is that each line has a syslog style header prepended to it with date, time, host name and capsule name, followed by a colon and then the actual log entry. Do remember that log files are very compressible and the decompressed version of the log will be magnitudes larger than the displayed size.

When should I download a log? The facility is there to provide extra information when you are trying to solve a problem with your database. If, for example, your performance is not what you expect it to be, then downloading and analysing the log can give you some insight as to whether there were extenuating circumstances. The support team at Compose is still available to assist you – just mail support@compose.io or use the support form – but by being able to download your own logs, we hope you'll get a better understanding of how your database deployments behave.