Backing up Discourse with RDS

| community | devops | aws |

We are launching a community site with Discourse at CircleCI and I ran into some issues with performing backups.

Since we want to be #webscale, rather than installing Discourse using the easy Docker method, we opted to split up the services on AWS.

We are using EC2, RDS, ElasticCache, ELB and S3 for backups. When I initially launched PostgreSQL on RDS I just picked the latest version (9.4 at time of writing) and didn’t put much thought into it. The problem is that the version of pg_dump inside the Docker container provided by Discourse is 9.3.  Apparently you are not able to do a pg_dump when your client and server are mismatched.

When you try to do this, you get a sad error that states:

aborting because of server version mismatch

In order to fix this, we need to upgrade the client version on the Docker container (or alternatively avoid this all together by using the same version of PostgreSQL on RDS). Since it is easier to update the client than downgrade RDS, I opted to upgrade the client.

To do this:

  1. Log into the EC2 Instance that is running Discourse
  2. Go to the Discourse install location (mine is in /var/docker)
  3. Enter the container with:
    sudo ./launcher enter app
    
  4. Upgrade the version of PostgreSQL client
    apt-get install postgresql-9.4
    
  5. Swap out the pg_dump symbolic link for the newer version
        ln -s /usr/lib/postgresql/9.4/bin/pg_dump /usr/bin/pg_dump
    
  6. Perform your  backup
When you update the Docker container for the next release you will likely have to repeat these steps until Discourse gets to the same version of PostgreSQL as the one you chose on RDS.

Thank you for reading! Share your thoughts with me on bluesky, mastodon, or via email.

Check out some more stuff to read down below.

Most popular posts this month

Recent Favorite Blog Posts

This is a collection of the last 8 posts that I bookmarked.

Articles from blogs I follow around the net

One Year of Lifting Weights

We visited Portugal last year. I still remember how heavy the luggage felt that we had with us: 2 suitcases, weighing around 20 kg each. One year later, I now joke about that, and laugh, whenever I tell anyone about it. I didn’t think much of it at the tim…

via ttntm.me - Blog August 1, 2025

Secret Cinema - Grease

I was lucky enough to score tickets to last-night's dress rehearsal. It would be unfair to review this like a completed show, instead this is a preview on what to expect and some thoughts on the "immersive" genre. Very mild spoilers ahead. …

via Terence Eden’s Blog August 1, 2025

P&B: Emma Goto

This is the 101st edition of People and Blogs, the series where I ask interesting people to talk about themselves and their blogs. Today we have Emma Goto and her blog, emgoto.com To follow this series subscribe to the newsletter. A new int…

via Manuel Moreale August 1, 2025

Generated by openring