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Comment by cube2222 | Hacker News Reader

It's also a really nice combo for simple automation lambdas that need some state and you want an ergonomic DB without paying for full RDS.

Go + Lambda + EFS + SQLite work great for that.

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Do SQLite write locks work properly over EFS with many concurrent instances?

https://www.sqlite.org/useovernet.html

Yes, since 2017: https://aws.amazon.com/about-aws/whats-new/2017/03/amazon-el...

Wow, I did not expect that.

And you have had no issues writing to a single SQLite file over EFS from multiple instances?

I haven't really stress-tested it yet. My automation lambdas that use this tend to be low traffic.

It's not relational, but MongoDB has a generous free tier. Or maybe you can use Aurora Serverless, it's in the free tier as well (but it's designed for different use cases).

Do you limit concurrency to 1 with this setup?

You can, though then you get errors when invoking the Lambda too much at the same time. Just letting it block on SQLite db opening should be good enough.

there aren't any issues with having multiple lambdas opening the same sqlite file?

SQLite is designed for concurrent access to the same db from multiple processes. All relevant locking happens in the DB file itself.

My concern is mostly around EFS consistency. SQLite concurrency locking is only as good as EFS file consistency. I wasn't sure if you had to work around any oddities of NFS. https://twitter.com/benbjohnson/status/1360592483969810443?l...

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