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I'm surprised they just punt on concurrent updates [0] instead of locking with something like dynamodb, like terraform does. [0] https://github.com/awslabs/git

I'm surprised they just punt on concurrent updates [0] instead of locking with something like dynamodb, like terraform does. [0] https://github.com/awslabs/git-remote-s3?tab=readme-ov-file#concurrent-writes https://github.com/awslabs/git-remote-s3?tab=readme-ov-file#...

mdaniel 2y ago
I thank goodness I have access to a non-stupid Terraform state provider[1] so I've never tried that S3+dynamodb setup but, if I understand the situation correctly, introducing Yet Another AWS Service ™ into this mix would mandate that callers also be given a `dynamo:WriteSomething` IAM perm, which is actually different from S3 in that in S3 one can -- at their discretion -- set the policies on the bucket such that it would work without any explicit caller IAM 1: https://docs.gitlab.com/ee/user/infrastructure/iac/terraform_state.html https://docs.gitlab.com/ee/user/infrastructure/iac/terraform...
ncruces 2y ago
Google Cloud Storage is good enough to implement locks all by itself: https://reddit.com/r/golang/comments/t52d4f/gmutex_a_global_mutex_using_google_cloud_storage/ https://reddit.com/r/golang/comments/t52d4f/gmutex_a_global_... Doesn't S3 provide primitives to do the same? At least since moving to strong read-after-write consistency? PS: I wrote the above package. Happy to answer questions about it.
- kbumsik 2y ago
  Conditional write is just added to S3 2 month ago: https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3-conditional-writes/ https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3...
  - laurencerowe 2y ago
    Unfortunately this functionality is much more limited in S3 as you can only use `If-None-Match: *` to prevent overwrites. https://docs.aws.amazon.com/AmazonS3/latest/userguide/conditional-writes.html https://docs.aws.amazon.com/AmazonS3/latest/userguide/condit... GCS also allows for conditional overwrites using `If-Match: <etag>` which means you can do optimistic concurrency control. https://cloud.google.com/storage/docs/request-preconditions https://cloud.google.com/storage/docs/request-preconditions
    - ncruces 2y ago
      Yeah, it might still be possible to implement a mutex based on just the existence of an object, but it'll be harder to add expiration/liveness which I find essential.
noctune 2y ago
S3 recently got conditional writes and you can use do locking entirely in S3 - I don't think they are using this though. Must be too recent an addition.
- yencabulator 2y ago
  I believe S3 can only do create-if-not-exist, which won't help for overwriting a pre-existing branch ref only-if-not-concurrently-updated. https://docs.aws.amazon.com/AmazonS3/latest/userguide/conditional-requests.html#conditional-writes https://docs.aws.amazon.com/AmazonS3/latest/userguide/condit...

mdaniel 2y ago

I thank goodness I have access to a non-stupid Terraform state provider[1] so I've never tried that S3+dynamodb setup but, if I understand the situation correctly, introducing Yet Another AWS Service ™ into this mix would mandate that callers also be given a `dynamo:WriteSomething` IAM perm, which is actually different from S3 in that in S3 one can -- at their discretion -- set the policies on the bucket such that it would work without any explicit caller IAM 1: https://docs.gitlab.com/ee/user/infrastructure/iac/terraform_state.html https://docs.gitlab.com/ee/user/infrastructure/iac/terraform...

ncruces 2y ago

Google Cloud Storage is good enough to implement locks all by itself: https://reddit.com/r/golang/comments/t52d4f/gmutex_a_global_mutex_using_google_cloud_storage/ https://reddit.com/r/golang/comments/t52d4f/gmutex_a_global_... Doesn't S3 provide primitives to do the same? At least since moving to strong read-after-write consistency? PS: I wrote the above package. Happy to answer questions about it.

kbumsik 2y ago
Conditional write is just added to S3 2 month ago: https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3-conditional-writes/ https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3...
- laurencerowe 2y ago
  Unfortunately this functionality is much more limited in S3 as you can only use `If-None-Match: *` to prevent overwrites. https://docs.aws.amazon.com/AmazonS3/latest/userguide/conditional-writes.html https://docs.aws.amazon.com/AmazonS3/latest/userguide/condit... GCS also allows for conditional overwrites using `If-Match: <etag>` which means you can do optimistic concurrency control. https://cloud.google.com/storage/docs/request-preconditions https://cloud.google.com/storage/docs/request-preconditions
  - ncruces 2y ago
    Yeah, it might still be possible to implement a mutex based on just the existence of an object, but it'll be harder to add expiration/liveness which I find essential.

noctune 2y ago

S3 recently got conditional writes and you can use do locking entirely in S3 - I don't think they are using this though. Must be too recent an addition.

yencabulator 2y ago
I believe S3 can only do create-if-not-exist, which won't help for overwriting a pre-existing branch ref only-if-not-concurrently-updated. https://docs.aws.amazon.com/AmazonS3/latest/userguide/conditional-requests.html#conditional-writes https://docs.aws.amazon.com/AmazonS3/latest/userguide/condit...