Need a way to compare schemas that is formatting agnostic

[theronic]

Problem Statement

If you call .readSchema after calling .writeSchema (via GRPC), Spice returns a schema string with reordered definitions that does not match the string that was written. I want to compare if my schema is up-to-date without writing a parser for the SpiceDB schema language.

Solution Brainstorm

Return the same schema text string that was written via .writeSchema.

Alternatively, is there a "compareSchema" function somewhere?

[josephschorr]

@theronic https://github.com/authzed/spicedb/tree/main/pkg/diff has a diff package which can be used after parsing the schema

SpiceDB always returns the normalized, ordered schema and that won't be changing; we don't store the actual text

[theronic]

Thanks @josephschorr, but my application is not written in Golang. Can diff be exposed via gRPC? If it's part of zed CLI, would have to shell out, or add a Golang wrapper in my Clojure application.

[josephschorr]

@theronic What, exactly, are you trying to do? What is your intention around if the schema has changed?

[theronic]

I'm trying to compare if the schema in prod SpiceDB instance differs from the Spice schema I have on-disk, e.g. when deploying a new version of app. At this stage, just convenient to check that I know I'm querying the right schema.

I guess I'll need schema migrations anyway 🤔

[josephschorr]

We could look into adding a SchemaDiff API, but you could just also call WriteSchema; if there are no changes, it'll no-op

[theronic]

Thanks. How do you keep track of Spice schema versioning?

Practical example similar to mismatched database schema: given a set of schema migrations, prod might think it has v3 of Spice Schema, but since schema is stateful, a different schema could have been written to Spice, so I'd like to ensure that the current production schema matches the previous migration that was run before running additional migrations.

[josephschorr]

We have our database migrations also call WriteSchema, so they move in sync

[josephschorr]

We should look into exporting the diff library via the API

[theronic]

Thanks. How do you keep track of which schema version was written to Spice? External hash / commit / version number in DB?

Would be nice if SchemaService took a DiffSchemaRequest and returned whatever the diff pkg would return.

[josephschorr]

Thanks. How do you keep track of which schema version was written to Spice? External hash / commit / version number in DB?

Yep

Would be nice if SchemaService took a DiffSchemaRequest and returned whatever the diff pkg would return.

Yeah, I updated the issue for that and reopened it

[theronic]

Is there a BNF syntax spec somewhere for the Schema language in the meantime so I can parse the schema text and compare the sorted parse tree?

[josephschorr]

Is there a BNF syntax spec somewhere for the Schema language in the meantime so I can parse the schema text and compare the sorted parse tree?

No. The implementation is considered the spec