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adr/0019-decouple-transformation-library-from-zarf.md

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+# 19. Decouple Transformation Library from Zarf
+
+Date: 2023-05-28
+
+## Status
+
+Pending
+
+## Context
+
+We need a way to decouple transformations from Zarf. We know the Zarf transformation library is battle tested, hardened, and reliable. As Pepr takes admission responsibilities from the Zarf Agent, we need a way to synchronize the TypeScript with the Go code instead of maintaining two disparate libraries which will be expected to grow. 
+
+We considered:
+- WASM
+- gRPC
+- REST
+- Rewrite the code in TypeScript
+
+#### WASM
+
+**PROS**
+- Shared codebase between TypeScript and Go
+- Fast
+- API Contract
+- No network overhead
+**CONS**
+- New technology
+- Requires new features in Pepr
+
+#### gRPC
+
+**PROS**
+- Shared codebase between TypeScript and Go
+- Fast
+- API Contract
+**CONS**
+- Network overhead
+- Pepr is considering adding a sidecar and we did not want potentially 3 containers in the Pepr Pod.
+
+#### REST
+
+**PROS**
+- Shared codebase between TypeScript and Go
+- Proven
+- API Contract
+**CONS**
+- Network overhead
+- Pepr is considering adding a sidecar and we did not want potentially 3 containers in the Pepr Pod.
+
+#### Rewrite in TypeScript
+
+**PROS**
+- Low hanging fruit
+**CONS**
+- Two codebases to maintain
+- TypeScript is not as battle tested as Go
+
+
+
+## Decision
+
+We conformed around using WASM because we can leverage the battle tested transform library from Zarf without incurring network overhead cost from pod to pod or container to container communications.
+
+## Consequences
+
+- Requires an Update to Pepr Core to package the WASM file because it is too large to fit in a ConfigMap
+- This will require standardization around the objects that are passed from Pepr to the WASM functions to testability and maintainability.