Core SDK that can be used as a base for other Temporal SDKs. It is currently used as the base of:

• TypeScript SDK
• Python SDK

For the reasoning behind the Core SDK, see:

• Why Rust powers Temporal’s new Core SDK.

Getting started

See the Architecture doc for some high-level information.

Dependencies

• Protobuf compiler

Development

This repo is composed of multiple crates:

• temporal-sdk-core-protos ./sdk-core-protos - Holds the generated proto code and extensions
• temporal-client ./client - Defines client(s) for interacting with the Temporal gRPC service
• temporal-sdk-core-api ./core-api - Defines the API surface exposed by Core
• temporal-sdk-core ./core - The Core implementation
• temporal-sdk ./sdk - A (currently prototype) Rust SDK built on top of Core. Used for testing.
• rustfsm ./fsm - Implements a procedural macro used by core for defining state machines (contains subcrates). It is temporal agnostic.

Visualized (dev dependencies are in blue):

All the following commands are enforced for each pull request:

Building and testing

You can buld and test the project using cargo: cargo build cargo test

Run integ tests with cargo integ-test. You will need to already be running the server: docker-compose -f .buildkite/docker/docker-compose.yaml up

Formatting

To format all code run: cargo fmt --all

Linting

We are using clippy for linting. You can run it using: cargo clippy --all -- -D warnings

Debugging

The crate uses tracing to help with debugging. To enable it for a test, insert the below snippet at the start of the test. By default, tracing data is output to stdout in a (reasonably) pretty manner.

crate::telemetry::test_telem_console();

The passed in options to initialization can be customized to export to an OTel collector, etc.

To run integ tests with OTel collection on, you can use integ-with-otel.sh. You will want to make sure you are running the collector via docker, which can be done like so:

docker-compose -f .buildkite/docker/docker-compose.yaml -f .buildkite/docker/docker-compose-telem.yaml up

If you are working on a language SDK, you are expected to initialize tracing early in your main equivalent.

Proto files

This repo uses a subtree for upstream protobuf files. The path protos/api_upstream is a subtree. To update it, use:

git pull --squash -s subtree ssh://git@github.com/temporalio/api.git master --allow-unrelated-histories

Do not question why this git command is the way it is. It is not our place to interpret git's ways.

The java testserver protos are also pulled from the sdk-java repo, but since we only need a subdirectory of that repo, we just copy the files with read-tree:

# add sdk-java as a remote if you have not already
git remote add -f -t master --no-tags testsrv-protos git@github.com:temporalio/sdk-java.git
# delete existing protos
git rm -rf protos/testsrv_upstream
# pull from upstream & commit
git read-tree --prefix protos/testsrv_upstream -u testsrv-protos/master:temporal-test-server/src/main/proto
git commit

Fetching Histories

Tests which would like to replay stored histories rely on that history being made available in binary format. You can fetch histories in that format like so (from a local docker server):

cargo run --bin histfetch {workflow_id} [{run_id}]

You can change the TEMPORAL_SERVICE_ADDRESS env var to fetch from a different address.

Style Guidelines

Error handling

Any error which is returned from a public interface should be well-typed, and we use thiserror for that purpose.

Errors returned from things only used in testing are free to use anyhow for less verbosity.