Linera Playground

A browser-based GraphQL playground for Linera applications. Enter a faucet URL, a chain ID and an application ID, type a GraphQL query, and run it. The whole client runs in the browser via the @linera/client WASM package: it spins up a Client, creates a ChainClient for the chosen chain, synchronizes it from the validators, and queries the application's GraphQL service. Mutations go through the same path and are signed by a connected signer.

See DESIGN.md for the architecture.

Requirements

• Node.js and pnpm (the repo uses pnpm workspaces).
• The @linera/client and @linera/metamask packages under ../web are consumed as workspace packages. pnpm install builds them if needed (this compiles the WASM client and requires the Rust toolchain from ../web/rust-toolchain.toml).

Install and run

cd linera-playground
pnpm install
pnpm dev

Open the printed URL (default http://localhost:5173).

Using it

1. Faucet URL — the network to connect to (provides the genesis config and validators). For a local network this is the faucet started by linera net up --with-faucet (see below).
2. Chain ID and Application ID — the application to query.
3. Click Apply to load the application's GraphQL schema into the editor (this powers the docs explorer and autocomplete). Use the editor's refresh-schema button, or click Apply again, after changing the target.
4. Type a query and run it with the ▶ button.

Mutations

Reads work with no signer connected (the playground uses a throwaway key). To run a mutation you must connect a signer that owns the target chain:

• Use key — paste a private key (hex) or mnemonic.
• Connect MetaMask — sign with the MetaMask extension.

A mutation builds and signs a block; the validators reject it if the connected owner is not an owner of the chain.

Deploy with Docker

A self-contained image builds the WASM client from source and serves the static site with nginx (including the cross-origin-isolation headers the client needs). Build it from the repository root:

docker build -f docker/Dockerfile.playground -t linera-playground .

The first build compiles the whole workspace to WASM, so it is slow (~15-30 min) and needs network access for the toolchain and crates. Then run it:

docker run --rm -p 8080:80 linera-playground

Open http://localhost:8080 and set the faucet URL, chain ID and application ID in the UI. The faucet URL must be reachable from the browser (a public testnet faucet, or a local faucet exposed to the host).

Manual end-to-end test (local network)

From the root of the repository, start a local network with a faucet and deploy an example application (here, the counter):

export PATH="$PWD/target/debug:$PATH"
eval "$(linera net helper 2>/dev/null)"

LINERA_FAUCET_PORT=8079
export LINERA_FAUCET_URL=http://localhost:$LINERA_FAUCET_PORT
linera_spawn linera net up --with-faucet --faucet-port $LINERA_FAUCET_PORT

# In another shell, set up a wallet from the faucet and deploy the counter app,
# following examples/counter/README.md. Note the resulting CHAIN ID and
# APPLICATION ID.

Then in the playground:

1. Faucet URL: http://localhost:8079
2. Chain ID / Application ID: the values from the deployment.
3. Apply, then run query { value } — it should return the counter value.
4. Use key with the chain owner's key, then run mutation { increment(value: 1) }, and re-run query { value } to see it change.