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Bastian Köcher
923cb8eea1
* Build every wasm crate in its own project with wasm-builder Building all wasm crates in one workspace was a nice idea, however it just introduced problems: 1. We needed to prune old members, but this didn't worked for old git deps. 2. We locked the whole wasm workspace while building one crate. This could lead to infinitely locking the workspace on a crash. Now we just build every crate in its own project, this means we will build the dependencies multiple times. While building the dependencies multiple times, we still decrease the build time by around 30 seconds for Polkadot and Substrate because of the new parallelism ;) * Remove the requirement on wasm-builder-runner This removes the requirement on wasm-builder-runner by using the new `build_dep` feature of cargo. We use nightly anyway and that enables us to use this feature. This solves the problem of not mixing build/proc-macro deps with normal deps. By doing this we get rid off this complicated project structure and can depend directly on `wasm-builder`. This also removes all the code from wasm-builder-runner and mentions that it is deprecated. * Copy the `Cargo.lock` to the correct folder * Remove wasm-builder-runner * Update docs * Fix deterministic check Modified-by: Bastian Köcher <git@kchr.de> * Try to make the ui test happy * Switch to `SKIP_WASM_BUILD` * Rename `SKIP_WASM_BINARY` to the correct name... * Update utils/wasm-builder/src/builder.rs Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com> * Update utils/wasm-builder/src/builder.rs Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com> Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
83 lines
3.8 KiB
Markdown
83 lines
3.8 KiB
Markdown
# Wasm builder is a utility for building a project as a Wasm binary
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The Wasm builder is a tool that integrates the process of building the WASM binary of your project into the main
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`cargo` build process.
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## Project setup
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A project that should be compiled as a Wasm binary needs to:
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1. Add a `build.rs` file.
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2. Add `wasm-builder` as dependency into `build-dependencies`.
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The `build.rs` file needs to contain the following code:
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```rust
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use substrate_wasm_builder::WasmBuilder;
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fn main() {
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WasmBuilder::new()
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// Tell the builder to build the project (crate) this `build.rs` is part of.
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.with_current_project()
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// Make sure to export the `heap_base` global, this is required by Substrate
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.export_heap_base()
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// Build the Wasm file so that it imports the memory (need to be provided by at instantiation)
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.import_memory()
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// Build it.
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.build()
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}
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```
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As the final step, you need to add the following to your project:
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```rust
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include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs"));
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```
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This will include the generated Wasm binary as two constants `WASM_BINARY` and `WASM_BINARY_BLOATY`.
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The former is a compact Wasm binary and the latter is the Wasm binary as being generated by the compiler.
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Both variables have `Option<&'static [u8]>` as type.
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### Features
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Wasm builder supports to enable cargo features while building the Wasm binary. By default it will
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enable all features in the wasm build that are enabled for the native build except the
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`default` and `std` features. Besides that, wasm builder supports the special `runtime-wasm`
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feature. This `runtime-wasm` feature will be enabled by the wasm builder when it compiles the
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Wasm binary. If this feature is not present, it will not be enabled.
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## Environment variables
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By using environment variables, you can configure which Wasm binaries are built and how:
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- `SKIP_WASM_BUILD` - Skips building any Wasm binary. This is useful when only native should be recompiled.
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If this is the first run and there doesn't exist a Wasm binary, this will set both
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variables to `None`.
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- `WASM_BUILD_TYPE` - Sets the build type for building Wasm binaries. Supported values are `release` or `debug`.
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By default the build type is equal to the build type used by the main build.
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- `FORCE_WASM_BUILD` - Can be set to force a Wasm build. On subsequent calls the value of the variable
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needs to change. As wasm-builder instructs `cargo` to watch for file changes
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this environment variable should only be required in certain circumstances.
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- `WASM_BUILD_RUSTFLAGS` - Extend `RUSTFLAGS` given to `cargo build` while building the wasm binary.
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- `WASM_BUILD_NO_COLOR` - Disable color output of the wasm build.
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- `WASM_TARGET_DIRECTORY` - Will copy any build Wasm binary to the given directory. The path needs
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to be absolute.
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- `WASM_BUILD_TOOLCHAIN` - The toolchain that should be used to build the Wasm binaries. The
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format needs to be the same as used by cargo, e.g. `nightly-2020-02-20`.
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Each project can be skipped individually by using the environment variable `SKIP_PROJECT_NAME_WASM_BUILD`.
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Where `PROJECT_NAME` needs to be replaced by the name of the cargo project, e.g. `node-runtime` will
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be `NODE_RUNTIME`.
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## Prerequisites:
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Wasm builder requires the following prerequisites for building the Wasm binary:
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- rust nightly + `wasm32-unknown-unknown` toolchain
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If a specific rust nightly is installed with `rustup`, it is important that the wasm target is installed
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as well. For example if installing the rust nightly from 20.02.2020 using `rustup install nightly-2020-02-20`,
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the wasm target needs to be installed as well `rustup target add wasm32-unknown-unknown --toolchain nightly-2020-02-20`.
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License: Apache-2.0
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