bazelbuildTypeScript rules for Bazel
The TypeScript rules integrate the TypeScript compiler with Bazel.
Alternatives
This package provides Bazel wrappers around the TypeScript compiler.
At a high level, there are four alternatives provided. This section describes the trade-offs between these rules.
Option 1: tsc
tsc is the TypeScript compiler published by the team at Microsoft.
You can call it without any custom Bazel rules.
To use this option, you do not need to install the @bazel/typescript package.
The only reason to use raw tsc is if you want to compile a directory of .ts files and cannot enumerate them ahead-of-time in your BUILD file so that Bazel can predict all the output files.
(For example if the .ts files are generated by some tool).
This will produce an opaque directory of .js file outputs, which you won't be able to individually reference.
Any other use case for tsc is better served by using ts_project, see below.
Like we do for any npm package that exposes a binary, rules_nodejs will see your dependency on
typescript and will generate an index.bzl file allowing you to run tsc.
To use it, add the load statement load("@npm//typescript:index.bzl", "tsc") to your BUILD file.
(Possibly replacing @npm with the name of the repository where you installed dependencies)
Then call it, using the npm_package_bin documentation.
Here is an example: https://github.com/bazelbuild/rules_nodejs/blob/3.2.2/internal/node/test/BUILD.bazel#L491-L507
Option 2: tsc_test
tsc_test is generated alongside tsc.
It is identical, except that Bazel treats it as a test target, producing only an exit code
rather than files to be consumed by other steps in the build.
This can be used for a build with --noEmit, so that TypeScript is purely used for
type-checking and not for producing any build outputs.
To use it, add the load statement load("@npm//typescript:index.bzl", "tsc_test") to your BUILD file.
(Possibly replacing @npm with the name of the repository where you installed dependencies)
To get the typings available in the test (as "runfiles"), you may need to gather them from dependencies if they are not included as default outputs of those dependencies, like so:
filegroup(name = "types", srcs = ["//some:js_library"], output_group = "types")And then include the :types target in the data of the tsc_test.
See example in https://github.com/bazelbuild/rules_nodejs/tree/stable/packages/typescript/test/tsc_test
Option 3: ts_project
ts_project simply runs tsc --project, with Bazel knowing which outputs to expect based on the TypeScript compiler options,
and with interoperability with other TypeScript rules via the DeclarationInfo Provider that transmits the type information.
It is intended as an easy on-boarding for existing TypeScript code and should be familiar if your background is in frontend ecosystem idioms.
Any behavior of ts_project should be reproducible outside of Bazel, with a couple of caveats noted in the rule documentation below.
ts_project is recommended for all new code.
Exhaustive examples of calling ts_project are in the test suite:
https://github.com/bazelbuild/rules_nodejs/tree/stable/packages/typescript/test/ts_project
And there are also many uses of it in our examples.
Option 4: ts_library
ts_library should not be used for new code, and may be deprecated in the future.
ts_library is an open-sourced version of the rule used to compile TS code at Google.
However there is no support from the team that maintains that internal version.
It is very complex, involving code generation of the tsconfig.json file, a custom compiler binary, and a lot of extra features.
It is also opinionated, and may not work with existing TypeScript code. For example:
- Your TS code must compile under the
--declarationflag so that downstream libraries depend only on types, not implementation. This makes Bazel faster by avoiding cascading rebuilds in cases where the types aren't changed. - We control the output format and module syntax so that downstream rules can rely on them.
- Some other options are incompatible. For example you cannot use the
--noEmitcompiler option intsconfig.json.
The only reason to use ts_library for new code is if you are bought-in to using a concatjs bundler, which requires the named AMD module format. This may be faster than other tooling, and this format can be consumed by the Closure Compiler (via integration with tsickle).
However it is very challenging to configure and there is little available support for problems you'll run into.
Installation
Add a devDependency on @bazel/typescript
$ yarn add -D @bazel/typescript
# or
$ npm install --save-dev @bazel/typescriptWatch for any peerDependency warnings - we assume you have already installed the typescript package from npm.
Typical Usage
The ts_project rule invokes the TypeScript compiler on one compilation unit,
or "library" (generally one directory of source files). In TypeScript terms, this is one "Project"
which can use "Project References" to break up a large application.
Create a BUILD file next to your sources:
load("@npm//@bazel/typescript:index.bzl", "ts_project")
ts_project(
name = "my_code",
# glob is a quick way to select all the code,
# but has performance penalty in that Bazel must evaluate it.
srcs = glob(["*.ts"]),
deps = ["//path/to/other:library"],
)Here, //path/to/other:library is another target in your repo that produces TypeScript typings (for example, another ts_project rule).
Be sure to set the rootDirs in your tsconfig.json as noted below, so that TypeScript can find the .d.ts files produced by that other target.
To use third-party libraries from npm, first install them (likely using npm_install or yarn_install rules) then add those to the deps as well:
ts_project(
name = "my_code",
srcs = glob(["*.ts"]),
deps = [
"@npm//@types/node",
"@npm//@types/foo",
"@npm//somelib",
"//path/to/other:library",
],
)You can also use the @npm//@types grouping target which will include all
packages in the @types scope as dependencies.
To build a ts_library target run:
bazel build //path/to/package:target
Note that the tsconfig.json file used for compilation should be the same one
your editor references, or extends from it, to keep consistent settings for the TypeScript compiler.
Anything you do with TypeScript is possible with ts_project, including json imports, type-checking only,
transpile only, outdir, rootdir, and so on.
To use
ts_projectfor typecheck-only, you'll still need to use --declaration so that .d.ts files are produced. Alternatively, see thetsc_testrule documented above.
See many examples in our test cases: https://github.com/bazelbuild/rules_nodejs/tree/stable/packages/typescript/test/ts_project
ts_config
USAGE
ts_config(name, deps, src)
Allows a tsconfig.json file to extend another file.
Normally, you just give a single tsconfig.json file as the tsconfig attribute
of a ts_library or ts_project rule. However, if your tsconfig.json uses the extends
feature from TypeScript, then the Bazel implementation needs to know about that
extended configuration file as well, to pass them both to the TypeScript compiler.
ATTRIBUTES
name
(Name, mandatory): A unique name for this target.
deps
(List of labels): Additional tsconfig.json files referenced via extends
Defaults to []
src
(Label, mandatory): The tsconfig.json file passed to the TypeScript compiler
ts_project
USAGE
ts_project(name, tsconfig, srcs, args, data, deps, extends, allow_js, declaration, source_map, declaration_map, resolve_json_module, preserve_jsx, composite, incremental, emit_declaration_only, transpiler, ts_build_info_file, tsc, typescript_package, typescript_require_path, validate, supports_workers, declaration_dir, out_dir, root_dir, link_workspace_root, kwargs)
Compiles one TypeScript project using tsc --project
This is a drop-in replacement for the tsc rule automatically generated for the "typescript"
package, typically loaded from @npm//typescript:index.bzl. Unlike bare tsc, this rule understands
the Bazel interop mechanism (Providers) so that this rule works with others that produce or consume
TypeScript typings (.d.ts files).
Unlike ts_library, this rule is the thinnest possible layer of Bazel interoperability on top
of the TypeScript compiler. It shifts the burden of configuring TypeScript into the tsconfig.json file.
See https://github.com/bazelbuild/rules_nodejs/blob/master/docs/TypeScript.md#alternatives
for more details about the trade-offs between the two rules.
Some TypeScript options affect which files are emitted, and Bazel wants to know these ahead-of-time. So several options from the tsconfig file must be mirrored as attributes to ts_project. See https://www.typescriptlang.org/tsconfig for a listing of the TypeScript options.
Any code that works with tsc should work with ts_project with a few caveats:
ts_projectalways produces some output files, or else Bazel would never run it. Therefore you shouldn't use it with TypeScript'snoEmitoption. Seetsc_testunder the Alternatives section above.- Bazel requires that the
outDir(anddeclarationDir) be set tobazel-out/[target architecture]/bin/path/to/packageso we override whatever settings appear in your tsconfig. - Bazel expects that each output is produced by a single rule.
Thus if you have two
ts_projectrules with overlapping sources (the same.tsfile appears in more than one) then you get an error about conflicting.jsoutput files if you try to build both together. Worse, if you build them separately then the output directory will contain whichever one you happened to build most recently. This is highly discouraged.
As a thin wrapper, this rule doesn't try to compensate for behavior of the TypeScript compiler. See https://github.com/bazelbuild/rules_nodejs/wiki/Debugging-problems-with-ts_project for notes that may help you debug issues.
Note: in order for TypeScript to resolve relative references to the bazel-out folder, we recommend that the base tsconfig contain a rootDirs section that includes all possible locations they may appear.
We hope this will not be needed in some future release of TypeScript. Follow https://github.com/microsoft/TypeScript/issues/37378 for more info.
For example, if the base tsconfig file relative to the workspace root is
path/to/tsconfig.jsonthen you should configure like:"compilerOptions": { "rootDirs": [ ".", "../../bazel-out/host/bin/path/to", "../../bazel-out/darwin-fastbuild/bin/path/to", "../../bazel-out/darwin_arm64-fastbuild/bin/path/to", "../../bazel-out/k8-fastbuild/bin/path/to", "../../bazel-out/x64_windows-fastbuild/bin/path/to", "../../bazel-out/darwin-dbg/bin/path/to", "../../bazel-out/k8-dbg/bin/path/to", "../../bazel-out/x64_windows-dbg/bin/path/to", ] }See some related discussion including both "rootDirs" and "paths" for a monorepo setup using custom import paths: https://github.com/bazelbuild/rules_nodejs/issues/2298
Issues when running non-sandboxed
When using a non-sandboxed spawn strategy (which is the default on Windows), you may observe these problems which require workarounds:
1) Bazel deletes outputs from the previous execution before running tsc.
This causes a problem with TypeScript's incremental mode: if the .tsbuildinfo file
is not known to be an output of the rule, then Bazel will leave it in the output
directory, and when tsc runs, it may see that the outputs written by the prior
invocation are up-to-date and skip the emit of these files. This will cause Bazel
to intermittently fail with an error that some outputs were not written.
This is why we depend on composite and/or incremental attributes to be provided,
so we can tell Bazel to expect a .tsbuildinfo output to ensure it is deleted before a
subsequent compilation.
At present, we don't do anything useful with the .tsbuildinfo output, and this rule
does not actually have incremental behavior. Deleting the file is actually
counter-productive in terms of TypeScript compile performance.
Follow https://github.com/bazelbuild/rules_nodejs/issues/1726
2) When using Project References, TypeScript will expect to verify that the outputs of referenced
projects are up-to-date with respect to their inputs.
(This is true even without using the --build option).
When using a non-sandboxed spawn strategy, tsc can read the sources from other ts_project
rules in your project, and will expect that the tsconfig.json file for those references will
indicate where the outputs were written. However the outDir is determined by this Bazel rule so
it cannot be known from reading the tsconfig.json file.
This problem is manifested as a TypeScript diagnostic like
error TS6305: Output file '/path/to/execroot/a.d.ts' has not been built from source file '/path/to/execroot/a.ts'.
As a workaround, you can give the Windows "fastbuild" output directory as the outDir in your tsconfig file.
On other platforms, the value isn't read so it does no harm.
See https://github.com/bazelbuild/rules_nodejs/tree/stable/packages/typescript/test/ts_project as an example.
We hope this will be fixed in a future release of TypeScript;
follow https://github.com/microsoft/TypeScript/issues/37378
3) When TypeScript encounters an import statement, it adds the source file resolved by that reference to the program. However you may have included that source file in a different project, so this causes the problem mentioned above where a source file is in multiple programs. (Note, if you use Project References this is not the case, TS will know the referenced file is part of the other program.) This will result in duplicate emit for the same file, which produces an error since the files written to the output tree are read-only. Workarounds include using using Project References, or simply grouping the whole compilation into one program (if this doesn't exceed your time budget).
PARAMETERS
name
A name for the target.
We recommend you use the basename (no .json extension) of the tsconfig file that should be compiled.
Defaults to "tsconfig"
tsconfig
Label of the tsconfig.json file to use for the compilation
To support "chaining" of more than one extended config, this label could be a target that
provides TsConfigInfo such as ts_config.
By default, we assume the tsconfig file is "tsconfig.json" in the same folder as the ts_project rule.
EXPERIMENTAL: generated tsconfig
Instead of a label, you can pass a dictionary of tsconfig keys.
In this case, a tsconfig.json file will be generated for this compilation, in the following way:
- all top-level keys will be copied by converting the dict to json.
So
tsconfig = {"compilerOptions": {"declaration": True}}will result in a generatedtsconfig.jsonwith{"compilerOptions": {"declaration": true}} - each file in srcs will be converted to a relative path in the
filessection. - the
extendsattribute will be converted to a relative path
Note that you can mix and match attributes and compilerOptions properties, so these are equivalent:
ts_project(
tsconfig = {
"compilerOptions": {
"declaration": True,
},
},
)and
ts_project(
declaration = True,
)Defaults to None
srcs
List of labels of TypeScript source files to be provided to the compiler.
If absent, the default is set as follows:
- Include
**/*.ts[x](all TypeScript files in the package). - If
allow_jsis set, include**/*.js[x](all JavaScript files in the package). - If
resolve_json_moduleis set, include**/*.json(all JSON files in the package), but exclude**/package.json,**/package-lock.json, and**/tsconfig*.json.
Defaults to None
args
List of strings of additional command-line arguments to pass to tsc.
Defaults to []
data
files needed at runtime by binaries or tests that transitively depend on this target.
See https://bazel.build/reference/be/common-definitions#typical-attributes
Defaults to []
deps
List of labels of other rules that produce TypeScript typings (.d.ts files)
Defaults to []
extends
Label of the tsconfig file referenced in the extends section of tsconfig
To support "chaining" of more than one extended config, this label could be a target that
provdes TsConfigInfo such as ts_config.
Defaults to None
allow_js
boolean; Specifies whether TypeScript will read .js and .jsx files. When used with declaration, TypeScript will generate .d.ts files from .js files.
Defaults to False
declaration
if the declaration bit is set in the tsconfig.
Instructs Bazel to expect a .d.ts output for each .ts source.
Defaults to False
source_map
if the sourceMap bit is set in the tsconfig.
Instructs Bazel to expect a .js.map output for each .ts source.
Defaults to False
declaration_map
if the declarationMap bit is set in the tsconfig.
Instructs Bazel to expect a .d.ts.map output for each .ts source.
Defaults to False
resolve_json_module
None | boolean; Specifies whether TypeScript will read .json files. Defaults to None. If set to True or False and tsconfig is a dict, resolveJsonModule is set in the generated config file. If set to None and tsconfig is a dict, resolveJsonModule is unset in the generated config and typescript default or extended tsconfig value will be load bearing.
Defaults to None
preserve_jsx
if the jsx value is set to "preserve" in the tsconfig.
Instructs Bazel to expect a .jsx or .jsx.map output for each .tsx source.
Defaults to False
composite
if the composite bit is set in the tsconfig.
Instructs Bazel to expect a .tsbuildinfo output and a .d.ts output for each .ts source.
Defaults to False
incremental
if the incremental bit is set in the tsconfig.
Instructs Bazel to expect a .tsbuildinfo output.
Defaults to False
emit_declaration_only
if the emitDeclarationOnly bit is set in the tsconfig.
Instructs Bazel not to expect .js or .js.map outputs for .ts sources.
Defaults to False
transpiler
A custom transpiler tool to run that produces the JavaScript outputs instead of tsc.
This attribute accepts a rule or macro with this signature:
name, srcs, js_outs, map_outs, **kwargs
where the **kwargs attribute propagates the tags, visibility, and testonly attributes from ts_project.
If you need to pass additional attributes to the transpiler rule, you can use a partial to bind those arguments at the "make site", then pass that partial to this attribute where it will be called with the remaining arguments. See the packages/typescript/test/ts_project/swc directory for an example.
When a custom transpiler is used, then the ts_project macro expands to these targets:
[name]- the default target is ajs_librarywhich can be included in thedepsof downstream rules. Note that it will successfully build even if there are typecheck failures because thetscbinary is not needed to produce the default outputs. This is considered a feature, as it allows you to have a faster development mode where type-checking is not on the critical path.[name]_typecheck- provides typings (.d.tsfiles) as the default output, therefore building this target always causes the typechecker to run.[name]_typecheck_test- abuild_testtarget which simply depends on the[name]_typechecktarget. This ensures that typechecking will be run underbazel testwith--build_tests_only.[name]_typings- internal target which runs the binary from thetscattribute- Any additional target(s) the custom transpiler rule/macro produces. Some rules produce one target per TypeScript input file.
By default, ts_project expects .js outputs to be written in the same action
that does the type-checking to produce .d.ts outputs.
This is the simplest configuration, however tsc is slower than alternatives.
It also means developers must wait for the type-checking in the developer loop.
In theory, Persistent Workers (via the supports_workers attribute) remedies the
slow compilation time, however it adds additional complexity because the worker process
can only see one set of dependencies, and so it cannot be shared between different
ts_project rules. That attribute is documented as experimental, and may never graduate
to a better support contract.
Defaults to None
ts_build_info_file
the user-specified value of tsBuildInfoFile from the tsconfig.
Helps Bazel to predict the path where the .tsbuildinfo output is written.
Defaults to None
tsc
Label of the TypeScript compiler binary to run.
For example, tsc = "@my_deps//typescript/bin:tsc"
Or you can pass a custom compiler binary instead.
One possible compiler is the Angular compiler, provided by the
@angular/compiler-cli package as the ngc binary, which can be set typically with
tsc = "@npm//@angular/compiler-cli/bin:ngc"
Note that you'll also need to pass .html and .css files to the srcs of the ts_project
so that they're declared as inputs for the Angular compiler to read them.
An example can be found in the rules_nodejs repo under packages/typescript/test/ts_project/ngc.
> To use the ngc program from Angular versions prior to 11, you'll need a fix for
> https://github.com/angular/angular/issues/36290
> To apply the fix, you can use the patch-package package to apply this patch:
> https://gist.github.com/alexeagle/ba44b2601bd7c953d29c6e8ec44d1ef9
Defaults to Label("@npm//typescript/bin:tsc")
typescript_package
Label of the package containing all data deps of tsc.
For example, typescript_package = "@my_deps//typescript"
Defaults to "@npm//typescript"
typescript_require_path
Module name which resolves to typescript_package when required
For example, typescript_require_path = "typescript"
Defaults to "typescript"
validate
boolean; whether to check that the tsconfig JSON settings match the attributes on this target.
Set this to False to skip running our validator, in case you have a legitimate reason for these to differ,
e.g. you have a setting enabled just for the editor but you want different behavior when Bazel runs tsc.
Defaults to True
supports_workers
Experimental! Use only with caution.
Allows you to enable the Bazel Persistent Workers strategy for this project. See https://docs.bazel.build/versions/main/persistent-workers.html
This requires that the tsc binary support a --watch option.
NOTE: this does not work on Windows yet. We will silently fallback to non-worker mode on Windows regardless of the value of this attribute. Follow https://github.com/bazelbuild/rules_nodejs/issues/2277 for progress on this feature.
Defaults to False
declaration_dir
a string specifying a subdirectory under the bazel-out folder where generated declaration outputs are written. Equivalent to the TypeScript --declarationDir option. By default declarations are written to the out_dir.
Defaults to None
out_dir
a string specifying a subdirectory under the bazel-out folder where outputs are written. Equivalent to the TypeScript --outDir option. Note that Bazel always requires outputs be written under a subdirectory matching the input package, so if your rule appears in path/to/my/package/BUILD.bazel and out_dir = "foo" then the .js files will appear in bazel-out/[arch]/bin/path/to/my/package/foo/*.js. By default the out_dir is '.', meaning the packages folder in bazel-out.
Defaults to None
root_dir
a string specifying a subdirectory under the input package which should be consider the root directory of all the input files. Equivalent to the TypeScript --rootDir option. By default it is '.', meaning the source directory where the BUILD file lives.
Defaults to None
link_workspace_root
Link the workspace root to the bin_dir to support absolute requires like 'my_wksp/path/to/file'. If source files need to be required then they can be copied to the bin_dir with copy_to_bin.
Defaults to False
kwargs
passed through to underlying rule, allows eg. visibility, tags