# Kubeflow Pipelines Management Frontend

## Tools you need

You need `node v14` and `npm`.
Recommend installing `node` and `npm` using https://github.com/nvm-sh/nvm. After installing nvm,
you can install `node v14` by `nvm install 14`.

## Manage dev environment with npm

### First time

1. Clone this repo
2. Navigate to frontend folder: `cd $KFP_SRC/frontend`.
3. Install dependencies: `npm ci`.

`npm ci` makes sure your installed dependencies have the exact same version as others. (Usually, you just
need to run this once, but after others installed extra dependencies, you need to run `npm ci` again to
get package updates.)

### Package management

Run `npm install --save <package>` (or `npm i -S <package>` for short) to install runtime dependencies and save them to package.json.
Run `npm install --save-dev <package>` (or `npm i -D <package>` for short) to install dev dependencies and save them to package.json.

After adding a dependency, validate licenses are correctly added for all dependencies first by running `npm run gen-licenses`.

### Daily workflow

You will see a lot of `npm run xxx` commands in instructions below, the actual script being run is defined in the "scripts" field of [package.json](https://github.com/kubeflow/pipelines/blob/91db95a601fa7fffcb670cb744a5dcaeb08290ae/frontend/package.json#L32). Development common scripts are maintained in package.json, and we use npm to call them conveniently.

### npm next step

You can learn more about npm in https://docs.npmjs.com/about-npm/.

## Start frontend development server

You can then do `npm start` to run a webpack dev server at port 3000 that
watches the source files. It also redirects api requests to localhost:3001. For
example, requesting the pipelines page sends a fetch request to
http://localhost:3000/apis/v1beta1/pipelines, which is proxied by the
webserver to http://localhost:3001/apis/v1beta1/pipelines,
which should return the list of pipelines.

Follow the next section to start an api mock/proxy server to let localhost:3001
respond to api requests.

## Start api mock/proxy server

### Api mock server

This is the easiest way to start developing, but it does not support all apis during
development.

Run `npm run mock:api` to start a mock backend api server handler so it can
serve basic api calls with mock data.

If you want to port real MLMD store to be used for mock backend scenario, you can run the following command. Note that a mock MLMD store doesn't exist yet. 

```
kubectl port-forward svc/metadata-envoy-service 9090:9090
```

### Proxy to a real cluster

This requires you already have a real KFP cluster, you can proxy requests to it.

1. [Install Kubeflow Pipelines](https://www.kubeflow.org/docs/pipelines/installation/overview/) based on your use case and environment.
1. Configure `kubectl` with access to your KFP cluster. (For GCP, follow [Access to GCP cluster](https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-access-for-kubectl) guide).
1. Use the following table to determine which script to run.

| What to develop?                     | Script to run                                               | Extra notes                                                        |
| ------------------------------------ | ----------------------------------------------------------- | ------------------------------------------------------------------ |
| Client UI                            | `NAMESPACE=kubeflow npm run start:proxy`                    |                                                                    |
| Client UI + Node server              | `NAMESPACE=kubeflow npm run start:proxy-and-server`         | You need to rerun the script every time you edit node server code. |
| Client UI + Node server (debug mode) | `NAMESPACE=kubeflow npm run start:proxy-and-server-inspect` | Same as above, and you can use chrome to debug the server.         |

## Unit testing FAQ

There are a few typees of tests during presubmit:

* formatting, refer to [Code Style Section](#code-style)
* linting, you can also run locally with `npm run lint`
* client UI unit tests, you can run locally with `npm test`
* UI node server unit tests, you can run locally with `cd server && npm test`

There is a special type of unit test called [snapshot tests](https://jestjs.io/docs/en/snapshot-testing). When
snapshot tests are failing, you can update them automatically with `npm test -u` and run all tests. Then commit
the snapshot changes.

## Production Build

You can do `npm run build` to build the frontend code for production, which
creates a ./build directory with the minified bundle. You can test this bundle
using `server/server.js`. Note you need to have an API server running, which
you can then feed its address (host + port) as environment variables into
`server.js`. See the usage instructions in that file for more.

## Container Build

You can also do `npm run docker` if you have docker installed to build an
image containing the production bundle and the server pieces. In order to run
this image, you'll need to port forward 3000, and pass the environment
variables `ML_PIPELINE_SERVICE_HOST` and
`ML_PIPELINE_SERVICE_PORT` with the details of the API server.

## Code Style

We use [prettier](https://prettier.io/) for code formatting, our prettier config
is [here](https://github.com/kubeflow/pipelines/blob/master/frontend/.prettierrc.yaml).

To understand more what prettier is: [What is Prettier](https://prettier.io/docs/en/index.html).

### IDE Integration

* For vscode, install the plugin "Prettier - Code formatter" and it will pick
  this project's config automatically.
  Recommend setting the following in [settings.json](https://code.visualstudio.com/docs/getstarted/settings#_settings-file-locations) for vscode to autoformat on save.
  ```
  "[typescript]": {
    "editor.formatOnSave": true,
    "files.trimTrailingWhitespace": false,
  },
  "[typescriptreact]": {
    "editor.formatOnSave": true,
    "files.trimTrailingWhitespace": false,
  },
  ```
  Also, vscode builtin trailing whitespace [conflicts with jest inline snapshot](https://github.com/Microsoft/vscode/issues/52711), so recommend disabling it.
* For others, refer to https://prettier.io/docs/en/editors.html.

### Format Code Manually

Run `npm run format`.

### Escape hatch

If there's some code that you don't want being formatted by prettier, follow
guide [here](https://prettier.io/docs/en/ignore.html). (Most likely you don't need this.)

## Api client code generation

If you made any changes to protos (see backend/README), you'll need to
regenerate the Typescript client library from swagger. We use
swagger-codegen-cli@2.4.7, which you can get
[here](https://repo1.maven.org/maven2/io/swagger/swagger-codegen-cli/2.4.7/).
Make sure the jar file is somewhere on your path with the name
swagger-codegen-cli.jar, then run `npm run apis`.

After code generation, you should run `npm run format` to format the output and avoid creating a large PR.

## MLMD components

* `src/mlmd` - components for visualizing data from an `ml-metadata` store. For more information see the
 [google/ml-metadata](https://github.com/google/ml-metadata) repository.

This module previously lived in [kubeflow/frontend](https://github.com/kubeflow/frontend) repository. It contains tsx files for visualizing MLMD components.

MLMD protos lives in `pipelines/third_party/ml-metadata/ml_metadata/`, and the generated JS files live in `pipelines/frontend/src/third_party/mlmd`.

### Building generated metadata Protocol Buffers

* `build:protos` - for compiling Protocol Buffer definitions


This project contains a mix of natively defined classes and classes generated by the Protocol
Buffer Compiler from definitions in the [pipelines/third_party/ml-metadata/ml_metadata/](third_party/ml-metadata/ml_metadata/) directory. Copies of the generated classes are
included in the [pipelines/frontend/src/third_party/mlmd](frontend/src/third_party/mlmd) directory to allow the build process to succeed without a dependency on
the Protocol Buffer compiler, `protoc`, being in the system PATH.

If a file in [pipelines/third_party/ml-metadata/ml_metadata/proto](third_party/ml-metadata/ml_metadata/proto) is modified or you need to manually re-generate the protos, you'll need to:

* Add `protoc` ([download](https://github.com/protocolbuffers/protobuf/releases)) to your system
  PATH
* Add `protoc-gen-grpc-web` ([download](https://github.com/grpc/grpc-web/releases)) to your system
  PATH
* Replace `metadata_store.proto` and `metadata_store_service.proto` proto files with target mlmd version by running

  ```bash
  npm run build:replace -- {mlmd_versions}
  // example:
  // npm run build:replace -- 1.0.0
  ```

* Generate new protos by running

  ```bash
  npm run build:protos
  ```

The script run by `npm run build:replace` can be found at `scripts/replace_protos.js`.
The script run by `npm run build:protos` can be found at `scripts/gen_grpc_web_protos.js`.

The current TypeScript proto library was generated with `protoc-gen-grpc-web` version 1.2.1 with
`protoc` version 3.17.3.

The Protocol Buffers in [pipelines/third_party/ml-metadata/ml_metadata/proto](third_party/ml-metadata/ml_metadata/proto) are taken from the target version(v1.0.0 by default) of the `ml_metadata` proto
package from
[google/ml-metadata](https://github.com/google/ml-metadata/tree/master/ml_metadata/proto).


## Pipeline Spec (IR) API

For KFP v2, we use pipeline spec or IR(Intermediate Representation) to represent a Pipeline defintion. It is saved as json payload when transmitted. You can find the API in [api/v2alpha1/pipeline_spec.proto](api/v2alpha1/pipeline_spec.proto). To take the latest of this file and compile it to Typescript classes, follow the below step:

```
npm run build:pipeline-spec
```

See explaination it does below:


### Convert buffer to runtime object using protoc


Prerequisite: Add `protoc` ([download](https://github.com/protocolbuffers/protobuf/releases)) to your system PATH

Compile pipeline_spec.proto to Typed classes in TypeScript, 
so it can convert a payload stream to a PipelineSpec object during runtime.

You can check out the result like `pipeline_spec_pb.js`, `pipeline_spec_pb.d.ts` in [frontend/src/generated/pipeline_spec](/frontend/src/generated/pipeline_spec).

The plugin tool for convertion we currently use is [ts-proto](https://github.com/stephenh/ts-proto). We previously use 
[protobuf.js](https://github.com/protobufjs/protobuf.js) but it doesn't natively support Protobuf.Value processing. 

You can checkout the generated TypeScript interfaces in [frontend/src/generated/pipeline_spec/pipeline_spec.ts](/frontend/src/generated/pipeline_spec/pipeline_spec.ts) 

<!-- ARCHIVE: We switched to use ts-proto for now.
### Encode plain object to buffer using protobuf.js

protoc doesn't provide a way to convert plain object to
payload stream, therefore we need a helper tool `protobuf.js` to validate and encode plain object.

You can check out the result like `pbjs_ml_pipelines.js`, `pbjs_ml_pipelines.d.ts` in [frontend/src/generated/pipeline_spec](frontend/src/generated/pipeline_spec).
-->

## Large features development

To accommodate KFP v2 development, we create a `frontend feature flag` capability which hides features under development behind a flag. Only when developer explicitly enables these flags, they can see those features. To control the visiblity of these features, check out a webpage similar to pattern http://localhost:3000/#/frontend_features. 

To manage feature flags default values, visit [frontend/src/feature.ts](frontend/src/feature.ts) for `const features`. To apply the default feature flags locally in your browser, run `localStorage.setItem('flags', "")` in browser console.

## Storybook

For component driven UI development, KFP UI integrates with Storybook to develop v2 features. To run Storybook locally, run `npm run storybook` and visit `localhost:6006` in browser.
