Now that babel is upgraded, upgrading webpack was pretty
straightforward.
- We take advantage of the new `mode` config option, and no longer need
to manually set up Uglify plugin
- Uglifyjs is back, I checked the prod build output: it's very ugly
- I updated the RemoveBuildDirectoryPlugin per instructions, and
verified it still works.
- I verified that of `yarn backend`, `yarn build`, and `yarn start` all
still work as expected.
Test Plan:
Run `mkdir /tmp/out; cd /tmp/out; python -m SimpleHTTPServer`. In
another shell, run `./scripts/build_static_site.sh --target /tmp/out`.
Then, `curl localhost:8000`. Before this commit, this would have yielded
an `OSError` because the cwd of the Python process had been removed.
As of this commit, it works fine.
Also, run `git grep -c rimraf` and note only `yarn.lock:15`.
wchargin-branch: webpack-empty-build-directory
Summary:
We were asking the `clean-webpack-plugin` to remove the `build/`
directory in all cases. However, Webpack accepts a command-line
parameter `--output-path`. When such a parameter is passed, we would be
removing the wrong directory.
The proper behavior is to remove “whatever the actual output path is”.
Webpack exposes this information, but it appears that the
`clean-webpack-plugin` does not take advantage of it. Therefore, this
commit includes a small Webpack plugin to do the right thing.
Test Plan:
Test that the behavior is correct when no output directory is specified:
```
mkdir -p build && touch build/wat && yarn build && ! [ -e build/wat ]
```
Test that the behavior is correct with an explicit `--output-path`:
```
outdir="$(mktemp -d)" && touch "${outdir}/wat" && \
yarn build --output-path "${outdir}" && \
! [ -e "${outdir}/wat" ]
```
Test that the plugin refuses to remove the root directory:
```
! yarn build --output-path . && \
sed -i '/path: /d' config/makeWebpackConfig.js && ! yarn build
```
(Feel free to comment out the actual `rimraf.sync` line in the plugin
when testing this.)
wchargin-branch: clean-actual-build-directory