direnvをインストールする

$ brew install direnv

Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> New Formulae
gptfdisk                                 pijul
==> Updated Formulae
abcde                      grpc                       puzzles
angle-grinder              gtk-vnc                    quicktype
angular-cli                gutenberg                  rabbitmq
awscli                     harfbuzz                   redis
cargo-completion           hashcat                    ripgrep
cassandra                  kerl                       rust
chronograf                 knot-resolver              sceptre
composer                   kotlin                     shfmt
cryptol                    libpst                     shibboleth-sp
csvprintf                  libxkbcommon               skaffold
cython                     liquigraph                 snakemake
dartsim                    logtalk                    taskell
dbus                       macvim                     teleport
dcos-cli                   mariadb@10.0               tmux-xpanes
django-completion          mercurial                  todolist
dxpy                       mkdocs                     tox
emscripten                 node                       trafficserver
erlang@20                  node-build                 uhd
faas-cli                   ocrmypdf                   vcftools
firebase-cli               openshift-cli              webpack
flow                       paket                      wireguard-tools
fluent-bit                 passenger                  wxmac
gammaray                   percona-server-mongodb     xml-security-c
git-lfs                    phpunit                    xtensor
go-jira                    pilosa                     yarn
go-statik                  presto                     youtube-dl
goenv                      proselint                  zebra

Error: Could not link:
/usr/local/share/man/man1/brew.1

Please delete these paths and run `brew update`.
Error: Could not link:
/usr/local/share/doc/homebrew

Please delete these paths and run `brew update`.
==> Downloading https://homebrew.bintray.com/bottles/direnv-2.17.0.sierra.bottle
######################################################################## 100.0%
==> Pouring direnv-2.17.0.sierra.bottle.tar.gz
🍺  /usr/local/Cellar/direnv/2.17.0: 9 files, 5.4MB

.bashrcをエディタで開く

open ~/.bashrc

以下を追記する

eval "$(direnv hook bash)"

.envrcに環境変数を設定する

.envrc

export APIKEY=<APIKEY>
export AUTHDOMAIN=<AUTHDOMAIN>
export DATABASEURL=<DATABASEURL>
export PROJECTID=<PROJECTID>
export STORAGEBUCKET=<STORAGEBUCKET>
export MESSAGINGSENDERID=<MESSAGINGSENDERID>

direnv: loading .envrc
direnv: export +APIKEY +AUTHDOMAIN +DATABASEURL +MESSAGINGSENDERID +PROJECTID +STORAGEBUCKET

direnv: unloading

direnv: error .envrc is blocked. Run `direnv allow` to approve its content.

$ direnv allow