diff --git a/.gitignore b/.gitignore
index 4a86daa..e1dbcd6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,93 +1,96 @@
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]
 *$py.class
 
 # C extensions
 *.so
 
 # Distribution / packaging
 .Python
 env/
 build/
 develop-eggs/
 dist/
 downloads/
 eggs/
 .eggs/
 lib/
 lib64/
 parts/
 sdist/
 var/
 *.egg-info/
 .installed.cfg
 *.egg
 
 # PyInstaller
 #  Usually these files are written by a python script from a template
 #  before PyInstaller builds the exe, so as to inject date/other infos into it.
 *.manifest
 *.spec
 
 # Installer logs
 pip-log.txt
 pip-delete-this-directory.txt
 sentry_install_log*.txt
 
 # Unit test / coverage reports
 htmlcov/
 .tox/
 .coverage
 .coverage.*
 .cache
 nosetests.xml
 coverage.xml
 *.cover
 .hypothesis/
 
 # Translations
 *.mo
 *.pot
 
 # Django stuff:
 *.log
 local_settings.py
 
 # Sphinx documentation
 docs/_build/
 
 # PyBuilder
 target/
 
 # Ipython Notebook
 .ipynb_checkpoints
 
 # pyenv
 .python-version
 
 # https://docs.docker.com/compose/extends/
 docker-compose.override.yml
 
+# https://docs.docker.com/compose/environment-variables/#using-the---env-file--option
+.env.custom
+
 *.tar
 data/
 .vscode/tags
 
 # custom Sentry config
 sentry/sentry.conf.py
 sentry/config.yml
 sentry/*.bak
 sentry/requirements.txt
 relay/credentials.json
 relay/config.yml
 symbolicator/config.yml
 geoip/GeoIP.conf
 geoip/*.mmdb
 geoip/.geoipupdate.lock
 
 # wal2json download
 postgres/wal2json
 
 # integration testing
 _integration-test/custom-ca-roots/nginx/*
 sentry/test-custom-ca-roots.py
diff --git a/README.md b/README.md
index 5c93853..7265016 100644
--- a/README.md
+++ b/README.md
@@ -1,50 +1,60 @@
 # Self-Hosted Sentry nightly
 
 Official bootstrap for running your own [Sentry](https://sentry.io/) with [Docker](https://www.docker.com/).
 
 ## Requirements
 
 * Docker 19.03.6+
 * Compose 1.28.0+
 * 4 CPU Cores
 * 8 GB RAM
 * 20 GB Free Disk Space
 
 ## Setup
 
+### Customize DotEnv (.env) file
+
+Environment specific configurations can be done in the `.env.custom` file. It will be located in the root directory of the Sentry installation.
+
+By default, there exists no `.env.custom` file. In this case, you can manually add this file by copying the `.env` file to a new `.env.custom` file and adjust your settings in the `.env.custom` file.
+
+Please keep in mind to check the `.env` file for changes, when you perform an upgrade of Sentry, so that you can adjust your `.env.custom` accordingly, if required.
+
+### Installation
+
 To get started with all the defaults, simply clone the repo and run `./install.sh` in your local check-out. Sentry uses Python 3 by default since December 4th, 2020 and Sentry 21.1.0 is the last version to support Python 2.
 
 During the install, a prompt will ask if you want to create a user account. If you require that the install not be blocked by the prompt, run `./install.sh --no-user-prompt`.
 
 Please visit [our documentation](https://develop.sentry.dev/self-hosted/) for everything else.
 
 ## Tips & Tricks
 
 ### Event Retention
 
 Sentry comes with a cleanup cron job that prunes events older than `90 days` by default. If you want to change that, you can change the `SENTRY_EVENT_RETENTION_DAYS` environment variable in `.env` or simply override it in your environment. If you do not want the cleanup cron, you can remove the `sentry-cleanup` service from the `docker-compose.yml`file.
 
 ### Installing a specific SHA
 
 If you want to install a specific release of Sentry, use the tags/releases on this repo.
 
 We continously push the Docker image for each commit made into [Sentry](https://github.com/getsentry/sentry), and other services such as [Snuba](https://github.com/getsentry/snuba) or [Symbolicator](https://github.com/getsentry/symbolicator) to [our Docker Hub](https://hub.docker.com/u/getsentry) and tag the latest version on master as `:nightly`. This is also usually what we have on sentry.io and what the install script uses. You can use a custom Sentry image, such as a modified version that you have built on your own, or simply a specific commit hash by setting the `SENTRY_IMAGE` environment variable to that image name before running `./install.sh`:
 
 ```shell
 SENTRY_IMAGE=getsentry/sentry:83b1380 ./install.sh
 ```
 
 Note that this may not work for all commit SHAs as this repository evolves with Sentry and its satellite projects. It is highly recommended to check out a version of this repository that is close to the timestamp of the Sentry commit you are installing.
 
 ### Using Linux
 
 If you are using Linux and you need to use `sudo` when running `./install.sh`, make sure to place the environment variable *after* `sudo`:
 
 ```shell
 sudo SENTRY_IMAGE=us.gcr.io/sentryio/sentry:83b1380 ./install.sh
 ```
 
 Where you replace `83b1380` with the sha you want to use.
 
 [build-status-image]: https://github.com/getsentry/onpremise/workflows/test/badge.svg
 [build-status-url]: https://git.io/JUYkh
diff --git a/install/_lib.sh b/install/_lib.sh
index 06bfcbb..a957e96 100644
--- a/install/_lib.sh
+++ b/install/_lib.sh
@@ -1,50 +1,55 @@
 set -euo pipefail
 test "${DEBUG:-}" && set -x
 
 # Thanks to https://unix.stackexchange.com/a/145654/108960
 log_file="sentry_install_log-`date +'%Y-%m-%d_%H-%M-%S'`.txt"
 exec &> >(tee -a "$log_file")
 
 # Work from /install/ for install.sh, project root otherwise
 if [[ "$(basename $0)" = "install.sh"  ]]; then
   cd "$(dirname $0)/install/"
 else
   cd "$(dirname $0)"  # assume we're a test script or some such
 fi
 
-_ENV="$(realpath ../.env)"
+# Allow `.env` overrides using the `.env.custom` file
+if [[ -f "../.env.custom" ]]; then
+  _ENV="$(realpath ../.env.custom)"
+else
+  _ENV="$(realpath ../.env)"
+fi
 
 # Read .env for default values with a tip o' the hat to https://stackoverflow.com/a/59831605/90297
 t=$(mktemp) && export -p > "$t" && set -a && . $_ENV && set +a && . "$t" && rm "$t" && unset t
 
 if [ "${GITHUB_ACTIONS:-}" = "true" ]; then
   _group="::group::"
   _endgroup="::endgroup::"
 else
   _group="▶ "
   _endgroup=""
 fi
 
 dc_base="$(docker compose version &> /dev/null && echo 'docker compose' || echo 'docker-compose')"
-dc="$dc_base --ansi never"
+dc="$dc_base --ansi never --env-file ${_ENV}"
 dcr="$dc run --rm"
 
 # A couple of the config files are referenced from other subscripts, so they
 # get vars, while multiple subscripts call ensure_file_from_example.
 function ensure_file_from_example {
   if [[ -f "$1" ]]; then
     echo "$1 already exists, skipped creation."
   else
     echo "Creating $1..."
     cp -n $(echo "$1" | sed 's/\.[^.]*$/.example&/') "$1"
     # sed from https://stackoverflow.com/a/25123013/90297
   fi
 }
 SENTRY_CONFIG_PY='../sentry/sentry.conf.py'
 SENTRY_CONFIG_YML='../sentry/config.yml'
 
 # Increase the default 10 second SIGTERM timeout
 # to ensure celery queues are properly drained
 # between upgrades as task signatures may change across
 # versions
 STOP_TIMEOUT=60 # seconds
diff --git a/install/wrap-up.sh b/install/wrap-up.sh
index 6f1128b..91638ca 100644
--- a/install/wrap-up.sh
+++ b/install/wrap-up.sh
@@ -1,26 +1,30 @@
 if [[ "$MINIMIZE_DOWNTIME" ]]; then
   echo "${_group}Waiting for Sentry to start ..."
 
   # Start the whole setup, except nginx and relay.
   $dc up -d --remove-orphans $($dc config --services | grep -v -E '^(nginx|relay)$')
   $dc restart relay
   $dc exec -T nginx nginx -s reload
 
   docker run --rm --network="${COMPOSE_PROJECT_NAME}_default" alpine ash \
     -c 'while [[ "$(wget -T 1 -q -O- http://web:9000/_health/)" != "ok" ]]; do sleep 0.5; done'
 
   # Make sure everything is up. This should only touch relay and nginx
   $dc up -d
 
   echo "${_endgroup}"
 else
   echo ""
   echo "-----------------------------------------------------------------"
   echo ""
   echo "You're all done! Run the following command to get Sentry running:"
   echo ""
+  if [[ "${_ENV}" =~ ".env.custom" ]]; then
+  echo "  $dc_base --env-file ${_ENV} up -d"
+  else
   echo "  $dc_base up -d"
+  fi
   echo ""
   echo "-----------------------------------------------------------------"
   echo ""
 fi