diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..81eafdd
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,3 @@
+# Custom configs.
+DATA_DIR=./public_data
+#DATA_DIR=/var/www/html
diff --git a/.gitignore b/.gitignore
index d4b4ec5..e595f0a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,6 @@
 # Contents generated by the Python script.
 /public_data
+
+
+# Docker environment file.
+/.env
diff --git a/README.md b/README.md
index dae17f1..033f0fb 100644
--- a/README.md
+++ b/README.md
@@ -1,38 +1,51 @@
 # GTFS GTT Checker
 
 ## Usage with Docker Compose
 
-You can execute the one-shot command with:
+Install the default configuration file:
+
+```
+cp .env.example .env
+```
+
+Then you can execute the one-shot command with:
 
 ```
 docker compose up
 ```
 
 Look into the `public_data/` directory. It should contain these files:
 
 ```
 $ tree public_data
 
 public_data/
 ├── agency.txt.gz
 ├── calendar_dates.txt.gz
 ├── calendar.txt.gz
 ├── fare_attributes.txt.gz
 ├── fare_rules.txt.gz
 ├── feed_info.txt.gz
 ├── routes.txt.gz
 ├── shapes.txt.gz
 ├── stop_attributes.txt.gz
 ├── stops.txt.gz
 ├── stop_times.txt.gz
 ├── timetable_pages.txt.gz
 ├── timetable_stop_order.txt.gz
 ├── timetables.txt.gz
 ├── trips_booking.txt.gz
 ├── trips.txt.gz
 ├── vehicle_categories.txt.gz
 ├── vehicles.txt.gz
 └── versions.json
 ```
 
-The suggestion is to add the `docker compose up` in a crontab, every some minutes.
+To automatically update these files, run `docker compose up` from a crontab, every some minutes. Example:
+
+```
+$ sudo crontab -l
+
+# Run every 10 minutes
+*/10 * * * * cd /path/to/gtfs_gtt_checker && /usr/bin/docker compose up --no-color > /dev/null
+```
diff --git a/compose.yaml b/docker-compose.yaml
similarity index 55%
rename from compose.yaml
rename to docker-compose.yaml
index 2171ec4..43a0373 100644
--- a/compose.yaml
+++ b/docker-compose.yaml
@@ -1,6 +1,8 @@
+version: '3.3'
+
 services:
   gtfs-parser:
     build: .
     command: python parse_gtfs.py
     volumes:
-      - ./public_data:/app/public_data
+      - ${DATA_DIR:-./public_data}:/app/public_data