Ping DB instead of trying migration

Dockerfile

@@ -1,7 +1,7 @@
 FROM python:3.9-alpine3.12
 
 #Install all dependencies.
-RUN apk add --no-cache postgresql-libs gettext zlib libjpeg libwebp libxml2-dev libxslt-dev py-cryptography
+RUN apk add --no-cache postgresql-libs postgresql-client gettext zlib libjpeg libwebp libxml2-dev libxslt-dev py-cryptography
 
 #Print all logs without buffering it.
 ENV PYTHONUNBUFFERED 1

boot.sh

@@ -1,28 +1,28 @@
 #!/bin/sh
 source venv/bin/activate
 
-echo "Migrating database"
+echo "Waiting for database to be ready..."
 
 attempt=0
 max_attempts=20
-while python manage.py migrate; \
-      status=$?; \
-      attempt=$((attempt+1)); \
-      [ $status -eq 1 ] \
-   && [ $attempt -le $max_attempts ]; do
-    echo -e "\n!!! Migration failed (error ${status}, attempt ${attempt}/${max_attempts})."
-    echo "!!! Database may not be ready yet or system is misconfigured."
-    echo -e "!!! Retrying in 5 seconds...\n"
+while pg_isready --host=${POSTGRES_HOST} -q; status=$?; attempt=$((attempt+1)); [ $status -ne 0 ] && [ $attempt -le $max_attempts ]; do
     sleep 5
 done
 
 if [ $attempt -gt $max_attempts ]; then
-    echo -e "\n!!! Migration failed. Maximum attempts exceeded."
-    echo "!!! Please check logs above - misconfiguration is very likely."
-    echo "!!! Shutting down container."
+    echo -e "\nDatabase not reachable. Maximum attempts exceeded."
+    echo "Please check logs above - misconfiguration is very likely."
+    echo "Make sure the DB container is up and POSTGRES_HOST is set properly."
+    echo "Shutting down container."
     exit 1 # exit with error to make the container stop
 fi
 
+echo "Database is ready"
+
+echo "Migrating database"
+
+python manage.py migrate
+
 echo "Generating static files"
 
 python manage.py collectstatic_js_reverse