build: add bash script to handle migrations at startup

src/backend/migrate-entrypoint.sh

@@ -2,35 +2,206 @@
 
 set -eo pipefail
 
-while !</dev/tcp/${FMTM_DB_HOST:-fmtm-db}/5432;
-do
-    sleep 1;
-done;
-
-# Check all vars present
-if [ -z "${FMTM_DB_HOST}" ]; then
-    echo "Environment variable FMTM_DB_HOST is not set."
-    exit 1
-fi
-if [ -z "${FMTM_DB_USER}" ]; then
-    echo "Environment variable FMTM_DB_USER is not set."
-    exit 1
-fi
-if [ -z "${FMTM_DB_PASSWORD}" ]; then
-    echo "Environment variable FMTM_DB_PASSWORD is not set."
-    exit 1
-fi
-if [ -z "${FMTM_DB_NAME}" ]; then
-    echo "Environment variable FMTM_DB_NAME is not set."
-    exit 1
+### Functions START ###
+
+pretty_echo() {
+    local message="$1"
+    local length=${#message}
+    local separator=""
+
+    for ((i=0; i<length+4; i++)); do
+        separator="$separator-"
+    done
+
+    echo ""
+    echo "$separator"
+    echo "$message"
+    echo "$separator"
+    echo ""
+}
+
+check_all_db_vars_present() {
+    if [ -z "${FMTM_DB_HOST}" ]; then
+        echo "Environment variable FMTM_DB_HOST is not set."
+        exit 1
+    fi
+    if [ -z "${FMTM_DB_USER}" ]; then
+        echo "Environment variable FMTM_DB_USER is not set."
+        exit 1
+    fi
+    if [ -z "${FMTM_DB_PASSWORD}" ]; then
+        echo "Environment variable FMTM_DB_PASSWORD is not set."
+        exit 1
+    fi
+    if [ -z "${FMTM_DB_NAME}" ]; then
+        echo "Environment variable FMTM_DB_NAME is not set."
+        exit 1
+    fi
+}
+
+wait_for_db() {
+    max_retries=30
+    retry_interval=5
+
+    for ((i = 0; i < max_retries; i++)); do
+        if </dev/tcp/${FMTM_DB_HOST:-fmtm-db}/5432; then
+            echo "Database is available."
+            return 0  # Database is available, exit successfully
+        fi
+        echo "Database is not yet available. Retrying in ${retry_interval} seconds..."
+        sleep ${retry_interval}
+    done
+
+    echo "Timed out waiting for the database to become available."
+    exit 1  # Exit with an error code
+}
+
+create_db_schema_if_missing() {
+    table_count=$(psql -t "$db_url" -c "
+        SELECT COUNT(*) FROM information_schema.tables
+        WHERE table_schema NOT IN ('pg_catalog', 'information_schema');
+    ")
+
+    if [ "$table_count" -gt 0 ]; then
+        echo "Data exists in the database. Skipping schema creation."
+        return 0
+    else
+        echo "No data found in the database. Creating schema."
+        psql "$db_url" -f "/opt/migrations/init/fmtm_base_schema.sql"
+        echo "Schema created successfully."
+        return 1
+    fi
+}
+
+create_migrations_table_if_missing() {
+    echo "Creating _migrations table if not exists."
+    psql "$db_url" <<SQL
+    DO \$\$
+    BEGIN
+        CREATE TABLE public."_migrations" (
+            script_name TEXT,
+            date_executed TIMESTAMP,
+            CONSTRAINT "_migrations_pkey" PRIMARY KEY (script_name)
+        );
+        ALTER TABLE IF EXISTS public."_migrations" OWNER TO fmtm;
+        RAISE NOTICE 'Table "_migrations" successfully added to database.';
+    EXCEPTION
+        WHEN OTHERS THEN
+            RAISE NOTICE 'Table "migrations" already exists. Skipping...';    
+    END\$\$;
+SQL
+}
+
+check_if_missing_migrations() {
+    # Get the list of existing migration script names from the migrations table
+    existing_scripts=$(psql -t "$db_url" -c "
+        SELECT script_name FROM public.\"_migrations\" ORDER BY date_executed ASC;
+    ")
+    echo "Existing migrations: ${existing_scripts}"
+
+    # Iterate through files under /opt/migrations
+    for script_file in /opt/migrations/*.sql; do
+        # Extract the script name from the file path
+        script_name=$(basename "$script_file")
+
+        # Check if the script_name is in the list of existing scripts
+        if ! echo "$existing_scripts" | grep -q "$script_name"; then
+            echo "Migration script '$script_name' needs to be executed. Adding to list."
+            scripts_to_execute+=("$script_name")
+        fi
+    done
+}
+
+backup_db() {
+    echo "Backing up database, prior to migrations."
+    db_backup_file="$HOME/fmtm_pre_migrate_$(date +'%Y%m%d%H%M%S').dump"
+
+    echo "Running VACUUM ANALYZE on the database."
+    PGPASSWORD="$FMTM_DB_PASSWORD" psql --host "$FMTM_DB_HOST" \
+        --username "$FMTM_DB_USER" "$FMTM_DB_NAME" -c "VACUUM ANALYZE;"
+
+    pretty_echo "Dumping current database to backup file."
+    PGPASSWORD="$FMTM_DB_PASSWORD" pg_dump --verbose --format c \
+        --file "${db_backup_file}" \
+        --host "$FMTM_DB_HOST" --username "$FMTM_DB_USER" "$FMTM_DB_NAME"
+
+    gzip "$db_backup_file"
+    pretty_echo "Backup complete: $db_backup_file.gz"
+}
+
+execute_migrations() {
+    for script_name in "${scripts_to_execute[@]}"; do
+        script_file="/opt/migrations/$script_name"
+        pretty_echo "Executing migration: $script_name"
+        psql "$db_url" -a -f "$script_file"
+
+        # Add an entry in the migrations table to indicate completion
+        psql "$db_url" <<SQL
+    DO \$\$
+    BEGIN
+        INSERT INTO public."_migrations" (date_executed, script_name)
+        VALUES (NOW(), '$script_name');
+    EXCEPTION
+        WHEN OTHERS THEN
+            RAISE NOTICE 'Failed to add migration to database: $script_name';
+    END\$\$;
+SQL
+    done
+}
+
+create_svc_user() {
+    pretty_echo "Creating default svcfmtm user."
+    psql "$db_url" <<SQL
+    DO \$\$
+    BEGIN
+        INSERT INTO users (id, username, role, mapping_level, tasks_mapped, tasks_validated, tasks_invalidated)
+        VALUES (20386219, 'svcfmtm', 'MAPPER', 'BEGINNER', 0, 0, 0);
+        RAISE NOTICE 'User "svcfmtm" (uid 20386219) successfully created.';
+    EXCEPTION   
+        WHEN OTHERS THEN
+            RAISE NOTICE 'User "svcfmtm" (uid 20386219) already exists.';
+    END\$\$;
+SQL
+}
+### Functions END ###
+
+
+
+####################
+### Script START ###
+####################
+
+pretty_echo "### Script Start ###"
+
+# Var: array of migration files to run
+scripts_to_execute=()
+
+# DB startup
+check_all_db_vars_present
+wait_for_db
+db_url="postgresql://${FMTM_DB_USER}:${FMTM_DB_PASSWORD}@${FMTM_DB_HOST}/${FMTM_DB_NAME}"
+
+# Apply schema, if needed
+create_db_schema_if_missing
+create_migrations_table_if_missing
+
+# Run migrations, if needed
+check_if_missing_migrations
+if [ ${#scripts_to_execute[@]} -gt 0 ]; then
+    backup_db
+    execute_migrations
+else
+    pretty_echo "No new migrations found."
 fi
+pretty_echo "Migrations complete."
+
+# Create service user account, if not exists
+create_svc_user
+
+pretty_echo "### Script End ###"
 
-echo "Crerating default svcfmtm user"
-# Create default svc user
-psql "postgresql://${FMTM_DB_USER}:${FMTM_DB_PASSWORD}@${FMTM_DB_HOST}/${FMTM_DB_NAME}" \
-    -c "INSERT INTO users (id, username, role, mapping_level, tasks_mapped, tasks_validated, tasks_invalidated) \
-        VALUES (20386219, 'svcfmtm', 'MAPPER', 'BEGINNER', 0, 0, 0) \
-        ON CONFLICT (id) DO NOTHING;"
-echo "User creation complete"
+####################
+###  Script END  ###
+####################
 
 exec "$@"