docker: factor out cron stuff into schedule.sh

It can be easily reused that way.

1 files changed, 60 insertions, 0 deletions

diff --git a/docker/schedule.sh b/docker/schedule.sh
new file mode 100755
index 0000000..0f3fa20
--- /dev/null
+++ b/docker/schedule.sh
@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+# Copyright (c) 2021 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cgitize" project.
+# For details, see https://github.com/egor-tensin/cgitize.
+# Distributed under the MIT License.
+
+set -o errexit -o nounset -o pipefail
+shopt -s inherit_errexit lastpipe
+
+schedule_to_cron() {
+    local schedule
+    for schedule; do
+        case "$schedule" in
+            15min)   echo '*/15 * * * *' ;;
+            hourly)  echo '0 * * * *'    ;;
+            daily)   echo '0 0 * * *'    ;;
+            weekly)  echo '0 0 * * 1'    ;;
+            monthly) echo '0 0 1 * *'    ;;
+            *)
+                echo "$schedule"
+                ;;
+        esac
+    done
+}
+
+make_task_script() {
+    echo "#!/bin/bash
+cd -- "$( pwd )" && $( printf -- ' %q' "$@" )"
+}
+
+setup_cron_task() {
+    local schedule
+    schedule="${SCHEDULE:-once}"
+
+    if [ "$schedule" = once ]; then
+        exec "$@"
+    fi
+
+    schedule="$( schedule_to_cron "$schedule" )"
+
+    make_task_script "$@" > /task.sh
+    chmod +x /task.sh
+
+    # Run the task once when the container is started, regardless of schedule.
+    /task.sh
+
+    local crontab
+    crontab="$schedule /task.sh
+# This is the new crontab."
+
+    echo "$crontab" | crontab -
+    exec crond -f
+}
+
+main() {
+    setup_cron_task "$@"
+}
+
+main "$@"