Initial implementation of the nextcloud cronjob docker image

Dockerfile

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+FROM alpine
+
+RUN apk add --no-cache docker bash
+
+ENV NEXTCLOUD_CONTAINER_NAME=
+ENV NEXTCLOUD_PROJECT_NAME=
+ENV NEXTCLOUD_CRON_MINUTE_INTERVAL=15
+
+COPY scripts/*.sh /
+
+ENTRYPOINT ["/entrypoint.sh"]
+
+HEALTHCHECK --timeout=5s \
+    CMD ["/healthcheck.sh"]

scripts/cron-tasks.sh

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+#!/usr/bin/env bash
+set -ex
+
+containerName="$1"
+docker exec "$containerName" php -f /var/www/html/cron.php

scripts/entrypoint.sh

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+#!/usr/bin/env bash
+set -ex
+
+if [[ -z "$NEXTCLOUD_CONTAINER_NAME" ]]; then
+    echo "NEXTCLOUD_CONTAINER_NAME is a required variable"
+    exit 1
+fi
+
+if [[ ! -z "$NEXTCLOUD_PROJECT_NAME" ]]; then
+    containerName="${NEXTCLOUD_PROJECT_NAME}_"
+else
+    matchEnd=","
+fi
+
+containerName="${containerName}${NEXTCLOUD_CONTAINER_NAME}"
+
+# Get the ID of the container so we can exec something in it later
+export containerId=$(/find-container.sh "$containerName" "$matchEnd")
+
+if [[ -z "$containerId" ]]; then
+    echo "ERROR: Unable to find the Nextcloud container"
+    exit 1
+fi
+
+echo "$containerId" > /tmp/containerId
+
+echo "*/$NEXTCLOUD_CRON_MINUTE_INTERVAL * * * * /cron-tasks.sh $containerId" \
+    > /var/spool/cron/crontabs/root
+
+exec crond -f -l 0 -L /dev/stdout

scripts/find-container.sh

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+#!/usr/bin/env bash
+set -e
+
+containerName="$1"
+matchEnd="$2"
+
+docker ps --format '{{.Names}},{{.ID}}' | \
+    egrep "^${containerName}${matchEnd}" | \
+    awk '{split($0,a,","); print a[2]}'

scripts/healthcheck.sh

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+#!/usr/bin/env bash
+set -x
+
+# Make sure cron daemon is still running
+ps -o comm | grep crond || exit 1
+
+# Make sure the target container is still running/available
+docker inspect -f '{{.State.Running}}' "$(cat /tmp/containerId)" | grep true || exit 1