CODEWITHSUNDEEP
bashdocker
vivekyad4v
vivekyad4v

Reputation: 14843

How do I kill the container process (PID 1) from inside the container using bash/sh shell

I have a scenario where I have a shell script which is run using crond. I need to exit the container if that particular script fails. Seems like SIGKILL doesn't work with PID 1.

How do I kill the container process (PID 1) from inside the container using bash/sh shell?

Minimal example -

Dockerfile -

FROM alpine:3.5

ENV LOGS_DIR="/rest/logs/" CRON_LOG_FILE="${LOGS_DIR}/cron.log"

RUN apk add --update python py-pip zip bash && \
    pip install awscli && \
    mkdir -p ${LOGS_DIR} && \
    touch ${CRON_LOG_FILE}

COPY ./lr-s3.sh ./lr-entry.sh ./install_crontab.txt ./files_to_rotate.txt ./

RUN chmod +x /lr-s3.sh /lr-entry.sh && \
    crontab install_crontab.txt

ENTRYPOINT ["/lr-entry.sh"]

Entrypoint - 

#!/bin/bash

LOGS_DIR="${LOGS_DIR:-/rest/logs}"
CRON_LOG_FILE="${LOGS_DIR}/cron.log"

mkdir -p ${LOGS_DIR}
touch ${CRON_LOG_FILE}

ln -sf /proc/1/fd/1 ${CRON_LOG_FILE}

echo "Cron [Starting]"
exec crond -c /var/spool/cron/crontabs -f -L ${CRON_LOG_FILE} "$@"

Script to run via Cron - 

aws s3 cp ${LOGS_DIR}/${FL_NAME} s3://${BKTNAME}/${FL_NAME}

if [ "$?" -ne "0" ]; then
    echo "S3 Backup Failed"
    pkill crond
    exit 1
fi

pkill crond doesn't work inside the script, it has PID 1.

If container restarts or doesn't exist, we will come to know that there is an issue with the container or the script.

Upvotes: 5

Views: 10440

Answers (1)

Artemij Rodionov
Artemij Rodionov

Reputation: 1826

How do I kill the container process (PID 1) from inside the container using bash/sh shell?

PID 1 is protected, so you can't kill it, but you can setup a signal handler for it:

 # somewhere in entrypoint
 trap "exit" SIGINT SIGTERM

after that, the process will exit if you sent a kill -s SIGINT 1 from another process inside the container.

Upvotes: 6

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