init-plain

Script to provide an entrypoint and helpers for the plain docker image series.

entrypoint.sh

The script is supposed to be specified as ENTRYPOINT for a given Docker Image. E.g. within qnib/alplain-init.

It will iterate over the executables within /opt/qnib/entry and either execute or source them.

#!/bin/bash
set -e

for x in $(find /opt/qnib/entry/ -type f -perm /u+x |sort);do
     echo "> execute entrypoint '${x}'"
     if [[ "$x" == *.env ]];then
         source ${x}
     else
         ./${x}
     fi
done

if [ "X${ENTRY_USER}" != "X" ];then
  exec su -s /bin/bash -c "$@" ${ENTRY_USER}
else
  exec "$@"
fi

Once this is done, the command defined with CMD will be executed and the process control is handed over - in case an $ENTRY_USER is specified under a user other then root.

/opt/qnib/entry

Share log-socket

The first script (00-) executed will search for a log-device of an underlying syslog server and create a symlink to /dev/log, so that the container can naturally use this socket.

$ cat /opt/qnib/entry/00-logging.sh
#!/bin/bash

if [ ! -z ${LOGNAME} ] && [ -S /shareddev/${LOGNAME}/log ];then
    ln -s /shareddev/${LOGNAME}/log /dev/log
    logger -s "Created container specific symlink to syslog container"
elif [ -S /shareddev/log ];then
    ln -s /shareddev/log /dev/log
    logger -s "Created symlink from syslog container"
fi

environment variables

In case environment variables should be sourced before the main process starts, the prefix .env should be used.

This exemplary script sources docker-secrets as environment variables.

$ cat /opt/qnib/entry/10-docker-secrets.env
#!/bin/bash

########
## Check for /run/secrets and expose them as ENV variables
mkdir -p /run/secrets/
if [ -d /run/secrets/ ];then
    for sec in $(ls /run/secrets/);do
        KEY=$(echo ${sec} |tr '[:lower:]' '[:upper:]' |sed -e 's/-/_/g')
        echo "[II] Set environment variable ${KEY} from '/run/secrets/${sec}'"
        declare "$KEY=$(cat /run/secrets/${sec})"
        export $KEY
    done
else
    echo "[II] No /run/secrets directory, skip step"
fi