Simple PostgreSQL Backup Agent

Dockerized cron job to backup PostgreSQL database or multiple databases on different hosts. It’s based on Alpine docker image, so the image size is less than 11 Mb. The script can be also used without docker and docker compose or as a base for your own dockerized cron jobs. My general recommendation is to run docker container on your backup host to provide a kind of isolation from the management partition.

The script or “agent” does the following:

  • Reads content of /config/passfile to get pg_dump connection parameters
  • Verifies if the backup can be done by executing a dry run for each db
  • If the dry run is completed and plain format set, produces plain-text sql script and compresses it with gzip
  • If the dry run succeeds and custom format set, outputs a custom backup archive (more flexible and by default)
  • Cleans up the storage folder. Files older than 30 days are deleted
  • Redirects all cron job statuses to stdout
  • Keeps backup files under ./psql/backups/{hostname}/{dbname}/ on your host
  • Default settings: twice a day at 8:30 and 20:30 UTC; custom format; clean backups older than 30 days

Current limitations:

  • no encryption for specific databases (in to-do list)
  • no handling of wildcars in passfile (in to-do list)


  • Dockerfile – describes docker image
  • docker-compose.yml – docker compose file to build and run agent service
  • /config/cronfile – cron job schedule settings
  • /config/passfile – PostgreSQL .pgpass actually
  • /config/ – the script itself

Usage guide

  • check out the passfile and provide your own connection parameters
  • verify the cron job settings in the /config/cronfile
  • change make_backup function argument to set format output (plain/custom)
  • update cleaner function argument at the bottom of the script if necessary
  • edit dockerfile/docker-compose.yml or script itself if necessary
  • run docker compose build
  • run docker compose up -d
  • check out the stoud of the container to get the job’s status
  • TO RESTORE: use psql (if plain set) or pg_restore command (if custom format set)


FROM alpine:3.16.2
LABEL AUTHOR="Roman Levchenko"
RUN mkdir /etc/periodic/custom \
    && mkdir -p /backup/config \ 
    && touch /var/log/cron.log \
    && apk --no-cache add \
    postgresql14-client=14.5-r0 \
COPY /config/cronfile /etc/crontabs/root
COPY /config/ /etc/periodic/custom/backup
COPY ["/config/","/config/passfile","/backup/config/"]
RUN chmod 755 /etc/periodic/custom/backup \
    && chmod 0600 /backup/config/passfile
CMD ["-f","-l","8", "-L", "/dev/stdout"]
ENTRYPOINT ["crond"]

Script (excerpt)

# Clean old backup files
function cleaner()
set -o pipefail -e
	if [[ -n $(find $BACKUP_DIR \( -name "*.sql.gz" -o -name "*.custom" \) -type f -mtime +"$1") ]]; 
		echo -e "\n${GREEN}[INFO]${OFF} ${BOLD}There are backup files older than $1 days. Cleaning up the following files:${OFF}"
		find $BACKUP_DIR \(-name "*.sql.gz" -o -name "*.custom" \) -print -type f -mtime +"$1" -exec rm {} \;
		echo -e "\n${GREEN}[INFO]${OFF} ${BOLD}There are no backup files older than $1 days. \nHave a nice day!${OFF}"
set +o pipefail +e


Sample Output (w/error and success messages):

Application Gateway: Incorrect certificate chain or order

SSL management is always a pain. We should check SSL certificates periodically or implement a solution that carries all management tasks for us (let’s encrypt and cert-manager, for instance). And if there is an issue with a certificate, it’s a always a subject of downtime, so we have to find a solution as quickly as possible. Furthermore, all websites should meet requirements to complete tests and get a “green” mark from mozilla observatory or ssl shopper checker, for example. In this post, we’ll discuss possible issues you may face during the ssl check: “incorrect certificate chain” or “incorrect order. contains anchor”

Please note that my setup includes azure application gateway and azure kubernetes service. The following steps are general, however, may require using different certificate formats or signature algorithms. Check your environment’s requirements beforehand.

  • In my case, it was a wrong intermediate certificate provided by GoDaddy. So, I went to the godaddy site, clicked on certificate and copied intermediate certificate to cer file intermediate.cer > Intermediate certificate
  • Make sure you have openssl on your computer and create a new pfx that contains a certificate, private key and intermediate certificate:
    openssl pkcs12 -export -out appgw-cert.pfx -inkey .\pk.key -in .\ssl.crt -certfile .\intermediate.cer
  • If you have an old pfx with a valid certificate and key, do these commands:
    openssl pkcs12 -in old.pfx -nocerts -nodes -out pk.key
    openssl pkcs12 -in old.pfx -clcerts -nokeys -out cert.crt
    openssl pkcs12 -export -out new.pfx -inkey .\pk.key -in .\cert.crt -certfile .\intermediate.cer
  • Type password for the pfx, and then update azure application gateway if needed:
    $appGW = Get-AzApplicationGateway -Name "ApplicationGatewayName"ResourceGroupName "ResourceGroupName"
    $password = ConvertTo-SecureString $passwordPlainString -AsPlainText -Force
    $cert = Set-AzApplicationGatewaySslCertificate -ApplicationGateway $AppGW -Name "CertName" -CertificateFile "D:\certname.pfx" -Password $password
  • Also, export pfx certificate to your personal certificate store and make sure that the correct chain is used or use for already updated certificate. and certificate chain
  • ..and finally my certificate is “green” and overall rating
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