Fix & improve PostgreSQL backup/restore scripts (#1571)

* Fix & imporve postgres backup/restore scripts

* Update PostgreSQL backup/restore docs

* Fix postgres Dockerfile regression

* Extend error messages in PostgreSQL maintenance scipts
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Nikita Shupeyko 2018-03-14 13:44:16 +03:00 committed by GitHub
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============================
Database Backups with Docker
============================
PostgreSQL Backups with Docker
==============================
The database has to be running to create/restore a backup. These examples show local examples. If you want to use it on a remote server, use ``-f production.yml`` instead.
Prerequisites:
Running Backups
================
#. the project was generated with ``use_docker`` set to ``y``.
Run the app with `docker-compose -f local.yml up`.
For brevity it is assumed that will be running the below commands against local environment, however, this is by no means mandatory so feel free switching to ``production.yml`` when needed.
Note that the application stack should not necessarily be running when applying any of the instructions below, unless explicitly stated otherwise. For instance, suppose the stack has been down for quite some time or have never even been up yet -- rather than starting it beforehand use a single ``$ docker-compose -f local.yml run --rm <command>`` with the desired command. By contrast, should you already have your application up and running do not bother waiting for ``run`` instruction to finish (they usually take a bit longer due to bootstrapping phase), just use ``$ docker-compose -f local.yml exec <command>`` instead; note that any ``exec`` command fails unless all of the required containers are running. From now on, we will be using ``run``-style examples for general-case compatibility.
Creating a Backup
-----------------
To create a backup, run::
docker-compose -f local.yml run --rm postgres backup
$ docker-compose -f local.yml run --rm postgres backup
Assuming your project's database is named ``my_project`` here is what you will see: ::
Backing up the 'my_project' database...
SUCCESS: 'my_project' database backup 'backup_2018_03_13T09_05_07.sql.gz' has been created and placed in '/backups'.
Keep in mind that ``/backups`` is the ``postgres`` container directory.
To list backups, run::
Viewing the Existing Backups
----------------------------
docker-compose -f local.yml run --rm postgres list-backups
To list existing backups, ::
$ docker-compose -f local.yml run --rm postgres backups
These are the sample contents of ``/backups``: ::
These are the backups you have got:
total 24K
-rw-r--r-- 1 root root 5.2K Mar 13 09:05 backup_2018_03_13T09_05_07.sql.gz
-rw-r--r-- 1 root root 5.2K Mar 12 21:13 backup_2018_03_12T21_13_03.sql.gz
-rw-r--r-- 1 root root 5.2K Mar 12 21:12 backup_2018_03_12T21_12_58.sql.gz
To restore a backup, run::
Copying Backups Locally
-----------------------
docker-compose -f local.yml run --rm postgres restore filename.sql
If you want to copy backups from your ``postgres`` container locally, ``docker cp`` command_ will help you on that.
Where <containerId> is the ID of the Postgres container. To get it, run::
For example, given ``9c5c3f055843`` is the container ID copying all the backups over to a local directory is as simple as ::
docker ps
$ docker cp 9c5c3f055843:/backups ./backups
To copy the files from the running Postgres container to the host system::
With a single backup file copied to ``.`` that would be ::
docker cp <containerId>:/backups /host/path/target
$ docker cp 9c5c3f055843:/backups/backup_2018_03_13T09_05_07.sql.gz .
Restoring From Backups
======================
.. _`command`: https://docs.docker.com/engine/reference/commandline/cp/
To restore the production database to a local PostgreSQL database::
createdb NAME_OF_DATABASE
psql NAME_OF_DATABASE < NAME_OF_BACKUP_FILE
Restoring from the Existing Backup
----------------------------------
To restore from one of the backups you have already got (take the ``backup_2018_03_13T09_05_07.sql.gz`` for example), ::
$ docker-compose -f local.yml run --rm postgres restore backup_2018_03_13T09_05_07.sql.gz
You will see something like ::
Restoring the 'my_project' database from the '/backups/backup_2018_03_13T09_05_07.sql.gz' backup...
INFO: Dropping all connections to the database...
pg_terminate_backend
----------------------
(0 rows)
INFO: Dropping the database...
INFO: Creating a new database...
INFO: Applying the backup to the new database...
SET
SET
SET
SET
SET
set_config
------------
(1 row)
SET
# ...
ALTER TABLE
SUCCESS: The 'my_project' database has been restored from the '/backups/backup_2018_03_13T09_05_07.sql.gz' backup.

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FROM postgres:{{ cookiecutter.postgresql_version }}
COPY ./compose/production/postgres/backup.sh /usr/local/bin/backup
RUN chmod +x /usr/local/bin/backup
COPY ./compose/production/postgres/restore.sh /usr/local/bin/restore
RUN chmod +x /usr/local/bin/restore
COPY ./compose/production/postgres/list-backups.sh /usr/local/bin/list-backups
RUN chmod +x /usr/local/bin/list-backups
COPY ./compose/production/postgres/maintenance /usr/local/bin/maintenance
RUN chmod +x /usr/local/bin/maintenance/*
RUN mv /usr/local/bin/maintenance/* /usr/local/bin \
&& rmdir /usr/local/bin/maintenance

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#!/usr/bin/env bash
set -o errexit
set -o pipefail
set -o nounset
# we might run into trouble when using the default `postgres` user, e.g. when dropping the postgres
# database in restore.sh. Check that something else is used here
if [ "$POSTGRES_USER" == "postgres" ]
then
echo "creating a backup as the postgres user is not supported, make sure to set the POSTGRES_USER environment variable"
exit 1
fi
# export the postgres password so that subsequent commands don't ask for it
export PGPASSWORD=$POSTGRES_PASSWORD
echo "creating backup"
echo "---------------"
FILENAME=backup_$(date +'%Y_%m_%dT%H_%M_%S').sql.gz
pg_dump -h postgres -U $POSTGRES_USER | gzip > /backups/$FILENAME
echo "successfully created backup $FILENAME"

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#!/usr/bin/env bash
set -o errexit
set -o pipefail
set -o nounset
echo "listing available backups"
echo "-------------------------"
ls /backups/

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#!/usr/bin/env bash
BACKUP_DIR_PATH='/backups'
BACKUP_FILE_PREFIX='backup'

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#!/usr/bin/env bash
countdown() {
declare desc="A simple countdown. Source: https://superuser.com/a/611582"
local seconds="${1}"
local d=$(($(date +%s) + "${seconds}"))
while [ "$d" -ge `date +%s` ]; do
echo -ne "$(date -u --date @$(($d - `date +%s`)) +%H:%M:%S)\r";
sleep 0.1
done
}

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#!/usr/bin/env bash
message_newline() {
echo
}
message_debug()
{
echo -e "DEBUG: ${@}"
}
message_welcome()
{
echo -e "\e[1m${@}\e[0m"
}
message_warning()
{
echo -e "\e[33mWARNING\e[0m: ${@}"
}
message_error()
{
echo -e "\e[31mERROR\e[0m: ${@}"
}
message_info()
{
echo -e "\e[37mINFO\e[0m: ${@}"
}
message_suggestion()
{
echo -e "\e[33mSUGGESTION\e[0m: ${@}"
}
message_success()
{
echo -e "\e[32mSUCCESS\e[0m: ${@}"
}

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#!/usr/bin/env bash
yes_no() {
declare desc="Prompt for confirmation. \$\"\{1\}\": confirmation message."
local arg1="${1}"
local response=
read -r -p "${arg1} (y/[n])? " response
if [[ "${response}" =~ ^[Yy]$ ]]
then
exit 0
else
exit 1
fi
}

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#!/usr/bin/env bash
### Create a database backup.
###
### Usage:
### $ docker-compose -f <environment>.yml (exec |run --rm) postgres backup
set -o errexit
set -o pipefail
set -o nounset
working_dir="$(dirname ${0})"
source "${working_dir}/_sourced/constants.sh"
source "${working_dir}/_sourced/messages.sh"
message_welcome "Backing up the '${POSTGRES_DB}' database..."
if [[ "${POSTGRES_USER}" == "postgres" ]]; then
message_error "Backing up as 'postgres' user is not supported. Assign 'POSTGRES_USER' env with another one and try again."
exit 1
fi
export PGPASSWORD="${POSTGRES_PASSWORD}"
backup_filename="${BACKUP_FILE_PREFIX}_$(date +'%Y_%m_%dT%H_%M_%S').sql.gz"
pg_dump \
--host=postgres \
--dbname="${POSTGRES_DB}" \
--username="${POSTGRES_USER}" \
| gzip > "${BACKUP_DIR_PATH}/${backup_filename}"
message_success "'${POSTGRES_DB}' database backup '${backup_filename}' has been created and placed in '${BACKUP_DIR_PATH}'."

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#!/usr/bin/env bash
### View backups.
###
### Usage:
### $ docker-compose -f <environment>.yml (exec |run --rm) postgres backups
set -o errexit
set -o pipefail
set -o nounset
working_dir="$(dirname ${0})"
source "${working_dir}/_sourced/constants.sh"
source "${working_dir}/_sourced/messages.sh"
message_welcome "These are the backups you have got:"
ls -lht "${BACKUP_DIR_PATH}"

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#!/usr/bin/env bash
### Restore database from a backup.
###
### Parameters:
### <1> filename of an existing backup.
###
### Usage:
### $ docker-compose -f <environment>.yml (exec |run --rm) postgres restore <1>
set -o errexit
set -o pipefail
set -o nounset
working_dir="$(dirname ${0})"
source "${working_dir}/_sourced/constants.sh"
source "${working_dir}/_sourced/messages.sh"
if [[ -z ${1+x} ]]; then
message_error "Backup filename is not specified yet it is a required parameter. Make sure you provide one and try again."
exit 1
fi
backup_filename="${BACKUP_DIR_PATH}/${1}"
if [[ ! -f "${backup_filename}" ]]; then
message_error "No backup with the specified filename found. Check out the 'backups' maintenance script output to see if there is one and try again."
exit 1
fi
message_welcome "Restoring the '${POSTGRES_DB}' database from the '${backup_filename}' backup..."
if [[ "${POSTGRES_USER}" == "postgres" ]]; then
message_error "Restoring as 'postgres' user is not supported. Assign 'POSTGRES_USER' env with another one and try again."
exit 1
fi
export PGPASSWORD="${POSTGRES_PASSWORD}"
message_info "Dropping all connections to the database..."
# Source: http://dba.stackexchange.com/a/11895
drop_postgres_connections_sql='UPDATE pg_database'
drop_postgres_connections_sql+=" SET datallowconn = 'false'"
drop_postgres_connections_sql+=" WHERE datname = '${POSTGRES_DB}';"
drop_postgres_connections_sql+='SELECT pg_terminate_backend(pid)'
drop_postgres_connections_sql+=' FROM pg_stat_activity'
drop_postgres_connections_sql+=" WHERE datname = '${POSTGRES_DB}';"
psql \
--host=localhost \
--username=postgres \
--dbname=postgres \
--command="${drop_postgres_connections_sql}"
message_info "Dropping the database..."
dropdb \
--host=postgres \
--username="${POSTGRES_USER}" \
"${POSTGRES_DB}"
message_info "Creating a new database..."
createdb \
--host=postgres \
--username="${POSTGRES_USER}" \
--owner="${POSTGRES_USER}" \
"${POSTGRES_DB}"
message_info "Applying the backup to the new database..."
gunzip -c "${backup_filename}" \
| psql \
--host=postgres \
--username="${POSTGRES_USER}" \
"${POSTGRES_DB}"
message_success "The '${POSTGRES_DB}' database has been restored from the '${backup_filename}' backup."

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#!/usr/bin/env bash
set -o errexit
set -o pipefail
set -o nounset
# we might run into trouble when using the default `postgres` user, e.g. when dropping the postgres
# database in restore.sh. Check that something else is used here
if [ "$POSTGRES_USER" == "postgres" ]
then
echo "restoring as the postgres user is not supported, make sure to set the POSTGRES_USER environment variable"
exit 1
fi
# export the postgres password so that subsequent commands don't ask for it
export PGPASSWORD=$POSTGRES_PASSWORD
# check that we have an argument for a filename candidate
if [[ $# -eq 0 ]] ; then
echo 'usage:'
echo ' docker-compose -f production.yml run postgres restore <backup-file>'
echo ''
echo 'to get a list of available backups, run:'
echo ' docker-compose -f production.yml run postgres list-backups'
exit 1
fi
# set the backupfile variable
BACKUPFILE=/backups/$1
# check that the file exists
if ! [ -f $BACKUPFILE ]; then
echo "backup file not found"
echo 'to get a list of available backups, run:'
echo ' docker-compose -f production.yml run postgres list-backups'
exit 1
fi
echo "beginning restore from $1"
echo "-------------------------"
# delete the db
# deleting the db can fail. Spit out a comment if this happens but continue since the db
# is created in the next step
echo "deleting old database $POSTGRES_USER"
if dropdb -h postgres -U $POSTGRES_USER $POSTGRES_USER
then echo "deleted $POSTGRES_USER database"
else echo "database $POSTGRES_USER does not exist, continue"
fi
# create a new database
echo "creating new database $POSTGRES_USER"
createdb -h postgres -U $POSTGRES_USER $POSTGRES_USER -O $POSTGRES_USER
# restore the database
echo "restoring database $POSTGRES_USER"
gunzip -c $BACKUPFILE | psql -h postgres -U $POSTGRES_USER