Running PostgreSQL in Docker inside VirtualBox Ubuntu VM

Friday, 8 March 2019

Running PostgreSQL in Docker inside VirtualBox Ubuntu VM

The last time I used PostgreSQL (and databases in general) was in my Brand Communications days, around 2010-2011. I was then designing and implementing DB support for customer care events coming from VPN clients connected to Apollo server. Today, 9 years later I am coming back to data bases and am witnessing how one software product and overall environment has drastically changed.

Back in 2012, pgAdmin used to be a standalone native desktop application (written in C++ and wxWidgets) and PostgreSQL DB would be running directly on top of the OS. Today, pgAdmin runs in a browser as a web application (written in Python and JavaScript) and connects to a DB instance running more often inside a Docker container in a cloud then on some in-house server...What a nice example of technology evolution! :)

I wanted to catch up with pgAdmin evolution and found the article written by its lead developer where he said:

Aside from it being extremely hard to find C++ developers these days (...) the world is shifting to a web based model these days. Cloud deployments are becoming more widely used, as well as simple instances supplied through hosting providers. Users are getting used to being able to pickup their laptop or a tablet and do whatever they need to do without having to install software – open a browser, read and write email, build a spreadsheet or create a database.

Let's then dive into new paradigms of using PostgreSQL:

PostgreSQL image is available in Docker Hub
pgAdmin 4 Windows installer can be downloaded from postgresql.org but host has to have some browser installed

Running PostgreSQL in Docker inside VirtualBox Ubuntu image

To pull the official PostgreSQL image from the DockerHub (if not already downloaded) and launch it on your local system, execute the following command:

$ docker run -d -p 5432:5432 --name my-postgres -e POSTGRES_PASSWORD=mysecretpassword postgres

Let's dissect it:

docker run
-d // runs container in detached mode
-p 5432:5432 // opens port 5432 for incoming connections from external applications
--name my-postgres // sets container name "my-postgres"
-e POSTGRES_PASSWORD=mysecretpassword // sets environment variable
postgres // image name in Docker Hub

To start a terminal in the container use docker exec. From now on, the prompt will show the current user in the container and container ID:

$ sudo docker exec -it my-postgres bash
root@a4a7485fea59:/# ls
bin boot dev docker-entrypoint-initdb.d docker-entrypoint.sh etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
root@a4a7485fea59:/# pwd
/

To launch PostgreSQL interactive terminal use psql.

To connect to the database as some specific user, use -U <USERNAME>.

root@a4a7485fea59:/# psql -U postgres
psql (11.2 (Debian 11.2-1.pgdg90+1))
Type "help" for help.

To see the help menu, type help:

postgres=# help
You are using psql, the command-line interface to PostgreSQL.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

To see the list of SQL commands for which help is provided, use \h:

postgres=# \h

Available help:

ABORT ALTER TEXT SEARCH TEMPLATE CREATE PUBLICATION DROP FUNCTION IMPORT FOREIGN SCHEMA

ALTER AGGREGATE ALTER TRIGGER CREATE ROLE ...

To see help for some particular SQL command type help <COMMAND>:

postgres-# \help abort

Command: ABORT

Description: abort the current transaction

Syntax:

ABORT [ WORK | TRANSACTION ]

To list all psql commands use \?:

postgres-# \?

General

\copyright show PostgreSQL usage and distribution terms

\crosstabview [COLUMNS] execute query and display results in crosstab

\errverbose show most recent error message at maximum verbosity

\g [FILE] or ; execute query (and send results to file or |pipe)

\gdesc describe result of query, without executing it

\gexec execute query, then execute each value in its result

\gset [PREFIX] execute query and store results in psql variables

\gx [FILE] as \g, but forces expanded output mode

\q quit psql

\watch [SEC] execute query every SEC seconds

Help

\? [commands] show help on backslash commands

\? options show help on psql command-line options

\? variables show help on special variables

\h [NAME] help on syntax of SQL commands, * for all commands

Query Buffer

\e [FILE] [LINE] edit the query buffer (or file) with external editor

\ef [FUNCNAME [LINE]] edit function definition with external editor

\ev [VIEWNAME [LINE]] edit view definition with external editor

\p show the contents of the query buffer

\r reset (clear) the query buffer

\s [FILE] display history or save it to file

\w FILE write query buffer to file

Input/Output

\copy ... perform SQL COPY with data stream to the client host

\echo [STRING] write string to standard output

\i FILE execute commands from file

\ir FILE as \i, but relative to location of current script

\o [FILE] send all query results to file or |pipe

\qecho [STRING] write string to query output stream (see \o)

Conditional

\if EXPR begin conditional block

\elif EXPR alternative within current conditional block

\else final alternative within current conditional block

\endif end conditional block

Informational

(options: S = show system objects, + = additional detail)

\d[S+] list tables, views, and sequences

\d[S+] NAME describe table, view, sequence, or index

\da[S] [PATTERN] list aggregates

\dA[+] [PATTERN] list access methods

\db[+] [PATTERN] list tablespaces

\dc[S+] [PATTERN] list conversions

\dC[+] [PATTERN] list casts

\dd[S] [PATTERN] show object descriptions not displayed elsewhere

\dD[S+] [PATTERN] list domains

\ddp [PATTERN] list default privileges

\dE[S+] [PATTERN] list foreign tables

\det[+] [PATTERN] list foreign tables

\des[+] [PATTERN] list foreign servers

\deu[+] [PATTERN] list user mappings

\dew[+] [PATTERN] list foreign-data wrappers

\df[anptw][S+] [PATRN] list [only agg/normal/procedures/trigger/window] functions

\dF[+] [PATTERN] list text search configurations

\dFd[+] [PATTERN] list text search dictionaries

\dFp[+] [PATTERN] list text search parsers

\dFt[+] [PATTERN] list text search templates

\dg[S+] [PATTERN] list roles

\di[S+] [PATTERN] list indexes

\dl list large objects, same as \lo_list

\dL[S+] [PATTERN] list procedural languages

\dm[S+] [PATTERN] list materialized views

\dn[S+] [PATTERN] list schemas

\do[S] [PATTERN] list operators

\dO[S+] [PATTERN] list collations

\dp [PATTERN] list table, view, and sequence access privileges

\drds [PATRN1 [PATRN2]] list per-database role settings

\dRp[+] [PATTERN] list replication publications

\dRs[+] [PATTERN] list replication subscriptions

\ds[S+] [PATTERN] list sequences

\dt[S+] [PATTERN] list tables

\dT[S+] [PATTERN] list data types

\du[S+] [PATTERN] list roles

\dv[S+] [PATTERN] list views

\dx[+] [PATTERN] list extensions

\dy [PATTERN] list event triggers

\l[+] [PATTERN] list databases

\sf[+] FUNCNAME show a function's definition

\sv[+] VIEWNAME show a view's definition

\z [PATTERN] same as \dp

Formatting

\a toggle between unaligned and aligned output mode

\C [STRING] set table title, or unset if none

\f [STRING] show or set field separator for unaligned query output

\H toggle HTML output mode (currently off)

\pset [NAME [VALUE]] set table output option

(NAME := {border|columns|expanded|fieldsep|fieldsep_zero|

tuples_only|unicode_border_linestyle|

unicode_column_linestyle|unicode_header_linestyle})

\t [on|off] show only rows (currently off)

\T [STRING] set HTML <table> tag attributes, or unset if none

\x [on|off|auto] toggle expanded output (currently off)

Connection

\c[onnect] {[DBNAME|- USER|- HOST|- PORT|-] | conninfo}

connect to new database (currently "postgres")

\conninfo display information about current connection

\encoding [ENCODING] show or set client encoding

\password [USERNAME] securely change the password for a user

Operating System

\cd [DIR] change the current working directory

\setenv NAME [VALUE] set or unset environment variable

\timing [on|off] toggle timing of commands (currently off)

\! [COMMAND] execute command in shell or start interactive shell

Variables

\prompt [TEXT] NAME prompt user to set internal variable

\set [NAME [VALUE]] set internal variable, or list all if no parameters

\unset NAME unset (delete) internal variable

Large Objects

\lo_export LOBOID FILE

\lo_import FILE [COMMENT]

\lo_list

\lo_unlink LOBOID large object operations

To check the PostgreSQL version use:

postgres=# select version();

version

----------------------------------------------------------------------------------------------------------------------------------

PostgreSQL 11.2 (Debian 11.2-1.pgdg90+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516, 64-bit

(1 row)

To list all databases, use \l:

postgres-# \l

List of databases

-----------+----------+----------+------------+------------+-----------------------

(3 rows)

To create a new database, execute this SQL command:

postgres=# CREATE DATABASE mytestdb;

CREATE DATABASE

This new database appears in the list of databases:

postgres=# \l

List of databases

-----------+----------+----------+------------+------------+-----------------------

(4 rows)

To connect to a database, use \c:

postgres-# \c postgres

You are now connected to database "postgres" as user "postgres".

To list all relations, use \dS:

postgres-# \dS

List of relations

Schema | Name | Type | Owner

------------+---------------------------------+-------+----------

pg_catalog | pg_aggregate | table | postgres

pg_catalog | pg_am | table | postgres

pg_catalog | pg_amop | table | postgres

pg_catalog | pg_amproc | table | postgres

pg_catalog | pg_attrdef | table | postgres

pg_catalog | pg_attribute | table | postgres

pg_catalog | pg_auth_members | table | postgres

pg_catalog | pg_authid | table | postgres

pg_catalog | pg_available_extension_versions | view | postgres

pg_catalog | pg_available_extensions | view | postgres

pg_catalog | pg_cast | table | postgres

pg_catalog | pg_class | table | postgres

pg_catalog | pg_collation | table | postgres

pg_catalog | pg_config | view | postgres

pg_catalog | pg_constraint | table | postgres

pg_catalog | pg_conversion | table | postgres

pg_catalog | pg_cursors | view | postgres

pg_catalog | pg_database | table | postgres

pg_catalog | pg_db_role_setting | table | postgres

pg_catalog | pg_default_acl | table | postgres

pg_catalog | pg_depend | table | postgres

pg_catalog | pg_description | table | postgres

pg_catalog | pg_enum | table | postgres

pg_catalog | pg_event_trigger | table | postgres

pg_catalog | pg_extension | table | postgres

pg_catalog | pg_file_settings | view | postgres

pg_catalog | pg_foreign_data_wrapper | table | postgres

pg_catalog | pg_foreign_server | table | postgres

pg_catalog | pg_foreign_table | table | postgres

pg_catalog | pg_group | view | postgres

pg_catalog | pg_hba_file_rules | view | postgres

pg_catalog | pg_index | table | postgres

pg_catalog | pg_indexes | view | postgres

pg_catalog | pg_inherits | table | postgres

pg_catalog | pg_init_privs | table | postgres

pg_catalog | pg_language | table | postgres

pg_catalog | pg_largeobject | table | postgres

pg_catalog | pg_largeobject_metadata | table | postgres

pg_catalog | pg_locks | view | postgres

pg_catalog | pg_matviews | view | postgres

pg_catalog | pg_namespace | table | postgres

pg_catalog | pg_opclass | table | postgres

pg_catalog | pg_operator | table | postgres

pg_catalog | pg_opfamily | table | postgres

pg_catalog | pg_partitioned_table | table | postgres

pg_catalog | pg_pltemplate | table | postgres

pg_catalog | pg_policies | view | postgres

pg_catalog | pg_policy | table | postgres

pg_catalog | pg_prepared_statements | view | postgres

pg_catalog | pg_prepared_xacts | view | postgres

pg_catalog | pg_proc | table | postgres

pg_catalog | pg_publication | table | postgres

pg_catalog | pg_publication_rel | table | postgres

pg_catalog | pg_publication_tables | view | postgres

pg_catalog | pg_range | table | postgres

pg_catalog | pg_replication_origin | table | postgres

pg_catalog | pg_replication_origin_status | view | postgres

pg_catalog | pg_replication_slots | view | postgres

pg_catalog | pg_rewrite | table | postgres

pg_catalog | pg_roles | view | postgres

pg_catalog | pg_rules | view | postgres

pg_catalog | pg_seclabel | table | postgres

pg_catalog | pg_seclabels | view | postgres

pg_catalog | pg_sequence | table | postgres

pg_catalog | pg_sequences | view | postgres

pg_catalog | pg_settings | view | postgres

pg_catalog | pg_shadow | view | postgres

pg_catalog | pg_shdepend | table | postgres

pg_catalog | pg_shdescription | table | postgres

pg_catalog | pg_shseclabel | table | postgres

pg_catalog | pg_stat_activity | view | postgres

pg_catalog | pg_stat_all_indexes | view | postgres

pg_catalog | pg_stat_all_tables | view | postgres

pg_catalog | pg_stat_archiver | view | postgres

pg_catalog | pg_stat_bgwriter | view | postgres

pg_catalog | pg_stat_database | view | postgres

pg_catalog | pg_stat_database_conflicts | view | postgres

pg_catalog | pg_stat_progress_vacuum | view | postgres

pg_catalog | pg_stat_replication | view | postgres

pg_catalog | pg_stat_ssl | view | postgres

pg_catalog | pg_stat_subscription | view | postgres

pg_catalog | pg_stat_sys_indexes | view | postgres

pg_catalog | pg_stat_sys_tables | view | postgres

pg_catalog | pg_stat_user_functions | view | postgres

pg_catalog | pg_stat_user_indexes | view | postgres

pg_catalog | pg_stat_user_tables | view | postgres

pg_catalog | pg_stat_wal_receiver | view | postgres

pg_catalog | pg_stat_xact_all_tables | view | postgres

pg_catalog | pg_stat_xact_sys_tables | view | postgres

pg_catalog | pg_stat_xact_user_functions | view | postgres

pg_catalog | pg_stat_xact_user_tables | view | postgres

pg_catalog | pg_statio_all_indexes | view | postgres

pg_catalog | pg_statio_all_sequences | view | postgres

pg_catalog | pg_statio_all_tables | view | postgres

pg_catalog | pg_statio_sys_indexes | view | postgres

pg_catalog | pg_statio_sys_sequences | view | postgres

pg_catalog | pg_statio_sys_tables | view | postgres

pg_catalog | pg_statio_user_indexes | view | postgres

pg_catalog | pg_statio_user_sequences | view | postgres

pg_catalog | pg_statio_user_tables | view | postgres

pg_catalog | pg_statistic | table | postgres

pg_catalog | pg_statistic_ext | table | postgres

pg_catalog | pg_stats | view | postgres

pg_catalog | pg_subscription | table | postgres

pg_catalog | pg_subscription_rel | table | postgres

pg_catalog | pg_tables | view | postgres

pg_catalog | pg_tablespace | table | postgres

pg_catalog | pg_timezone_abbrevs | view | postgres

pg_catalog | pg_timezone_names | view | postgres

pg_catalog | pg_transform | table | postgres

pg_catalog | pg_trigger | table | postgres

pg_catalog | pg_ts_config | table | postgres

pg_catalog | pg_ts_config_map | table | postgres

pg_catalog | pg_ts_dict | table | postgres

pg_catalog | pg_ts_parser | table | postgres

pg_catalog | pg_ts_template | table | postgres

pg_catalog | pg_type | table | postgres

pg_catalog | pg_user | view | postgres

pg_catalog | pg_user_mapping | table | postgres

pg_catalog | pg_user_mappings | view | postgres

pg_catalog | pg_views | view | postgres

(121 rows)

To leave psql interactive terminal use \q:

postgres=# \q
root@a4a7485fea59:/#

If docker container is stopped (by executing docker stop my-postgres, in some other terminal) prompt of the Ubuntu will appear:

root@a4a7485fea59:/# bojan@bojan-VirtualBox:~$

Using pgAdmin on Windows to query PostgreSQL running in Docker on Ubuntu VirtualBox VM

PostgreSQL by default listens on port 5432 and that's why we opened a port on Docker and mapped 5432 onto it. We chose the same port number to be opened on Docker. Now, we need to open that port on our Ubuntu Virtual Machine: