Vagrant, Ansible and Posgtresql

How to setup Vagrant, Ansible and Postgresql

In this story I’ll be setting up Vagrant with a Postgresql server provisioned by Ansible. The setup will be pretty bare bone, so don’t use it as a blueprint for a production setup.

Setup Vagrant

Create a file named ‘Vagrantfile’ in the root directory of your project. This file holds all the information about the Vagrant box we are going to create.

# -*- mode: ruby -*-
# vi: set ft=ruby :
Vagrant.configure(2) do |config|
  config.vm.box = "bento/ubuntu-18.04"
  config.vm.network "forwarded_port", guest: 5432, host: 5433, host_ip: "127.0.0.1"
  config.vm.network "private_network", ip: "192.168.60.70"
  config.vm.provider "virtualbox" do |vb|
     vb.memory = "2048"
  end
end

config.vm.box = “bento/ubuntu-18.04” -> Tells Vagrant to base itself on a ubuntu 18.04 installation

config.vm.network “forwarded_port”, guest: 5432, host: 5433, host_ip: “127.0.0.1” -> Forwards the port 5432 on the Vagrant box to port 5433 on the host machine (the machine running Vagrant). We forward port 5432, which is the default port for postgresql to a different port on our host machine to avoid any collision in case we have a local installation of postgresql running (on the host machine). This is relevant when you access the Vagrant box as localhost (127.0.0.1), not when you use the “private_network”.

config.vm.network “private_network”, ip: “192.168.60.70” -> setup a private network so we can access the Vagrant box through the specified IP on your host machine (instead of using localhost).

You can now start up the Vagrant box by typing:

$ vagrant up

The first time we power up Vagrant it will take a bit of time, but subsequent start ups will be much faster as the image (ubuntu) will already be downloaded.

You can also log in to the Vagrant box by typing:

$ vagrant ssh

Setup Ansible

We want to do several things when setting up Ansible.
1. create a inventory file (hosts_vagrant) which specifies the server that Ansible should work on. 2. create a playbook (playbook.yml) with all the tasks that needs to be run on the Vagrant box. 3. create a task for updating the Vagrant box with basic packages 4. create a task for installing postgresql 5. create specific tasks to setup postgresql configuration

1 Create the inventory file “hosts_vagrant”:
[all:vars]
env=vagrant
[postgresdb]
192.168.60.70
[postgresdb:vars]
  ansible_user=vagrant 
  ansible_private_key_file="./.vagrant/machines/default/virtualbox/private_key"

We are telling Ansible the IP address of our box as well as some login information specific for Vagrant.

2 Create playbook “playbook.yml”
---
- name: postgresdb
  hosts: all
  become: yes
  gather_facts: False
  pre_tasks:
    - name: Install python for Ansible
      raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal)
      changed_when: False
    - setup: # aka gather_facts

We setup a few basic things like creating python for Ansible.

Run the below commands to ensure that you can actually connect to the Vagrant box.

$ ansible all -m ping -i hosts_vagrant
$ ansible -i ./hosts_vagrant postgresdb -m ping
$ ansible-playbook -i ./hosts_vagrant playbook.yml
3, 4 Install base packages and Postgresql

Update the playbook to contain the 2 roles below.

---
- name: postgresdb
  hosts: all
  become: yes
  gather_facts: False
  pre_tasks:
    - name: Install python for Ansible
      raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal)
      changed_when: False
    - setup: # aka gather_facts
roles:
    - base
    - postgresql

Now, create the file ‘main.yml’ in the subfolder specified.

(roles/base/tasks/main.yml)
- name: Install base dependencies
  apt:
    name: "{{ packages }}"
  vars:
    packages:
      - locales
      - build-essential
      - acl
      - ntp
      - htop
      - git
      - python-pip
      - python3-pip
      - libpq-dev
    state: present
  tags:
    - packages
- name: Upgrade pip
  pip: name=pip state=latest
  tags:
    - packages

Also create the task to setup the postgresql.

(roles/postgresql/tasks/main.yml)
- name: Install postgresql
  apt:
    name: "{{ packages }}"
  vars:
    packages:
      - postgresql
      - postgresql-contrib
      - postgresql-server-dev-10
      - python-psycopg2
    state: present
  tags:
    - postgres
- name: Enable passwordless sudo
  lineinfile: dest=/etc/sudoers regexp=^vagrant line="vagrant ALL=(postgres) NOPASSWD:/bin/sh"
- name: Create a PostgreSQL database user
  postgresql_user: name=project password=project role_attr_flags=CREATEDB state=present
  become: yes
  become_user: postgres
  become_method: sudo
- name: Create acme database
  become: yes
  become_user: postgres
  postgresql_db:
    name: acme
    encoding: UTF-8
5 Need to change these files in Vagrant
(pg_hba.conf), add:
host all all 0.0.0.0/0 trust
(postgresql.conf) update:
listen_addresses = '*'

Restart server:

sudo service postgresql restart

Now, to put this into Ansible we will create 2 templates and have Ansible copy them to the Vagrant box.

Create the file “pg_hba.conf.j2” in ‘roles/postgresql/templates’

# Database administrative login by Unix domain socket
local   all             postgres                                peer
# TYPE  DATABASE        USER            ADDRESS                 METHOD
# "local" is for Unix domain socket connections only
local   all             all                                     peer
host    all             all             0.0.0.0/0               trust
host    all             all             all                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
host    all             all             192.168.60.70/24        trust
# IPv6 local connections:
host    all             all             ::1/128                 ident
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             127.0.0.1/32            md5
host    replication     all             ::1/128                 md5

And the file “postgresql.conf.j2” in ‘roles/postgresql/templates’

# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.
data_directory = '/var/lib/postgresql/10/main'  # use data in another directory
     # (change requires restart)
hba_file = '/etc/postgresql/10/main/pg_hba.conf' # host-based authentication file
     # (change requires restart)
ident_file = '/etc/postgresql/10/main/pg_ident.conf' # ident configuration file
     # (change requires restart)
# If external_pid_file is not explicitly set, no extra PID file is written.
external_pid_file = '/var/run/postgresql/10-main.pid'   # write an extra PID file
     # (change requires restart)
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------
# - Connection Settings -
listen_addresses = '*'  # what IP address(es) to listen on;
     # comma-separated list of addresses;
     # defaults to 'localhost'; use '*' for all
     # (change requires restart)
port = 5432    # (change requires restart)
max_connections = 100   # (change requires restart)
#superuser_reserved_connections = 3 # (change requires restart)
unix_socket_directories = '/var/run/postgresql' # comma-separated list of directories
     # (change requires restart)
#unix_socket_group = ''   # (change requires restart)
#unix_socket_permissions = 0777  # begin with 0 to use octal notation
     # (change requires restart)
#bonjour = off    # advertise server via Bonjour
     # (change requires restart)
#bonjour_name = ''   # defaults to the computer name
     # (change requires restart)
# - Security and Authentication -
#authentication_timeout = 1min  # 1s-600s
ssl = on
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_dh_params_file = ''
ssl_cert_file = '/etc/ssl/certs/ssl-cert-snakeoil.pem'
ssl_key_file = '/etc/ssl/private/ssl-cert-snakeoil.key'
#ssl_ca_file = ''
#ssl_crl_file = ''
#password_encryption = md5  # md5 or scram-sha-256
#db_user_namespace = off
#row_security = on
# GSSAPI using Kerberos
#krb_server_keyfile = ''
#krb_caseins_users = off
# - TCP Keepalives -
# see "man 7 tcp" for details
#tcp_keepalives_idle = 0  # TCP_KEEPIDLE, in seconds;
     # 0 selects the system default
#tcp_keepalives_interval = 0  # TCP_KEEPINTVL, in seconds;
     # 0 selects the system default
#tcp_keepalives_count = 0  # TCP_KEEPCNT;
     # 0 selects the system default
#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------
# - Memory -
shared_buffers = 128MB   # min 128kB
     # (change requires restart)
#huge_pages = try   # on, off, or try
     # (change requires restart)
#temp_buffers = 8MB   # min 800kB
#max_prepared_transactions = 0  # zero disables the feature
     # (change requires restart)
# Caution: it is not advisable to set max_prepared_transactions nonzero unless
# you actively intend to use prepared transactions.
#work_mem = 4MB    # min 64kB
#maintenance_work_mem = 64MB  # min 1MB
#replacement_sort_tuples = 150000 # limits use of replacement selection sort
#autovacuum_work_mem = -1  # min 1MB, or -1 to use maintenance_work_mem
#max_stack_depth = 2MB   # min 100kB
dynamic_shared_memory_type = posix # the default is the first option
     # supported by the operating system:
     #   posix
     #   sysv
     #   windows
     #   mmap
     # use none to disable dynamic shared memory
     # (change requires restart)
# - Disk -
#temp_file_limit = -1   # limits per-process temp file space
     # in kB, or -1 for no limit
# - Kernel Resource Usage -
#max_files_per_process = 1000  # min 25
     # (change requires restart)
#shared_preload_libraries = ''  # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0   # 0-100 milliseconds
#vacuum_cost_page_hit = 1  # 0-10000 credits
#vacuum_cost_page_miss = 10  # 0-10000 credits
#vacuum_cost_page_dirty = 20  # 0-10000 credits
#vacuum_cost_limit = 200  # 1-10000 credits
# - Background Writer -
#bgwriter_delay = 200ms   # 10-10000ms between rounds
#bgwriter_lru_maxpages = 100  # 0-1000 max buffers written/round
#bgwriter_lru_multiplier = 2.0  # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 512kB  # measured in pages, 0 disables
# - Asynchronous Behavior -
#effective_io_concurrency = 1  # 1-1000; 0 disables prefetching
#max_worker_processes = 8  # (change requires restart)
#max_parallel_workers_per_gather = 2 # taken from max_parallel_workers
#max_parallel_workers = 8  # maximum number of max_worker_processes that
     # can be used in parallel queries
#old_snapshot_threshold = -1  # 1min-60d; -1 disables; 0 is immediate
     # (change requires restart)
#backend_flush_after = 0  # measured in pages, 0 disables
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
#wal_level = replica   # minimal, replica, or logical
     # (change requires restart)
#fsync = on    # flush data to disk for crash safety
     # (turning this off can cause
     # unrecoverable data corruption)
#synchronous_commit = on  # synchronization level;
     # off, local, remote_write, remote_apply, or on
#wal_sync_method = fsync  # the default is the first option
     # supported by the operating system:
     #   open_datasync
     #   fdatasync (default on Linux)
     #   fsync
     #   fsync_writethrough
     #   open_sync
#full_page_writes = on   # recover from partial page writes
#wal_compression = off   # enable compression of full-page writes
#wal_log_hints = off   # also do full page writes of non-critical updates
     # (change requires restart)
#wal_buffers = -1   # min 32kB, -1 sets based on shared_buffers
     # (change requires restart)
#wal_writer_delay = 200ms  # 1-10000 milliseconds
#wal_writer_flush_after = 1MB  # measured in pages, 0 disables
#commit_delay = 0   # range 0-100000, in microseconds
#commit_siblings = 5   # range 1-1000
# - Checkpoints -
#checkpoint_timeout = 5min  # range 30s-1d
#max_wal_size = 1GB
#min_wal_size = 80MB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 256kB  # measured in pages, 0 disables
#checkpoint_warning = 30s  # 0 disables
# - Archiving -
#archive_mode = off  # enables archiving; off, on, or always
    # (change requires restart)
#archive_command = ''  # command to use to archive a logfile segment
    # placeholders: %p = path of file to archive
    #               %f = file name only
    # e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0  # force a logfile segment switch after this
    # number of seconds; 0 disables
#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
#max_wal_senders = 10  # max number of walsender processes
    # (change requires restart)
#wal_keep_segments = 0  # in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s # in milliseconds; 0 disables
#max_replication_slots = 10 # max number of replication slots
    # (change requires restart)
#track_commit_timestamp = off # collect timestamp of transaction commit
    # (change requires restart)
# - Master Server -
# These settings are ignored on a standby server.
#synchronous_standby_names = '' # standby servers that provide sync rep
    # method to choose sync standbys, number of sync standbys,
    # and comma-separated list of application_name
    # from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
# - Standby Servers -
# These settings are ignored on a master server.
#hot_standby = on   # "off" disallows queries during recovery
     # (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
     # when reading WAL from archive;
     # -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
     # when reading streaming WAL;
     # -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
     # 0 disables
#hot_standby_feedback = off  # send info from standby to prevent
     # query conflicts
#wal_receiver_timeout = 60s  # time that receiver waits for
     # communication from master
     # in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s # time to wait before retrying to
     # retrieve WAL after a failed attempt
# - Subscribers -
# These settings are ignored on a publisher.
#max_logical_replication_workers = 4 # taken from max_worker_processes
     # (change requires restart)
#max_sync_workers_per_subscription = 2 # taken from max_logical_replication_workers
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
#seq_page_cost = 1.0   # measured on an arbitrary scale
#random_page_cost = 4.0   # same scale as above
#cpu_tuple_cost = 0.01   # same scale as above
#cpu_index_tuple_cost = 0.005  # same scale as above
#cpu_operator_cost = 0.0025  # same scale as above
#parallel_tuple_cost = 0.1  # same scale as above
#parallel_setup_cost = 1000.0 # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB
# - Genetic Query Optimizer -
#geqo = on
#geqo_threshold = 12
#geqo_effort = 5   # range 1-10
#geqo_pool_size = 0   # selects default based on effort
#geqo_generations = 0   # selects default based on effort
#geqo_selection_bias = 2.0  # range 1.5-2.0
#geqo_seed = 0.0   # range 0.0-1.0
# - Other Planner Options -
#default_statistics_target = 100 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1  # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8  # 1 disables collapsing of explicit
     # JOIN clauses
#force_parallel_mode = off
#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------
# - Where to Log -
#log_destination = 'stderr'  # Valid values are combinations of
     # stderr, csvlog, syslog, and eventlog,
     # depending on platform.  csvlog
     # requires logging_collector to be on.
# This is used when logging to stderr:
#logging_collector = off  # Enable capturing of stderr and csvlog
     # into log files. Required to be on for
     # csvlogs.
     # (change requires restart)
# These are only used if logging_collector is on:
#log_directory = 'log'   # directory where log files are written,
     # can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
     # can include strftime() escapes
#log_file_mode = 0600   # creation mode for log files,
     # begin with 0 to use octal notation
#log_truncate_on_rotation = off  # If on, an existing log file with the
     # same name as the new log file will be
     # truncated rather than appended to.
     # But such truncation only occurs on
     # time-driven rotation, not on restarts
     # or size-driven rotation.  Default is
     # off, meaning append to existing files
     # in all cases.
#log_rotation_age = 1d   # Automatic rotation of logfiles will
     # happen after that time.  0 disables.
#log_rotation_size = 10MB  # Automatic rotation of logfiles will
     # happen after that much log output.
     # 0 disables.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
#syslog_sequence_numbers = on
#syslog_split_messages = on
# This is only relevant when logging to eventlog (win32):
# (change requires restart)
#event_source = 'PostgreSQL'
# - When to Log -
#client_min_messages = notice  # values in order of decreasing detail:
     #   debug5
     #   debug4
     #   debug3
     #   debug2
     #   debug1
     #   log
     #   notice
     #   warning
     #   error
#log_min_messages = warning  # values in order of decreasing detail:
     #   debug5
     #   debug4
     #   debug3
     #   debug2
     #   debug1
     #   info
     #   notice
     #   warning
     #   error
     #   log
     #   fatal
     #   panic
#log_min_error_statement = error # values in order of decreasing detail:
     #   debug5
     #   debug4
     #   debug3
     #   debug2
     #   debug1
     #   info
     #   notice
     #   warning
     #   error
     #   log
     #   fatal
     #   panic (effectively off)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
     # and their durations, > 0 logs only
     # statements running at least this number
     # of milliseconds
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default  # terse, default, or verbose messages
#log_hostname = off
log_line_prefix = '%m [%p] %q%u@%d '  # special values:
     #   %a = application name
     #   %u = user name
     #   %d = database name
     #   %r = remote host and port
     #   %h = remote host
     #   %p = process ID
     #   %t = timestamp without milliseconds
     #   %m = timestamp with milliseconds
     #   %n = timestamp with milliseconds (as a Unix epoch)
     #   %i = command tag
     #   %e = SQL state
     #   %c = session ID
     #   %l = session line number
     #   %s = session start timestamp
     #   %v = virtual transaction ID
     #   %x = transaction ID (0 if none)
     #   %q = stop here in non-session
     #        processes
     #   %% = '%'
     # e.g. '<%u%%%d> '
#log_lock_waits = off   # log lock waits >= deadlock_timeout
#log_statement = 'none'   # none, ddl, mod, all
#log_replication_commands = off
#log_temp_files = -1   # log temporary files equal or larger
     # than the specified size in kilobytes;
     # -1 disables, 0 logs all temp files
log_timezone = 'UTC'
# - Process Title -
cluster_name = '10/main'   # added to process titles if nonempty
     # (change requires restart)
#update_process_title = on
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#track_io_timing = off
#track_functions = none   # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
stats_temp_directory = '/var/run/postgresql/10-main.pg_stat_tmp'
# - Statistics Monitoring -
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off
#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------
#autovacuum = on   # Enable autovacuum subprocess?  'on'
     # requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
     # their durations, > 0 logs only
     # actions running at least this number
     # of milliseconds.
#autovacuum_max_workers = 3  # max number of autovacuum subprocesses
     # (change requires restart)
#autovacuum_naptime = 1min  # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
     # vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
     # analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
     # (change requires restart)
#autovacuum_multixact_freeze_max_age = 400000000 # maximum multixact age
     # before forced vacuum
     # (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
     # autovacuum, in milliseconds;
     # -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
     # autovacuum, -1 means use
     # vacuum_cost_limit
#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------
# - Statement Behavior -
#search_path = '"$user", public' # schema names
#default_tablespace = ''  # a tablespace name, '' uses the default
#temp_tablespaces = ''   # a list of tablespace names, '' uses
     # only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0   # in milliseconds, 0 is disabled
#lock_timeout = 0   # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_freeze_table_age = 150000000
#bytea_output = 'hex'   # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_fuzzy_search_limit = 0
#gin_pending_list_limit = 4MB
# - Locale and Formatting -
datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
timezone = 'UTC'
#timezone_abbreviations = 'Default'     # Select the set of available time zone
     # abbreviations.  Currently, there are
     #   Default
     #   Australia (historical usage)
     #   India
     # You can create your own file in
     # share/timezonesets/.
#extra_float_digits = 0   # min -15, max 3
#client_encoding = sql_ascii  # actually, defaults to database
     # encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8'   # locale for system error message
     # strings
lc_monetary = 'en_US.UTF-8'   # locale for monetary formatting
lc_numeric = 'en_US.UTF-8'   # locale for number formatting
lc_time = 'en_US.UTF-8'    # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#dynamic_library_path = '$libdir'
#local_preload_libraries = ''
#session_preload_libraries = ''
#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------
#deadlock_timeout = 1s
#max_locks_per_transaction = 64  # min 10
     # (change requires restart)
#max_pred_locks_per_transaction = 64 # min 10
     # (change requires restart)
#max_pred_locks_per_relation = -2 # negative values mean
     # (max_pred_locks_per_transaction
     #  / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2            # min 0
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#operator_precedence_warning = off
#quote_all_identifiers = off
#standard_conforming_strings = on
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------
#exit_on_error = off   # terminate session on any error?
#restart_after_crash = on  # reinitialize after backend crash?
#data_sync_retry = off   # retry or panic on failure to fsync data?
#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------
# These options allow settings to be loaded from files other than the
# default postgresql.conf.
include_dir = 'conf.d'   # include files ending in '.conf' from
     # directory 'conf.d'
#include_if_exists = 'exists.conf' # include file only if it exists
#include = 'special.conf'  # include file
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------
# Add settings for extensions here

Actually, compared to the default config file, we are only changing one thing, the line 59 to: “listen_addresses = ‘*’”.

We also want to create a handler that restarts the postgresql server after we have written the two config files to the Vagrant box.

Create the file ‘main.yml’ in a folder “roles/postgresql/handlers”:

- name: restart postgresql
  service:
    name: postgresql
    state: restarted

Now, you can run:

$ ansible-playbook -i ./hosts_vagrant playbook.yml

and you should see something like:

PLAY [postgresdb] ***********************************************************************************************************************
TASK [Install python for Ansible] *******************************************************************************************************
ok: [192.168.60.70]
TASK [setup] ****************************************************************************************************************************
ok: [192.168.60.70]
TASK [base : Install base dependencies] *************************************************************************************************
ok: [192.168.60.70]
TASK [base : Upgrade pip] ***************************************************************************************************************
ok: [192.168.60.70]
TASK [postgresql : Install postgresql] **************************************************************************************************
ok: [192.168.60.70]
TASK [postgresql : Create pg_hba.conf file in /etc/postgresql/10/main] ******************************************************************
ok: [192.168.60.70]
TASK [postgresql : Create posgtresql.conf file in /etc/postgresql/10/main] **************************************************************
ok: [192.168.60.70]
TASK [postgresql : Enable passwordless sudo] ********************************************************************************************
ok: [192.168.60.70]
TASK [postgresql : Create a PostgreSQL database user] ***********************************************************************************
ok: [192.168.60.70]
TASK [postgresql : Create acme database] ************************************************************************************************
ok: [192.168.60.70]
PLAY RECAP ******************************************************************************************************************************
192.168.60.70              : ok=10   changed=0    unreachable=0    failed=0

(instead of the green ‘ok’ you might see a different message if it the first time you run the script).

If you want to test that you can access the database on the Vagrant box, you can create this little Python3 script (call the file test_db.py):

import psycopg2
try:
    connection = psycopg2.connect(
        user = "project",
        password = "project",
        host = "192.168.60.70",
        # host = "127.0.0.1",
        port = "5432",  # use 5433 if you use localhost
        database = "acme",
)
    cursor = connection.cursor()
    # Print PostgreSQL Connection properties
    print ( connection.get_dsn_parameters(),"\n")
    # Print PostgreSQL version
    cursor.execute("SELECT version();")
    record = cursor.fetchone()
    print("You are connected to - ", record,"\n")
except (Exception, psycopg2.Error) as error :
    print ("Error while connecting to PostgreSQL", error)
    connection = None
finally:
    #closing database connection.
        if(connection):
            cursor.close()
            connection.close()
            print("PostgreSQL connection is closed")

and run it with:

$ python3 test_db.py

and you should see something like:

{'user': 'project', 'dbname': 'acme', 'host': '192.168.60.70', 'port': '5432', 'tty': '', 'options': '', 'sslmode': 'prefer', 'sslcompression': '1', 'krbsrvname': 'postgres', 'target_session_attrs': 'any'}
You are connected to -  ('PostgreSQL 10.7 (Ubuntu 10.7-0ubuntu0.18.04.1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.3.0-27ubuntu1~18.04) 7.3.0, 64-bit',)
PostgreSQL connection is closed