How to configure package stellar-horizon-postgres?

Question

Using stellar-quickstart, I am able to install, then start and sync stellar-core. However, my attempts to install stellar-horizon fail with the following message:

  Package stellar-horizon-postgres is not configured yet.

How to configure it? Thanks in advance. More info, if required:

alec@alec-MS-7596 ~/product $ sudo systemctl stop stellar-core
alec@alec-MS-7596 ~/product $ sudo systemctl mask stellar-core
Created symlink from /etc/systemd/system/stellar-core.service to /dev/null.
alec@alec-MS-7596 ~/product $ sudo apt-get update && sudo apt-get install stellar-horizon
Hit:1 https://deb.nodesource.com/node_8.x xenial InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease          
Get:3 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]           
Hit:4 http://ppa.launchpad.net/jonathonf/vim/ubuntu xenial InRelease                  
Get:5 http://security.ubuntu.com/ubuntu xenial-security InRelease [109 kB]            
Hit:6 https://apt.stellar.org/public stable/ InRelease                                
Get:7 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease [107 kB]         
Hit:8 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu xenial InRelease        
Fetched 325 kB in 1s (306 kB/s)                                                     
Reading package lists... Done
Reading package lists... Done
Building dependency tree       
Reading state information... Done
stellar-horizon is already the newest version (0.17.4-45).
0 upgraded, 0 newly installed, 0 to remove and 84 not upgraded.
2 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] 
Setting up stellar-horizon-postgres (0.1-5) ...
2019/04/05 11:30:38 exec failed: pq: relation "gorp_migrations" already exists
dpkg: error processing package stellar-horizon-postgres (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of stellar-quickstart:
 stellar-quickstart depends on stellar-horizon-postgres; however:
  Package stellar-horizon-postgres is not configured yet.

dpkg: error processing package stellar-quickstart (--configure):
 dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
                   Errors were encountered while processing:
 stellar-horizon-postgres
 stellar-quickstart
E: Sub-process /usr/bin/dpkg returned an error code (1)

Answer 1

All it took was to drop the horizon database! Many thanks to ire_and_curses for the tip! Steps below outline the fix.

  458  sudo -u stellar psql -c 'DROP DATABASE horizon' postgres
  459  sudo apt-get update && sudo apt-get install stellar-horizon
  460  sudo -u stellar psql -d horizon
  462  sudo systemctl unmask stellar-core
  463  sudo systemctl start stellar-core
  464  sudo stellar-core-cmd info # wait for "state" : "Synced!"
  465  sudo systemctl start stellar-horizon
  466  sudo systemctl status stellar-horizon

Answer 2

@alec-missine, @ire_and_curses Thank you both for reporting this issue!

The stellar-horizon package does not create a horizon database, creating the horizon db is handled by the stellar-horizon-postgres package. This is by design.

The edge case you encountered exists because although the stellar-horizon package doesn't create the horizon db it does run the Horizon migrations as part of it's stellar-horizon.postinst configure maintainer script step. We do this to ensure seamless schema migrations during installs/upgrades of Horizon.

I believe that in this instance, you must have created a horizon database but not run stellar-horizon-cmd db init to create the db schema. When you installed the stellar-horizon package it would have attempted to run the migrations on an empty horizon db (creating the gorp_migrations table only).

When you subsequently installed the stellar-quickstart package the database already existed but not the schema which caused the installation of stellar-horizon-postgres to fail, cascading all the way back to the stellar-quickstart installation failure.

Going forwards, I have modified the stellar-horizon postinst script to check if the schema has been created prior to running db migrate up (#43), this should prevent this from occurring again.