osm2pgrouting can't connect to postGIS

Question

I want to do some isochrones with pgrouting, and I am failing in setting up the network in the first place.

osm2pgrouting doesn't find my postGIS installation. Also, the error message is not very helpful (ERROR: postGIS not found) and I don't know what to do (reinstalling already tried).

What is your advice?

osm2pgrouting -f lebanon-latest.osm -d routing_lb -U jb -W 
***************************************************
           COMMAND LINE CONFIGURATION             *
***************************************************
Filename = lebanon-latest.osm
Configuration file = /usr/share/osm2pgrouting/mapconfig.xml
host = localhost
port = 5432
dbname = routing_lb
username = jb
password = 
schema= 
prefix = 
suffix = 
Don't drop tables
Don't add nodes
***************************************************
Connecting to the database
host=localhost user=jb dbname=routing_lb port=5432 password=
connection success
ERROR: postGIS not found

In PostgreSQL, the postGIS extension is installed:

postgres=# create extension postgis;
CREATE EXTENSION
postgres=# create extension pgrouting;
CREATE EXTENSION

Test:

postgres=# create extension postGIS;
ERROR:  extension "postgis" already exists

Not surprisingly, no tables in the database have been created:

postgres=# \c routing_lb
You are now connected to database "routing_lb" as user "postgres".
routing_lb=# \dt
No relations found.

Answer 1

You may need to create postgis extension in the routing_lb database. Right now you are creating it in postgres database and it may not be in same schema

Answer 2

Turns out you have to create the extensions in the database itself and not only once for the whole postgreSQL installation:

routing_lb=# create extension postgis;
CREATE EXTENSION
routing_lb=# create extension pgrouting;
CREATE EXTENSION
routing_lb=# \dx+ pgrouting
routing_lb=# select pgr_version();
              pgr_version               
----------------------------------------
 (2.5.2,v2.5.2,60585f1f7,master,1.58.0)
(1 row)