In the peer container:
root@3249b8857f6f:/opt/datomic# bin/repl
Clojure 1.11.4
user=> (Class/forName "org.postgresql.Driver")
org.postgresql.Driver
user=> (require 'datomic.peer-server)
nil
user=> (datomic.peer-server/-main
"-h" "0.0.0.0"
"-p" "8998"
"-a" "none,none"
"-d" "datomic,datomic:sql://mydb?jdbc=postgresql://catalyst-postgres-1:5432/datomic?user=datomic&password=datomic&jdbc-class=org.postgresql.Driver")
Execution error (SQLException) at java.sql.DriverManager/getDriver (DriverManager.java:299).
No suitable driver
user=>