Juju run is cool because it lets you execute stuff inside an anonymous hook context. So if you were say prompted with the following topology.
services:
mediawiki:
charm: cs:precise/mediawiki-16
exposed: true
relations:
db:
- mysql
website:
- siege
units:
mediawiki/0:
agent-state: started
agent-version: 1.18.3
machine: "5"
open-ports:
- 80/tcp
public-address: XXX
mysql:
charm: cs:precise/mysql-44
exposed: false
relations:
cluster:
- mysql
db:
- mediawiki
units:
mysql/0:
agent-state: started
agent-version: 1.18.3
machine: "3"
public-address: XXX
siege:
charm: cs:~dannf/precise/siege-4
exposed: false
relations:
website:
- mediawiki
units:
siege/0:
agent-state: started
agent-version: 1.18.3
machine: "4"
public-address: XXX
Which is just mediawiki powered by mysql with siege attached to mediawiki. Say you want to know more details mysql's relationships.
# bash shell
unit='mysql/0'
relations=$(juju run --unit ${unit} 'ls ./hooks/ | grep relation | cut -d '-' -f1 | uniq')
for rel in $relations
do
echo "testing for relationships in $rel"
juju run --unit ${unit} "relation-ids ${rel} --format=json"
done
...
testing for relationships in ceph
[]
testing for relationships in cluster
["cluster:2"]
testing for relationships in db
["db:4"]
testing for relationships in ha
[]
testing for relationships in ha_relations.py
[]
testing for relationships in local
[]
testing for relationships in master
[]
testing for relationships in monitors
[]
testing for relationships in munin
[]
testing for relationships in shared
[]
testing for relationships in shared_db_relations.py
[]
testing for relationships in slave
[]
Cool, there's the DB relationship, now you can probe it.
ppetraki@:cabs-sandbox$ juju run --unit ${unit} "relation-get database ${unit} -r db:4 --format=json"
"mediawiki"
ppetraki@:cabs-sandbox$ juju run --unit ${unit} "relation-get password ${unit} -r db:4 --format=json"
"alaeyomooxaesee"
