registration-relation-changed fails on bionic due to python2 vs python3 string handling

[Dmitrii Shcherbakov]

1) deploy landscape 18.03 via charms
2) deploy landscape-client on bionic ubuntu system
3) configure landscape with a registration key and config that on the client side

The charm fails with "TypeError: write() argument must be str, not bytes" which is a python2 vs python3 string handling error.

which is triggered by

file.write(base64.b64decode(certificate))

bundle:
http://paste.ubuntu.com/p/wxDKfbYPnp/

unit-landscape-server-0: 17:24:08 DEBUG unit.landscape-server/0.registration-relation-changed == landscape-async-frontend ==
unit-landscape-server-0: 17:24:10 DEBUG unit.landscape-server/0.registration-relation-changed == landscape-job-handler ==
unit-landscape-server-0: 17:24:13 DEBUG unit.landscape-server/0.registration-relation-changed == landscape-msgserver ==
unit-landscape-server-0: 17:24:17 DEBUG unit.landscape-server/0.registration-relation-changed == landscape-pingserver ==
unit-landscape-server-0: 17:24:21 DEBUG unit.landscape-server/0.registration-relation-changed == landscape-api ==
unit-landscape-client-0: 17:24:21 INFO juju.worker.uniter awaiting error resolution for "relation-changed" hook
unit-landscape-client-0: 17:24:22 INFO unit.landscape-client/0.juju-log registration:8: In config-changed for landscape-client/0
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed Traceback (most recent call last):
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed File "/var/lib/juju/agents/unit-landscape-client-0/charm/hooks/hooks.py", line 223, in <module>
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed sys.exit(hooks.execute(sys.argv[1:]))
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed File "/var/lib/juju/agents/unit-landscape-client-0/charm/hooks/charmhelpers/core/hookenv.py", line 731, in execute
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed self._hooks[hook_name]()
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed File "/var/lib/juju/agents/unit-landscape-client-0/charm/hooks/hooks.py", line 38, in registration_relation
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed landscape_broker=landscape_broker)
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed File "/var/lib/juju/agents/unit-landscape-client-0/charm/hooks/hooks.py", line 74, in config_changed
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed _write_certificate(relation_data["ssl-public-key"][7:], CERT_FILE)
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed File "/var/lib/juju/agents/unit-landscape-client-0/charm/hooks/hooks.py", line 218, in _write_certificate
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed file.write(base64.b64decode(certificate))
unit-landscape-client-0: 17:24:22 DEBUG unit.landscape-client/0.registration-relation-changed TypeError: write() argument must be str, not bytes
unit-landscape-client-0: 17:24:22 ERROR juju.worker.uniter.operation hook "registration-relation-changed" failed: exit status 1

[Dmitrii Shcherbakov (dmitriis)]

Fixed in charm rev 31.