progress

.gitignore

@@ -127,3 +127,9 @@ dmypy.json
 
 # Pyre type checker
 .pyre/
+
+*.swp
+*.swo
+id_rsa
+kubeconfig
+*.charm

.testfaster.yml

@@ -22,6 +22,8 @@ base:
     # You can also pull docker images like this. Always use
     # immutable tags for reproducibility!
     - nginx:1.19.5
+    - jujusolutions/juju-db:4.0
+    - jujusolutions/jujud-operator:2.9-rc3
 
   prewarm_script: |-
     # This gets run after each individual VM starts up, so
@@ -35,13 +37,19 @@ base:
     # pod to the apiserver. so give it an ip address that resolves to the host
     # from inside the pods.
     cd /root
-    snap install juju --classic --channel=latest/edge
+    snap install juju --classic --channel=2.9/edge
     # Set kubeconfig to point to k8s apiserver on an address that's routable
     # from inside the pods, so jujud can access it.  In this case the docker
     # bridge.
     sed -i 's/localhost/172.17.0.1/' .kube/config
+
     juju add-k8s --client testfaster
     juju bootstrap testfaster
+    
+    # default service account has registry credentials, but juju needs them too
+    # (testfaster created the secret regcred already.)
+    kubectl patch serviceaccount -n controller-testfaster default -p '{"imagePullSecrets": [{"name": "regcred"}]}'
+
     juju add-model kf
     # cs: means "charm store", which is the "old place".
     # ch: means "charm hub", which is the "new place".

bundle.yaml

@@ -0,0 +1,13 @@
+---
+applications:
+  mlflow:
+    charm: "./mlflow.charm"
+    scale: 1
+  postgres:
+    charm: "cs:~postgresql-charmers/postgresql-k8s"
+    scale: 1
+bundle: kubernetes
+description: "MLflow"
+relations:
+  - - mlflow:db
+    - postgres:db

integration_test

@@ -5,6 +5,15 @@ testctl get
 export KUBECONFIG=$(pwd)/kubeconfig
 (cd mlflow && charmcraft build)
 ./testctl-rsync.sh mlflow/mlflow.charm /root
-#./testctl-ssh.sh -- /snap/bin/juju deploy --resource oci-image=gcr.io/kubeflow-images-public/admission-webhook:vmaster-gaf96e4e3 ./mlflow.charm
-./testctl-ssh.sh -- /snap/bin/juju deploy ./mlflow.charm
+./testctl-rsync.sh bundle.yaml /root
+
+# How to iterate quickly without getting a new VM every time:
+#./testctl-ssh.sh -- /snap/bin/juju destroy model kf
+#./testctl-ssh.sh -- /snap/bin/juju destroy controller
+#./testctl-ssh.sh -- /snap/bin/juju unregister controller
+
+./testctl-ssh.sh -- /snap/bin/juju deploy ./bundle.yaml
+
 echo "Try: testctl ssh -- /snap/bin/juju debug-log --include mlflow"
+
+#./testctl-ssh.sh -- /snap/bin/juju deploy --resource oci-image=gcr.io/kubeflow-images-public/admission-webhook:vmaster-gaf96e4e3 ./mlflow.charm

mlflow/.flake8

@@ -0,0 +1,9 @@
+[flake8]
+max-line-length = 99
+select: E,W,F,C,N
+exclude:
+  venv
+  .git
+  build
+  dist
+  *.egg_info

mlflow/.jujuignore

@@ -0,0 +1,3 @@
+/venv
+*.py[cod]
+*.charm

mlflow/metadata.yaml

@@ -11,3 +11,8 @@ series: [kubernetes]
 #    type: oci-image
 #    description: Backing OCI image
 #    auto-fetch: true
+requires:
+  db:
+    interface: pgsql
+    limit: 1  # Most charms only handle a single PostgreSQL Application.
+

mlflow/requirements.txt

@@ -1,2 +1,3 @@
-ops
+ops==0.8.0
 git+git://github.com/johnsca/resource-oci-image.git#oci_image
+ops-lib-pgsql

mlflow/src/charm.py

@@ -10,6 +10,9 @@
 from ops.model import ActiveStatus, MaintenanceStatus
 logger = logging.getLogger(__name__)
 
+import ops.lib
+pgsql = ops.lib.use("pgsql", 1, "postgresql-charmers@lists.launchpad.net")
+
 class MlflowCharm(CharmBase):
     _stored = StoredState()
 
@@ -19,6 +22,12 @@ def __init__(self, *args):
         logger.info("================================")
         super().__init__(*args)
 
+        self._stored.set_default(db_conn_str=None, db_uri=None, db_ro_uris=[])
+        self.db = pgsql.PostgreSQLClient(self, 'db')  # 'db' relation in metadata.yaml
+        self.framework.observe(self.db.on.database_relation_joined, self._on_database_relation_joined)
+        self.framework.observe(self.db.on.master_changed, self._on_master_changed)
+        self.framework.observe(self.db.on.standby_changed, self._on_standby_changed)
+
         self.framework.observe(self.on.install, self.set_pod_spec)
         self.framework.observe(self.on.upgrade_charm, self.set_pod_spec)
 
@@ -47,5 +56,48 @@ def set_pod_spec(self, event):
         )
         self.model.unit.status = ActiveStatus()
 
+    def _on_database_relation_joined(self, event: pgsql.DatabaseRelationJoinedEvent):
+        if self.model.unit.is_leader():
+            # Provide requirements to the PostgreSQL server.
+            event.database = 'mydbname'  # Request database named mydbname
+            event.extensions = ['citext']  # Request the citext extension installed
+        elif event.database != 'mydbname':
+            # Leader has not yet set requirements. Defer, incase this unit
+            # becomes leader and needs to perform that operation.
+            event.defer()
+            return
+
+    def _on_master_changed(self, event: pgsql.MasterChangedEvent):
+        if event.database != 'mydbname':
+            # Leader has not yet set requirements. Wait until next event,
+            # or risk connecting to an incorrect database.
+            return
+
+        # The connection to the primary database has been created,
+        # changed or removed. More specific events are available, but
+        # most charms will find it easier to just handle the Changed
+        # events. event.master is None if the master database is not
+        # available, or a pgsql.ConnectionString instance.
+        self._stored.db_conn_str = None if event.master is None else event.master.conn_str
+        self._stored.db_uri = None if event.master is None else event.master.uri
+
+        # You probably want to emit an event here or call a setup routine to
+        # do something useful with the libpq connection string or URI now they
+        # are available.
+
+    def _on_standby_changed(self, event: pgsql.StandbyChangedEvent):
+        if event.database != 'mydbname':
+            # Leader has not yet set requirements. Wait until next event,
+            # or risk connecting to an incorrect database.
+            return
+
+        # Charms needing access to the hot standby databases can get
+        # their connection details here. Applications can scale out
+        # horizontally if they can make use of the read only hot
+        # standby replica databases, rather than only use the single
+        # master. event.stanbys will be an empty list if no hot standby
+        # databases are available.
+        self._stored.db_ro_uris = [c.uri for c in event.standbys]
+
 if __name__ == "__main__":
     main(MlflowCharm)