Istio Beacon
- Canonical Observability
| Channel | Revision | Published | Runs on |
|---|---|---|---|
| latest/edge | 20 | 29 Jan 2025 |
juju deploy istio-beacon-k8s --channel edge
Deploy universal operators easily with Juju, the Universal Operator Lifecycle Manager.
Platform:
charms.istio_beacon_k8s.v0.service_mesh
-
- Last updated 13 Jan 2025
- Revision Library version 0.2
#Service Mesh Library.
The service mesh library is used to facilitate adding your charmed application to a service mesh.
The library leverages the service_mesh and cross_model_mesh interfaces.
##Consumer
Service meshes provide a range of capabilities for routing, controlling, and monitoring traffic. A key feature of many service meshes is the ability to restrict traffic between Pods based on L4 and L7 criteria. For example, defining that a Pod MetricsScraper can GET from Pod MetricsProducer at /metrics on port 9090, but SomeOtherPod cannot.
The ServiceMeshConsumer object is used to subscribe a charm and its workloads to a related service mesh. Since it is common for a relation between applications to indicate traffic flow (ex: if DbConsumer Requires a DbProducer), the ServiceMeshConsumer provides an optional way to automate creation of traffic rules based on app relations.
To add service mesh support to your charm, you must add 3 relations in your charmcraft.yaml.
requires:
service-mesh:
limit: 1
interface: service_mesh
require-cmr-mesh:
interface: cross_model_mesh
provides:
provide-cmr-mesh:
interface: cross_model_mesh
Then instantiate a ServiceMeshConsumer object in the
__init__ method of your charm:
from charms.istio_beacon_k8s.v0.service_mesh import Policy, ServiceMeshConsumer
...
self._mesh = ServiceMeshConsumer(
self,
policies=[
Policy(
relation="metrics",
endpoints=[
Endpoint(
hosts=[self._my_host_name],
ports=[HTTP_LISTEN_PORT],
methods=["GET"],
paths=["/metrics"],
),
],
),
Policy(
relation="data",
endpoint=[
Endpoint(
hosts=[self._my_host_name],
ports[HTTP_LISTEN_PORT],
methods=["GET"]
paths=["/data"],
),
],
),
],
)
The example above specifies two policies. The resulting behaviour would be that when related over the metrics relation, the service mesh will allow traffic to the /metrics endpoint for the remote application and when related over the data endpoint, the service mesh will allow traffic to the /data endpoint.
By using the above method, you can specify exactly which endpoints can be reached over which relations.
###Cross Model relations
If a ServiceMeshConsumer is creating a Policy for a relation that is cross model, additional information is required to construct the policy. To facilitate this, the charms can also be related over the cross_model_mesh interface. When that relation is established, traffic will be allowed from the requirer to the provider.
###Joining the Mesh
For most charms, simply instantiating ServiceMeshConsumer should automatically configure the charm to be on the mesh. If your charm is the one of the old "podspec" style charms or your charm deploys custom k8s resources there is an addition step. You must apply the labels returned by ServiceMeshConsumer.labels() to your pods.
##Provider
To provide a service mesh, instantiate the ServiceMeshProvider object in the init method of your charm:
from charms.istio_beacon_k8s.v0.service_mesh import ServiceMeshProvider
...
self._mesh = ServiceMeshProvider(
charm = self,
labels = {"my_service_mesh": "enable"},
mesh_relation_name = "service-mesh",
)
The labels argument is the dict of labels that indicate to the service mesh that a Pod should be subscribed to the mesh. These will be sent to each related ServiceMeshConsumer to be used by the charm for per-Pod subscription. These labels are service-mesh dependent - for example, for an Istio ambient mesh this should be {"istio.io/dataplane-mode": "ambient"}.
The provider also exposes the method mesh_info that returns a list of MeshPolicy objects. These MeshPolicy objects can be used to configure the service mesh.
for policy in self._mesh.mesh_info():
set_up_my_mesh(policy)
Index
class Method
Description
HTTP method. None
class Endpoint
Description
Data type for a policy endpoint. None
class Policy
Description
Data type for defining a policy for your charm. None
class MeshPolicy
Description
Data type for storage service mesh policy information. None
class CMRData
Description
Data type containing the info required for cross-model relations. None
class ServiceMeshConsumer
Description
Class used for joining a service mesh. None
Methods
ServiceMeshConsumer. __init__( self , charm: CharmBase , mesh_relation_name: str , cross_model_mesh_requires_name: str , cross_model_mesh_provides_name: str , policies , auto_join: bool )
Class used for joining a service mesh.
Arguments
The charm instantiating this object.
The relation name as defined in metadata.yaml or charmcraft.yaml for the relation which uses the service_mesh interface.
The relation name as defined in metadata.yaml or charmcraft.yaml for the relation which requires the cross_model_mesh interface.
The relation name as defined in metadata.yaml or charmcraft.yaml for the relation which provides the cross_model_mesh interface.
List of access policies this charm supports.
Automatically join the mesh by applying labels to charm pods.
ServiceMeshConsumer. update_service_mesh( self )
Update the service mesh.
Description
Gathers information from all relations of the charm and updates the mesh appropriately to allow communication.
ServiceMeshConsumer. labels( self )
Description
Labels required for a pod to join the mesh. None
class ServiceMeshProvider
Description
Provide a service mesh to applications. None
Methods
ServiceMeshProvider. __init__( self , charm: CharmBase , labels , mesh_relation_name: str )
Class used to provide information needed to join the service mesh.
Arguments
The charm instantiating this object.
The relation name as defined in metadata.yaml or charmcraft.yaml for the relation which uses the service_mesh interface.
The labels which related applications need to apply to use the mesh.
ServiceMeshProvider. update_relations( self )
Description
Update all relations with the labels needed to use the mesh. None
ServiceMeshProvider. mesh_info( self )
Description
Return the relation data that defines Policies requested by the related applications. None