Charmed MySQL How-To | Enable tracing

shayanp · 12 June 2024 12:28

Note: All commands are written for juju >= v3.1

If you’re using juju 2.9, check the juju 3.0 Release Notes.

Enable tracing

This guide contains the steps to enable tracing with Grafana Tempo for your MySQL application.

To summarize:

Deploy the Tempo charm in a COS K8s environment
Offer interfaces for cross-model integrations
Consume and integrate cross-model integrations
View MySQL traces on Grafana

Warning: This is feature is in development. It is not recommended for production environments.

This feature is available for Charmed MySQL revision 237+ only.

Prerequisites

Enabling tracing with Tempo requires that you:

Have deployed a Charmed MySQL application
- See How to manage units
Have deployed a ‘cos-lite’ bundle from the latest/edge track in a Kubernetes environment
- See Getting started on MicroK8s

Deploy Tempo

First, switch to the Kubernetes controller where the COS model is deployed:

juju switch <k8s_controller_name>:<cos_model_name>

Then, deploy the dependencies of Tempo following this tutorial. In particular, we would want to:

Deploy the minio charm
Deploy the s3 integrator charm
Add a bucket in minio using a python script
Configure s3 integrator with the minio credentials

Finally, deploy and integrate with Tempo HA in a monolithic setup.

Offer interfaces

Next, offer interfaces for cross-model integrations from the model where Charmed MySQL is deployed.

To offer the Tempo integration, run

juju offer <tempo_coordinator_k8s_application_name>:tracing

Then, switch to the Charmed MySQL VM model, find the offers, and integrate (relate) with them:

juju switch <machine_controller_name>:<mysql_model_name>

juju find-offers <k8s_controller_name>:

Do not miss the “:” in the command above.

Below is a sample output where k8s is the K8s controller name and cos is the model where cos-lite and tempo-k8s are deployed:

Store  URL                            Access  Interfaces
k8s    admin/cos.tempo                admin   tracing:tracing

Next, consume this offer so that it is reachable from the current model:

juju consume k8s:admin/cos.tempo

Consume interfaces

First, deploy Grafana Agent from the latest/edge channel:

juju deploy grafana-agent --channel latest/edge

Then, integrate Grafana Agent with Charmed MySQL:

juju integrate mysql:cos-agent grafana-agent:cos-agent

Finally, integrate Grafana Agent with the consumed interface from the previous section:

juju integrate grafana-agent:tracing tempo:tracing

Wait until the model settles. The following is an example of the juju status --relations on the Charmed MySQL model:

Model     Controller  Cloud/Region         Version  SLA          Timestamp
database  lxd         localhost/localhost  3.5.4    unsupported  19:15:55Z

SAAS   Status  Store       URL
tempo  active  k8s         admin/cos.tempo

App            Version          Status   Scale  Charm          Channel      Rev  Exposed  Message
grafana-agent                   blocked      1  grafana-agent  latest/edge  282  no       Missing ['grafana-cloud-config']|['grafana-dashboards-provider']|['logging-consumer']|['send-remote-write'] for cos-a...
mysql          8.0.37-0ubun...  active       1  mysql                         0  no       

Unit                Workload  Agent  Machine  Public address  Ports           Message
mysql/0*            active    idle   0        10.205.193.32   3306,33060/tcp  Primary
  grafana-agent/0*  blocked   idle            10.205.193.32                   Missing ['grafana-cloud-config']|['grafana-dashboards-provider']|['logging-consumer']|['send-remote-write'] for cos-a...

Machine  State    Address        Inst id        Base          AZ  Message
0        started  10.205.193.32  juju-4f3e50-0  ubuntu@22.04      Running

Integration provider  Requirer                 Interface              Type         Message
grafana-agent:peers   grafana-agent:peers      grafana_agent_replica  peer         
mysql:cos-agent       grafana-agent:cos-agent  cos_agent              subordinate  
mysql:database-peers  mysql:database-peers     mysql_peers            peer         
mysql:restart         mysql:restart            rolling_op             peer         
mysql:upgrade         mysql:upgrade            upgrade                peer         
tempo:tracing         grafana-agent:tracing    tracing                regular

Note: All traces are exported to Tempo using HTTP. Support for sending traces via HTTPS is an upcoming feature.

View traces

After this is complete, the Tempo traces will be accessible from Grafana under the Explore section with tempo-k8s as the data source. You will be able to select mysql as the Service Name under the Search tab to view traces belonging to Charmed MySQL.

Below is a screenshot demonstrating a Charmed MySQL trace:

Feel free to read through the Tempo HA documentation at your leisure to explore its deployment and its integrations.