Loki Charmed Operator for K8s
Welcome to the Loki Charmed Operator documentation!
This Charmed Operator handles instantiation, scaling, configuration, optimisation, networking, service mesh, observability, and Day 2 operations specific to Loki.
On the principle that an operator should “do one thing and do it well”, this operator drives Loki application only. However, it can be composed with other operators to deliver a complex application or service. Because operators package expert knowledge in a reusable and shareable form, they hugely simplify software management and operations.
Getting started
Basic deployment
Create a Juju model for your operator, say “observability”
juju add-model observability
The Loki Charmed Operator may be deployed using the Juju command line in a quite very way.
juju deploy loki-k8s --channel=edge --trust
Checking deployment status
Once the Charmed Operator is deployed, the status can be checked running:
juju status --color --relations
Model Controller Cloud/Region Version SLA Timestamp
observability mk8s microk8s/localhost 2.9.21 unsupported 16:19:00-03:00
App Version Status Scale Charm Store Channel Rev OS Address Message
loki-k8s active 1 loki-k8s charmhub edge 11 kubernetes 10.152.183.26
Unit Workload Agent Address Ports Message
loki-k8s/0* active idle 10.1.51.38
As we can appreciate, deploying Loki in Kubernetes using Juju involves only two commands!
Loki HTTP API
Loki Charmed Operator exposes its HTTP API over port 3100.
Example 1 - Get Loki version:
/loki/api/v1/status/buildinfo exposes the build information in a JSON object.
The fields are version, revision, branch, buildDate, buildUser, and goVersion.
loki_ip=$(juju status loki-k8s/0 | grep "loki-k8s/0" | awk '{print $4}')
curl http://$loki_ip:3100/loki/api/v1/status/buildinfo
{"version":"2.4.1","revision":"f61a4d261","branch":"HEAD","buildUser":"root@39a6e600b2df","buildDate":"2021-11-08T13:09:51Z","goVersion":""}
Example 2 - Send logs entries to Loki with curl:
/loki/api/v1/push is the endpoint used to send log entries to Loki. The default behavior is for the POST body to be a snappy-compressed protobuf message.
Alternatively, if the Content-Type header is set to application/json, a JSON post body can be sent in the following format:
loki_ip=$(juju status loki-k8s/0 | grep "loki-k8s/0" | awk '{print $4}')
curl -v -H "Content-Type: application/json" -XPOST -s "http://$loki_ip:3100/loki/api/v1/push" --data-raw \
'{"streams": [{ "stream": { "foo": "bar2" }, "values": [ [ "1570818238000000000", "fizzbuzz" ] ] }]}'
Example 3 - Send logs entries to Loki with Promtail:
Promtail is an agent which ships the contents of local logs to Loki. It is usually deployed to every machine that has applications needed to be monitored.
It primarily:
- Discovers targets
- Attaches labels to log streams
- Pushes them to the Loki instance.
Currently, Promtail can tail logs from two sources: local log files and the systemd journal (on AMD64 machines only).
To set up a Promtail instance to work with Loki Charmed Operator please refer to Configuring Promtail documentation. Anyway the most important part is the clients section in Promtail config file, for instance:
clients:
- url: http://<LOKI_ADDRESS>:3100/loki/api/v1/push
OCI Images
Every release of the Loki Charmed Operator uses the latest stable version of grafana/loki at the time of release.
Official Documentation
For further details about Loki configuration and usage, please refer to Grafana Loki Documentation