If you have an elixir app running on Fly.io, it’s easy to send telemetry data to GrafanaCloud.
Lets start with Logs.
Logs
Shipping logs to GrafanaCloud requires setup and deployment of another app called LogShipper.
Setting up LogShipper
-
Create a new directory
mkdir logshipper
-
Create a new app, but don’t launch yet
fly launch --no-deploy --image ghcr.io/superfly/fly-log-shipper:latest`
-
Configure your org and access token
fly secrets set ORG=personal fly secrets set ACCESS_TOKEN=$(fly auth token)
-
Configure your Loki credentials. Find these in the GrafanaCloud Portal, Loki section. Hint: you may have to generate an API key.
fly secrets set LOKI_URL= fly secrets set LOKI_USERNAME= fly secrets set LOKI_PASSWORD=
-
Add this to the newly generated fly.toml file:
[[services]] http_checks = [] internal_port = 8686
-
Deploy
flyctl deploy
Once deployed, this should start sending all the logs from all your fly apps in the configured organization to GrafanaCloud.
Find all configuration options for the LogShipper app in the repository
Also, I’d recommend shipping your logs in JSON format using something like the logger_json
library.
Traces
To send Traces to GrafanaCloud Tempo, first add the OpenTelemetry libraries. Depending on your needs, you may leave off some of these.
# ./mix.exs defp deps do
[
...
{:opentelemetry_exporter, "~> 1.0"},
{:opentelemetry, "~> 1.0"},
{:opentelemetry_api, "~> 1.0"},
{:opentelemetry_ecto, "~> 1.0"},
{:opentelemetry_liveview, "~> 1.0.0-rc.4"},
{:opentelemetry_phoenix, "~> 1.0"},
{:opentelemetry_cowboy, "~> 0.2"}
]
end
Now add some configuration to the config/runtime.exs file.
# ./config/runtime.exs if config_env() == :prod do
otel_auth = System.get_env("OTEL_AUTH") ||
raise """
OTEL_AUTH is a required variable
"""
config :opentelemetry_exporter,
otlp_protocol: :grpc,
otlp_traces_endpoint: System.fetch_env!("OTLP_ENDPOINT"),
otlp_headers: [{"Authorization", "Basic #{otel_auth}"}]
end
Next, setup the environment variables.
-
The value required for
OTLP_ENDPOINT
can be found on the GrafanaCloud Portal Tempo section, and will look something like:https://tempo-us-central1.grafana.net/tempo
(your URL may differ) -
The value for
OTEL_AUTH
is a base64 encoded value of{username}:{api token}
.
(replace username and password with the actual values)echo -n 'username:password' | base64`
-
And you’ll need the data source name (found on the same GrafanaCloud Portal page) which will be used to set the value of
OTEL_RESOURCE_ATTRIBUTES
All of these values can be set with one command:
flyctl secrets set OTLP_ENDPOINT=https://your_endpoint OTEL_RESOURCE_ATTRIBUTES=your_datasource_name OTEL_AUTH=your_base64_encoded_string
After setting these values and deploying the application, traces should start showing in Grafana!
Metrics
For Metrics, I really like to use Prometheus and I find the easiest way to get started with Prometheus is using prom_ex. PromEx provides excellent documentation and is worth reading, but a quick guide to get it working:
-
Add
:prom_ex, "~> 1.8"
to your dependencies inmix.exs
and runmix deps.get
-
Run the generator
mix prom_ex.gen.config --datasource curl`
-
Add configuration in
config.exs
for the metrics serverconfig :your_app, YourApp.PromEx, metrics_server: [ port: System.get_env("PROM_PORT") || 9091, path: "/metrics", protocol: :http, pool_size: 5 ]
-
Add
YourApp.PromEx
to your supervision tree inapplication.ex
def start(_type, _args) do children = [ YourAppWeb.Endpoint, # PromEx should be started after the Endpoint, to avoid unnecessary error messages YourApp.PromEx, ... ]
-
Lastly, uncomment any desired plugins in the generated
YourApp.PromEx
file.
Now running the app exposes the metrics at localhost:9091/metrics
.
Next, expose the metrics so that Fly can scrape them. As documented by Fly, just add the following to your fly.toml file:
[metrics] port = 9091
path = "/metrics"
Setup the Prometheus data source in GrafanaCloud with the following properties:
-
HTTP -> URL “https://api.fly.io/prometheus/<org-slug>/“ (replace
org_slug
with your org) - Custom HTTP Headers -> + Add Header:
-
Header: Authorization, Value: Bearer <token> (replace
token
with the result offlyctl auth token
You should now see fly metrics and prom_ex
defined metrics in GrafanaCloud.
Wrap up
I wrote this because I wanted to add observability to my Elixir/Phoenix apps that run on Fly and finding the information I needed was scattered throughout the docs.
Happy Observing