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Redis Receiver exercise

  • Run the Redis instance as a Docker container exposing it at 127.0.0.1:16379:

    docker run --rm --name redis -d -p 127.0.0.1:16379:6379 redis

  • Connect to Redis using the telnet command. When connected, issue the INFO command:

    $ telnet localhost 16379
Trying ::1...
Connected to localhost.
Escape character is '^]'.
INFO

    You should see information about your Redis instance

    $4713
# Server
redis_version:7.0.0
redis_git_sha1:00000000
redis_git_dirty:0
redis_build_id:1fad57151235ad0c
redis_mode:standalone
os:Linux 5.4.0-110-generic x86_64
arch_bits:64
...

    To exit issue the QUIT command.

    Notice that Redis's INFO is different from the OpenTelemetry or Prometheus one, it uses it's own schema. We need otelcol be able to work with this schema - so it needs to be translated during ingestion. That's the job for the Redis Receiver.

  • Read the Redis Receiver documentation

  • Take a look at the config.yaml configuration file and run otelcol with this config locally:

    otelcol-contrib --config config.yaml

  • You should see an error because your Redis instance is not running on a default 6379 port:

    2022-05-22T10:01:15.032+0200	error	scraperhelper/scrapercontroller.go:198	Error scraping metrics	{"kind": "receiver", "name": "redis", "error": "dial tcp [::1]:6379: connect: connection refused", "scraper": "redis"}
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).scrapeMetricsAndReport
  go.opentelemetry.io/collector@v0.51.0/receiver/scraperhelper/scrapercontroller.go:198
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).startScraping.func1
  go.opentelemetry.io/collector@v0.51.0/receiver/scraperhelper/scrapercontroller.go:173

    The error is caused by this configuration line: endpoint: $REDIS_ENDPOINT. If there is no such variable in our environment the receiver tries to connect using default values.

  • Export the environment variable end try running otelcol again:

    $ export REDIS_ENDPOINT=127.0.0.1:16379
$ otelcol-contrib --config config.yaml

  • You should be able to see the metrics ingested into otelcol at this point. Notice how they don't have any information about the host attached. We will show you how to do it in the Resource Detection Processor exercise. But that's later - for now go to the next step.

  • Remove the Redis container:

    docker rm -f redis