Difficulty: Moderate
Estimated Time: 10 minutes

Intro: Downsampling and unlimited metric retention for Prometheus

They say that Thanos is a set of components that can be composed into a highly available metric system with unlimited storage capacity and that it can be added seamlessly on top of existing Prometheus deployments. 🤔🤔

In this course you can experience all of this yourself.

In this tutorial, you will learn about:

  • How to start uploading your Prometheus data seamlessly to cheap object storage thanks to Thanos sidecar.
  • How to further query your data in object storage thanks to Thanos Store Gateway.
  • How to query both fresh and older data in easy way through Thanos Querier.

All of this allows you to keep your metrics in cheap and reliable object storage, allowing virtually unlimited metric retention for Prometheus.

NOTE: This course uses docker containers with pre-built Thanos, Prometheus, and Minio Docker images available publicly. However, a similar scenario will work with any other deployment method like Kubernetes or systemd, etc.


Please complete first intro course about GlobalView before jumping into this one! 🤗


Do you see any bug, typo in the tutorial or you have some feedback for us? Let us know on https://github.com/thanos-io/thanos or #thanos slack channel linked on https://thanos.io

Contributed by:

Intro: Downsampling and unlimited metric retention for Prometheus

Step 1 of 4

Configuring Initial Prometheus Server

Step 1 - Initial Prometheus Setup

In this tutorial, we will mimic the usual state with a Prometheus server running for... a year!. We will use it to seamlessly backup all old data in the object storage and configure Prometheus for continuous backup mode, which will allow us to cost-effectively achieve unlimited retention for Prometheus.

Last but not the least, we will go through setting all up for querying and automated maintenance (e.g compactions, retention and downsampling).

In order to showcase all of this, let's start with single cluster setup from the previous course. Let's start this initial Prometheus setup, ready?

Generate Artificial Metrics for 1 year

Actually, before starting Prometheus, let's generate some artificial data. You most likely want to learn about Thanos fast, so you probably don't have months to wait for this tutorial until Prometheus collects the month of metrics, do you? (:

We will use our handy thanosbench project to do so! Let's generate Prometheus data (in form of TSDB blocks) with just 5 series (gauges) that spans from a year ago until now (-6h)!

Execute the following command (should take few seconds):

mkdir -p /root/prom-eu1 && docker run -i quay.io/thanos/thanosbench:v0.2.0-rc.1 block plan -p continuous-365d-tiny --labels 'cluster="eu1"' --max-time=6h | docker run -v /root/prom-eu1:/prom-eu1 -i quay.io/thanos/thanosbench:v0.2.0-rc.1 block gen --output.dir prom-eu1

On successful block creation you should see following log lines:

level=info ts=2020-10-20T18:28:42.625041939Z caller=block.go:87 msg="all blocks done" count=13
level=info ts=2020-10-20T18:28:42.625100758Z caller=main.go:118 msg=exiting cmd="block gen"

Run below command to see dozens of generated TSDB blocks:

ls -lR /root/prom-eu1

Prometheus Configuration File

Here, we will prepare configuration files for the Prometheus instance that will run with our pre-generated data. It will also scrape our components we will use in this tutorial.

Click Copy To Editor for config to propagate the configs to file.

  scrape_interval: 5s
    cluster: eu1
    replica: 0
    tenant: team-eu # Not needed, but a good practice if you want to grow this to multi-tenant system some day.

  - job_name: 'prometheus'
      - targets: ['']
  - job_name: 'sidecar'
      - targets: ['']
  - job_name: 'minio'
    metrics_path: /minio/prometheus/metrics
      - targets: ['']
  - job_name: 'querier'
      - targets: ['']
  - job_name: 'store_gateway'
      - targets: ['']

Starting Prometheus Instance

Let's now start the container representing Prometheus instance.

Note -v /root/prom-eu1:/prometheus \ and --storage.tsdb.path=/prometheus that allows us to place our generated data in Prometheus data directory.

Let's deploy Prometheus now. Note that we disabled local Prometheus compactions storage.tsdb.max-block-duration and min flags. Currently, this is important for the basic object storage backup scenario to avoid conflicts between the bucket and local compactions. Read more here.

We also extend Prometheus retention: --storage.tsdb.retention.time=1000d. This is because Prometheus by default removes all data older than 2 weeks. And we have a year (:

Deploying "EU1"

docker run -d --net=host --rm \
    -v /root/editor/prometheus0_eu1.yml:/etc/prometheus/prometheus.yml \
    -v /root/prom-eu1:/prometheus \
    -u root \
    --name prometheus-0-eu1 \
    quay.io/prometheus/prometheus:v2.20.0 \
    --config.file=/etc/prometheus/prometheus.yml \
    --storage.tsdb.retention.time=1000d \
    --storage.tsdb.path=/prometheus \
    --storage.tsdb.max-block-duration=2h \
    --storage.tsdb.min-block-duration=2h \
    --web.listen-address=:9090 \
    --web.external-url=https://[[HOST_SUBDOMAIN]]-9090-[[KATACODA_HOST]].environments.katacoda.com \
    --web.enable-lifecycle \

Setup Verification

Once started you should be able to reach the Prometheus instance here and query.. 1 year of data!

Thanos Sidecar & Querier

Similar to previous course, let's setup global view querying with sidecar:

docker run -d --net=host --rm \
    --name prometheus-0-eu1-sidecar \
    -u root \
    quay.io/thanos/thanos:v0.16.0 \
    sidecar \
    --http-address \
    --grpc-address \

And Querier. As you remember Thanos sidecar exposes StoreAPI so we will make sure we point the Querier to the gRPC endpoints of the sidecar:

docker run -d --net=host --rm \
    --name querier \
    quay.io/thanos/thanos:v0.16.0 \
    query \
    --http-address \
    --query.replica-label replica \

Setup verification

Similar to previous course let's check if the Querier works as intended. Let's look on Querier UI Store page.

This should list the sidecar, including the external labels.

On graph you should also see our 5 series for 1y time, thanks to Prometheus and sidecar StorAPI: Graph.

Click Continue to see how we can move this data to much cheaper and easier to operate object storage.

Prometheus 0 EU1
Thanos Query