Prometheus 2.x has a different data format from 1.x, so how do you access your old data from 2.x?
Prometheus 2.0 isn't out yet, but let's look at one of the migration issues.
Due to nature of Prometheus 1.x's storage, doing a direct migration of the data isn't very practical and the tooling for that hasn't been built. However there is a way to transparently access your old data.
The high level approach is to have the new 2.0 Prometheus transparently read data from the old 1.x Prometheus via the remote read feature.
The first step is to upgrade your 1.x Prometheus to at least version 1.8.2, so that it has the required support.
Secondly remove all of the configuration file in the 1.x Prometheus, except for external_labels. The old Prometheus now only exists as a data store. The entire config would look something like:
global:
external_labels:
region: eu-west-1
env: prod
# End of file.
Thirdly bring up a brand new Prometheus 2.0 with the full configuration file, including the same external_labels. (Normally every single Prometheus server should have unique external_labels. However as the 1.x Prometheus is no longer doing anything other than remote read and is effectively acting as remote storage, it's okay to have a duplicate). Don't forget to point the storage to a different path with --storage.tsdb.path and different port with --web.listen-address!
In addition the Prometheus 2.0 should have a remote_read section pointing to the 1.x Prometheus:
global:
external_labels:
region: eu-west-1
env: prod
remote_read:
- url: :9090/api/v1/read
# Rest of config goes here.
And that's it! You can then keep the Prometheus 1.x running until the data its holding is no longer relevant. Any queries to the Prometheus 2.0 will transparently pull data from the Prometheus 1.x as needed.
Want help planning the upgrade to Prometheus 2.0? Contact us.
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