I consider to store data inside configmap(or secret). Can I trust GKE to keep the configmap up all the time? or its better to use PVC in order to keep such data?

Configmaps and Secrets are stored in etcd at master, so yes, you can trust it will be always available to the cluster and it's designed to host configuration files (and secrets, respectively).

What is the SLA in GKE for secrets\configmap?

• From GKE SLA:

As of November 28, 2017, Google Kubernetes Engine no longer charges a flat fee per hour per cluster for cluster management, regardless of cluster size, as provided at GKE Pricing. Accordingly, Google no longer offers a financially-backed service level agreement for the Google Kubernetes Engine service.

• However, the service availability of nodes in a Google Kubernetes Engine-managed cluster is covered by the Google Compute Engine SLA since each node is a Compute Engine instance you can expect availability of:

  • Instances in Multiple Zones >= 99.99%
  • A Single Instance >= 99.5%
  • Load balancing >= 99.99%

Nevertheless, Uptime for Google Kubernetes Engine is highly important to Google, and Google has an internal goal to keep the monthly uptime percentage at 99.5% for the Kubernetes API server for zonal clusters and 99.95% for regional clusters regardless of the applicability of a financially-backed service level agreement.

Since its not a big amount of data and its more like configuration thing, but its changing all the time, so I update the configmap with updates. So the question again - can we trust configmap\secret to be there all the time or should we store there only static information?

Yes you can trust it, just keep in mind that the hard limit for each object in etcd cluster be it configmap or secret is 1MB, since you mention the data is not small, it should be sufficient for configuration files.

You can learn more about etcd here:

• A Closer Look at Etcd: The Brain of a Kubernetes Cluster
• Etcd Official Documentation