Heroku Key-Value Store Metrics Logs

Last updated August 11, 2026

Customers using Heroku Key-Value Store instances see Valkey-related events on their app’s log stream. This can be useful for recording and analyzing usage over time.

Heroku Key-Value Store metrics which appear via heroku-redis are separate from standard alerts emitted from Valkey itself that appear for all apps via -p [redis-addon-name], for example, -p redis-metric-98068.

Log Format

You can view Heroku Key-Value Store metrics logs with heroku logs.

You can filter for Heroku Key-Value Store metrics logs on a specific app.

For Cedar-generation apps:

$ heroku logs -p heroku-redis -a example-app

For Fir-generation apps:

$ heroku logs -s heroku-redis -a example-app

For example, the Heroku Key-Value Store metrics logs can look like:

2025-12-10T12:10:39.000000+00:00 app[heroku-redis]: source=REDIS addon=redis-metric-98068 sample#active-connections=404 sample#load-avg-1m=0.115 sample#load-avg-5m=0.075 sample#load-avg-15m=0.07 sample#read-iops=0 sample#write-iops=54.758 sample#memory-total=15405660kB sample#memory-free=12639520kB sample#memory-cached=1911724kB sample#memory-redis=343477584bytes sample#hit-rate=0.7 sample#evicted-keys=0

The following attributes appear in app logs for all plans:

  • source: The instance attachment name that the measurements relate to.
  • addon: The instance add-on name that the measurements relate to.
  • The log line’s timestamp is the time at which the measurements were taken.

Key-Value Store Instance Metrics

These attributes apply to a particular Key-Value Store instance:

  • sample#active-connections: The number of connections established on the KVS instance.
  • sample#max-connections: The maximum number of connections available in the instance.
  • sample#connections-percentage-used: Percentage of connections used, between 0.0–1.0.
  • sample#memory-redis: Approximate amount of memory used by your KVS instance processes in bytes.
  • sample#hit-rate: The ratio of successful reads out of all read operations, rounded to five decimal points.
  • sample#evicted_keys: The number of evicted keys due to reaching your instance maxmemory limit.

Server Metrics

For multi-tenant plans, server metrics include other KVS instances running on the shared server, and may be misleading when diagnosing the performance of your KVS instance.

Server metrics come directly from the server operating system:

  • sample#load-avg-1m, sample#load-avg-5m and sample#load-avg-15m: The average system load over a period of 1 minute, 5 minutes and 15 minutes, divided by the number of available CPUs. A load-avg of 1.0 indicates that, on average, processes were requesting CPU resources for 100% of the timespan. This number includes I/O wait.
  • sample#read-iops and sample#write-iops: Number of read or write operations in I/O sizes of 16-KB blocks.
  • sample#max-iops: The maximum number of IOPS available in the instance.
  • sample#iops-percentage-used: Percentage of IOPS used between read and write IOPS, between 0.0–1.0.
  • sample#memory-total: Total amount of server memory in use, in KB. This includes memory used by all Valkey processes, OS memory, and disk cache.
  • sample#memory-free: Amount of free memory available in KB.
  • sample#memory-cached: Amount of memory being used the OS for page cache, in KB.
  • sample#memory-percentage-used: Percentage of server memory used on the instance, between 0.0–1.0.