Redis

Spin up an isolated Redis branch with mirrord - in the cluster or on your own machine

This page covers DB branching for Redis. For the general concepts, the full list of config fields, and how a session behaves, see the DB Branching overview.

Redis is the only engine that supports both branch locations:

• "location": "remote" (default) provisions a branch pod in the cluster, like the other engines.
• "location": "local" spawns a Redis instance on your own machine.

Remote Redis branching requires operator 3.168.0, mirrord CLI 3.217.0, and operator Helm chart 3.168.0 with the operator.redisBranching value set to true. Local Redis branching only requires mirrord CLI 3.180.0 - there are no operator or chart version requirements, since a local branch runs entirely on your machine.

Remote Branches

{
  "feature": {
    "db_branches": [
      {
        "id": "cache-redis",
        "type": "redis",
        "version": "7.2",
        "name": "0",
        "connection": {
          "url": "REDIS_URL"
        },
        "copy": {
          "mode": "empty"
        }
      }
    ]
  }
}

The connection field describes how mirrord locates the source Redis connection details - a full connection URL or individual parameters (host, port, user, password, database). See Connection Modes for all supported sources, including Kubernetes Secrets, Google Secret Manager, literal values, and composite environment variables.

Database Index

For Redis, the name field is the database index Redis uses to select a logical database rather than a name, so it must be a valid non-negative number. If omitted, it defaults to index 0.

Copy Modes

Redis copy modes apply only to remote Redis branches. A local Redis branch always starts empty. Redis supports two modes:

Mode	What gets cloned
"empty" (default)	Nothing - a fresh, empty Redis instance
"all"	Keys from the source Redis instance, optionally filtered with patterns

By default "all" copies the entire keyspace. To copy only a subset, add patterns - a list of SCAN MATCH glob patterns. Only keys matching at least one pattern are copied.

{
  "copy": {
    "mode": "all",
    "patterns": ["user:*", "session:*"]
  }
}

In this example, only keys prefixed with user: or session: are copied; everything else is left out of the branch.

Redis has no schema, so there is no "schema" copy mode - only "empty" and "all" are available. Filtering is done by key pattern rather than by SQL query.

Local Redis

mirrord can spin up a local Redis instance, automatically redirecting your app's Redis traffic to it.

{
  "feature": {
    "db_branches": [
      {
        "type": "redis",
        "location": "local",                     // "remote" (default) or "local"
        "connection": {
          // Use "host" if your app reads Redis as host:port (e.g. REDIS_ADDR=redis:6379)
          // Use "url" if your app reads a full Redis URL (e.g. REDIS_URL=redis://user:pass@redis:6379/0)
          "host": { "type": "env", "variable": "REDIS_ADDR" }
        },
        "local": {                               // Optional runtime config
          "port": 6379,                          // Custom port (default: 6379)
          "runtime": "container",                // "container" (default), "redis_server", or "auto"
          "container_runtime": "docker"          // "docker" (default), "podman", or "nerdctl"
        }
      }
    ]
  }
}

mirrord overrides the env variable to point to localhost:<port> and cleans up the Redis instance on exit.

Notes on local branches:

• A local branch always starts empty - copy modes do not apply.
• The id field is not used for local Redis instances and has no effect on database selection or reuse.
• local.port: Sessions that use the same port share a single local Redis database. When a new session starts on that port, it creates a new database instance that replaces the existing one.