Redis proxy

• Redis architecture overview

• This filter should be configured with the type URL type.googleapis.com/envoy.extensions.filters.network.redis_proxy.v3.RedisProxy.

• v3 API reference

Statistics

Every configured Redis proxy filter has statistics rooted at redis.<stat_prefix>. with the following statistics:

Name	Type	Description
downstream_cx_active	Gauge	Total active connections
downstream_cx_protocol_error	Counter	Total protocol errors
downstream_cx_rx_bytes_buffered	Gauge	Total received bytes currently buffered
downstream_cx_rx_bytes_total	Counter	Total bytes received
downstream_cx_total	Counter	Total connections
downstream_cx_tx_bytes_buffered	Gauge	Total sent bytes currently buffered
downstream_cx_tx_bytes_total	Counter	Total bytes sent
downstream_cx_drain_close	Counter	Number of connections closed due to draining
downstream_rq_active	Gauge	Total active requests
downstream_rq_total	Counter	Total requests

Splitter statistics

The Redis filter will gather statistics for the command splitter in the redis.<stat_prefix>.splitter. with the following statistics:

Name	Type	Description
invalid_request	Counter	Number of requests with an incorrect number of arguments
unsupported_command	Counter	Number of commands issued which are not recognized by the command splitter

Per command statistics

The Redis filter will gather statistics for commands in the redis.<stat_prefix>.command.<command>. namespace. By default latency stats are in milliseconds and can be changed to microseconds by setting the configuration parameter latency_in_micros to true.

Name	Type	Description
total	Counter	Number of commands
success	Counter	Number of commands that were successful
error	Counter	Number of commands that returned a partial or complete error response
latency	Histogram	Command execution time in milliseconds (including delay faults)
error_fault	Counter	Number of commands that had an error fault injected
delay_fault	Counter	Number of commands that had a delay fault injected

Runtime

The Redis proxy filter supports the following runtime settings:

redis.drain_close_enabled

% of connections that will be drain closed if the server is draining and would otherwise attempt a drain close. Defaults to 100.

Fault Injection

The Redis filter can perform fault injection. Currently, Delay and Error faults are supported. Delay faults delay a request, and Error faults respond with an error. Moreover, errors can be delayed.

Note that the Redis filter does not check for correctness in your configuration - it is the user’s responsibility to make sure both the default and runtime percentages are correct! This is because percentages can be changed during runtime, and validating correctness at request time is expensive. If multiple faults are specified, the fault injection percentage should not exceed 100% for a given fault and Redis command combination. For example, if two faults are specified; one applying to GET at 60 %, and one applying to all commands at 50%, that is a bad configuration as GET now has 110% chance of applying a fault. This means that every request will have a fault.

If a delay is injected, the delay is additive - if the request took 400ms and a delay of 100ms is injected, then the total request latency is 500ms. Also, due to implementation of the redis protocol, a delayed request will delay everything that comes in after it, due to the proxy’s need to respect the order of commands it receives.

Note that faults must have a fault_enabled field, and are not enabled by default (if no default value or runtime key are set).

Example configuration:

faults:
- fault_type: ERROR
  fault_enabled:
    default_value:
      numerator: 10
      denominator: HUNDRED
    runtime_key: "bogus_key"
    commands:
    - GET
  - fault_type: DELAY
    fault_enabled:
      default_value:
        numerator: 10
        denominator: HUNDRED
      runtime_key: "bogus_key"
    delay: 2s

This creates two faults- an error, applying only to GET commands at 10%, and a delay, applying to all commands at 10%. This means that 20% of GET commands will have a fault applied, as discussed earlier.

DNS lookups on redirections

As noted in the architecture overview, when Envoy sees a MOVED or ASK response containing a hostname it will not perform a DNS lookup and instead bubble up the error to the client. The following configuration example enables DNS lookups on such responses to avoid the client error and have Envoy itself perform the redirection:

typed_config:
  "@type": type.googleapis.com/envoy.extensions.filters.network.redis_proxy.v3.RedisProxy
  stat_prefix: redis_stats
  prefix_routes:
    catch_all_route:
      cluster: cluster_0
  settings:
    op_timeout: 5
    enable_redirection: true
    dns_cache_config:
      name: dns_cache_for_redis
      dns_lookup_family: V4_ONLY
      max_hosts: 100