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
.
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