Redis PubSub

Last updated: 4 minutes read.

Consume from a Redis publish/subscribe channel using either the SUBSCRIBE or PSUBSCRIBE commands.

Common

# Common config fields, showing default values
input:
  label: ""
  redis_pubsub:
    url: redis://:6397 # No default (required)
    channels: [] # No default (required)
    use_patterns: false
    auto_replay_nacks: true

Advanced

# All config fields, showing default values
input:
  label: ""
  redis_pubsub:
    url: redis://:6397 # No default (required)
    kind: simple
    master: ""
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    channels: [] # No default (required)
    use_patterns: false
    auto_replay_nacks: true

In order to subscribe to channels using the PSUBSCRIBE command set the field use_patterns to true, then you can include glob-style patterns in your channel names. For example:

  • h?llo subscribes to hello, hallo and hxllo
  • h*llo subscribes to hllo and heeeello
  • h[ae]llo subscribes to hello and hallo, but not hillo

Use \ to escape special characters if you want to match them verbatim.

Fields

url

The URL of the target Redis server. Database is optional and is supplied as the URL path.

Type: string

# Examples

url: redis://:6397

url: redis://localhost:6379

url: redis://foousername:foopassword@redisplace:6379

url: redis://:foopassword@redisplace:6379

url: redis://localhost:6379/1

url: redis://localhost:6379/1,redis://localhost:6380/1

kind

Specifies a simple, cluster-aware, or failover-aware redis client.

Type: string
Default: "simple"
Options: simple, cluster, failover.

master

Name of the redis master when kind is failover

Type: string
Default: ""

# Examples

master: mymaster

tls

Custom TLS settings can be used to override system defaults.

Troubleshooting

Some cloud hosted instances of Redis (such as Azure Cache) might need some hand holding in order to establish stable connections. Unfortunately, it is often the case that TLS issues will manifest as generic error messages such as “i/o timeout”. If you’re using TLS and are seeing connectivity problems consider setting enable_renegotiation to true, and ensuring that the server supports at least TLS version 1.2.

Type: object

tls.enabled

Whether custom TLS settings are enabled.

Type: bool
Default: false

tls.skip_cert_verify

Whether to skip server side certificate verification.

Type: bool
Default: false

tls.enable_renegotiation

Whether to allow the remote server to repeatedly request renegotiation. Enable this option if you’re seeing the error message local error: tls: no renegotiation.

Type: bool
Default: false

tls.root_cas

An optional root certificate authority to use. This is a string, representing a certificate chain from the parent trusted root certificate, to possible intermediate signing certificates, to the host certificate.

Type: string
Default: ""

# Examples

root_cas: |-
  -----BEGIN CERTIFICATE-----
  ...
  -----END CERTIFICATE-----  

tls.root_cas_file

An optional path of a root certificate authority file to use. This is a file, often with a .pem extension, containing a certificate chain from the parent trusted root certificate, to possible intermediate signing certificates, to the host certificate.

Type: string
Default: ""

# Examples

root_cas_file: ./root_cas.pem

tls.client_certs

A list of client certificates to use. For each certificate either the fields cert and key, or cert_file and key_file should be specified, but not both.

Type: array
Default: []

# Examples

client_certs:
  - cert: foo
    key: bar

client_certs:
  - cert_file: ./example.pem
    key_file: ./example.key

tls.client_certs[].cert

A plain text certificate to use.

Type: string
Default: ""

tls.client_certs[].key

A plain text certificate key to use.

Type: string
Default: ""

tls.client_certs[].cert_file

The path of a certificate to use.

Type: string
Default: ""

tls.client_certs[].key_file

The path of a certificate key to use.

Type: string
Default: ""

tls.client_certs[].password

A plain text password for when the private key is password encrypted in PKCS#1 or PKCS#8 format. The obsolete pbeWithMD5AndDES-CBC algorithm is not supported for the PKCS#8 format. Warning: Since it does not authenticate the ciphertext, it is vulnerable to padding oracle attacks that can let an attacker recover the plaintext.

Type: string
Default: ""

# Example

password: foo

channels

A list of channels to consume from.

Type: array

use_patterns

Whether to use the PSUBSCRIBE command, allowing for glob-style patterns within target channel names.

Type: bool
Default: false

auto_replay_nacks

Whether messages that are rejected (nacked) at the output level should be automatically replayed indefinitely, eventually resulting in back pressure if the cause of the rejections is persistent. If set to false these messages will instead be deleted. Disabling auto replays can greatly improve memory efficiency of high throughput streams as the original shape of the data can be discarded immediately upon consumption and mutation.

Type: bool
Default: true