Redis

Performs actions against Redis that aren’t possible using a cache processor.

Actions are performed for each message and the message contents are replaced with the result.

In order to merge the result into the original message compose this processor within a branch processor.

Common

# Common config fields, showing default values
label: ""
redis:
  url: redis://:6397 # No default (required)
  command: scard # No default (optional)
  args_mapping: root = [ this.key ] # No default (optional)

Advanced

# All config fields, showing default values
label: ""
redis:
  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: [ ]
  command: scard # No default (optional)
  args_mapping: root = [ this.key ] # No default (optional)
  retries: 3
  retry_period: 500ms

Examples

Querying Cardinality

If given payloads containing a metadata field set_key it’s possible to query and store the cardinality of the set for each message using a branch processor in order to augment rather than replace the message contents:

pipeline:
  processors:
    - branch:
        processors:
          - redis:
              url: TODO
              command: scard
              args_mapping: 'root = [ meta("set_key") ]'
        result_map: 'root.cardinality = this'

Running Total

If we have JSON data containing number of friends visited during covid 19:

{
  "name": "ash",
  "month": "feb",
  "year": 2019,
  "friends_visited": 10
}
{
  "name": "ash",
  "month": "apr",
  "year": 2019,
  "friends_visited": -2
}
{
  "name": "bob",
  "month": "feb",
  "year": 2019,
  "friends_visited": 3
}
{
  "name": "bob",
  "month": "apr",
  "year": 2019,
  "friends_visited": 1
}

We can add a field that contains the running total number of friends visited:

{
  "name": "ash",
  "month": "feb",
  "year": 2019,
  "friends_visited": 10,
  "total": 10
}
{
  "name": "ash",
  "month": "apr",
  "year": 2019,
  "friends_visited": -2,
  "total": 8
}
{
  "name": "bob",
  "month": "feb",
  "year": 2019,
  "friends_visited": 3,
  "total": 3
}
{
  "name": "bob",
  "month": "apr",
  "year": 2019,
  "friends_visited": 1,
  "total": 4
}

Using the incrby command:

pipeline:
  processors:
    - branch:
        processors:
          - redis:
              url: TODO
              command: incrby
              args_mapping: 'root = [ this.name, this.friends_visited ]'
        result_map: 'root.total = this'

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

command

The command to execute.

This field supports interpolation functions.

Type: string

# Examples

command: scard

command: incrby

command: ${! meta("command") }

args_mapping

A Bloblang mapping which should evaluate to an array of values matching in size to the number of arguments required for the specified Redis command.

Type: string

# Examples

args_mapping: root = [ this.key ]

args_mapping: root = [ meta("kafka_key"), this.count ]

retries

The maximum number of retries before abandoning a request.

Type: int
Default: 3

retry_period

The time to wait before consecutive retry attempts.

Type: string
Default: "500ms"