nats_jetstream

Reads messages from NATS JetStream subjects.

Introduced in version 1.0.0.

Common
Advanced

# Common config fields, showing default values
input:
  label: ""
  nats_jetstream:
    urls: [] # No default (required)
    queue: "" # No default (optional)
    subject: foo.bar.baz # No default (optional)
    durable: "" # No default (optional)
    stream: "" # No default (optional)
    bind: false # No default (optional)
    deliver: all

# All config fields, showing default values
input:
  label: ""
  nats_jetstream:
    urls: [] # No default (required)
    queue: "" # No default (optional)
    subject: foo.bar.baz # No default (optional)
    durable: "" # No default (optional)
    stream: "" # No default (optional)
    bind: false # No default (optional)
    deliver: all
    ack_wait: 30s
    max_ack_pending: 1024
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    auth:
      nkey_file: ./seed.nk # No default (optional)
      user_credentials_file: ./user.creds # No default (optional)
      user_jwt: "" # No default (optional)
      user_nkey_seed: "" # No default (optional)
    extract_tracing_map: root = @ # No default (optional)

Consuming Mirrored Streams

In the case where a stream being consumed is mirrored from a different JetStream domain the stream cannot be resolved from the subject name alone, and so the stream name as well as the subject (if applicable) must both be specified.

Metadata

This input adds the following metadata fields to each message:

- nats_subject
- nats_sequence_stream
- nats_sequence_consumer
- nats_num_delivered
- nats_num_pending
- nats_domain
- nats_timestamp_unix_nano

You can access these metadata fields using function interpolation.

Connection Name

When monitoring and managing a production NATS system, it is often useful to know which connection a message was send/received from. This can be achieved by setting the connection name option when creating a NATS connection.

Bento will automatically set the connection name based off the label of the given NATS component, so that monitoring tools between NATS and bento can stay in sync.

Authentication

There are several components within Bento which utilise NATS services. You will find that each of these components support optional advanced authentication parameters for NKeys and User Credentials.

An in depth tutorial can be found here.

NKey file

The NATS server can use these NKeys in several ways for authentication. The simplest is for the server to be configured with a list of known public keys and for the clients to respond to the challenge by signing it with its private NKey configured in the nkey_file field.

More details here.

User Credentials

NATS server supports decentralized authentication based on JSON Web Tokens (JWT). Clients need an user JWT and a corresponding NKey secret when connecting to a server which is configured to use this authentication scheme.

The user_credentials_file field should point to a file containing both the private key and the JWT and can be generated with the nsc tool.

Alternatively, the user_jwt field can contain a plain text JWT and the user_nkey_seedcan contain the plain text NKey Seed.

More details here.

Fields

`urls`

A list of URLs to connect to. If an item of the list contains commas it will be expanded into multiple URLs.

Type: array

# Examples

urls:
  - nats://127.0.0.1:4222

urls:
  - nats://username:password@127.0.0.1:4222

`queue`

An optional queue group to consume as.

Type: string

`subject`

A subject to consume from. Supports wildcards for consuming multiple subjects. Either a subject or stream must be specified.

Type: string

# Examples

subject: foo.bar.baz

subject: foo.*.baz

subject: foo.bar.*

subject: foo.>

`durable`

Preserve the state of your consumer under a durable name.

Type: string

`stream`

A stream to consume from. Either a subject or stream must be specified.

Type: string

`bind`

Indicates that the subscription should use an existing consumer.

Type: bool

`deliver`

Determines which messages to deliver when consuming without a durable subscriber.

Type: string
Default: "all"

Option	Summary
`all`	Deliver all available messages.
`last`	Deliver starting with the last published messages.
`last_per_subject`	Deliver starting with the last published message per subject.
`new`	Deliver starting from now, not taking into account any previous messages.

`ack_wait`

The maximum amount of time NATS server should wait for an ack from consumer.

Type: string
Default: "30s"

# Examples

ack_wait: 100ms

ack_wait: 5m

`max_ack_pending`

The maximum number of outstanding acks to be allowed before consuming is halted.

Type: int
Default: 1024

`tls`

Custom TLS settings can be used to override system defaults.

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
Requires version 1.0.0 or newer

`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.

Secret

This field contains sensitive information that usually shouldn't be added to a config directly, read our secrets page for more info.

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.

Secret

This field contains sensitive information that usually shouldn't be added to a config directly, read our secrets page for more info.

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.

Secret

This field contains sensitive information that usually shouldn't be added to a config directly, read our secrets page for more info.

Type: string
Default: ""

# Examples

password: foo

password: ${KEY_PASSWORD}

`auth`

Optional configuration of NATS authentication parameters.

Type: object

`auth.nkey_file`

An optional file containing a NKey seed.

Type: string

# Examples

nkey_file: ./seed.nk

`auth.user_credentials_file`

An optional file containing user credentials which consist of an user JWT and corresponding NKey seed.

Type: string

# Examples

user_credentials_file: ./user.creds

`auth.user_jwt`

An optional plain text user JWT (given along with the corresponding user NKey Seed).

Secret

This field contains sensitive information that usually shouldn't be added to a config directly, read our secrets page for more info.

Type: string

`auth.user_nkey_seed`

An optional plain text user NKey Seed (given along with the corresponding user JWT).

Secret

This field contains sensitive information that usually shouldn't be added to a config directly, read our secrets page for more info.

Type: string

`extract_tracing_map`

EXPERIMENTAL: A Bloblang mapping that attempts to extract an object containing tracing propagation information, which will then be used as the root tracing span for the message. The specification of the extracted fields must match the format used by the service wide tracer.

Type: string
Requires version 4.23.0 or newer

# Examples

extract_tracing_map: root = @

extract_tracing_map: root = this.meta.span

Consuming Mirrored Streams​

Metadata​

Connection Name​

Authentication​

NKey file​

User Credentials​

Fields​

urls​

queue​

subject​

durable​

stream​

bind​

deliver​

ack_wait​

max_ack_pending​

tls​

tls.enabled​

tls.skip_cert_verify​

tls.enable_renegotiation​

tls.root_cas​

tls.root_cas_file​

tls.client_certs​

tls.client_certs[].cert​

tls.client_certs[].key​

tls.client_certs[].cert_file​

tls.client_certs[].key_file​

tls.client_certs[].password​

auth​

auth.nkey_file​

auth.user_credentials_file​

auth.user_jwt​

auth.user_nkey_seed​

extract_tracing_map​

Consuming Mirrored Streams

Metadata

Connection Name

Authentication

NKey file

User Credentials

Fields

`urls`

`queue`

`subject`

`durable`

`stream`

`bind`

`deliver`

`ack_wait`

`max_ack_pending`

`tls`

`tls.enabled`

`tls.skip_cert_verify`

`tls.enable_renegotiation`

`tls.root_cas`

`tls.root_cas_file`

`tls.client_certs`

`tls.client_certs[].cert`

`tls.client_certs[].key`

`tls.client_certs[].cert_file`

`tls.client_certs[].key_file`

`tls.client_certs[].password`

`auth`

`auth.nkey_file`

`auth.user_credentials_file`

`auth.user_jwt`

`auth.user_nkey_seed`

`extract_tracing_map`