Skip to main content

nats_stream

Subscribe to a NATS Stream subject. Joining a queue is optional and allows multiple clients of a subject to consume using queue semantics.

# Common config fields, showing default values
input:
  label: ""
  nats_stream:
    urls: [] # No default (required)
    cluster_id: "" # No default (required)
    client_id: ""
    queue: ""
    subject: ""
    durable_name: ""
    unsubscribe_on_close: false
Deprecation Notice

The NATS Streaming Server is being deprecated. Critical bug fixes and security fixes will be applied until June of 2023. NATS-enabled applications requiring persistence should use JetStream.

Tracking and persisting offsets through a durable name is also optional and works with or without a queue. If a durable name is not provided then subjects are consumed from the most recently published message.

When a consumer closes its connection it unsubscribes, when all consumers of a durable queue do this the offsets are deleted. In order to avoid this you can stop the consumers from unsubscribing by setting the field unsubscribe_on_close to false.

Metadata​

This input adds the following metadata fields to each message:

- nats_stream_subject
- nats_stream_sequence

You can access these metadata fields using function interpolation.

Authentication​

There are several components within Benthos 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

cluster_id​

The ID of the cluster to consume from.

Type: string

client_id​

A client ID to connect as.

Type: string
Default: ""

queue​

The queue to consume from.

Type: string
Default: ""

subject​

A subject to consume from.

Type: string
Default: ""

durable_name​

Preserve the state of your consumer under a durable name.

Type: string
Default: ""

unsubscribe_on_close​

Whether the subscription should be destroyed when this client disconnects.

Type: bool
Default: false

start_from_oldest​

If a position is not found for a queue, determines whether to consume from the oldest available message, otherwise messages are consumed from the latest.

Type: bool
Default: true

max_inflight​

The maximum number of unprocessed messages to fetch at a given time.

Type: int
Default: 1024

ack_wait​

An optional duration to specify at which a message that is yet to be acked will be automatically retried.

Type: string
Default: "30s"

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 3.45.0 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