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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. 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 from the subject; to preserve durable offsets when the last consumer disconnects, set unsubscribe_on_close to false.

# 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
    start_from_oldest: true
    max_inflight: 1024
    ack_wait: 30s
    max_reconnects: 0
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    tls_handshake_first: false
    auth:
      nkey_file: ""
      nkey: ""
      user_credentials_file: ""
      user_jwt: ""
      user_nkey_seed: ""
      user: ""
      password: ""
      token: ""
    extract_tracing_map: ""

Examples​

Consume messages from a subject on a NATS Streaming cluster.

input:
  nats_stream:
    urls:
      - nats://127.0.0.1:4222
    cluster_id: test-cluster
    subject: foo.bar
    queue: my-queue

Fields​

urls​

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

Type: array

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"

max_reconnects​

The maximum number of times to attempt to reconnect to the server. If negative, it will never stop trying to reconnect.

Type: int

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

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. :::warning 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.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: ""

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: []

tls.client_certs[].cert​

A plain text certificate to use.

Type: string
Default: ""

tls.client_certs[].cert_file​

The path of a certificate to use.

Type: string
Default: ""

tls.client_certs[].key​

A plain text certificate key to use. :::warning 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[].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 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_handshake_first​

Whether to perform the initial TLS handshake before sending the NATS INFO protocol message. This is required when connecting to some NATS servers that expect TLS to be established immediately after connection, before any protocol negotiation.

Type: bool
Default: false

auth​

Optional configuration of NATS authentication parameters.

Type: object

auth.nkey_file​

An optional file containing a NKey seed.

Type: string
Default: ""

auth.nkey​

Your NKey seed or private key for NATS authentication. NKeys provide secure, cryptographic authentication without passwords. :::warning 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: ""

auth.user_credentials_file​

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

Type: string
Default: ""

auth.user_jwt​

An optional plaintext user JWT to use along with the corresponding user NKey seed. :::warning 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: ""

auth.user_nkey_seed​

An optional plaintext user NKey seed to use along with the corresponding user JWT. :::warning 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: ""

auth.user​

An optional plain text user name (given along with the corresponding user password).

Type: string
Default: ""

auth.password​

An optional plain text password (given along with the corresponding user name). :::warning 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: ""

auth.token​

An optional plain text token. :::warning 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: ""

extract_tracing_map​

EXPERIMENTAL: A Bloblang mapping that attempts to extract an object containing tracing propagation information, which is then 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