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File configuration

gnmic configuration by means of the command line flags is both consistent and reliable. But sometimes its not the best way forward.

With lots of configuration options that gnmic supports it might get tedious to pass them all via CLI flags. In cases like that the file-based configuration comes handy.

With a configuration file a user can specify all the command line flags by means of a single file. gnmic will read this file and retrieve the configuration options from it.

What options can be in a file?#

Configuration file allows a user to specify everything that can be supplied over the CLI and more.

Global flags#

All of the global flags can be put in a conf file. Consider the following example of a typical configuration file in YAML format:

# gNMI target address; CLI flag `--address`
address: "10.0.0.1:57400"
# gNMI target user name; CLI flag `--username`
username: admin
# gNMI target user password; CLI flag `--password`
password: admin
# connection mode; CLI flag `--insecure`
insecure: true
# log file location; CLI flag `--log-file`
log-file: /tmp/gnmic.log
With such a file located at a default path the gNMI requests can be made in a very short and concise form:

# configuration file is read by its default path
gnmi capabilities

# cfg file has all the global options set, so only the local flags are needed
gnmi get --path /configure/system/name

Local flags#

Local flags have the scope of the command where they have been defined. Local flags can be put in a configuration file as well.

To avoid flags names overlap between the different commands a command name should prepend the flag name - <cmd name>-<flag name>.

So, for example, we can provide the path flag of a get command in the file by adding the get- prefix to the local flag name:

address: "router.lab:57400"
username: admin
password: admin
insecure: true
get-path: /configure/system/name  # `get` command local flag

Another example: the update-path flag of a set will be set-update-path in the configuration file.

Targets#

It is possible to specify multiple targets with different configurations (credentials, timeout,...). This is described in Multiple targets documentation article.

Subscriptions#

It is possible to specify multiple subscriptions and associate them with different targets in a flexible way. This configuration option is described in Multiple subscriptions documentation article.

Outputs#

The other mode gnmic supports (in contrast to CLI) is running as a daemon and exporting the data received from gNMI subscriptions to multiple outputs like stan/nats, kafka, file, prometheus, influxdb, etc...

Inputs#

gnmic supports reading gNMI data from a set of inputs and export the data to any of the configured outputs. This is used when building data pipelines with gnmic

Repeated flags#

If a flag can appear more than once on the CLI, it can be represented as a list in the file.

For example one can set multiple paths for get/set/subscribe operations. In the following example we define multiple paths for the get command to operate on:

address: "router.lab:57400"
username: admin
password: admin
insecure: true
get-path:
    - /configure/system/name
    - /state/system/version

Options preference#

Configuration passed via CLI flags and Env variables take precedence over the file config.

Environment variables in file#

Environment variables can be used in the configuration file and will be expanded at the time the configuration is read.

outputs:
  output1:
    type: nats
    address: ${NATS_IP}:4222
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