Memory Resolver

The MEMORY resolver is a server built-in resolver for account JWTs. If there are a small number of accounts, or they do not change too often this can be a simpler configuration that does not require an external account resolver. Server configuration reload is supported, meaning the preloads can be updated in the server configuration and reloaded without a server restart.

The basic configuration for the server requires:

  • The operator JWT
  • resolver set to MEMORY
  • resolver_preload set to an object where account public keys are mapped to account JWTs.

Create Required Entities

Let's create the setup:

> nsc add operator -n memory
Generated operator key - private key stored "~/.nkeys/memory/memory.nk"
Success! - added operator "memory"

> nsc add account --name A
Generated account key - private key stored "~/.nkeys/memory/accounts/A/A.nk"
Success! - added account "A"

> nsc describe account -W
│                                   Account Details                                    │
│ Name                      │ A                                                        │
│ Issued                    │ 2019-04-30 20:21:34 UTC                                  │
│ Expires                   │                                                          │
│ Max Connections           │ Unlimited                                                │
│ Max Leaf Node Connections │ Unlimited                                                │
│ Max Data                  │ Unlimited                                                │
│ Max Exports               │ Unlimited                                                │
│ Max Imports               │ Unlimited                                                │
│ Max Msg Payload           │ Unlimited                                                │
│ Max Subscriptions         │ Unlimited                                                │
│ Exports Allows Wildcards  │ True                                                     │
│ Imports                   │ None                                                     │
│ Exports                   │ None                                                     │

> nsc add user --name TA
Generated user key - private key stored "~/.nkeys/memory/accounts/A/users/TA.nk"
Generated user creds file "~/.nkeys/memory/accounts/A/users/TA.creds"
Success! - added user "TA" to "A"

Create the Server Config

The nsc tool can generate a configuration file automatically. You provide a path to the server configuration and operator jwt. The nsc tool will copy the operator JWT to the file specified, and generate the server config for you:

> nsc generate config --mem-resolver --config-file /tmp/server.conf --operator-jwt /tmp/memory.jwt
Success!! - generated "/tmp/server.conf"
            generated "/tmp/memory.jwt"

If you require additional settings, you may want to consider using include in your main configuration, to reference the generated files. Otherwise, you can start a server and reference the generated configuration:

> nats-server -c /tmp/server.conf

You can then test it.

Manual Server Config

While generating a configuration file is easy, you may want to craft one by hand to know the details. With the entities created, and a standard location for the .nsc directory. You can reference the operator JWT and the account JWT in a server configuration. Remember that your configuration will be in $NSC_HOME/nats/<operator_name>/<operator_name>.jwt for the operator. The account JWT will be in $NSC_HOME/nats/<operator_name>/accounts/<account_name>/<account_name>.jwt

For the configuration you'll need:

  • The path to the operator JWT
  • A copy of the contents of the account JWT file

The format of the file is:

operator: <path to the operator jwt>
resolver: MEMORY
resolver_preload: {
    <public key for an account>: <contents of the account jwt>
    ### add as many accounts as you want

In this example this translates to:

operator: /Users/synadia/.nsc/nats/memory/memory.jwt
resolver: MEMORY
resolver_preload: {

Save the config at server.conf and start the server:

> nats-server -c server.conf

You can then test it.

Testing the Configuration

To test the configuration, simply use one of the standard tools:

> nats-pub -creds ~/.nkeys/memory/accounts/A/users/TA.creds hello world
Published [hello] : 'world'

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