Memory Resolver Tutorial
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 MEMORYresolver_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"
Add an account 'A'
Generated account key - private key stored "~/.nkeys/memory/accounts/A/A.nk"
Success! - added account "A"
Describe the account
╭──────────────────────────────────────────────────────────────────────────────────────╮
│ Account Details │
├───────────────────────────┬──────────────────────────────────────────────────────────┤
│ Name │ A │
│ Account ID │ ACSU3Q6LTLBVLGAQUONAGXJHVNWGSKKAUA7IY5TB4Z7PLEKSR5O6JTGR │
│ Issuer ID │ ODWZJ2KAPF76WOWMPCJF6BY4QIPLTUIY4JIBLU4K3YDG3GHIWBVWBHUZ │
│ 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 │
╰───────────────────────────┴──────────────────────────────────────────────────────────╯
Create a new user '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. The nsc tool will generate the server config for you:
nsc generate config --mem-resolver --config-file /tmp/server.conf
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 or the JWT string directly. 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 or jwt itself>
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: {
ACSU3Q6LTLBVLGAQUONAGXJHVNWGSKKAUA7IY5TB4Z7PLEKSR5O6JTGR: eyJ0eXAiOiJqd3QiLCJhbGciOiJlZDI1NTE5In0.eyJqdGkiOiJPRFhJSVI2Wlg1Q1AzMlFJTFczWFBENEtTSDYzUFNNSEZHUkpaT05DR1RLVVBISlRLQ0JBIiwiaWF0IjoxNTU2NjU1Njk0LCJpc3MiOiJPRFdaSjJLQVBGNzZXT1dNUENKRjZCWTRRSVBMVFVJWTRKSUJMVTRLM1lERzNHSElXQlZXQkhVWiIsIm5hbWUiOiJBIiwic3ViIjoiQUNTVTNRNkxUTEJWTEdBUVVPTkFHWEpIVk5XR1NLS0FVQTdJWTVUQjRaN1BMRUtTUjVPNkpUR1IiLCJ0eXBlIjoiYWNjb3VudCIsIm5hdHMiOnsibGltaXRzIjp7InN1YnMiOi0xLCJjb25uIjotMSwibGVhZiI6LTEsImltcG9ydHMiOi0xLCJleHBvcnRzIjotMSwiZGF0YSI6LTEsInBheWxvYWQiOi0xLCJ3aWxkY2FyZHMiOnRydWV9fX0._WW5C1triCh8a4jhyBxEZZP8RJ17pINS8qLzz-01o6zbz1uZfTOJGvwSTS6Yv2_849B9iUXSd-8kp1iMXHdoBA
}
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/creds/memory/A/TA.creds hello world