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Evaluation Guide for "nats auth"

The nats auth command is a new addition that aims to bring the most common features of nsc into the nats command. The aim is not to have 100% feature parity but rather to provide a easy to use solution for what most people will use.

It remains compatible with the nsc store and so users can switch between these commands.

It is implemented using a new Go SDK allowing programmatic interaction with the nsc store.

This guide is based on the nsc documentation and attempts to achieve the same outcome.

Limitations

  • We only support the full resolver type for pushing accounts
  • We do not support import/export activations only account token positions

Storage

The SDK support both a nsc file based storage and a new Key-Value based storage, today in the CLI we only support the nsc compatible storage which for most users means files in ~/.local/share/nats/nsc.

Creating an Operator, Account and User

For every operator a system account and signing key is generated. After creation use nats auth op info MyOperator to show the operator settings again:

# nats auth op add MyOperator
Operator MyOperator (OCJDWJ7PYUMG3R7G4RZHWZRLHGMTXDXWNFBVN6TXBRILG5EVGSRW4OUH)

Configuration:

            Name: MyOperator
         Subject: OCJDWJ7PYUMG3R7G4RZHWZRLHGMTXDXWNFBVN6TXBRILG5EVGSRW4OUH
        Accounts: 1
  System Account: SYSTEM (ACSU3XZAMG3HT2OXGXF56YXXPGPCKD3V3RZJYOROIGEKUN2PTPYOEOEY)
    Signing Keys: OC5LYPBJEEYGKPDDF4E4X7DCRS2URYSS77IER3UDXSIY3QUNREBLPALE

We add an account, several limits can be set as options, the most common ones are prompted for. After creation use nats auth account info MyAccount to show the account settings again:

# nats auth account add MyAccount
? Maximum Connections -1
? Maximum Subscriptions -1

Account MyAccount (ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF)

Configuration:

                   Name: MyAccount
                 Issuer: OC5LYPBJEEYGKPDDF4E4X7DCRS2URYSS77IER3UDXSIY3QUNREBLPALE
               Operator: MyOperator
         System Account: false
              JetStream: false
                  Users: 0
            Revocations: 0
        Service Exports: 0
         Stream Exports: 0
        Service Imports: 0
         Stream Imports: 0

Limits:

  Bearer Tokens Allowed: false
          Subscriptions: unlimited
            Connections: unlimited
        Maximum Payload: unlimited
              Leafnodes: unlimited
                Imports: unlimited
                Exports: unlimited

We add a user, if no account is given you will be presented with a list, again numerous options exist with the most common ones being prompted. After creation use nats auth user info MyUser to show the account settings again:

# nats auth user add MyUser
? Select an Account MyAccount
? Maximum Payload -1
? Maximum Subscriptions -1
User MyUser (UD6LMPVXNZOBXHBTWBHWY3LTCXYUCTYDD3GSYCZS6TVERC3NVU6TGVAG)

Configuration:

            Account: MyAccount (ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF)
             Issuer: ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF
             Scoped: false
       Bearer Token: false

Limits:

        Max Payload: unlimited
           Max Data: unlimited
  Max Subscriptions: unlimited

Permissions:

  Publish:

   No permissions defined

  Subscribe:

   No permissions defined

Configuring NATS Server

TODO: Full resolver generate

$ nats-server --config nats-server.conf
...
[31] 2024/04/23 09:49:20.430678 [INF] Trusted Operators
[31] 2024/04/23 09:49:20.430681 [INF]   System  : ""
[31] 2024/04/23 09:49:20.430684 [INF]   Operator: "MyOperator"
[31] 2024/04/23 09:49:20.430687 [INF]   Issued  : 2024-04-23 09:33:43 +0000 UTC
[31] 2024/04/23 09:49:20.430708 [INF]   Expires : Never

The dynamic account - MyAccount in this case - needs to be sent to the NATS Server SYSTEM account before you can use it. To do this we need a SYSTEM account user and credential.

Unlike nsc that makes credentials on demand to push to the servers we use contexts to authenticate to the system account which feels more in-line with how the nats command works. We need a user and credentials for a system user, if we do not supply the username or account they will be prompted for:

# nats auth user add admin SYSTEM
# nats auth user cred system.cred admin SYSTEM
Wrote credential for admin to /path/to/system.cred
# nats ctx add system --description "System Account" --server localhost:4222 --creds /path/to/system.cred

Next we use the credential we just made to push to the server:

# nats auth account push MyAccount --context system
Updating account MyAccount (ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF) on 1 server(s)

✓ Update completed on servertest

Success 1 Failed 0 Expected 1

User Authorization

To do a basic test of publish / subscribe we can use the user we created earlier:

# nats auth user cred myuser.cred
? Select an Account MyAccount
? Select a User MyUser
Wrote credential for MyUser to myuser.cred

First we setup a responder:

# nats reply echo --echo --creds myuser.cred

And in a another terminal we communicate with it:

# nats req echo x --creds myuser.cred
10:20:41 Sending request on "echo"
10:20:41 Received with rtt 627.799µs
x

Now lets lock the requester and responder down, we'll add a user for the service with appropriate permissions.

First the user for the service and in the same command we save its credential:

# nats auth user add echosrv --sub-allow echo --pub-allow '_INBOX.>' --credential service.cred 
# nats reply echo --echo  --creds service.cred
10:31:53 Listening on "echo" in group "NATS-RPLY-22"

Next we update the MyUser so he can only talk to the echo service and we save the credential and then test the access:

# nats auth user edit --pub-allow 'echo' --sub-allow '_INBOX.>' --credential myuser.cred
...
Permissions:

  Publish:

                Allow: echo

  Subscribe:

                Allow: _INBOX.>

# nats req echo x --creds myuser.cred
10:36:10 Sending request on "echo"
10:36:10 Received with rtt 767.011µs
10:36:10 NATS-Reply-Counter: 0

x

And we confirm the limits are applied by subscribing to an invalid subject:

# nats req other x --creds myuser.cred
10:36:36 Sending request on "other"
10:36:36 Unexpected NATS error from server nats://127.0.0.1:4222: nats: Permissions Violation for Publish to "other"

Imports and Exports

For the examples below we'll add an account and some users with their credentials:

# nats auth acct add OTHER --defaults
# nats auth user add test MyAccount --credential myaccount.cred --defaults
# nats auth user add test OTHER --credential other.cred --defaults

This creates the OTHER account and adds credentials files myaccount.cred and other.cred.

Sharing NATS Core Streams

Note: A Stream in this context describes a one directional flow of nats-core messages, not a Stream stored in JetStream.

To share data cross accounts the origin account has to export it:

# nats auth a export add abc "a.b.c.>" 
? Select an Account: MyAccount
Export info for abc exporting a.b.c.>

Configuration:

                    Name: abc
                 Subject: a.b.c.>
     Activation Required: false
  Account Token Position: 0
              Advertised: false

Revocations:

 No revocations found

The other side needs to import it:

# nats auth a import add "MyAccount abc" "a.b.c.>" OTHER
? Select the Source account ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF
Import info for MyAccount abc importing a.b.c.>

Configuration:

                     Name: MyAccount abc
             From Account: (MyAccount) ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF
            Local Subject: a.b.c.>
           Remote Subject: a.b.c.>
  Sharing Connection Info: false
   Allows Message Tracing: false

We have to push these accounts to the servers now since we changed the account JWTs:

# nats auth account push MyAccount --context system
# nats auth account push OTHER --context system

In one terminal we can publish messages using the MyAccount user:

# nats pub a.b.c.d '{{.Count}}' --count 100 --sleep 1s --creds myaccount.cred

And in another terminal we can receive them on the OTHER account user:

# nats sub a.b.c.d --creds other.cred
12:38:02 Subscribing on a.b.c.d
[#1] Received on "a.b.c.d"
14
...

Sharing NATS Core Services

To share data cross accounts the origin account has to export it, the example will be a weather service:

# nats auth account export add weather.v1 'weather.v1.>' --service
? Select an Account MyAccount
Export info for weather.v1 exporting weather.v1.>

Configuration:

                    Name: weather.v1
                 Subject: weather.v1.>
     Activation Required: false
  Account Token Position: 0
              Advertised: false

Revocations:

 No revocations found

The other account needs to import it, we import the weather.v1.> subjects to weather.> in the OTHER account:

# nats auth account import add weather 'weather.v1.>' --local 'weather.>' --service
? Select an Account OTHER
? Select the Source account ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF
Import info for import "weather" importing "weather.>"

Configuration:

                     Name: weather
             From Account: MyAccount (ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF)
            Local Subject: weather.>
           Remote Subject: weather.v1.>
  Sharing Connection Info: false

We have to push the accounts since we edited the JWTs:

# nats auth account push MyAccount --context system
# nats auth account push OTHER --context system

To test it we set up a weather service in the MyAccount, note we listen on weather.v1.>:

# nats reply 'weather.v1.>' --command "curl -s wttr.in/{{2}}?format=3" --creds myaccount.cred

On the importing account we access the service via weather.>:

# nats req weather.malta '' --creds other.cred
08:53:45 Sending request on "weather.malta"
08:53:45 Received with rtt 228.858489ms
malta: ⛅️  +17°C

Account token authentication for imports and exports

nats auth supports securing Exports by forcing account tokens in subjects. Let's create a weather export that will require the account ID in imports:

$ nats auth account export add weatherAPI 'weather.*.>' MyAccount --token-position 2 --service
Export info for weatherAPI exporting weather.*.>

Configuration:

                    Name: weatherAPI
                    Kind: Service
                 Subject: weather.*.>
     Activation Required: false
  Account Token Position: 2
              Advertised: false

Revocations:

 No revocations found
 
$ nats auth account push USERS  --creds admin.cred

Now we create an account and import the service:

$ nats auth account add CLIENT --defaults
Account CLIENT (ABAFX7CGEL5Z63ZYSR6VZX67VBXCK5BFXAGKLRTE4KEDDLX6BSTYM3ET)

Configuration:

                   Name: CLIENT
                 Issuer: OCBIIO6GFBV4C3O66WNYOALWLQKEW3RNLXYRDFXLISNLNUK6BIYA6HGP
               Operator: DEMO
         System Account: false
              JetStream: false
                  Users: 1
            Revocations: 0
        Service Exports: 0
         Stream Exports: 0
        Service Imports: 0
         Stream Imports: 1

Limits:

  Bearer Tokens Allowed: false
          Subscriptions: unlimited
            Connections: unlimited
        Maximum Payload: unlimited
              Leafnodes: unlimited
                Imports: unlimited
                Exports: unlimited

Note the account ID here is ABAFX7CGEL5Z63ZYSR6VZX67VBXCK5BFXAGKLRTE4KEDDLX6BSTYM3ET, this means when importing the service we must add this token in the subject:

$ nats auth account import add weatherAPI 'weather.ABAFX7CGEL5Z63ZYSR6VZX67VBXCK5BFXAGKLRTE4KEDDLX6BSTYM3ET.>' --local 'weather.>' CLIENT --service
$ nats auth user add user --credential client.cred CLIENT --defaults
$ nats auth account push CLIENT --creds admin.cred

? Select the Source account ACJFET46AFRLXBHFTHRTCB3NQR2KZAWUH66HXUYVEUU4I2425SQBZKOU
Import info for import "weatherAPI" importing "weather.>"

Configuration:

                     Name: weatherAPI
             From Account: MyAccount (ADNJMEHSIAQAE3X5EKGABVVOFX3GECHZKG6M4DK72ZDHEPQ5YW4CA3OF)
            Local Subject: weather.>
                     Kind: Service
           Remote Subject: weather.ABAFX7CGEL5Z63ZYSR6VZX67VBXCK5BFXAGKLRTE4KEDDLX6BSTYM3ET.>
  Sharing Connection Info: false

We can now run the weather service in the one account:

$ nats reply 'weather.*.>' --command "curl -s wttr.in/{{3}}?format=3" --creds myaccount.cred

And in another we can access the service:

$ nats req weather.lon '' --creds client.cred
12:26:18 Sending request on "weather.lon"
12:26:19 Received with rtt 686.31243ms
3: ⛅️  +13°C