Update Notifications

The nats-account-server can notify a nats-server about JWT updates, enabling the NATS server to update itself to the newly updated JWT.
To push notifications, the nats-account-server makes use of system accounts.
Here's a nats-account-server configuration with updates enabled:
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operatorjwtpath: "/users/synadia/.nsc/nats/AAA/AAA.jwt",
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systemaccountjwtpath: "/users/synadia/.nsc/nats/AAA/accounts/SYS/SYS.jwt"
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http {
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    port: 9090
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},
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store {
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    dir: "/tmp/as_store",
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    readonly: false,
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    shard: true
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}
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nats {
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  servers: [nats://localhost:4222]
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  usercredentials: "/Users/synadia/.nkeys/AAA/accounts/SYS/users/sys.creds"
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}
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The above configuration:
Sets the operatorjwtpath to verify pushed JWTs are signed by the operator
Sets the systemaccountjwtpath so that the nats-server can ask for the system account (which the nats-account-server will trigger when it connects to the nats-server)
The nats section:
Sets the servers with a list of NATS urls
Sets usercredentials to the credentials file for the system account user that issues notifications.
When the account server starts:
It makes a connection to the NATS server using the usercredentials of the system account.
The NATS server configuration looks like:
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operator: /users/synadia/.nsc/nats/AAA/AAA.jwt
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resolver: URL(http://localhost:9090/jwt/v1/accounts/)
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system_account: AAUR7CJU5WTR2RROXOJJFTJFJQPZ6B4VF2NOX6OQ6SQMPIKLQYQ7T37U
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It specifies:
The operator JWT
The resolver URL where the nats-account-server will create requests. Note the nats-account-server log prints the exact value you should provide for this setting:
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...
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2019/05/31 16:47:50.519361 [INF] configure the nats-server with:
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2019/05/31 16:47:50.519368 [INF]   resolver: URL(http://localhost:9090/jwt/v1/accounts/)
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...
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The nats-account-server has to be running before that nats-server starts, as currently, the nats-server will verify that it can connect to the resolver on startup.
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> nats-account-server -c nas_not.conf
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2019/05/31 18:00:26.327583 [INF] loading configuration from "/Users/synadia/Desktop/nats_jwt_doc/as_dir/nas_not.conf"
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2019/05/31 18:00:26.327833 [INF] starting NATS Account server, version 0.0-dev
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2019/05/31 18:00:26.327852 [INF] server time is Fri May 31 18:00:26 CDT 2019
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2019/05/31 18:00:26.327862 [INF] loading operator from /users/synadia/.nsc/nats/AAA/AAA.jwt
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2019/05/31 18:00:26.328278 [INF] loading system account from /users/synadia/.nsc/nats/AAA/accounts/SYS/SYS.jwt
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2019/05/31 18:00:26.328590 [INF] creating a store at /tmp/as_store
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2019/05/31 18:00:26.328619 [INF] connecting to NATS for notifications
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2019/05/31 18:00:26.329875 [ERR] failed to connect to NATS, nats: no servers available for connection
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2019/05/31 18:00:26.329884 [ERR] will try to connect again in 1000 milliseconds
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2019/05/31 18:00:26.330541 [INF] http listening on port 9090
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2019/05/31 18:00:26.330548 [INF] nats-account-server is running
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2019/05/31 18:00:26.330551 [INF] configure the nats-server with:
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2019/05/31 18:00:26.330557 [INF]   resolver: URL(http://localhost:9090/jwt/v1/accounts/)
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2019/05/31 18:00:27.330103 [INF] connecting to NATS for notifications
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2019/05/31 18:00:27.331215 [ERR] failed to connect to NATS, nats: no servers available for connection
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2019/05/31 18:00:27.331223 [ERR] will try to connect again in 1000 milliseconds
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Then start the NATS server:
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> nats-server -c /tmp/server.conf
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[57440] 2019/05/31 18:01:29.940149 [INF] Starting nats-server version 1.4.1
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[57440] 2019/05/31 18:01:29.940234 [INF] Git commit [not set]
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[57440] 2019/05/31 18:01:29.940468 [INF] Listening for client connections on 0.0.0.0:4222
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[57440] 2019/05/31 18:01:29.940476 [INF] Server is ready
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At this point, you have both servers running. You can submit updates to the nats-account-server using nsc:
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> nsc push -A
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successfully pushed all accounts [A, B, SYS]
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The account server should show the updates in its log:
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2019/05/31 18:02:29.702044 [INF] updated JWT for account - ACVEO3LPVRGE - GSO7ZQPXXNTBBEEGXFFLFXZLCGOA5ABUOADZBPASYGCDIEJ6QQPQ
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2019/05/31 18:02:29.702988 [INF] updated JWT for account - ADDVBX4VPWSN - VPBI4OHVJ7ITKX6S2RWHHJ3BB6JFZ7NPJN33JH6L752T2YI2QJKA
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2019/05/31 18:02:29.703745 [INF] updated JWT for account - AAUR7CJU5WTR - NHEPTVMURCQEURAWHX6LUUMO4KCQUAP4JCLIQANP3JTNPMG3IFWQ
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