printSecondaryReplicationInfo as JSON output

When you run rs.printSecondaryReplicationInfo(); then the output is like this:

source: d-mipmdb-cfg-02:27019
	syncedTo: Sat Apr 02 2022 20:01:01 GMT+0200 (W. Europe Daylight Time)
	0 secs (0 hrs) behind the primary 
source: d-mipmdb-cfg-03:27019
	syncedTo: Sat Apr 02 2022 20:00:58 GMT+0200 (W. Europe Daylight Time)
	3 secs (0 hrs) behind the primary 

The documentation says “Use rs.printSecondaryReplicationInfo() for manual inspection, and rs.status() in scripts.” but it does not tell me directly where to see this information.

I guess with rs.status() you get the same information with a script like this:

const members = rs.status().members
const primary = members.filter(x=> x.stateStr == "PRIMARY").shift().optimeDate;
members.filter(x=> x.stateStr == "SECONDARY").map(x=> {return `${x.name} is ${(primary - x.optimeDate)/1000} Seconds behind the primary`});

[
	"d-mipmdb-cfg-02:27019 is 2 Seconds behind the primary",
	"d-mipmdb-cfg-03:27019 is 3 Seconds behind the primary"
]

Is this correct or do I need to run something else?

Kind Regards
Wernfried

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Hi @Wernfried_Domscheit,

MongoDB shell helpers derive replication lag from rs.status(), so your approach looks correct.

The implementations in the new and legacy MongoDB shells may be helpful references, although they have additional logic and error handling to try to cover broader usage scenarios than your example.

mongosh (mongodb-js/mongosh):

The new MongoDB shell uses the MongoDB Node.js driver and TypeScript:

mongo shell (mongodb/mongo/src/mongo/shell)

The legacy mongo shell uses an embedded JavaScript engine:

Regards,
Stennie

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