I have a mongo (2.0.3) replica set.
If I connect to a specific node (i.e. my connection string does not include more than one host) using the standard c# driver, and specify slaveOk(), will that query be satisfied by a random member of the set, or only ever by the node I connected to?
If the former, how can I achieve the latter?
Thank you.
If your connection string only has one host name (and does not have either replicaSet=name or connect=replicaSet) the C# driver will connect in direct mode to that one server and use only it.
Replica set semantics (where it uses the whole set) is triggered either by listing more than one host name (called the seed list), or by using replicaSet=name or connect=replicaSet.
So if you want to use just that one host you are on the right track. You will have to specify slaveOk on the connection string or the connect will fail if that server is not the primary.
specifying connect=direct as a parameter in the connection string solved my issue of connecting to secondaries via Powershell.
Use .WithReadPreference(ReadPreference.Secondary) for the collection provider
Related
Is there a way to specify a postgresql database name to connect to in the cloud foundry manifest.yml file? I've been raking through the documentation and haven't yet found this specific information.
I'm imagining something like this:
applications:
- name: my-app
routes:
- route: my-app.mybluemix.net
services:
- postgres
dbname: database2
With that approach, a postgresql connection can be made by just the connection string provided by VCAP_SERVICES parsing modules (cfenv in the case of node).
If this is not possible, I will just set a dbname environment variable and build my own connection string.
There is nothing like that in a Cloud Foundry application manifest.yml.
The manifest.yml only takes a list of service instance names and the services with those names will be bound to your app. It does not allow you set other metadata.
https://docs.cloudfoundry.org/devguide/deploy-apps/manifest-attributes.html#services-block
I don't know if these will help, but when you cf bind-service directly there are two additional provisions you can make use of (these are not supported by manifest.yml as of me writing this):
Arbitrary bind parameters. These probably won't help unless your service broker supports them, but it's a way to pass additional info to the service broker. If your broker supported it, you could in theory say give me a database named XYZ by passing it some config this way.
Named service bindings. This provides what amounts to a second name. The intent is that you can create the service with a name of X, but your application can look for a service binding with name Y. You can use this to swap in differently named services, but still expose the same binding name to the application so it will always find the service.
If you are trying to pass in some other service instance related metadata to your application, you'd need to do it some other way. Like if you want to tell it the database name or the connection pool size, etc.. Using environment variables like you mentioned is one option. You could use a config file or cli arguments passed to your application. What you pick is probably a matter of preference/support in the library/framework you're using.
For what it's worth, most service brokers I've seen pass in and tell you a specific database name to use. If the broker said connect to db XYZ and you made your connection to myCoolDb, the connection would fail. Just wanted to mention this. Your mileage may vary.
In the PostgreSQL documentation https://www.postgresql.org/docs/10/libpq-connect.html, it has been said that multiple hosts can be specified in a single connection string such that all the hosts will be tried in order one after the other until one of the server gets succeeds.
But when i tried to implement the same setting in the tag present in my ASP.net web.config file, it is throwing error as no such host name. I am using NpgSQL provider in order to connect to PostgreSQL database.
I need to add multiple server names in the connection string such that if the server#1 fails then it should try for the next server server#2 immediately provided in the order until it succeeds
Can you please suggest on how multiple hosts can be provided in the connection string?
The Npgsql driver does not currently support this functionality. The issue tracking this is https://github.com/npgsql/npgsql/issues/732, I'm still hoping we can get this into the next release but there's a lot going on.
Load balancing and failover is avaialble in Npgsql version 6. At the time of writing v.6 is in preview.
Simple failover example (server2 is only used if a connection could not be established to server1):
Host=server1,server2;Username=test;Password=test
Example with load balancing (round robin I guess):
Host=server1,server2,server3,server4,server5;Username=test;Password=test;Load
Balance Hosts=true;Target Session Attributes=prefer-standby
https://www.npgsql.org/doc/failover-and-load-balancing.html
(I'm afraid I'm probably about to reveal myself as completely unfit for the task at hand!)
I'm trying to setup a Redshift cluster and database to help manage data for a class/group project.
I have a dc2.large cluster running with either default options, or what looked like the most generic in the couple of place I was forced to make entries.
I have downloaded Aginity (Win64) as it is described as being specialized for Redshift. That said, I can't find any instructions for connecting using it. The connection dialog requests the follwoing:
Server: using the endpoint for my cluster (less :57xx at the end).
UserID: the Master username for the database defined for the cluster.
Password: to match the UserID
SSL Mode (Disable, Allow, Prefer, Require): trying various options
Database: as named in cluster setup
Port: as defined in cluster setup
I can't get it to connect ("failed to establish connection") and don't know if I'm entering something wrong in Aginity or if I haven't set up my cluster properly.
Message: Failed to establish a connection to 'abc1234-smtm.crone7m2jcwv.us-east-1.redshift.amazonaws.com'.
Type : Npgsql.NpgsqlException
Source : Npgsql
Trace : at Npgsql.NpgsqlClosedState.Open(NpgsqlConnector context, Int32 timeout)
at Npgsql.NpgsqlConnector.Open()
at Npgsql.NpgsqlConnection.Open()
at Aginity.MPP.Common.BaseDataProvider.get_Connection()
at Aginity.MPP.Common.BaseDataProvider.CreateCommand(String commandText, CommandType commandType, IDataParameter[] commandParams)
at Aginity.MPP.Common.BaseDataProvider.ExecuteReader(String commandText, CommandType commandType, IDataParameter[] commandParams)
--- Inner Exception: ---
......
It seems there is not enough information going into Aginity to authorize connection to my cluster - no account credential are supplied. For UserID, am I meant to enter the ID of a valid user? Can I use the root account? What would the ID look like? I have setup a User with FullAccess to S3 and Redshift, then entered the UserID in this format
arn:aws:iam::600123456789:user/john
along with the matching password, but that hasn't worked either.
The only training/tutorial I have been able to find/do on this is the Intro AWS direct you to, at https://qwiklabs.com/focuses/2366, which uses a web-based client that I can't find outside of the tutorial (pgweb).
Any advice what I am doing wrong, and how to do it right?
Well, I think I got it working - I haven't had a chance to see if I can actually create table yet, but it seems to be connected. I had to allow inbound traffic from outside the VPC, as per the above snapshot.
I'm guessing there's a better way than opening it up to all IP addresses, but I don't know the users' (fellow team members) IPs, and aren't they all subject to change depending on the device they're using to connect?
How does one go about getting inside the VPC to connect that way, presumably more securely?
I am triyng to connect pyeve with a MongoDB Atlas replica set (https://cloud.mongodb.com/). I've connected successfully DB management tools from the same host, to make sure the deployment is working OK.
One particularity is that using Atlas, all users must authenticate against auth database, I cannot put my users in the application database, so I need to set authSource in MONGO_URI.
Now, when defining the MONGO_URI for the replica set, in settings.py, like this:
MONGO_URI = mongodb://<USER>:<PASS>#my-shard-00-00-tlati.mongodb.net:27017,my-shard-00-01-tlati.mongodb.net:27017,my-shard-00-02-tlati.mongodb.net:27017/<MY_DB>?ssl=true&replicaSet=my-shard-0&authSource=admin
The authSource=admin parameter seems to be ignored, (I've checked debugging pymongo's auth and the authentication source used is None).
MONGO_AUTH_SOURCE could be used to set the authorization database, but it has no effect since MONGO_URI is used in preference of the other configuration variables, according to eve's documentation.
Is this an issue or am I doing it wrong?
Found out that the problem was that I was using version 0.4.1 for flask-pymongo. Updating it to version 0.5.1 fixed the problem.
I have configured MongoDB for Sitecore using a replica set.
I set up keyfile access control and added a user.
But I'm facing problems while creating connection strings.
Lets assume my replica set name is rsHelloWorld with several mongod instances: localhost:21017,localhost:21018,localhost:21019,localhost:21020,localhost:21021(arbitor)
username: mongo_admin
password: test#123
The default connection string in Sitecore is:
<add name="analytics" connectionString="mongodb://localhost/analytics" />
How to specify the connection string for my MongoDB database with a replica set and authentication?
Sitecore xDB uses the standard MongoDB connection string format.
In the provided example, the connection string will be this:
mongodb://mongo_admin:test%40123#localhost:21017,localhost:21018,localhost:21019,localhost:21020,localhost:21021/?replicaSet=rsHelloWorld
Note that I have replaced the # symbol in your password with %40. This is because # in a connection string is the separator between credentials and host names. See more here.
Also, keep in mind that you don't have to specify all of your servers in the connection string. You need to specify at least one, and upon connecting to it, xDB will receive full information about the replica set, including the addresses of all data-bearing nodes. Nevertheless, it is a best practice to include several servers in order to ensure that if one of them goes down, the application will still find a server to connect to. In your case, including the arbiter doesn't make much sense since xDB (or any other MongoDB client) will never have to communicate with it.