my aim is to add only slaves URIs, because master is not available in my case. But lettuce library returns
io.lettuce.core.RedisException: Master is currently unknown: [RedisMasterSlaveNode [redisURI=RedisURI [host='127.0.0.1', port=6382], role=SLAVE], RedisMasterSlaveNode [redisURI=RedisURI [host='127.0.0.1', port=6381], role=SLAVE]]
So the question is: Is it possible so avoid this exception somehow? Maybe configuration. Thank you in advance
UPDATE: Forgot to say that after borrowing object from pool I set connection.readFrom(ReadFrom.SLAVE) before running commands.
GenericObjectPoolConfig config = fromRedisConfig(properties);
List<RedisURI> nodes = new ArrayList<>(properties.getUrl().length);
for (String url : properties.getUrl()) {
nodes.add(RedisURI.create(url));
}
return ConnectionPoolSupport.createGenericObjectPool(
() -> MasterSlave.connect(redisClient, new ByteArrayCodec(), nodes), config);
The problem was that I tried to set data, which is possible only with master node. So there is no problem with MasterSlave. Get data works perfectly
Related
I've worked through the documentation on Akka.Net PersistenceQuery here, but I'm struggling to figure out how I would hook up any of those queries inside an ASP.Net6 Blazor Server startup pipeline using the new Akka.Net Hosting model.
What I have in mind is to Sink such a query out to a SignalR hub that will cause views to refresh their data based on the output of a ReadForJournal stream.
Has anyone done this, and if so, please can you provide me with some guidance in this regard?
I have not done this before, much less an expert are this, but I can try to point you in the right direction! :)
If you want to run a local actor, you can spawn the ProjectionBehavior as any other Behavior. This can be useful for testing or when running a local ActorSystem without Akka Cluster.
SourceProvider<Offset, EventEnvelope<ShoppingCart.Event>> sourceProvider(String tag) {
return EventSourcedProvider.eventsByTag(system, CassandraReadJournal.Identifier(), tag);
}
Projection<EventEnvelope<ShoppingCart.Event>> projection(String tag) {
return CassandraProjection.atLeastOnce(
ProjectionId.of("shopping-carts", tag), sourceProvider(tag), ShoppingCartHandler::new);
}
Projection<EventEnvelope<ShoppingCart.Event>> projection1 = projection("carts-1");
ActorRef<ProjectionBehavior.Command> projection1Ref =
context.spawn(ProjectionBehavior.create(projection1), projection1.projectionId().id());
You can combine this with your predefined query, e.g.:
var queries = PersistenceQuery.Get(actorSystem)
.ReadJournalFor<SqlReadJournal>("akka.persistence.query.my-read-journal");
var mat = ActorMaterializer.Create(actorSystem);
Source<string, NotUsed> src = queries.AllPersistenceIds();
So I was thinking maybe your queries could be linked to your ProjectionBehavior for the akka hosting model to host it.
Related sources:
Getakka.net persistence-query
Akka projection dox
Akka hosting
I have a celery app which has to be pinged by another app. This other app uses json to serialize celery task parameters, but my app has a custom serialization protocol. When the other app tries to ping my app (app.control.ping), it throws the following error:
"Celery ping failed: Refusing to deserialize untrusted content of type application/x-stjson (application/x-stjson)"
My whole codebase relies on this custom encoding, so I was wondering if there is a way to configure a json serialization but only for this ping, and to continue using the custom encoding for the other tasks.
These are the relevant celery settings:
accept_content = [CUSTOM_CELERY_SERIALIZATION, "json"]
result_accept_content = [CUSTOM_CELERY_SERIALIZATION, "json"]
result_serializer = CUSTOM_CELERY_SERIALIZATION
task_serializer = CUSTOM_CELERY_SERIALIZATION
event_serializer = CUSTOM_CELERY_SERIALIZATION
Changing any of the last 3 to [CUSTOM_CELERY_SERIALIZATION, "json"] causes the app to crash, so that's not an option.
Specs: celery=5.1.2
python: 3.8
OS: Linux docker container
Any help would be much appreciated.
Changing any of the last 3 to [CUSTOM_CELERY_SERIALIZATION, "json"] causes the app to crash, so that's not an option.
Because result_serializer, task_serializer, and event_serializer doesn't accept list but just a single str value, unlike e.g. accept_content
The list for e.g. accept_content is possible because if there are 2 items, we can check if the type of an incoming request is one of the 2 items. It isn't possible for e.g. result_serializer because if there were 2 items, then what should be chosen for the result of task-A? (thus the need for a single value)
This means that if you set result_serializer = 'json', this will have a global effect where all the results of all tasks (the returned value of the tasks which can be retrieved by calling e.g. response.get()) would be serialized/deserialized using the json-serializer. Thus, it might work for the ping but it might not for the tasks that can't be directly serialized/deserialized to/from JSON which really needs the custom stjson-serializer.
Currently with Celery==5.1.2, it seems that task-specific setting of result_serializer isn't possible, thus we can't set a single task to be encoded in 'json' and not 'stjson' without setting it globally for all, I assume the same case applies to ping.
Open request to add result_serializer option for tasks
A short discussion in another question
Not the best solution but a workaround is that instead of fixing it in your app's side, you may opt to just add support to serialize/deserialize the contents of type 'application/x-stjson' in the other app.
other_app/celery.py
import ast
from celery import Celery
from kombu.serialization import register
# This is just a possible implementation. Replace with the actual serializer/deserializer for stjson in your app.
def stjson_encoder(obj):
return str(obj)
def stjson_decoder(obj):
obj = ast.literal_eval(obj)
return obj
register(
'stjson',
stjson_encoder,
stjson_decoder,
content_type='application/x-stjson',
content_encoding='utf-8',
)
app = Celery('other_app')
app.conf.update(
accept_content=['json', 'stjson'],
)
You app remains to accept and respond stjson format, but now the other app is configured to be able to parse such format.
When running a Neo4J database server standalone (on Ubuntu 14.04), configuration options are set for the global installation in etc/neo4j/neo4j.conf or possibly $NEO4J_HOME/conf/neo4j.conf.
However, when instantiating a Neo4j database from Java or Scala using Apache's Neo4jGraph class (org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jGraph), there is no global installation, and the constructor does not (as far as I can tell) look for any configuration files.
In particular, when running the test suite for my application, I end up with many simultaneous instances of Neo4jGraph, which ends up throwing a java.net.BindException: Address already in use because all of these instances are trying to communicate over a small range of ports for online backup, which I don't actually need. These channels are set with config options dbms.backup.address (default value: 127.0.0.1:6362-6372) and dbms.backup.enabled (default value: true).
My problem would be solved by setting dbms.backup.enabled to false, or expanding the port range.
Things that have not worked:
Creating /etc/neo4j/neo4j.conf containing the line dbms.backup.enabled=false.
Creating the same file in my project's src/main/resources directory.
Creating the same file in src/main/resources/neo4j.
Manually setting the configuration property inside the Scala code:
val db = new Neo4jGraph(dataDirectory)
db.configuration.addProperty("dbms.backup.enabled",false)
or
db.configuration.addProperty("neo4j.conf.dbms.backup.enabled",false)
or
db.configuration.addProperty("gremlin.neo4j.conf.dbms.backup.enabled",false)
How should I go about setting this property?
Neo4jGraph configuration through TinkerPop is accomplished by a pass-through of configuration keys. In TinkerPop 3.x, that would mean that all Neo4j keys prefixed with gremlin.neo4j.conf that are provided via Configuration object to Neo4jGraph.open() or GraphFactory.open() will be passed down directly to the Neo4j instance. You can see examples of this here in the TinkerPop documentation on high availability configuration.
In TinkerPop 2.x, the same approach was taken however the key prefix was instead blueprints.neo4j.conf.* as discussed here.
Manipulating db.configuration after the database connection had already been opened was definitely futile.
stephen mallette's answer was on the right track, but this particular configuration doesn't appear to pass through in the way his linked example does. There is a naming mismatch between the configuration keys expected in neo4j.conf and those expected in org.neo4j.backup.OnlineBackupKernelExtension. Instead of dbms.backup.address and dbms.backup.enabled, that class looks for config keys online_backup_server and online_backup_enabled.
I was not able to get these keys passed down to the underlying Neo4jGraphAPI instance correctly. What I had to do, instead, was the following:
import org.neo4j.tinkerpop.api.impl.Neo4jFactoryImpl
import scala.collection.JavaConverters._
val factory = new Neo4jFactoryImpl()
val config = Map(
"online_backup_enabled" -> "true",
"online_backup_server" -> "0.0.0.0:6350-6359"
).asJava
val db = Neo4jGraph.open(factory.newGraphDatabase(dataDirectory,config))
With this initialization, the instance correctly listened for backups on port 6350; changing "true" to "false" disabled backup listening.
Using Neo4j 3.0.0 the following disables port listening for me (Java code)
import org.apache.commons.configuration.BaseConfiguration;
import org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jGraph;
BaseConfiguration conf = new BaseConfiguration();
conf.setProperty(Neo4jGraph.CONFIG_DIRECTORY, "/path/to/db");
conf.setProperty(Neo4jGraph.CONFIG_CONF + "." + "dbms.backup.enabled", "false");
graph = Neo4jGraph.open(config);
I have an akka.net cluster and I want to send a message to actors that are both local and remote, and that all have the path "/user/foobar" (at least locally). Should I use ActorSelection, and what should the path look like in order to target both matching local and remote actors?
It's unclear from the question whether you mean you want to send a message locally within one node in your cluster, or across multiple nodes.
If you just want to send it in one node, you can use an ActorSelection and just send it to whatever the desired actor path is (e.g. /user/*/processingActor). If you want to message across the cluster itself, you'll need to set up a cluster-aware Group router.
See the docs here for router configuration, which is where you'll define the routees.
In a nutshell, you'll be doing something like this:
# inside akka.actor.deployment HOCON
/some-group-router {
router = round-robin-group
routees.paths = ["/user/*/processingActor",]
nr-of-instances=3
cluster {
enabled=on
use-role=targetRoleName
allow-local-routees=on
}
}
When trying to run the following in Redis using booksleeve.
using (var conn = new RedisConnection(server, port, -1, password))
{
var result = conn.Server.FlushDb(0);
result.Wait();
}
I get an error saying:
This command is not available unless the connection is created with
admin-commands enabled"
I am not sure how do i execute commands as admin? Do I need to create an a/c in db with admin access and login with that?
Updated answer for StackExchange.Redis:
var conn = ConnectionMultiplexer.Connect("localhost,allowAdmin=true");
Note also that the object created here should be created once per application and shared as a global singleton, per Marc:
Because the ConnectionMultiplexer does a lot, it is designed to be
shared and reused between callers. You should not create a
ConnectionMultiplexer per operation. It is fully thread-safe and ready
for this usage.
Basically, the dangerous commands that you don't need in routine operations, but which can cause lots of problems if used inappropriately (i.e. the equivalent of drop database in tsql, since your example is FlushDb) are protected by a "yes, I meant to do that..." flag:
using (var conn = new RedisConnection(server, port, -1, password,
allowAdmin: true)) <==== here
I will improve the error message to make this very clear and explicit.
You can also set this in C# when you're creating your multiplexer - set AllowAdmin = true
private ConnectionMultiplexer GetConnectionMultiplexer()
{
var options = ConfigurationOptions.Parse("localhost:6379");
options.ConnectRetry = 5;
options.AllowAdmin = true;
return ConnectionMultiplexer.Connect(options);
}
For those who like me faced the error:
StackExchange.Redis.RedisCommandException: This operation is not
available unless admin mode is enabled: ROLE
after upgrading StackExchange.Redis to version 2.2.4 with Sentinel connection: it's a known bug, the workaround was either to downgrade the client back or to add allowAdmin=true to the connection string and wait for the fix.
Starting from 2.2.50 public release the issue is fixed.