raft | Golang implementation of the Raft consensus protocol | Architecture library

 by   hashicorp Go Version: v1.5.0 License: MPL-2.0

kandi X-RAY | raft Summary

kandi X-RAY | raft Summary

raft is a Go library typically used in Architecture applications. raft has no bugs, it has no vulnerabilities, it has a Weak Copyleft License and it has medium support. You can download it from GitHub.

Golang implementation of the Raft consensus protocol
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              raft has a medium active ecosystem.
              It has 7161 star(s) with 899 fork(s). There are 410 watchers for this library.
              OutlinedDot
              It had no major release in the last 12 months.
              There are 26 open issues and 202 have been closed. On average issues are closed in 170 days. There are 7 open pull requests and 0 closed requests.
              It has a neutral sentiment in the developer community.
              The latest version of raft is v1.5.0

            kandi-Quality Quality

              raft has 0 bugs and 0 code smells.

            kandi-Security Security

              raft has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              raft code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              raft is licensed under the MPL-2.0 License. This license is Weak Copyleft.
              Weak Copyleft licenses have some restrictions, but you can use them in commercial projects.

            kandi-Reuse Reuse

              raft releases are available to install and integrate.
              Installation instructions are not available. Examples and code snippets are available.
              It has 12128 lines of code, 639 functions and 58 files.
              It has medium code complexity. Code complexity directly impacts maintainability of the code.

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            raft Key Features

            No Key Features are available at this moment for raft.

            raft Examples and Code Snippets

            No Code Snippets are available at this moment for raft.

            Community Discussions

            QUESTION

            How does Raft guarantee that a leader can always be elected?
            Asked 2022-Apr-08 at 20:25

            The Raft paper says:

            Raft uses the voting process to prevent a candidate from winning an election unless its log contains all committed entries. A candidate must contact a majority of the cluster in order to be elected, which means that every committed entry must be present in at least one of those servers. If the candidate’s log is at least as up-to-date as any other log in that majority, then it will hold all the committed entries. The RequestVote RPC implements this restriction: the RPC includes information about the candidate’s log, and the voter denies its vote if its own log is more up-to-date than that of the candidate

            How does it guarantee, however, that there will always even be an electable leader (i.e. one that's as up-to-date as a majority of cluster)?

            For example, let's say we have a cluster of three servers A, B, C with A as the leader. First log entry is stored in A and B, second log entry is stored in A and C. Then A crashes, and B and C try to elect a leader. But at this point there is no majority (i.e. 2 out of 3) servers that have both first and second entries. So it seems like leader election can't ever happen (unless A restarts, but Raft's supposed to be resilient to a failure of 1 out of 3 servers..)

            ...

            ANSWER

            Answered 2022-Apr-08 at 20:25

            The paper defines a "Log Matching Property" that is relevant to this scenario:

            • [..]
            • If two entries in different logs have the same index and term, then the logs are identical in all preceding entries.

            Since A and C both contain the same second entry, C must also contain the first entry. This is ensured because:

            The second property is guaranteed by a simple consistency check performed by AppendEntries. When sending an AppendEntries RPC, the leader includes the index and term of the entry in its log that immediately precedes the new entries. If the follower does not find an entry in its log with the same index and term, then it refuses the new entries.

            Until C has the entry that B has, it will reject further appends. So at some point in your scenario, C must have received that entry to finally accept the newer entry from A.

            Therefore, C is the most up to date between B and C. (It would reject a leadership vote from B.)

            Source https://stackoverflow.com/questions/71801967

            QUESTION

            Docker healthcheck stops working after a while
            Asked 2022-Mar-15 at 17:16

            I am running docker in a Raspberry Pi 3 Model B Plus Rev 1.3, running Raspberry pi OS with all packages up to date.

            TL;DR

            The healthchecks on a given container works fine for some time (around 30 min, some times less some times more), but at some point they get "stuck" and so the container remains healthy, even though it is not the case. Is there a way to debug what's going on with the healthchecks and so try to figure out what is happening?

            the healthcheck is not configured in the Dockerfile, but instead in the yml file I use to deploy the stack as follows

            ...

            ANSWER

            Answered 2022-Mar-15 at 17:16

            This issue appears to no longer be happening. I upgraded to Raspbian bullseye, and healthchecks have been running for a week straight, without issues.

            Source https://stackoverflow.com/questions/69385308

            QUESTION

            Hyperledger Fabric | Orderer PODs keeps restarting | Error: Was the raft log corrupted, truncated, or lost?
            Asked 2022-Feb-18 at 05:48

            I'm running Hyperledger Fabric network in Azure Kubernetes Cluster. I'm using single Azure Files volume (1000 GB) as my persistent volume.

            However, my Orderer POD keeps restarting over and over again.

            Orderer POD is logging following error:

            ...

            ANSWER

            Answered 2022-Feb-18 at 05:48

            Turns out my WAL logs directory was deleted. Anyone landing on this question, please set following (if not already set) ENV variables on your Orderer deployments:

            Source https://stackoverflow.com/questions/71098325

            QUESTION

            ImageBackground won't render react native
            Asked 2022-Feb-09 at 01:01

            I'm doing a project in react native and my ImageBackgroud component does not want to render. The odd thing is I am already using ImageBackground in another component and it works there. I tried resizing the image but that didn't help.

            Here is my component that renders child component with ImageBackground:

            ...

            ANSWER

            Answered 2022-Feb-09 at 01:01
            image: {
                flex: 1,
                overflow:'hidden',
                justifyContent:'center',
             padding:30
              },
            

            Source https://stackoverflow.com/questions/71040908

            QUESTION

            How to failover in etcd cluster
            Asked 2022-Feb-04 at 12:31

            I have 3 nodes etcd cluster i.e. one master and two slaves. I need to bring down the master node for some maintenance activity. So, I tried conducting elections to elect a new master but it didn't work.

            Below is the current state of the etcd cluster

            ...

            ANSWER

            Answered 2022-Feb-04 at 12:31

            QUESTION

            Overwrite of Kafka Version in Spring Boot fails for some dependencies
            Asked 2022-Jan-28 at 20:46

            I have a fresh Spring Boot 2.6.3 Java 11 application with a Spring Kafka Dependency (generated with start.spring.io).

            By default Kafka 3.0.0 is is used. I want to change the Kafka version to 3.1.0 and added

            ...

            ANSWER

            Answered 2022-Jan-28 at 20:46

            According to the docs section on overriding dependencies

            You could manually add the one it's looking for

            Source https://stackoverflow.com/questions/70891088

            QUESTION

            etcd - save data to custom database
            Asked 2022-Jan-27 at 09:08
            Trying to figure out how to create a simple distributed database

            etcd is use to consensus metadata in Kubernetes. I can see Dgraph BadgerDB and other key value stores are using etcd, but I don't know quite how they are using it. Update: It looks like they are using a raft subset of etcd.

            My question:

            etcd is for storing metadata and not data as such - is it possible/recommended to combine etcd with another key value store to handle large data?

            I have also looked at hashicorp raft

            ...

            ANSWER

            Answered 2022-Jan-27 at 09:08

            The etcd service was conceived to handle metadata: retrieve one key, get some data wich usually in the kilobytes range. Not megabytes.

            You cannot "offlad" etcd to another database / datastore. Etcd need to have its data with low latency on the majority of nodes.

            The biggest criticism about etcd are hardware requirements: 8GB RAM x 3 machines might be too much for some use cases.

            Is it etcd good for you? It depends a lot on:

            • Your workload (mostly read-oriented than write-oriented)
            • How many requests you need from etcd in a short time period: do not 'fire' too many requests at once to etcd or you might trigger a leader election.
            • And your data size: use --auto-compaction enabled to keep disk usage as low as possible removing old data versions.

            Source https://stackoverflow.com/questions/70608845

            QUESTION

            Akka ask pattern: how to make request and replies context-aware?
            Asked 2022-Jan-24 at 18:23

            For a University assignment, I have to implement a simulation of the Raft protocol in Akka (I am using Akka typed, using Behaviors). In the Raft protocol, interactions between actors have a 1:1 mapping between a request and a response; responses must be delivered in a timely manner. Therefore, it makes sense to use the ask pattern as demonstrated by the documentation in the Request-Response with ask between two actors example.

            In my implementation, requests and responses must be context-aware: this means that, when an actor that performed a query receives a response, it must know what query the response was for. The example in the documentation suggests to include a query ID in the message.

            What I need to solve can be described with the following example:

            • Actor A sends a query with ID=1 to actor B (it includes the query ID in the message).
            • B does not reply in time (the network, or B itself, may be slow), thus A re-issues a query with ID=2 to B.
            • Actor B receives the query with ID=1, and replies to actor A (including the query ID in the message).
            • Actor A receives B's reply with ID=1. A knows that the last query it sent had ID=2, thus must NOT process the reply but wait for the one with ID=2.

            I think that, to "filter" replies that do not have a correct query ID, I can put a BehaviorInterceptor in actor A that checks that the ID in the reply matches the expected query ID.

            To summarize:

            • Actor A writes in a hashmap the query ID to be expected from actor B's next reply,
            • The interceptor uses this hashmap to check the ID in the reply. Is this a good design?

            Moreover, I don't understand whether ask is blocking or not. Ideally, I would like to use ask in a non-blocking way: actor A asks actor B, and, while waiting for B's reply, A can do other operations. While waiting for B's reply, actor A can also change its behavior if needed (also a Behavior that does not handle B's replies).

            Thank you for any insight!

            ...

            ANSWER

            Answered 2022-Jan-24 at 18:23

            An ask between two actors (using the ActorContext) is non-blocking.

            Since the high watermark of the requests to a given target is an important part of protocol state for the actor, I would just store it in the asking actor's state (e.g. in Scala a Map[ActorRef[Request], Int]). The adapted response contains the target and the id it's in response to (you define how this is incorporated when performing the ask); when receiving the adapted response, the first thing is comparing the id in the response to the high watermark for the target.

            In Scala, for example:

            Source https://stackoverflow.com/questions/70835240

            QUESTION

            In Akka, how can network delays be simulated?
            Asked 2022-Jan-15 at 19:16

            I have a question that is more of a design one rather than a coding one.

            I'm currently using Akka (we're transitioning from Classic to Typed) to implement a Raft cluster, using the Java version. Our assignment requires the cluster - like the paper implementation - to operate on harsh network conditions, and as such I would like to implement Akka-side a way to systematically delay messages. Timings and selectivity do not matter - e.g., assume we want to delay ALL messages going through the system by 200ms.u

            My idea was to use Routers - https://doc.akka.io/docs/akka/current/typed/routers.html - but I would like to know what's the best approach to write something that is both scalable and does not add unpredictable bugs (like using Thread.sleep() does, which delays message queue handling)

            EDIT: The raft cluster is hosted on a single machine, so transmission is basically instantaneous now, and any interaction is handled by Akka itself. No network stack is ever involed.

            ...

            ANSWER

            Answered 2022-Jan-15 at 17:23

            Based on understanding your question, since you are looking at network level, you should be taking a look at chaos testing tools.

            You can check for bunch of these tools here: https://github.com/dastergon/awesome-chaos-engineering

            Source https://stackoverflow.com/questions/70723121

            QUESTION

            TypeError: generateActiveToken is not a function
            Asked 2022-Jan-15 at 13:07

            I have a problem in Nodejs but I dont't know why this error happening

            in config folder I have a file with name generateToken.js and this file have this code:

            ...

            ANSWER

            Answered 2022-Jan-15 at 13:07

            First of all, generateActiveToken is a async function so put an await before function call.

            The proper way to export a module is like below:

            Source https://stackoverflow.com/questions/70721202

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network

            Vulnerabilities

            No vulnerabilities reported

            Install raft

            You can download it from GitHub.

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            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
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            https://github.com/hashicorp/raft.git

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            gh repo clone hashicorp/raft

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            git@github.com:hashicorp/raft.git

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