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crazylion lee

Databricks makes Spark easy through a cloud-based integrated workspace. - 0 views

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    "We believe big data should be simple. Apache® Spark™ made a big step towards this goal. Databricks makes Spark easy through a cloud-based integrated workspace."
crazylion lee

google/seesaw: Seesaw v2 is a Linux Virtual Server (LVS) based load balancing platform. - 1 views

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    "Seesaw v2 is a Linux Virtual Server (LVS) based load balancing platform. It is capable of providing basic load balancing for servers that are on the same network, through to advanced load balancing functionality such as anycast, Direct Server Return (DSR), support for multiple VLANs and centralised configuration. Above all, it is designed to be reliable and easy to maintain."
張 旭

Automated Docker-based Rails deployments - 0 views

  • how to automate the whole deployment process with a real world
  • use Unicorn as our webserver
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    "This is the third post in a series of 3 on how my company moved its infrastructure from PaaS to Docker based deployment."
crazylion lee

GitHub - sindresorhus/ky: Tiny and elegant HTTP client based on the browser Fetch API - 0 views

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    "Tiny and elegant HTTP client based on the browser Fetch API"
chiehting

Top 5 Kubernetes Best Practices From Sandeep Dinesh (Google) - DZone Cloud - 0 views

  • Best Practices for Kubernetes
  • #1: Building Containers
  • Don’t Trust Arbitrary Base Images!
  • ...29 more annotations...
  • There’s a lot wrong with this: you could be using the wrong version of code that has exploits, has a bug in it, or worse it could have malware bundled in on purpose—you just don’t know.
  • Keep Base Images Small
  • Node.js for example, it includes an extra 600MB of libraries you don’t need.
  • Use the Builder Pattern
  • #2: Container Internals
  • Use a Non-Root User Inside the Container
  • Make the File System Read-Only
  • One Process per Container
  • Don’t Restart on Failure. Crash Cleanly Instead.
  • Log Everything to stdout and stderr
  • #3: Deployments
  • Use the “Record” Option for Easier Rollbacks
  • Use Plenty of Descriptive Labels
  • Use Sidecars for Proxies, Watchers, Etc.
  • Don’t Use Sidecars for Bootstrapping!
  • Don’t Use :Latest or No Tag
  • Readiness and Liveness Probes are Your Friend
  • #4: Services
  • Don’t Use type: LoadBalancer
  • Type: Nodeport Can Be “Good Enough”
  • Use Static IPs They Are Free!
  • Map External Services to Internal Ones
  • #5: Application Architecture
  • Use Helm Charts
  • All Downstream Dependencies Are Unreliable
  • Use Weave Cloud
  • Make Sure Your Microservices Aren’t Too Micro
  • Use Namespaces to Split Up Your Cluster
  • Role-Based Access Control
crazylion lee

gregdurrett/berkeley-doc-summarizer: The Berkeley Document Summarizer is a learning-bas... - 0 views

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    "The Berkeley Document Summarizer is a learning-based, single-document summarization system that extracts source document content, exploits syntactic information to compress it, and uses coreference constraints to ensure clarity."
crazylion lee

flood-io/ruby-jmeter: A Ruby based DSL for building JMeter test plans - 0 views

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    "A Ruby based DSL for building JMeter test plans"
crazylion lee

GitHub - olark/up: Zero-downtime reloads and requests load balancer based on distribute. - 0 views

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    "Zero-downtime reloads and requests load balancer based on distribute."
張 旭

Understanding Nginx Server and Location Block Selection Algorithms | DigitalOcean - 0 views

  • A server block is a subset of Nginx’s configuration that defines a virtual server used to handle requests of a defined type. Administrators often configure multiple server blocks and decide which block should handle which connection based on the requested domain name, port, and IP address.
  • A location block lives within a server block and is used to define how Nginx should handle requests for different resources and URIs for the parent server. The URI space can be subdivided in whatever way the administrator likes using these blocks. It is an extremely flexible model.
  • Nginx logically divides the configurations meant to serve different content into blocks, which live in a hierarchical structure. Each time a client request is made, Nginx begins a process of determining which configuration blocks should be used to handle the request.
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  • Nginx is one of the most popular web servers in the world. It can successfully handle high loads with many concurrent client connections, and can easily function as a web server, a mail server, or a reverse proxy server.
  • The main server block directives that Nginx is concerned with during this process are the listen directive, and the server_name directive.
  • The listen directive typically defines which IP address and port that the server block will respond to.
  • 0.0.0.0:8080 if Nginx is being run by a normal, non-root user
  • Nginx translates all “incomplete” listen directives by substituting missing values with their default values so that each block can be evaluated by its IP address and port.
  • In any case, the port must be matched exactly.
  • If there are multiple server blocks with the same level of specificity matching, Nginx then begins to evaluate the server_name directive of each server block.
  • Nginx will only evaluate the server_name directive when it needs to distinguish between server blocks that match to the same level of specificity in the listen directive.
  • Nginx checks the request’s “Host” header. This value holds the domain or IP address that the client was actually trying to reach.
  • Nginx will first try to find a server block with a server_name that matches the value in the “Host” header of the request exactly.
  • If no exact match is found, Nginx will then try to find a server block with a server_name that matches using a leading wildcard (indicated by a * at the beginning of the name in the config).
  • If no match is found using a leading wildcard, Nginx then looks for a server block with a server_name that matches using a trailing wildcard (indicated by a server name ending with a * in the config)
  • If no match is found using a trailing wildcard, Nginx then evaluates server blocks that define the server_name using regular expressions (indicated by a ~ before the name).
  • If no regular expression match is found, Nginx then selects the default server block for that IP address and port.
  • There can be only one default_server declaration per each IP address/port combination.
  • Location blocks live within server blocks (or other location blocks) and are used to decide how to process the request URI (the part of the request that comes after the domain name or IP address/port).
  • If no modifiers are present, the location is interpreted as a prefix match.
  • =: If an equal sign is used, this block will be considered a match if the request URI exactly matches the location given.
  • ~: If a tilde modifier is present, this location will be interpreted as a case-sensitive regular expression match.
  • ~*: If a tilde and asterisk modifier is used, the location block will be interpreted as a case-insensitive regular expression match.
  • ^~: If a carat and tilde modifier is present, and if this block is selected as the best non-regular expression match, regular expression matching will not take place.
  • Keep in mind that if this block is selected and the request is fulfilled using an index page, an internal redirect will take place to another location that will be the actual handler of the request
  • Keeping in mind the types of location declarations we described above, Nginx evaluates the possible location contexts by comparing the request URI to each of the locations.
  • Nginx begins by checking all prefix-based location matches (all location types not involving a regular expression).
  • First, Nginx looks for an exact match.
  • If no exact (with the = modifier) location block matches are found, Nginx then moves on to evaluating non-exact prefixes.
  • After the longest matching prefix location is determined and stored, Nginx moves on to evaluating the regular expression locations (both case sensitive and insensitive).
  • by default, Nginx will serve regular expression matches in preference to prefix matches.
  • regular expression matches within the longest prefix match will “jump the line” when Nginx evaluates regex locations.
  • The exceptions to the “only one location block” rule may have implications on how the request is actually served and may not align with the expectations you had when designing your location blocks.
  • The index directive always leads to an internal redirect if it is used to handle the request.
  • In the case above, if you really need the execution to stay in the first block, you will have to come up with a different method of satisfying the request to the directory.
  • one way of preventing an index from switching contexts, but it’s probably not useful for most configurations
  • the try_files directive. This directive tells Nginx to check for the existence of a named set of files or directories.
  • the rewrite directive. When using the last parameter with the rewrite directive, or when using no parameter at all, Nginx will search for a new matching location based on the results of the rewrite.
  • The error_page directive can lead to an internal redirect similar to that created by try_files.
  • when certain status codes are encountered.
張 旭

How Percona XtraBackup Works - 0 views

  • Percona XtraBackup is based on InnoDB‘s crash-recovery functionality.
  • it performs crash recovery on the files to make them a consistent, usable database again
  • InnoDB maintains a redo log, also called the transaction log. This contains a record of every change to InnoDB data.
  • ...14 more annotations...
  • When InnoDB starts, it inspects the data files and the transaction log, and performs two steps. It applies committed transaction log entries to the data files, and it performs an undo operation on any transactions that modified data but did not commit.
  • Percona XtraBackup works by remembering the log sequence number (LSN) when it starts, and then copying away the data files.
  • Percona XtraBackup runs a background process that watches the transaction log files, and copies changes from it.
  • Percona XtraBackup needs to do this continually
  • Percona XtraBackup needs the transaction log records for every change to the data files since it began execution.
  • Percona XtraBackup uses Backup locks where available as a lightweight alternative to FLUSH TABLES WITH READ LOCK.
  • Locking is only done for MyISAM and other non-InnoDB tables after Percona XtraBackup finishes backing up all InnoDB/XtraDB data and logs.
  • xtrabackup tries to avoid backup locks and FLUSH TABLES WITH READ LOCK when the instance contains only InnoDB tables. In this case, xtrabackup obtains binary log coordinates from performance_schema.log_status
  • When backup locks are supported by the server, xtrabackup first copies InnoDB data, runs the LOCK TABLES FOR BACKUP and then copies the MyISAM tables.
  • the STDERR of xtrabackup is not written in any file. You will have to redirect it to a file, e.g., xtrabackup OPTIONS 2> backupout.log
  • During the prepare phase, Percona XtraBackup performs crash recovery against the copied data files, using the copied transaction log file. After this is done, the database is ready to restore and use.
  • the tools enable you to do operations such as streaming and incremental backups with various combinations of copying the data files, copying the log files, and applying the logs to the data.
  • To restore a backup with xtrabackup you can use the --copy-back or --move-back options.
  • you may have to change the files’ ownership to mysql before starting the database server, as they will be owned by the user who created the backup.
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    "Percona XtraBackup is based on InnoDB's crash-recovery functionality."
張 旭

How to Benchmark Performance of MySQL & MariaDB Using SysBench | Severalnines - 1 views

  • SysBench is a C binary which uses LUA scripts to execute benchmarks
  • support for parallelization in the LUA scripts, multiple queries can be executed in parallel
  • by default, benchmarks which cover most of the cases - OLTP workloads, read-only or read-write, primary key lookups and primary key updates.
  • ...21 more annotations...
  • SysBench is not a tool which you can use to tune configurations of your MySQL servers (unless you prepared LUA scripts with custom workload or your workload happen to be very similar to the benchmark workloads that SysBench comes with)
  • it is great for is to compare performance of different hardware.
  • Every new server acquired should go through a warm-up period during which you will stress it to pinpoint potential hardware defects
  • by executing OLTP workload which overloads the server, or you can also use dedicated benchmarks for CPU, disk and memory.
  • bulk_insert.lua. This test can be used to benchmark the ability of MySQL to perform multi-row inserts.
  • All oltp_* scripts share a common table structure. First two of them (oltp_delete.lua and oltp_insert.lua) execute single DELETE and INSERT statements.
  • oltp_point_select, oltp_update_index and oltp_update_non_index. These will execute a subset of queries - primary key-based selects, index-based updates and non-index-based updates.
  • you can run different workload patterns using the same benchmark.
  • Warmup helps to identify “regular” throughput by executing benchmark for a predefined time, allowing to warm up the cache, buffer pools etc.
  • By default SysBench will attempt to execute queries as fast as possible. To simulate slower traffic this option may be used. You can define here how many transactions should be executed per second.
  • SysBench gives you ability to generate different types of data distribution.
  • decide if SysBench should use prepared statements (as long as they are available in the given datastore - for MySQL it means PS will be enabled by default) or not.
  • sysbench ./sysbench/src/lua/oltp_read_write.lua  help
  • By default, SysBench will attempt to execute queries in explicit transaction. This way the dataset will stay consistent and not affected: SysBench will, for example, execute INSERT and DELETE on the same row, making sure the data set will not grow (impacting your ability to reproduce results).
  • specify error codes from MySQL which SysBench should ignore (and not kill the connection).
  • the two most popular benchmarks - OLTP read only and OLTP read/write.
  • 1 million rows will result in ~240 MB of data. Ten tables, 1000 000 rows each equals to 2.4GB
  • by default, SysBench looks for ‘sbtest’ schema which has to exist before you prepare the data set. You may have to create it manually.
  • pass ‘--histogram’ argument to SysBench
  • ~48GB of data (20 tables, 10 000 000 rows each).
  • if you don’t understand why the performance was like it was, you may draw incorrect conclusions out of the benchmarks.
張 旭

What is Kubernetes Ingress? | IBM - 0 views

  • expose an application to the outside of your Kubernetes cluster,
  • ClusterIP, NodePort, LoadBalancer, and Ingress.
  • A service is essentially a frontend for your application that automatically reroutes traffic to available pods in an evenly distributed way.
  • ...23 more annotations...
  • Services are an abstract way of exposing an application running on a set of pods as a network service.
  • Pods are immutable, which means that when they die, they are not resurrected. The Kubernetes cluster creates new pods in the same node or in a new node once a pod dies. 
  • A service provides a single point of access from outside the Kubernetes cluster and allows you to dynamically access a group of replica pods. 
  • For internal application access within a Kubernetes cluster, ClusterIP is the preferred method
  • To expose a service to external network requests, NodePort, LoadBalancer, and Ingress are possible options.
  • Kubernetes Ingress is an API object that provides routing rules to manage external users' access to the services in a Kubernetes cluster, typically via HTTPS/HTTP.
  • content-based routing, support for multiple protocols, and authentication.
  • Ingress is made up of an Ingress API object and the Ingress Controller.
  • Kubernetes Ingress is an API object that describes the desired state for exposing services to the outside of the Kubernetes cluster.
  • An Ingress Controller reads and processes the Ingress Resource information and usually runs as pods within the Kubernetes cluster.  
  • If Kubernetes Ingress is the API object that provides routing rules to manage external access to services, Ingress Controller is the actual implementation of the Ingress API.
  • The Ingress Controller is usually a load balancer for routing external traffic to your Kubernetes cluster and is responsible for L4-L7 Network Services. 
  • Layer 7 (L7) refers to the application level of the OSI stack—external connections load-balanced across pods, based on requests.
  • if Kubernetes Ingress is a computer, then Ingress Controller is a programmer using the computer and taking action.
  • Ingress Rules are a set of rules for processing inbound HTTP traffic. An Ingress with no rules sends all traffic to a single default backend service. 
  • the Ingress Controller is an application that runs in a Kubernetes cluster and configures an HTTP load balancer according to Ingress Resources.
  • The load balancer can be a software load balancer running in the cluster or a hardware or cloud load balancer running externally.
  • ClusterIP is the preferred option for internal service access and uses an internal IP address to access the service
  • A NodePort is a virtual machine (VM) used to expose a service on a Static Port number.
  • a NodePort would be used to expose a single service (with no load-balancing requirements for multiple services).
  • Ingress enables you to consolidate the traffic-routing rules into a single resource and runs as part of a Kubernetes cluster.
  • An application is accessed from the Internet via Port 80 (HTTP) or Port 443 (HTTPS), and Ingress is an object that allows access to your Kubernetes services from outside the Kubernetes cluster. 
  • To implement Ingress, you need to configure an Ingress Controller in your cluster—it is responsible for processing Ingress Resource information and allowing traffic based on the Ingress Rules.
張 旭

3. Hello, world! - Err 9.9.9 documentation - 0 views

  • The first is a Message object, which represents the full message object received by Errbot.
  • The second is a string (or a list, if using the split_args_with parameter of botcmd()) with the arguments passed to the command.
  • args would be the string “Mister Errbot”.
  • ...6 more annotations...
  • If you return None, Errbot will not respond with any kind of message when executing the command.
  • a file that ends with the extension .plug and it is used by Errbot to identify and load plugins.
  • The key Module should point to a module that Python can find and import.
  • The key Name should be identical to the name you gave to the class in your plugin file
  • The presence of __init__.py indicates lib is a Python regular package.
  • the !status command,
crazylion lee

Eve - 0 views

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    "Eve is a programming language and IDE based on years of research into building a human-first programming platform. From code embedded in documents to a language without order, it presents an alternative take on what programming could be - one that focuses on us instead of the machine. This is Eve:"
crazylion lee

eMotion | Adrien M / Claire B - 0 views

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    "eMotion est une application fonctionnant sur OS X destinée à écrire des interactions entre des objets et des informations. Elle se base sur des modèles physiques pour animer des situations. "
crazylion lee

Proxmox VE - 0 views

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    " Proxmox Virtual Environment is an open source server virtualization management solution based on QEMU/KVM and LXC. You can manage virtual machines, containers, highly available clusters, storage and networks with an integrated, easy-to-use web interface or via CLI. Proxmox VE code is licensed under the GNU Affero General Public License, version 3. The project is developed and maintained by Proxmox Server Solutions GmbH."
crazylion lee

Homepage | Celery: Distributed Task Queue - 0 views

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    "Celery is an asynchronous task queue/job queue based on distributed message passing. It is focused on real-time operation, but supports scheduling as well. The execution units, called tasks, are executed concurrently on a single or more worker servers using multiprocessing, Eventlet, or gevent. Tasks can execute asynchronously (in the background) or synchronously (wait until ready)."
crazylion lee

https://states-language.net/spec.html#example - 0 views

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    "This document describes a JSON-based language used to describe state machines declaratively. The state machines thus defined may be executed by software. In this document, the software is referred to as "the interpreter"."
crazylion lee

Google Web Designer - 0 views

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    "Create engaging, interactive HTML5-based designs and motion graphics that can run on any device. "
crazylion lee

Raft Consensus Algorithm - 0 views

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    " Raft is a consensus algorithm that is designed to be easy to understand. It's equivalent to Paxos in fault-tolerance and performance. The difference is that it's decomposed into relatively independent subproblems, and it cleanly addresses all major pieces needed for practical systems. We hope Raft will make consensus available to a wider audience, and that this wider audience will be able to develop a variety of higher quality consensus-based systems than are available today."
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