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crazylion lee

GitHub - novnc/noVNC: VNC client using HTML5 (Web Sockets, Canvas) with encryption (wss... - 0 views

github.com/noVNC

vnc html5

shared by crazylion lee on 12 Nov 18 - No Cached
  • crazylion lee on 12 Nov 18
     
    "VNC client using HTML5 (Web Sockets, Canvas) with encryption (wss://) support. http://novnc.com"
張 旭

cryptography - What's the difference between SSL, TLS, and HTTPS? - Information Securit... - 0 views

security.stackexchange.com/...ence-between-ssl-tls-and-https

security ssl system https

shared by 張 旭 on 23 Jun 17 - No Cached
  • TLS is the new name for SSL
  • HTTPS is HTTP-within-SSL/TLS
  • SSL (TLS) establishes a secured, bidirectional tunnel for arbitrary binary data between two hosts
  • ...10 more annotations...
  • HTTP is meant to run over a bidirectional tunnel for arbitrary binary data; when that tunnel is an SSL/TLS connection, then the whole is called "HTTPS".
  • "SSL" means "Secure Sockets Layer".
  • "TLS" means "Transport Layer Security".
  • The name was changed to avoid any legal issues with Netscape so that the protocol could be "open and free" (and published as a RFC).
    • 張 旭
      張 旭 on 23 Jun 17
       
      看起來其實就指同一件事，只是講 TLS 可以避開 SSL 這個有產權糾紛的名諱。
  • not just Internet-based sockets
  • "HTTPS" is supposed to mean "HyperText Transfer Protocol Secure",
  • Other protocol acronyms have been built the same way, e.g. SMTPS, IMAPS, FTPS... all of them being a bare protocol that "got secured" by running it within some SSL/TLS.
  • To make the confusing perfect: SSL (secure socket layer) often refers to the old protocol variant which starts with the handshake right away and therefore requires another port for the encrypted protocol such as 443 instead of 80.
  • TLS (transport layer security) often refers to the new variant which allows to start with an unencrypted traditional protocol and then issuing a command (usually STARTTLS) to initialize the handshake.
  • Whether you use SSL or TLS for this depends on the configuration of your browser and of the server (there usually is an option to allow SSLv2, SSLv3 or TLS 1.x).
crazylion lee

Shadowsocks - A secure socks5 proxy - 0 views

shadowsocks.org/index.html

python socket proxy

shared by crazylion lee on 24 Jul 16 - No Cached
  • crazylion lee on 24 Jul 16
     
    "A secure socks5 proxy, designed to protect your Internet traffic."
張 旭

http - nginx upload client_max_body_size issue - Stack Overflow - 0 views

stackoverflow.com/...oad-client-max-body-size-issue

nginx upload file http server

shared by 張 旭 on 26 Sep 16 - No Cached
  • nginx "fails fast" when the client informs it that it's going to send a body larger than the client_max_body_size by sending a 413 response and closing the connection.
  • Because nginx closes the connection, the client sends data to the closed socket, causing a TCP RST.
  • Most clients don't read responses until the entire request body is sent.
  • ...2 more annotations...
  • Client body and buffers are key because nginx must buffer incoming data.
  • The clean setting frees up memory and consumption limits by instructing nginx to store incoming buffer in a file and then clean this file later from disk by deleting it.
張 旭

The Rails Command Line - Ruby on Rails Guides - 0 views

guides.rubyonrails.org/command_line.html

rails console command

shared by 張 旭 on 28 Nov 14 - Cached
  • rake --tasks
  • Think of destroy as the opposite of generate.
  • runner runs Ruby code in the context of Rails non-interactively
  • ...28 more annotations...
  • rails dbconsole figures out which database you're using and drops you into whichever command line interface you would use with it
  • The console command lets you interact with your Rails application from the command line. On the underside, rails console uses IRB
  • rake about gives information about version numbers for Ruby, RubyGems, Rails, the Rails subcomponents, your application's folder, the current Rails environment name, your app's database adapter, and schema version
  • You can precompile the assets in app/assets using rake assets:precompile and remove those compiled assets using rake assets:clean.
  • rake db:version is useful when troubleshooting
  • The doc: namespace has the tools to generate documentation for your app, API documentation, guides.
  • rake notes will search through your code for comments beginning with FIXME, OPTIMIZE or TODO.
  • You can also use custom annotations in your code and list them using rake notes:custom by specifying the annotation using an environment variable ANNOTATION.
  • rake routes will list all of your defined routes, which is useful for tracking down routing problems in your app, or giving you a good overview of the URLs in an app you're trying to get familiar with.
  • rake secret will give you a pseudo-random key to use for your session secret.
  • Custom rake tasks have a .rake extension and are placed in Rails.root/lib/tasks.
  • rails new . --git --database=postgresql
  • All commands can run with -h or --help to list more information
  • The rails server command launches a small web server named WEBrick which comes bundled with Ruby
  • rails server -e production -p 4000
  • You can run a server as a daemon by passing a -d option
  • The rails generate command uses templates to create a whole lot of things.
  • Using generators will save you a large amount of time by writing boilerplate code, code that is necessary for the app to work.
  • All Rails console utilities have help text.
  • generate controller ControllerName action1 action2.
  • With a normal, plain-old Rails application, your URLs will generally follow the pattern of http://(host)/(controller)/(action), and a URL like http://(host)/(controller) will hit the index action of that controller.
  • A scaffold in Rails is a full set of model, database migration for that model, controller to manipulate it, views to view and manipulate the data, and a test suite for each of the above.
  • Unit tests are code that tests and makes assertions about code.
  • Unit tests are your friend.
  • rails console --sandbox
  • rails db
  • Each task has a description, and should help you find the thing you need.
  • rake tmp:clear clears all the three: cache, sessions and sockets.
張 旭

Let's Encrypt & Docker - Træfik - 0 views

docs.traefik.io/...docker-and-lets-encrypt

traefik docker networking proxy

shared by 張 旭 on 19 Sep 18 - No Cached
  • automatically discover any services on the Docker host and let Træfik reconfigure itself automatically when containers get created (or shut down) so HTTP traffic can be routed accordingly.
  • use Træfik as a layer-7 load balancer with SSL termination for a set of micro-services used to run a web application.
  • Docker containers can only communicate with each other over TCP when they share at least one network.
  • ...15 more annotations...
  • Docker under the hood creates IPTable rules so containers can't reach other containers unless you'd want to
  • Træfik can listen to Docker events and reconfigure its own internal configuration when containers are created (or shut down).
  • Enable the Docker provider and listen for container events on the Docker unix socket we've mounted earlier.
  • Enable automatic request and configuration of SSL certificates using Let's Encrypt. These certificates will be stored in the acme.json file, which you can back-up yourself and store off-premises.
  • there isn't a single container that has any published ports to the host -- everything is routed through Docker networks.
  • Thanks to Docker labels, we can tell Træfik how to create its internal routing configuration.
  • container labels and service labels
  • With the traefik.enable label, we tell Træfik to include this container in its internal configuration.
  • tell Træfik to use the web network to route HTTP traffic to this container.
  • Service labels allow managing many routes for the same container.
  • When both container labels and service labels are defined, container labels are just used as default values for missing service labels but no frontend/backend are going to be defined only with these labels.
  • In the example, two service names are defined : basic and admin. They allow creating two frontends and two backends.
  • Always specify the correct port where the container expects HTTP traffic using traefik.port label.
  • all containers that are placed in the same network as Træfik will automatically be reachable from the outside world
  • With the traefik.frontend.auth.basic label, it's possible for Træfik to provide a HTTP basic-auth challenge for the endpoints you provide the label for.
crazylion lee

GitHub - hugmanrique/turbo-ws: Blazing fast low-level WebSocket server - 0 views

github.com/turbo-ws

web socket websockets

shared by crazylion lee on 12 Mar 18 - No Cached
  • crazylion lee on 12 Mar 18
     
    "
張 旭

Ruby and AOP: Decouple your code even more - Arkency Blog - 0 views

blog.arkency.com/...p-decouple-your-code-even-more

ruby aop programming algorithm pattern code

shared by 張 旭 on 03 Jun 17 - No Cached
  • Dark Parts in our apps - persistence, networking, logging, notifications… these parts are scattered in our code
  • aspect-oriented programming!
  • components are parts we can easily encapsulate into some kind of code abstraction - a methods, objects or procedures.
  • ...16 more annotations...
  • application’s logic is a great example of a component
  • Aspects cross-cut our application - when we use some kind of persistence (e.g. a database) or network communication (such as ZMQ sockets) our components need to know about it.
  • Aspect-oriented programming aims to get rid of cross-cuts by separating aspect code from component code using injections of our aspects in certain join points in our component code.
  • It’s responsible for pushing snippets scenario
  • SRP-conformant object
  • the join points in Ruby
  • advice
    • 張 旭
      張 旭 on 03 Jun 17
       
      AOP 裡面的術語
  • In most cases after and before advice are sufficient.
  • what does it mean to “evaluate code around” something? In our case it means: Don’t run this method. Take it and push to my advice as an argument and evaluate this advice
  • to provide a join point
  • You’ll often see empty methods in code written in AOP paradigm
  • provide aspect code to link with our use case
  • use case is a pure domain object, without even knowing it’s connected with some kind of persistence and logging layer.
  • Aspect-oriented programming is fixing the problem with polluting pure logic objects with technical context of our applications.
  • we treat our glues as a configuration part, not the logic part of our apps.
  • Glues should not contain any logic at all
張 旭

Kubernetes Deployments: The Ultimate Guide - Semaphore - 1 views

semaphoreci.com/...kubernetes-deployment

docker kubernetes devops system

shared by 張 旭 on 21 Oct 19 - No Cached
  • Continuous integration gives you confidence in your code. To extend that confidence to the release process, your deployment operations need to come with a safety belt.
  • these Kubernetes objects ensure that you can progressively deploy, roll back and scale your applications without downtime.
  • A pod is just a group of containers (it can be a group of one container) that run on the same machine, and share a few things together.
  • ...34 more annotations...
  • the containers within a pod can communicate with each other over localhost
  • From a network perspective, all the processes in these containers are local.
  • we can never create a standalone container: the closest we can do is create a pod, with a single container in it.
  • Kubernetes is a declarative system (by opposition to imperative systems).
  • All we can do, is describe what we want to have, and wait for Kubernetes to take action to reconcile what we have, with what we want to have.
  • In other words, we can say, “I would like a 40-feet long blue container with yellow doors“, and Kubernetes will find such a container for us. If it doesn’t exist, it will build it; if there is already one but it’s green with red doors, it will paint it for us; if there is already a container of the right size and color, Kubernetes will do nothing, since what we have already matches what we want.
  • The specification of a replica set looks very much like the specification of a pod, except that it carries a number, indicating how many replicas
  • What happens if we change that definition? Suddenly, there are zero pods matching the new specification.
  • the creation of new pods could happen in a more gradual manner.
  • the specification for a deployment looks very much like the one for a replica set: it features a pod specification, and a number of replicas.
  • Deployments, however, don’t create or delete pods directly.
  • When we update a deployment and adjust the number of replicas, it passes that update down to the replica set.
  • When we update the pod specification, the deployment creates a new replica set with the updated pod specification. That replica set has an initial size of zero. Then, the size of that replica set is progressively increased, while decreasing the size of the other replica set.
  • we are going to fade in (turn up the volume) on the new replica set, while we fade out (turn down the volume) on the old one.
  • During the whole process, requests are sent to pods of both the old and new replica sets, without any downtime for our users.
  • A readiness probe is a test that we add to a container specification.
  • Kubernetes supports three ways of implementing readiness probes:Running a command inside a container;Making an HTTP(S) request against a container; orOpening a TCP socket against a container.
  • When we roll out a new version, Kubernetes will wait for the new pod to mark itself as “ready” before moving on to the next one.
  • If there is no readiness probe, then the container is considered as ready, as long as it could be started.
  • MaxSurge indicates how many extra pods we are willing to run during a rolling update, while MaxUnavailable indicates how many pods we can lose during the rolling update.
  • Setting MaxUnavailable to 0 means, “do not shutdown any old pod before a new one is up and ready to serve traffic“.
  • Setting MaxSurge to 100% means, “immediately start all the new pods“, implying that we have enough spare capacity on our cluster, and that we want to go as fast as possible.
  • kubectl rollout undo deployment web
  • the replica set doesn’t look at the pods’ specifications, but only at their labels.
  • A replica set contains a selector, which is a logical expression that “selects” (just like a SELECT query in SQL) a number of pods.
  • it is absolutely possible to manually create pods with these labels, but running a different image (or with different settings), and fool our replica set.
  • Selectors are also used by services, which act as the load balancers for Kubernetes traffic, internal and external.
  • internal IP address (denoted by the name ClusterIP)
  • during a rollout, the deployment doesn’t reconfigure or inform the load balancer that pods are started and stopped. It happens automatically through the selector of the service associated to the load balancer.
  • a pod is added as a valid endpoint for a service only if all its containers pass their readiness check. In other words, a pod starts receiving traffic only once it’s actually ready for it.
  • In blue/green deployment, we want to instantly switch over all the traffic from the old version to the new, instead of doing it progressively
  • We can achieve blue/green deployment by creating multiple deployments (in the Kubernetes sense), and then switching from one to another by changing the selector of our service
  • kubectl label pods -l app=blue,version=v1.5 status=enabled
  • kubectl label pods -l app=blue,version=v1.4 status-
  • 張 旭 on 21 Oct 19
     
    "Continuous integration gives you confidence in your code. To extend that confidence to the release process, your deployment operations need to come with a safety belt."
張 旭

Logstash Alternatives: Pros & Cons of 5 Log Shippers [2019] - Sematext - 0 views

sematext.com/...logstash-alternatives

log monitor system logstash fluentd

shared by 張 旭 on 05 Nov 19 - No Cached
  • In this case, Elasticsearch. And because Elasticsearch can be down or struggling, or the network can be down, the shipper would ideally be able to buffer and retry
  • Logstash is typically used for collecting, parsing, and storing logs for future use as part of log management.
  • Logstash’s biggest con or “Achille’s heel” has always been performance and resource consumption (the default heap size is 1GB).
  • ...37 more annotations...
  • This can be a problem for high traffic deployments, when Logstash servers would need to be comparable with the Elasticsearch ones.
  • Filebeat was made to be that lightweight log shipper that pushes to Logstash or Elasticsearch.
  • differences between Logstash and Filebeat are that Logstash has more functionality, while Filebeat takes less resources.
  • Filebeat is just a tiny binary with no dependencies.
  • For example, how aggressive it should be in searching for new files to tail and when to close file handles when a file didn’t get changes for a while.
  • For example, the apache module will point Filebeat to default access.log and error.log paths
  • Filebeat’s scope is very limited,
  • Initially it could only send logs to Logstash and Elasticsearch, but now it can send to Kafka and Redis, and in 5.x it also gains filtering capabilities.
  • Filebeat can parse JSON
  • you can push directly from Filebeat to Elasticsearch, and have Elasticsearch do both parsing and storing.
  • You shouldn’t need a buffer when tailing files because, just as Logstash, Filebeat remembers where it left off
  • For larger deployments, you’d typically use Kafka as a queue instead, because Filebeat can talk to Kafka as well
  • The default syslog daemon on most Linux distros, rsyslog can do so much more than just picking logs from the syslog socket and writing to /var/log/messages.
  • It can tail files, parse them, buffer (on disk and in memory) and ship to a number of destinations, including Elasticsearch.
  • rsyslog is the fastest shipper
  • Its grammar-based parsing module (mmnormalize) works at constant speed no matter the number of rules (we tested this claim).
  • use it as a simple router/shipper, any decent machine will be limited by network bandwidth
  • It’s also one of the lightest parsers you can find, depending on the configured memory buffers.
  • rsyslog requires more work to get the configuration right
  • the main difference between Logstash and rsyslog is that Logstash is easier to use while rsyslog lighter.
  • rsyslog fits well in scenarios where you either need something very light yet capable (an appliance, a small VM, collecting syslog from within a Docker container).
  • rsyslog also works well when you need that ultimate performance.
  • syslog-ng as an alternative to rsyslog (though historically it was actually the other way around).
  • a modular syslog daemon, that can do much more than just syslog
  • Unlike rsyslog, it features a clear, consistent configuration format and has nice documentation.
  • Similarly to rsyslog, you’d probably want to deploy syslog-ng on boxes where resources are tight, yet you do want to perform potentially complex processing.
  • syslog-ng has an easier, more polished feel than rsyslog, but likely not that ultimate performance
  • Fluentd was built on the idea of logging in JSON wherever possible (which is a practice we totally agree with) so that log shippers down the line don’t have to guess which substring is which field of which type.
  • Fluentd plugins are in Ruby and very easy to write.
  • structured data through Fluentd, it’s not made to have the flexibility of other shippers on this list (Filebeat excluded).
  • Fluent Bit, which is to Fluentd similar to how Filebeat is for Logstash.
  • Fluentd is a good fit when you have diverse or exotic sources and destinations for your logs, because of the number of plugins.
  • Splunk isn’t a log shipper, it’s a commercial logging solution
  • Graylog is another complete logging solution, an open-source alternative to Splunk.
  • everything goes through graylog-server, from authentication to queries.
  • Graylog is nice because you have a complete logging solution, but it’s going to be harder to customize than an ELK stack.
  • it depends
張 旭

Docker image building on GitLab CI | $AYMDEV() - 0 views

aymdev.io/...er-image-building-on-gitlab-ci

devops cicd

shared by 張 旭 on 11 Mar 22 - No Cached
  • Continuous Integration (or CI) is a practice where you continously test an application to detect errors as soon as possible.
  • Docker is a container technology, many CI tools execute jobs (the tasks of a pipeline) in container to have an isolated environment.
  • Docker in Docker (« DinD » in short) means executing Docker in a Docker container.
  • ...11 more annotations...
  • images are saved in the host registry, we can benefit from Docker layer caching
  • All jobs will share the same environment, if many of them run simultaneously they might get into conflicts.
  • storage management (accumulating images)
  • The Docker socket binding technique means making a volume of /var/run/docker.sock between host and containers.
  • all containers would share the same Docker daemon.
  • Add privileged = true in the [runners.docker] section, the privileged mode is mandatory to use DinD.
  • To avoid that the runner only run one job at a time, change the concurrent value on the first line.
  • To avoid building a Docker image at each job, it can be built in a first job, pushed to the image registry provided by GitLab, and pulled in the next jobs.
  • functional tests depending on a database.
  • Docker Compose allows you to easily start multiple containers, but it has no more feature than Docker itself
  • Docker in Docker works well, but has its drawbacks, like Docker layer caching which needs some more commands to be used.
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