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main.js A service worker is an event-driven worker registered against an origin and a path. It takes the form of a JavaScript file that can control the web page/site it is associated with, intercepting and modifying navigation and resource requests, and caching resources in a very granular fashio...

Data-only containers are obsolete and are now considered an anti-pattern! In the days of yore, before Docker's volume subcommand, and before it was possible to create named volumes, Docker deleted volumes when there were no more references to them in any containers. Data-only containers are obsolet...

The vast majority of modern JavaScript environments work according to an event loop. This is a common concept in computer programming which essentially means that your program continually waits for new things to happen, and when they do, reacts to them. The host environment calls into your program, ...

Many interesting operations in common JavaScript programming environments are asynchronous. For example, in the browser we see things like window.setTimeout(() => { console.log("this happens later"); }, 100); and in Node.js we see things like fs.readFile("file.txt", (...

docker-compose.yml version: '2' services: php: image: phpmyadmin/phpmyadmin links: - mysql:db depends_on: - mysql mysql: image: k0st/alpine-mariadb volumes: - ./data/mysql:/var/lib/mysql environment: - MYSQL_DATABASE=mydb ...

Used by awk to split each record into multiple fields: echo "a-b-c d-e-f" | awk 'BEGIN {FS="-"} {print $2}' will result in: b e The variable FS can also be set using the option -F: echo "a-b-c d-e-f" | awk -F '-' '{print $2}' By default, the fields are se...

Used by awk to split the input into multiple records. For example: echo "a b c|d e f" | awk 'BEGIN {RS="|"} {print $0}' produces: a b c d e f By default, the record separator is the newline character. Similarly: echo "a b c|d e f" | awk 'BEGIN {RS="|&quo...

An Akka MessageDispatcher is what makes Akka Actors "tick", it is the engine of the machine so to speak. All MessageDispatcher implementations are also an ExecutionContext, which means that they can be used to execute arbitrary code, for instance Futures. Every ActorSystem will have a def...

So in case you want to give your Actor a different dispatcher than the default, you need to do two things, of which the first is to configure the dispatcher in your application.conf: my-dispatcher { # Dispatcher is the name of the event-based dispatcher type = Dispatcher # What kind of Exe...

Listing docker-machines will return the state, address and version of Docker of each docker machines. docker-machine ls Will print something like: NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS docker-machine-1 - ovh Running ...

In Common Lisp, if is the simplest conditional construct. It has the form (if test then [else]) and is evaluated to then if test is true and else otherwise. The else part can be omitted. (if (> 3 2) "Three is bigger!" "Two is bigger!") ;;=> "Three is bigger...

Tagging an image is useful for keeping track of different image versions: docker tag ubuntu:latest registry.example.com/username/ubuntu:latest Another example of tagging: docker tag myApp:1.4.2 myApp:latest docker tag myApp:1.4.2 registry.example.com/company/myApp:1.4.2

docker save -o ubuntu.latest.tar ubuntu:latest This command will save the ubuntu:latest image as a tarball archive in the current directory with the name ubuntu.latest.tar. This tarball archive can then be moved to another host, for example using rsync, or archived in storage. Once the tarball h...

Use the lazy_static crate to create global immutable variables which are initialized at runtime. We use HashMap as a demonstration. In Cargo.toml: [dependencies] lazy_static = "0.1.*" In main.rs: #[macro_use] extern crate lazy_static; lazy_static! { static ref HASHMAP: Hash...

Docker is just a fancy way to run a process, not a virtual machine. Therefore, debugging a process "in a container" is also possible "on the host" by simply examining the running container process as a user with the appropriate permissions to inspect those processes on the host (...

docker-compose run service-name command If, for example, you wanted to run rake db:create in your web service, you'd use the following command: docker-compose run web rake db:create

Install Docker Engine. If you get a Permission denied error, Run sudo -i before the two commands below, then exit. Pull Docker Compose to /usr/local/bin/docker-compose. curl -L https://github.com/docker/compose/releases/download/1.7.1/docker-compose-`uname -s`-`uname -m` > /usr/loc...

With benchmark tests you can test and measure the speed of the code, however benchmark tests are still unstable. To enable benchmarks in your cargo project you need nightly rust, put your integration benchmark tests to the benches/ folder in the root of your Cargo project, and run cargo bench. Exam...

Orders Table CustomerIdProductIdQuantityPrice12510013220014150021450356700 When grouping by a specific column, only unique values of this column are returned. SELECT customerId FROM orders GROUP BY customerId; Return value: customerId123 Aggregate functions like count() apply to each group...

Numeric CSS properties can be incremented and decremented with the += and -= syntax, respectively, using the .css() method: // Increment using the += syntax $("#target-element").css("font-size", "+=10"); // You can also specify the unit to increment by $...