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models directory is meant to hold tests for your models

controllers directory is meant to hold tests for your controllers

integration directory is meant to hold tests that involve any number of controllers interacting

Fixtures are a way of organizing test data; they reside in the fixtures folder

The test_helper.rb file holds the default configuration for your tests

Fixtures allow you to populate your testing database with predefined data before your tests run

Fixtures are database independent written in YAML.

one file per model.

Each fixture is given a name followed by an indented list of colon-separated key/value pairs.

Keys which resemble YAML keywords such as 'yes' and 'no' are quoted so that the YAML Parser correctly interprets them.

define a reference node between two different fixtures.

ERB allows you to embed Ruby code within templates

The YAML fixture format is pre-processed with ERB when Rails loads fixtures.

Rails by default automatically loads all fixtures from the test/fixtures folder for your models and controllers test.

Fixtures are instances of Active Record.

access the object directly

test_helper.rb specifies the default configuration to run our tests. This is included with all the tests, so any methods added to this file are available to all your tests.

test with method names prefixed with test_.

An assertion is a line of code that evaluates an object (or expression) for expected results.

bin/rake db:test:prepare

Every test contains one or more assertions. Only when all the assertions are successful will the test pass.

rake test command

run a particular test method from the test case by running the test and providing the test method name.

The . (dot) above indicates a passing test. When a test fails you see an F; when a test throws an error you see an E in its place.

we first wrote a test which fails for a desired functionality, then we wrote some code which adds the functionality and finally we ensured that our test passes. This approach to software development is referred to as Test-Driven Development (TDD).

A token that starts with quotes " is read literally (including whitespace) until the next instance of quotes " that is not escaped.

Only quotes are escapable.

Blank, unquoted lines are allowed and ignored.

Tokens are then evaluated by the parser for structure.

A label is a string identifier, and a definition is a body (one or more lines) of tokens grouped together in a block

a Caddyfile with more than one entry must enclose each definition in curly braces { }.

The first line of a Caddyfile is always a label line.

If many labels are to head a block, the labels may be suffixed with a comma.

as long as the last label of the line has a comma if the next line is to continue the list of labels

Commas are not acceptable delimiters for arguments

Arguments are delimited solely by same-line whitespace

Subdirectives cannot open new blocks.

Any token (label, directive, argument, etc.) may contain or consist solely of an environment variable

Where an import line is, that line will be replaced with the contents of the imported file, unmodified.

define snippets to be reused later in your Caddyfile by defining a block with a single-token label surrounded by parentheses

The x-hack is effective because no unary operators can start with x.

the x-hack could be used to work around certain bugs all the way up until 2015, seven years after StackOverflow wrote it off as an archaic relic of the past!

The Dash issue of [ "(" = ")" ] was originally reported in a form that affected both Bash 3.2.48 and Dash 0.5.4 in 2008. You can still see this on macOS bash today

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.

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).

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 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.

Splunk isn’t a log shipper, it’s a commercial logging solution

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

by default they react to !commands in your chatroom. Commands can also trigger on regular expression matches, with or without a bot prefix.

Errbot also supports Markdown responses with Jinja2 templating.

Errbot supports webhooks; It has a small web server that can translate endpoints to your custom plugins.

It’s recommended that you configure this behind a web server such as nginx or Apache.

It works with the If This Then That (IFTTT) principle, meaning that you define a set of rules that the system then uses to take action.

Lita is a chat bot written in Ruby. Like the other bots I’ve mentioned, it is also open source and supports different chat platforms via plugins.

Gort is a newer entrant to the ChatOps space. As the name suggests it has been written in Go, and it is still under active development.

can persist information in databases, supports advanced parsers, and is extendable with custom skills.