Path on Micha Kops' Tech Notes

AWS Snippets

Thu, 01 Mar 2018 00:00:00 +0100

AWS Command Line Interface

Installation

$ curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64-2.0.30.zip" -o "awscliv2.zip"
unzip awscliv2.zip
sudo ./aws/install

AWS Documentation

RDS

Export Database Configuration

Export instance configuration

aws rds describe-db-instances --db-instance-identifier arn:aws:rds:eu-central-1:123456789:db:hascode-prd-db --no-paginate

Export parameter group configuration

aws rds describe-db-parameters --db-parameter-group-name PARAM_GROUP_NAME >> param_group_conf.json

Export option group configuration

aws rds describe-option-groups --option-group-name OPT_GROUP_NAME >> option_group_conf.json

Generate Signed URLs with Linux Tools

e.g. for accessing a website behind a CloudFront distribution using a canned policy.

Write the policy file

JAX-RS Server API Snippets

Sun, 28 Sep 2014 00:00:00 +0200

Because a lot of my current projects are using JAX-RS in different versions I’d like to write down and share some frequently used snippets for implementing RESTful web-services with the JAX-RS specification here.

Using RegEx in Path Expressions

Sometimes we need to extract multiple parameters from a path expression e.g. in the following example where year, month and day are fragments if the path.

@GET
@Path("/orders/{year:\\d{4}}-{month:\\d{2}}-{day:\\d{2}}")
@Produces(MediaType.TEXT_PLAIN)
public Response getOrders(@PathParam("year") final int year, @PathParam("month") final int month, @PathParam("day") final int day) {
	return Response.ok("Year: " + year + ", month: " + month + ", day: " + day).build();
}

jq Snippets

Mon, 01 Mar 2010 00:00:00 +0100

Sample JSON File

Sample JSON File containing well known programmers that we use for the following examples

coders.json

[
  {
    "name": "Bjarne Stroustrup",
    "languages": [
      {
        "name": "C++",
        "year_created": 1983
      }
    ],
    "details": {
      "nationality": "Danish",
      "awards": ["IEEE Computer Society Computer Pioneer Award", "Charles Stark Draper Prize"]
    }
  },
  {
    "name": "Guido van Rossum",
    "languages": [
      {
        "name": "Python",
        "year_created": 1991
      }
    ],
    "details": {
      "nationality": "Dutch",
      "awards": ["Free Software Foundation Award for the Advancement of Free Software", "NLUUG Award"]
    }
  },
  {
    "name": "James Gosling",
    "languages": [
      {
        "name": "Java",
        "year_created": 1995
      }
    ],
    "details": {
      "nationality": "Canadian",
      "awards": ["Order of Canada", "The Economist Innovation Award"]
    }
  },
  {
    "name": "Dennis Ritchie",
    "languages": [
      {
        "name": "C",
        "year_created": 1972
      },
      {
        "name": "Unix",
        "year_created": 1969
      }
    ],
    "details": {
      "nationality": "American",
      "awards": ["Turing Award", "National Medal of Technology"]
    }
  },
  {
    "name": "Brendan Eich",
    "languages": [
      {
        "name": "JavaScript",
        "year_created": 1995
      }
    ],
    "details": {
      "nationality": "American",
      "awards": ["Webby Award"]
    }
  }
]

Postgres Snippets

Mon, 01 Mar 2010 00:00:00 +0100

Administration & Configuration

Connections

Show Max Connections (value and source)

SELECT setting, source, sourcefile, sourceline
FROM pg_settings
WHERE name = 'max_connections';

Set Max Connections

ALTER system SET max_connections = 250;

Kill Connections for a Database

SELECT pg_terminate_backend(pid)
FROM pg_catalog.pg_stat_activity
-- we don't want to kill our own connection
WHERE pid != pg_backend_pid()
-- we don't want to kill connections to other databases
AND datname = 'MYDATABASE'

Show Statement Timeout Settings for All Users

SELECT r.rolname,
       (SELECT unnest(s.setconfig) FROM pg_db_role_setting s WHERE s.setrole = r.oid AND s.setconfig::text LIKE '%statement_timeout%' LIMIT 1) AS statement_timeout
FROM pg_roles r
WHERE r.rolcanlogin
ORDER BY r.rolname;