Author Archives: James Coyle

Docker Compose yml for WordPress

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version: '3.6'

services:
    db:
        image: mysql:5.7
        container_name: wp_mysql
        volumes:
          - ./data/mysql:/var/lib/mysql
        restart: unless-stopped
        environment:
            MYSQL_ROOT_PASSWORD: [root password]
            MYSQL_DATABASE: wordpress
            MYSQL_USER: wordpress
            MYSQL_PASSWORD: [wp password]
        networks:
            wordpress:

    wordpress:
        image: wordpress:latest
        container_name: wp_web
        depends_on:
            - db
        ports:
            - 8000:80
        restart: unless-stopped
        environment:
            WORDPRESS_DB_HOST: db:3306
            WORDPRESS_DB_USER: wordpress
            WORDPRESS_DB_NAME: wordpress
            WORDPRESS_DB_PASSWORD: [wp password]
        volumes:
            - ./data/wp_content:/var/www/html/wp-content
            - ./config/wordpress/uploads.ini:/usr/local/etc/php/conf.d/uploads.ini
networks:
  wordpress:

Create a new directory and save the above file inside it as docker-compose.yml

mkdir wordpress
vi docker-compose.yml

Run docker-compose up -d to fetch the images from the docker hub and create your wordpress instance. You’ll be able to access wordpress from a browser on port 8000.


rclone Systemd startup mount script

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rclone

Rclone is a command line utility used for reading and writing to almost any type of cloud or remote storage. From Google Drive to Ceph, rclone supports almost any cloud-based remote storage platform you can think of. You can perform upload, download or synchronisation operations between local storage and remote cloud storage, or between remote storage directly.

In addition to this, rclone has an experimental mount feature that lets a user mount a remote cloud storage provider, such as s3 or Google Drive, as a local filesystem. You can then use the mounted filesystem as if it were a local device, albeit with some performance considerations.

Before we get going, make sure you have rclone installed on your system and configured with a remote. 

curl https://rclone.org/install.sh | sudo bash
rclone config 

Once you have a remote defined, it’s time to create the mountpoint and systemd script. I’ll be using Google Drive for this example, but the mount command works for any supported remote.

Create the mount point directory to use for the remote storage:

mkdir /mnt/google-drive

Next, create the below systemd script and edit it as required:

vi /etc/systemd/system/rclone.service
# /etc/systemd/system/rclone.service
[Unit]
Description=Google Drive (rclone)
AssertPathIsDirectory=/mnt/google-drive
After=plexdrive.service

[Service]
Type=simple
ExecStart=/usr/bin/rclone mount \
        --config=/root/.config/rclone/rclone.conf \
        --allow-other \
        --cache-tmp-upload-path=/tmp/rclone/upload \
        --cache-chunk-path=/tmp/rclone/chunks \
        --cache-workers=8 \
        --cache-writes \
        --cache-dir=/tmp/rclone/vfs \
        --cache-db-path=/tmp/rclone/db \
        --no-modtime \
        --drive-use-trash \
        --stats=0 \
        --checkers=16 \
        --bwlimit=40M \
        --dir-cache-time=60m \
        --cache-info-age=60m gdrive:/ /mnt/google-drive
ExecStop=/bin/fusermount -u /mnt/google-drive
Restart=always
RestartSec=10

[Install]
WantedBy=default.target

The important parts are detailed below, however, there are various other options are detailed on the rclone mount documentation page.

  • –config – the path to the config file created by rclone config. This is usually located in the users home directory.
  • gdrive:/ /mnt/google-drive – details two things; firstly the config name created in rclone config, and secondly the mount point on the local filesystem to use.

Once all this is in place you’ll need to start the service and enable the service at system startup (if required)

systemctl start rclone
systemctl enable rclone

gitignore file for Go Projects

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This is a gitignore file for a Go project to ensure temporary files and build files are not added to git repository commits.

# Binaries, plugins, libs
*.dll
*.dylib
*.exe
*.exe~
*.so

# Testing
*.test
*.tmp

List of Bank Holidays For England in SQL Format

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First off let’s create a table to store the bank holiday values. You may need to adjust this slightly depending on your SQL server technology being used (this was tested on MySQL/ MariaDB Server) but this is standard SQL dialect and should work on any RDBMS that respects the current SQL standards.

DROP TABLE IF EXISTS bank_holidays;
CREATE TABLE bank_holidays (
  holiday_date date NULL
, holiday_description INT NULL
, PRIMARY KEY (holiday_date)
);

The next step is to insert the bank holiday values below. This table is currently for 2012 up to 2019 for England and Wales.

INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190419', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190422', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190506', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190527', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20190826', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20191225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20191226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20181226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20181225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180827', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180528', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180507', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180402', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180330', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20180101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20171226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20171225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170828', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170529', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170501', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170417', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170414', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20170102', 'New Year’s Day (substitute day)');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20161227', 'Christmas Day (substitute day)');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20161226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160829', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160530', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160502', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160328', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160325', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20160101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20151228', 'Boxing Day (substitute day)');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20151225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150831', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150525', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150504', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150406', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150403', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20150101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20141226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20141225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140825', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140526', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140505', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140421', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140418', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20140101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20131226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20131225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130826', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130527', 'Spring bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130506', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130401', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130329', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20130101', 'New Year’s Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20121226', 'Boxing Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20121225', 'Christmas Day');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120827', 'Summer bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120605', 'Queen’s Diamond Jubilee (extra bank holiday)');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120604', 'Spring bank holiday (substitute day)');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120507', 'Early May bank holiday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120409', 'Easter Monday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120406', 'Good Friday');
INSERT INTO bank_holidays(holiday_date, holiday_description) VALUES('20120102', 'New Year’s Day (substitute day)');

For a more up to date list, please see my github page.

Please submit a PR if you have collated a list yourself, or have any updates to an existing list. The repository currently covers the UK, but I’d be more than happy to accept a PR for other countries! 


MySQL/ MariaDB Error Code: 1329. No data – zero rows fetched, selected, or processed

Category : How-to

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The above error can occur when calling a cursor results in no rows, or no more rows if called in a loop. Whilst the error message is descriptive about what has happened physically, you may wish to catch the error so that you can do something else, or simply replace the generic database error with something more meaningful. 

If you’re not sure what I’m talking about, run the following code on a MySQL or MariaDB database:

DROP PROCEDURE IF EXISTS test_error;

DELIMITER $$
CREATE PROCEDURE test_error() 
BEGIN 
    DECLARE temp_column_name VARCHAR(100);
        
	DECLARE c_example CURSOR FOR 
        SELECT   column_name
        FROM     information_schema.columns
        WHERE    column_name != column_name;
    -- Get data from example cursor
    OPEN c_example;
    FETCH c_example INTO temp_column_name;
    CLOSE c_example;
  
END$$
DELIMITER ;

CALL test_error();

The response is:

Error Code: 1329. No data - zero rows fetched, selected, or processed

In order to trap the error we need to define a CONTINUE HANDLER and DECLARE a variable for the CONTINUE HANDLER to set. We can then manage the No data exception simply by checking the variable.

Following on from the above example, we’ve introduced a variable ch_done. When this variable is set to 1 then the last cursor to be FETCHed returned No data. If it returns a zero then data was returned and all is well.

DROP PROCEDURE IF EXISTS test_error;

DELIMITER $$
CREATE PROCEDURE test_error() 
BEGIN 
    DECLARE ch_done INT DEFAULT 0;
    DECLARE temp_column_name VARCHAR(100);
        
	DECLARE c_example CURSOR FOR 
        SELECT   column_name
        FROM     information_schema.columns
        WHERE    column_name != column_name;

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET ch_done = 1;
    
    -- Get data from example cursor
    OPEN c_example;
    FETCH c_example INTO temp_column_name;
    CLOSE c_example;
    
    IF(ch_done = 1) THEN 
        -- handle the No data error!
        SELECT 'Oh no!';
    END IF;
  
END$$
DELIMITER ;

CALL test_error();

Remember, if you call multiple cursors in a row, you may need to reset the ch_done back to 0.


How to exit from a MySQL/ MariaDB Stored Procedure/ Function Prematurely

Category : How-to

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MySQL and MariaDB enable you to define your own error conditions and to report back to the SQL client both a return code and an error message. As soon as you raise the condition then MySQL/ MariaDB will halt any further execution of the code and report the error back to the client. This can help the user calling the function understand what went wrong, rather than seeing a generic database error message.

DECLARE error_flag INT DEFAULT 0;
DECLARE REF_MISSING CONDITION FOR SQLSTATE '45000';

-- Your code, set the error_flag in the event of an error

IF (error_flag) THEN
    SIGNAL REF_MISSING
    SET MESSAGE_TEXT = 'An error occurred!';
END IF;

The above code defines a custom condition with an error code of 45000 which is the suggested user defined error code. Other error codes are available, which you may have seen, but are reserved by the database server to use for specific database error events – it’s best not to mix your user defined messages with these. The function then checks if the error_flag has been set and, if it has, halts further code execution and returns the error “An error occurred!” to the client.

View from MySQL Workbench

You could simplify this by just calling the below code at the point the error is detected, if you are already catching an error event in your stored procedure or function by simply using the below code without the error_flag declaration.

SIGNAL REF_MISSING
SET MESSAGE_TEXT = 'An error occurred!';


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