Originally published by Mark Drake at https://www.digitalocean.com
Managed databases have a number of benefits over self-managed databases, including automated updates, simplified scaling, and high availability. If you’re new to working with managed databases, though, the best way to perform certain tasks — like connecting to the database — may not be self-evident.
In this guide, we will go over how to install client programs for a variety of database management systems (DBMSs), including PostgreSQL, MySQL, and Redis, on an Ubuntu 18.04 server. We’ll also explain how to use these programs to connect to a managed database instance.
To follow the instructions detailed in this guide, you will need:
ufw
. Once you have these in place, jump to whichever section aligns with your DBMS.
To connect to a managed PostgreSQL database, you can use psql
, the standard command line client for Postgres. It’s open-source, maintained by the PostgreSQL Development Group, and is usually included when you download the PostgreSQL server. However, you can install psql
by itself by installing the postgresql-client
package with APT.
If you’ve not done so recently, update your server’s package index:
sudo apt update
Then run the following command to install psql
:
sudo apt install postgresql-client
APT will ask you to confirm that you want to install the package. Do so by pressing ENTER
.
Following that, you can connect to your managed Postgres database without any need for further configuration. For example, you might invoke psql
with the following flags:
-U
, the PostgreSQL user you want to connect as-h
, the managed database’s hostname or IP address-p
, the TCP port on which the managed database is listening for connections-d
, the specific database you want to connect to-v
, short for “variable,” precedes other connection variables, followed by an equal sign (=
) and the variables’ values. For example, if you want to validate the database’s CA certificate when you connect, you would include -v sslmode=require
in your command-W
, which tells psql
to prompt you for the PostgreSQL user’s password. Note that you could precede the psql
command with PGPASSWORD=password
, but it’s generally considered more secure to not include passwords on the command lineWith these flags included, the psql
command’s syntax would look like this:
psql -U user -h host -p port -d database -v variable=value -W
Alternatively, if your managed database provider offers a uniform resource identifer (URI) for connecting, you might use the following syntax:
psql postgresql://username:password@host:port/database?option_1=value&option_n=value
With that, you’re ready to begin using with your managed PostgreSQL instance. For more information on how to interact with PostgreSQL, see our guide on How to Manage an SQL Database.
To connect to a managed MySQL database, you can use the official MySQL database client. On Ubuntu, this client is typically installed by downloading the mysql-client
package through APT. If you’re using the default Ubuntu repositories, though, this will install version 5.7 of the program.
In order to access a DigitalOcean Managed MySQL database, you will need to install version 8.0 or above. To do so, you must first add the MySQL software repository before installing the package.
Note: If you don’t need to install the latest version of mysql-client
, you can just update your server’s package index and install mysql-client
without adding the MySQL software repository:
sudo apt update sudo apt install mysql-client
If you aren’t sure whether you need the latest version of mysql-client
, you should consult your cloud provider’s managed databases documentation.
Begin by navigating to the MySQL APT Repository page in your web browser. Find the Download button in the lower-right corner and click through to the next page. This page will prompt you to log in or sign up for an Oracle web account. You can skip that and instead look for the link that says No thanks, just start my download. Right-click the link and select Copy Link Address (this option may be worded differently, depending on your browser).
Now you’re ready to download the file. On your server, move to a directory you can write to:
cd /tmp
Download the file using curl
, remembering to paste the address you just copied in place of the highlighted portion of the following command. You also need to pass two command line flags to curl
. -O
instructs curl
to output to a file instead of standard output. The L
flag makes curl
follow HTTP redirects, which is necessary in this case because the address you copied actually redirects to another location before the file downloads:
curl -OL https://dev.mysql.com/get/mysql-apt-config_0.8.13-1_all.deb
The file should now be downloaded in your current directory. List the files to make sure:
ls
You will see the filename listed in the output:
Output mysql-apt-config_0.8.13-1_all.deb . . .
Now you can add the MySQL APT repository to your system’s repository list. The dpkg
command is used to install, remove, and inspect .deb
software packages. The following command includes the -i
flag, indicating that you’d like to install from the specified file:
sudo dpkg -i mysql-apt-config*
During the installation, you’ll be presented with a configuration screen where you can specify which version of MySQL you’d prefer, along with an option to install repositories for other MySQL-related tools. The defaults will add the repository information for the latest stable version of MySQL and nothing else. This is what we want, so use the down arrow to navigate to the Ok
menu option and hit ENTER
.
Following that, the package will finish adding the repository. Refresh your apt
package cache to make the new software packages available:
sudo apt update
Next, you can clean up your system a bit and delete the file you downloaded, as you won’t need it in the future:
rm mysql-apt-config*
Note: If you ever need to update the configuration of these repositories, run the following command to select your new options:
sudo dpkg-reconfigure mysql-apt-config
After selecting your new options, run the following command to refresh your package cache:
sudo apt update
Now that you’ve added the MySQL repositories, you’re ready to install the actual MySQL client software. Do so with the following apt
command:
sudo apt install mysql-client
Once that command finishes, check the software version number to ensure that you have the latest release:
mysql --version
Output mysql Ver 8.0.17-cluster for Linux on x86_64 (MySQL Community Server - GPL)
After you’ve installed the mysql-client
package, you can access your managed database by running the mysql
command with the following flags as arguments:
-u
, the MySQL user you want to connect as-p
, tells mysql
to prompt for the user’s password. You could include your password directly in the connection command following the -p
flag (without a space, as in -ppassword
) but, for security reasons, this is generally not recommended-h
, the database’s hostname or IP address-P
, the TCP port on which MySQL is listening for connections-D
, the specific database you want to connect toUsing these flags, the mysql
syntax will look like this:
mysql -u user -p -h host -P port -D database
Alternatively, if you have a connection URI you can use to connect, you would use a syntax like this:
mysql mysql://user:password@host:port/database?option_1=value&option_n=value
With that, you’re ready to begin using with your managed MySQL instance. For more information on how to interact with MySQL, see our guide on How to Manage an SQL Database.
In MySQL 8.0 and newer, the default authentication plugin is caching_sha2_password
. As of this writing, though, PHP does not support caching_sha2_password
. If you plan on using your managed MySQL database with an application that uses PHP, such as WordPress or phpMyAdmin, this may lead to issues when the application attempts to connect to the database.
If you have access to the database’s configuration file, you could add a setting to force it to use a PHP-supported authentication plugin — for example, mysql_native_password
— by default:
Example MySQL Configuration File
[mysqld] default-authentication-plugin=mysql_native_password
However, some managed database providers — including DigitalOcean — do not make the database configuration file available to end users. In this case, you could connect to the database and run an ALTER USER
command for any existing MySQL users which need to connect to the database, but can’t do so with the caching_sha2_password
plugin:
ALTER USER user IDENTIFIED WITH mysql_native_password BY 'password';
Of course, you can set new users to authenticate with mysql_native_password
by specifying the plugin in their respective CREATE USER
statements:
CREATE USER user IDENTIFIED WITH mysql_native_password BY 'password';
If you’re using a DigitalOcean Managed Database, be aware that if you configure a user to authenticate with a plugin other than caching_sha2_password
then you won’t be able to see that user’s password in your Cloud Control Panel. For this reason, you should make sure you note down the passwords of any users that authenticate with mysql_native_password
or other plugins in a secure location.
When you install Redis locally, it comes with redis-cli
, the Redis command line interface. You can use redis-cli
to connect to a remote, managed Redis instance, but it doesn’t natively support TLS/SSL connections. For that reason, it’s recommended that you use an alternative Redis client to enable secure connections to Redis.
For DigitalOcean Managed Redis Databases, we recommend that you install Redli, an open-source, interactive Redis terminal. To do so, navigate to the Releases Page on the Redli GitHub project and locate the Assets table for the latest release. As of this writing, this will be version 0.4.4.
There, find the link for the file ending in linux_amd64.tar.gz
. This link points to an archive file known as a tarball that, when extracted, will create a few files on your system. Right-click this link and select Copy link address (this option may differ depending on your web browser).
On your server, move to a directory you can write to:
cd /tmp
Then, paste the link into the following wget
command, replacing the highlighted URL. This command will download the file to your server:
wget https://github.com/IBM-Cloud/redli/releases/download/v0.4.4/redli_0.4.4_linux_amd64.tar.gz
Once the file has been downloaded to your server, extract the tarball:
tar xvf redli_0.4.4_linux_amd64.tar.gz
This will create the following files on your server:
Output LICENSE.txt README.md redli
The redli
file is the Redli binary file. Move it to the /usr/local/bin
directory, the location where Ubuntu looks for executable files:
sudo mv redli /usr/local/bin/
At this point, you can clean up your system a bit and remove the tarball:
rm redli 0.4.4_linux_amd64.tar.gz
Now you can use Redli to connect to your managed Redis instance. You could do so by running the redli
command followed by these flags:
-h
, the host to connect to. This can either be a hostname or an IP address-a
, the password used to authenticate to the Redis instance-p
, the port to connect toWith these flags included, the redli
syntax would be as follows. Note that this example also includes the --tls
option, which allows you to connect to a managed Redis database over TLS/SSL without the need for a tunnel:
redli --tls -h host -a password -p port
One benefit that Redli has over redis-cli
is that it understands the rediss
protocol, which is used to designate a URI pointing to a Redis database. This allows you to use a connection string to access your database:
redli --tls -u rediss://user:password@host:port
Note that this example includes the -u
flag, which specifies that the following argument will be a connection URI.
Following that, you can begin interacting with your managed Redis instance.
As a relatively new development in cloud services, many practices that are well known for self-managed databases aren’t widely or comprehensively documented for databases managed by cloud providers. One of the most fundamental of these practices, accessing the database, may not be immediately clear to those new to working with managed databases. Our goal for this tutorial is that it helps get you started as you begin using a managed database for storing data.
Thanks for reading ❤
If you liked this post, share it with all of your programming buddies!
Follow us on Facebook | Twitter
☞ The Ultimate MySQL Bootcamp: Go from SQL Beginner to Expert
☞ The Complete Oracle SQL Certification Course
☞ An Introduction to Queries in MySQL
☞ ArangoDB Tutorial - Getting Started with ArangoDB
☞ How To Troubleshoot MySQL Queries?
☞ SQL with MySQL - Complete Tutorial for Beginners
☞ How to import CSV file using MySQL?
#database #postgresql #mysql #sql #ubuntu