Sample web app written on Go and working with Oracle and Postgresql backends The Readme is still in progress. Please have a look the https://blog.gleb.ca/2022/09/23/sample-go-application-with-database-backend/ to get the basic instructions until the Readme is fully finished.
You need to create a database and provide a network connection from the application side. Depending on a database flavour the path can be different. Here are the basic steps to create an Oracle or Postgres backends.
- Oracle Cloud Autonomous database backend.
- Create a database. For Oracle Cloud Autonomous database register or login to your Oracle Cloud console,click on the “hamburger” (top left corner) and choose “Oracle Database” -> “Autonomous Database”. Then push the button “Create Autonomous Database” and fill up the required fields. Pay attention to the “Choose network access” section. The simplest way is to choose access from everywhere but if you choose private endpoints or allowed IPs then make sure it is going to be accessible from your application host.
- Create the user. Open SqlDeveloper or SQL*Plus application, connect as admin and create a user which will be used for connection. Write down the password for the user. If you are not familiar with Oracle you can start from using the user admin and password used during creation of the database but keep in mind it is not the best practice.
- Create the table and fill it with the sample data. You can use the statements from hr_cre.sql from the application’s “sql” directory.
- In the cloud console go to the database page, open “Database Connection” select “Instance Wallet” from the dropdown menu and download the wallet file.
- PostreSQL backend. (To be added)
- You can start from creating a Cloud SQL instance or AlloyDB cluster and instance. All the steps are described in the [GCP documentation] (https://cloud.google.com/sql/docs/postgres/create-instance).
- Create a database and user which is going to be used for connection and managing application objects. The user and database are created either using Cloud Console or gcloud command.
- If you connect without CloudSQL Auth Proxy then you need to put the source IP or IP range to allowlist for connection to the instance.
- Create the table in the database public schema and create the sample data using the hr_cre.sql.
- If you use SSL (highly recommended) then generate the clint certificate and key and download it along the instance root certificate to a directory (ssl directory for ecample). You will be using the path to all 3 files in the additional environment variables DBSSLROOTCA DBSSLCA DBSSLKEY. The example is provided later in the instruction.
- Install the necessary packages to the application host. I will be showing using Oracle 8 on a VM as an example.
$ sudo dnf update -y $ sudo dnf install golang git -y - Clone the application from GitHub.
$ git clone https://github.com/gotochkin/sample-app.git $ cd sample-app - Create a directory and unzip the wallet downloaded from the Oracle cloud to the directory
$ mkdir ssl $ unzip ~/Wallet_myatpdb.zip -d ssl/ - Create a file with environment variables and execute it or export the variables using command line one by one.
$ vi ~/sampleapp.env $ cat ~/sampleapp.env ###############The file with env variables for Oracle with SSL################ DBNAME=m5c5hcat3eqqydh_myatpdb_tp.adb.oraclecloud.com DBWALLET=~/sample-app/ssl DBHOST=adb.us-ashburn-1.oraclecloud.com DBPORT=1522 DBPASS=MyExtremelyDifficultToRememberPassword DBUSER=sampleapp DBVERSION=ORACLE export DBNAME DBHOST DBPORT DBPASS DBUSER DBWALLET DBVERSION ##################################################### #For Postres database the file would look like $ cat ~/sampleapp.env ###############The file with env variables for Postgres with SSL################ DBNAME=testdb DBHOST=10.10.14.23 DBPORT=5432 DBPASS=MyExtremelyDifficultToRememberPassword DBUSER=sampleapp DBVERSION=POSTGRESQL DBSSLROOTCA=ssl/server-ca.pem DBSSLCA=ssl/client-cert.pem DBSSLKEY=ssl/client-key.pem export DBNAME DBHOST DBPORT DBPASS DBUSER DBWALLET DBVERSION DBSSLROOTCA DBSSLCA DBSSLKEY ##################################################### $ source ~/sampleapp.env - Open port 8080 for web access to the application.
$ sudo firewall-cmd --permanent --zone=public --add-port=8080/tcp $ sudo firewall-cmd --reload
- Change directory to the application’s source code folder import the variables and run the application.
$ cd ~/sample-app $ source ~/sampleapp.env $ go run cmd/app/main.go #The expected output is 2022/09/23 15:06:47 Listening on port :8080
Try to access the application using http://:8080 You should see the last 10 rows from the table and a form to add a new employee information.
- Change directory to the application’s source code folder and build the application
$ cd ~/sample-app $ go build -v -o sampleapp ./cmd/app/ - Run the application
$ ./sampleapp #The expected output is 2022/09/23 15:06:47 Listening on port :8080
Assuming you already have the docker installed.
-
Copy the wallet file to the ssl directory in the root folder of the application.
$ cp ~/Wallet_myatpdb.zip ssl/wallet.zip -
Build the image
$ cd ~/sample-app $ docker build -t otochkin/sampleapp:0.01 . -
Prepare the ~/sampleapp.env with variables
###############The file with env variables################ DBNAME=m5c5hcat3eqqydh_myatpdb_tp.adb.oraclecloud.com DBWALLET=~/sample-app/ssl DBHOST=adb.us-ashburn-1.oraclecloud.com DBPORT=1522 DBPASS=MyExtremelyDifficultToRememberPassword DBUSER=sampleapp DBVERSION=ORACLE ##################################################### -
Create the container
$ docker run --name sampleapp -p 8080:8080 --env-file ~/sampleapp.env sampleapp:0.01#The expected output : 2022/09/22 19:22:18 Listening on port :8080
-
Access the application using url http://localhost:8080