Create a project folder:<\/p>\n\n\n
mkdir wordpress-env-demo\ncd wordpress-env-demo\n<\/code><\/span><\/pre>\n\n\nCreate a .env<\/code> file:<\/p>\n\n\nMYSQL_DATABASE=wordpressdb\nMYSQL_USER=wpuser\nMYSQL_PASSWORD=wppassword123\nMYSQL_ROOT_PASSWORD=rootpassword123\n\nWORDPRESS_PORT=8080\n<\/code><\/span><\/pre>\n\n\nCreate docker-compose.yml<\/code>:<\/p>\n\n\nservices:\n db:\n image: mysql:latest\n container_name<\/span>: wordpress_mysql\n restart<\/span>: always\n environment<\/span>:\n MYSQL_DATABASE: ${MYSQL_DATABASE}\n MYSQL_USER<\/span>: ${MYSQL_USER}\n MYSQL_PASSWORD<\/span>: ${MYSQL_PASSWORD}\n MYSQL_ROOT_PASSWORD<\/span>: ${MYSQL_ROOT_PASSWORD}\n volumes<\/span>:\n - mysql_data:\/var\/<\/span>lib\/mysql\n\n wordpress<\/span>:\n image: wordpress:latest\n container_name<\/span>: wordpress_app\n restart<\/span>: always\n depends_on<\/span>:\n - db\n ports<\/span>:\n - \"${WORDPRESS_PORT}:80\"<\/span>\n environment<\/span>:\n WORDPRESS_DB_HOST: db:3306<\/span>\n WORDPRESS_DB_NAME<\/span>: ${MYSQL_DATABASE}\n WORDPRESS_DB_USER<\/span>: ${MYSQL_USER}\n WORDPRESS_DB_PASSWORD<\/span>: ${MYSQL_PASSWORD}\n volumes<\/span>:\n - wordpress_data:\/var\/<\/span>www\/html\n\nvolumes<\/span>:\n mysql_data:\n wordpress_data:\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nStart the containers:<\/p>\n\n\n
docker compose up -d\n<\/code><\/span><\/pre>\n\n\nOpen WordPress:<\/p>\n\n\n
http:\/\/localhost:8080<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nNow students can see how environment variables are passed into both containers.<\/p>\n\n\n\n
Check MySQL container env:<\/p>\n\n\n
docker compose exec db printenv MYSQL_DATABASE\ndocker compose exec db printenv MYSQL_USER\ndocker compose exec db printenv MYSQL_PASSWORD\n<\/code><\/span><\/pre>\n\n\nCheck WordPress container env:<\/p>\n\n\n
docker compose exec wordpress printenv WORDPRESS_DB_HOST\ndocker compose exec wordpress printenv WORDPRESS_DB_NAME\ndocker compose exec wordpress printenv WORDPRESS_DB_USER\ndocker compose exec wordpress printenv WORDPRESS_DB_PASSWORD\n<\/code><\/span><\/pre>\n\n\nVerify both containers are using the same password:<\/p>\n\n\n
docker compose exec db printenv MYSQL_PASSWORD\ndocker compose exec wordpress printenv WORDPRESS_DB_PASSWORD\n<\/code><\/span><\/pre>\n\n\nCheck how WordPress reads env and creates database config:<\/p>\n\n\n
docker compose exec wordpress bash -lc 'grep DB_ \/var\/www\/html\/wp-config.php'<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nTest MySQL login using the env variable inside DB container:<\/p>\n\n\n
docker compose exec db bash -lc 'mysql -u$MYSQL_USER -p$MYSQL_PASSWORD $MYSQL_DATABASE -e \"SHOW TABLES;\"'<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nCheck service-name networking between containers:<\/p>\n\n\n
docker compose exec wordpress bash -lc 'getent hosts db'<\/span>\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\nThis works because Docker Compose creates an internal network where db<\/code> becomes the hostname of the MySQL container.<\/p>\n\n\n\nStop everything:<\/p>\n\n\n
docker compose down\n<\/code><\/span><\/pre>\n\n\nStop and delete volumes also:<\/p>\n\n\n
docker compose down -v\n<\/code><\/span><\/pre>\n\n\nFor teaching, this is perfect. For production, avoid latest<\/code>, use fixed versions like wordpress:6.8-apache<\/code> and mysql:8.4<\/code>, and never commit real passwords into Git.<\/p>\n","protected":false},"excerpt":{"rendered":"Create a project folder: Create a .env file: Create docker-compose.yml: Start the containers: Open WordPress: Now students can see how environment variables are passed into both containers…. <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_joinchat":[],"footnotes":""},"categories":[11138],"tags":[],"class_list":["post-77364","post","type-post","status-publish","format-standard","hentry","category-best-tools"],"_links":{"self":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/77364","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/comments?post=77364"}],"version-history":[{"count":1,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/77364\/revisions"}],"predecessor-version":[{"id":77365,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/posts\/77364\/revisions\/77365"}],"wp:attachment":[{"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/media?parent=77364"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/categories?post=77364"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devopsschool.com\/blog\/wp-json\/wp\/v2\/tags?post=77364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}