带有环境变量的 Dockerized Spring 应用程序

Question

我目前正在尝试在 Docker 容器中运行 Java Spring 应用程序。到目前为止，这没有任何问题。但现在我希望 application.properties 中没有固定值，只有占位符，它们作为环境变量传递给容器。

根据 Spring 文档，这应该是可能的，但是当我尝试这样做时，我总是收到以下错误：

无法与占位符 ${DB_CONFIG} 建立数据库连接（原因：java.lang.RuntimeException：驱动程序 com.mysql.cj.jdbc.Driver 声称不接受 jdbcUrl、${DB_CONFIG}）。

我已经尝试在外部传递 application.properties，而不是 env 文件直接将变量作为 Docker 环境变量传递，并且不是 JDBC url 的自定义变量 (DB_CONFIG) 而是传递 Spring 变量 (SPRING_DATASOURCE_URL)。这两种变体都不适合我。

供您参考：我不维护源代码，我只是从 CI/CD 获取源代码，将更改后的 application.properties 复制到其位置并编译项目。

---

docker-compose 文件：

version: '3'

services:
    arrowhead-serviceregistry:
        container_name: arrowhead-serviceregistry
        image: 'openjdk:11-jre-slim-buster'
        restart: always
        env_file: '.env'
        ports:
            - 8443:8443/tcp
        volumes:
            - ./arrowhead-serviceregistry-4.3.0.jar:/service.jar
        depends_on:
            - mysql
        command:
            -java -noverify -XX:TieredStopAtLevel=1 -jar /service.jar

application.properties 文件：

############################################
###       APPLICATION PARAMETERS         ###
############################################

# Database connection (mandatory)
# Change the server timezone if neccessary
spring.datasource.url=${DB_CONFIG}
spring.datasource.username=${SERVICEREGISTRY_DB_USERNAME}
spring.datasource.password=${SERVICEREGISTRY_DB_PASSWORD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
# use true only for debugging
spring.jpa.show-sql=false  
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.hibernate.ddl-auto=none

# Service Registry web-server parameters
server.address=0.0.0.0
server.port=${SERVICEREGISTRY_PORT}
domain.name=${SERVICEREGISTRY_ADDRESS}
domain.port=${SERVICEREGISTRY_PORT}

############################################
###       CUSTOM PARAMETERS              ###
############################################

# Name of the core system
core_system_name=SERVICE_REGISTRY 

# Show all request/response in debug log
log_all_request_and_response=${SERVICEREGISTRY_LOG_REQUESTS}

# Service Registry has an optional feature to ping service providers in a fixed time interval,
# and remove service offerings where the service provider was not available
# use this feature (true/false)
ping_scheduled=${SERVICEREGISTRY_PING_ENABLE}
# how much time the Service Registry should wait for the ping response (in milliseconds)
ping_timeout=${SERVICEREGISTRY_PING_TIMEOUT}
# how frequently should the ping happen, in minutes
ping_interval=${SERVICEREGISTRY_PING_INTERVAL}

# Service Registry has an optional feature to automatically remove service offerings, where the endOfValidity
# timestamp field is in the past, meaning the offering expired
# use this feature (true/false)
ttl_scheduled=${SERVICEREGISTRY_TTL_ENABLE}
# how frequently the database should be checked for expired services, in minutes
ttl_interval=${SERVICEREGISTRY_TTL_INTERVAL}

# Interface names has to follow this format <PROTOCOL>-<SECURITY>-<FORMAT>, where security can be SECURE or INSECURE and protocol and format must be a sequence of letters, numbers and underscore.
# A regexp checker will verify that. If this setting is set to true then the PROTOCOL and FORMAT must come from a predefined set.
use_strict_service_intf_name_verifier=${SERVICEREGISTRY_STRICT_INTERFACE_NAMES}

############################################
###           SECURE MODE                ###
############################################

# configure secure mode

# Set this to false to disable https mode
server.ssl.enabled=${SSL_ENABLED}

server.ssl.key-store-type=${SERVICEREGISTRY_SSL_KEYSTORE_TYPE}
server.ssl.key-store=${SERVICEREGISTRY_SSL_KEYSTORE}
server.ssl.key-store-password=${SERVICEREGISTRY_SSL_KEYSTORE_PASSWORD}
server.ssl.key-alias=${SERVICEREGISTRY_SSL_KEY_ALIAS}
server.ssl.key-password=${SERVICEREGISTRY_SSL_KEY_PASSWORD}
server.ssl.client-auth=${SERVICEREGISTRY_SSL_CLIENT_AUTH}
server.ssl.trust-store-type=${SERVICEREGISTRY_SSL_TRUSTSTORE_TYPE}
server.ssl.trust-store=${SERVICEREGISTRY_SSL_TRUSTSTORE_PATH}
server.ssl.trust-store-password=${SERVICEREGISTRY_SSL_TRUSTSTORE_PASSWORD}

#If true, http client does not check whether the hostname is match one of the server's SAN in its certificate
#Just for testing, DO NOT USE this feature in production environment 
disable.hostname.verifier=${SERVICEREGISTRY_DISABLE_HOSTNAME_VERIFIER}

环境文件：

# Basic settings
DB_CONFIG=jdbc:mysql://127.0.0.1:3306/arrowhead?serverTimezone=Europe/Berlin
SSL_ENABLED=false


# Service Registry settings
SERVICEREGISTRY_ADDRESS=127.0.0.1
SERVICEREGISTRY_PORT=8443
SERVICEREGISTRY_DB_USERNAME=myUser
SERVICEREGISTRY_DB_PASSWORD=xxx
SERVICEREGISTRY_LOG_REQUESTS=false
SERVICEREGISTRY_PING_ENABLE=false
SERVICEREGISTRY_PING_TIMEOUT=5000
SERVICEREGISTRY_PING_INTERVAL=60
SERVICEREGISTRY_TTL_ENABLE=false
SERVICEREGISTRY_TTL_INTERVAL=10
SERVICEREGISTRY_STRICT_INTERFACE_NAMES=false
SERVICEREGISTRY_DISABLE_HOSTNAME_VERIFIER=false
SERVICEREGISTRY_SSL_KEYSTORE_TYPE=PKCS12
SERVICEREGISTRY_SSL_KEYSTORE=classpath:certificates/service_registry.p12
SERVICEREGISTRY_SSL_KEYSTORE_PASSWORD=123456
SERVICEREGISTRY_SSL_KEY_ALIAS=service_registry
SERVICEREGISTRY_SSL_KEY_PASSWORD=123456
SERVICEREGISTRY_SSL_CLIENT_AUTH=need
SERVICEREGISTRY_SSL_TRUSTSTORE_TYPE=PKCS12
SERVICEREGISTRY_SSL_TRUSTSTORE_PATH=classpath:certificates/truststore.p12
SERVICEREGISTRY_SSL_TRUSTSTORE_PASSWORD=123456

Answer 1

在寻找问题的解决方案时，我遇到了 Spring Cloud Config Server（也只是一个可自托管的 Spring 应用程序）。这提供了配置文件存储位置和 Spring 应用程序之间的接口。该应用程序的设置不是静态 application.(properties|yml) 文件，而是使用配置服务器的 URL 存储 bootstrap.yml。当应用程序启动时，它会连接到配置服务器并通过 REST 接口接收它。配置文件可以存储在 Git/DB 中或作为文件。

Spring 文档 - 云配置服务器
Spring - 实施说明
Baeldung - 教程
Baeldung - 教程引导