我正在創建一個用于部署應用程式的新 docker 映像，但我無法使用變數環境來配置我的資料源。我已經使用其他語法來宣告環境變數（DB_URL，${env.DB_URL}，{DB_URL}[DB_URL]），有什么我必須配置的嗎？
- 來自 tomcat 的版本：tomcat:10.0.26-jdk8
- 來自tomcat的web.xml：
<?xml version="1.0" encoding="UTF-8"?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <!-- Note: A "Server" is not itself a "Container", so you may not
define subcomponents such as "Valves" at this level.
Documentation at /docs/config/server.html --> <Server port="8005" shutdown="SHUTDOWN"> <Listener className="org.apache.catalina.startup.VersionLoggerListener" /> <!-- Security listener. Documentation at /docs/config/listeners.html <Listener className="org.apache.catalina.security.SecurityListener" /> --> <!-- APR library loader. Documentation at /docs/apr.html --> <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" /> <!-- Prevent memory leaks due to use of particular java/javax APIs--> <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" /> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" /> <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />
<!-- Global JNDI resources
Documentation at /docs/jndi-resources-howto.html --> <GlobalNamingResources> <!-- Editable user database that can also be used by
UserDatabaseRealm to authenticate users --> <Resource name="UserDatabase" auth="Container"
type="org.apache.catalina.UserDatabase"
description="User database that can be updated and saved"
factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
pathname="conf/tomcat-users.xml" />
<Resource name="jdbc/myapp"
auth="Container"
type="javax.sql.DataSource"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
driverClassName="com.mysql.cj.jdbc.Driver"
url="jdbc:mysql://${DB_URL}:${DB_PORT}/${DB_SCHEMA}?autoReconnect=true"
defaultTransactionIsolation="READ_COMMITTED"
username="${DB_USER}"
password="${DB_PWD}"
testOnBorrow="true"
validationQuery="SELECT 1"
validationInterval="${DB_VAL_INTERVAL}"
maxActive="${DB_MAX_ACTIV}"
maxIdle="${DB_IDLE}"
minIdle="${DB_MIN_IDLE}" /> </GlobalNamingResources>
<!-- A "Service" is a collection of one or more "Connectors" that share
a single "Container" Note: A "Service" is not itself a "Container",
so you may not define subcomponents such as "Valves" at this level.
Documentation at /docs/config/service.html --> <Service name="Catalina">
<!--The connectors can use a shared executor, you can define one or more named thread pools--> <!-- <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
maxThreads="150" minSpareThreads="4"/> -->
<!-- A "Connector" represents an endpoint by which requests are received
and responses are returned. Documentation at :
Java HTTP Connector: /docs/config/http.html
Java AJP Connector: /docs/config/ajp.html
APR (HTTP/AJP) Connector: /docs/apr.html
Define a non-SSL/TLS HTTP/1.1 Connector on port 8080 --> <Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" /> <!-- A "Connector" using the shared thread pool--> <!-- <Connector executor="tomcatThreadPool"
port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" /> --> <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443
This connector uses the NIO implementation. The default
SSLImplementation will depend on the presence of the APR/native
library and the useOpenSSL attribute of the AprLifecycleListener.
Either JSSE or OpenSSL style configuration may be used regardless of
the SSLImplementation selected. JSSE style configuration is used below. --> <!-- <Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
maxThreads="150" SSLEnabled="true">
<SSLHostConfig>
<Certificate certificateKeystoreFile="conf/localhost-rsa.jks"
type="RSA" />
</SSLHostConfig> </Connector> --> <!-- Define an SSL/TLS HTTP/1.1 Connector on port 8443 with HTTP/2
This connector uses the APR/native implementation which always uses
OpenSSL for TLS.
Either JSSE or OpenSSL style configuration may be used. OpenSSL style
configuration is used below. --> <!-- <Connector port="8443" protocol="org.apache.coyote.http11.Http11AprProtocol"
maxThreads="150" SSLEnabled="true" >
<UpgradeProtocol className="org.apache.coyote.http2.Http2Protocol" />
<SSLHostConfig>
<Certificate certificateKeyFile="conf/localhost-rsa-key.pem"
certificateFile="conf/localhost-rsa-cert.pem"
certificateChainFile="conf/localhost-rsa-chain.pem"
type="RSA" />
</SSLHostConfig> </Connector> -->
<!-- Define an AJP 1.3 Connector on port 8009 --> <!-- <Connector protocol="AJP/1.3"
address="::1"
port="8009"
redirectPort="8443" /> -->
<!-- An Engine represents the entry point (within Catalina) that processes
every request. The Engine implementation for Tomcat stand alone
analyzes the HTTP headers included with the request, and passes them
on to the appropriate Host (virtual host).
Documentation at /docs/config/engine.html -->
<!-- You should set jvmRoute to support load-balancing via AJP ie : <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1"> --> <Engine name="Catalina" defaultHost="localhost">
<!--For clustering, please take a look at documentation at:
/docs/cluster-howto.html (simple how to)
/docs/config/cluster.html (reference documentation) -->
<!--
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
-->
<!-- Use the LockOutRealm to prevent attempts to guess user passwords
via a brute-force attack -->
<Realm className="org.apache.catalina.realm.LockOutRealm">
<!-- This Realm uses the UserDatabase configured in the global JNDI
resources under the key "UserDatabase". Any edits
that are performed against this UserDatabase are immediately
available for use by the Realm. -->
<Realm className="org.apache.catalina.realm.UserDatabaseRealm"
resourceName="UserDatabase"/>
</Realm>
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<!-- SingleSignOn valve, share authentication between web applications
Documentation at: /docs/config/valve.html -->
<!--
<Valve className="org.apache.catalina.authenticator.SingleSignOn" />
-->
<!-- Access log processes all example.
Documentation at: /docs/config/valve.html
Note: The pattern used is equivalent to using pattern="common" -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log" suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />
</Host> </Engine> </Service> </Server>
- 錯誤示例：
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89)
at com.mysql.cj.NativeSession.connect(NativeSession.java:120)
at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:842)
... 33 more
Caused by: java.net.UnknownHostException: ${DB_URL}
at java.net.InetAddress.getAllByName0(InetAddress.java:1287)
at java.net.InetAddress.getAllByName(InetAddress.java:1199)
at java.net.InetAddress.getAllByName(InetAddress.java:1127)
at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:130)
at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63)
... 35 more
uj5u.com熱心網友回復：
在 tomcat 任何版本和任何 xml 上獲取環境變數，請按照以下步驟操作：
- 創建一個新的環境變數呼叫
CATALINA_OPTS； - 將此值設定為在步驟 1 中創建的變數
-Dorg.apache.tomcat.util.digester.PROPERTY_SOURCE=org.apache.tomcat.util.digester.EnvironmentPropertySource； - 遵循前面的步驟后，您必須創建自己的變數，并使用以下語法將變數呼叫到 XML 中：
${ENV_VAR}
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