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Use JNDI DataSource in a project of Heroku

After deploy mi javaweb (war) app, not maven, in heroku i get the next error:
https://imgur.com/a/KThbLxa
Obviusly it´s because is not making the connection to the JNDI
context.xml
<Resource name="jdbc/conexion" auth="Container" type="javax.sql.DataSource" maxActive="30"
maxIdle="10" maxWait="15000" username="XXXXXXXXX" password="XXXXXXXXXXX" driverClassName="com.mysql.cj.jdbc.Driver" url="jdbc:mysql://XXXXXXXXXX/XXXXXXXXXXXXXX"/>
So, somebody knows how includes a context.xml file in the deployed project?

Failed to get initial context or DataSource: javax.naming.NameNotFoundException

I was trying to create Web-logic custom authentication provider. I created it and that was working well. Whereas when custom authentication is initializing, it will show this exception. But after that it is working perfectly.
According to my opinion, weblogic is first trying to login as a weblogic user when server is starting. At that time this error is occurred. Next time, it won't show any error.
This is the error when it is trying to login as a weblogic user
userName = weblogic
Data set name is = xxxDataSource
eeeeeeeeeeeeeeeeeeeeeee javax.naming.InitialContext#1ac745d4
Data set name is ######### = xxxDataSource
<Mar 6, 2018 6:27:47 AM CET> <Error> <Security.Authentication> <BEA-
000000> <Failed to get initial context or DataSource:
javax.naming.NameNotFoundException: Unable to resolve' xxxDataSource'. Resolved ''; remaining name 'xxxDataSource'
This is the user who is trying to login, when server start
your help would be really appreciated.

If the DataSource name is not found then that would mean it's not declared in your server.xml or web.xml. You should have something like this:
<Context>
<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
maxTotal="100" maxIdle="30" maxWaitMillis="10000"
username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/javatest"/>
</Context>
and/or
<web-app>
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
Check your authentication provider documentation on what to put in server.xml and/or web.xml.

Create JNDI Connection for Ingres Database

I have a Java project and I've been trying to create a JNDI connection for my Ingres database but have been unsuccessful. I'm not sure if there is something specific to ingres that needs to be included but after quite a bit of research I haven't been able to get things to work.
In my project I have my datasource info in the web.xml file and the context.xml
context.xml has the following info
<Context>
<Resource name="jdbc/myDB" auth="Container" type="javax.sql.Datasource"
username="myUser" password="password" driverClassName="com.ingres.jdbc.IngresDriver"
url="databaseURL" maxActive="8" maxIdle="4" maxWait="100" />
</Context>
My web.xml has the following info
<web-app>
<resource-ref>
<description>Project Descrip</description>
<res-ref-name>jdbc/myDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
In my java code I'm trying to get my connection using the following four lines
Context initContext = new InitialContext();
Context envContext = (Context) initContent.lookup("java:comp/env");
Datasource ds = (DataSource) envContext.lookup("jdbc/myDB");
return ds.getConnection();
After the third line is executed I get an exception that says: NamingException - Cannot create resource instance
I have found dozens of posts with this same exception and have tried the suggested solutions with no luck. I'm using a Tomcat 7 server and have made sure to include the necessary ingres jar (iijdbc.jar) to my WEB-INF/lib folder and to my tomcat lib folder.
Any help or suggestions would be greatly appreciated

I don't know much about Ingres, but if attempting to make a datasource is similar to JBOSS and DB2 or MySQL. I noticed that in your WEB.XML you define your resource-ref, but you don't mention the anything about the servlet parameters.
<servlet>
<description>Servlet Description</description>
<display-name>MyServlet</display-name>
<servlet-name>MyServlet</servlet-name>
<servlet-class>servlet.MyServlet</servlet-class>
<init-param>
<param-name>MyDB</param-name>
<param-value>java:comp/env/jdbc/MyDB</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
Then you would need to code in your sevlet:
InitialContext initialContext = new InitialContext();
DataSource dataSource = (DataSource)initialContext.lookup(this.getInitParameter("MyDB"));
Hope this helps.

Can you try adding global="jdbc/myDB" attribute as in your Resource tag as follows:
<Context>
<Resource name="jdbc/myDB" auth="Container" type="javax.sql.Datasource"
username="myUser" password="password" driverClassName="com.ingres.jdbc.IngresDriver"
url="databaseURL" maxActive="8" maxIdle="4" maxWait="100" global="jdbc/myDB"/>
</Context>

Should you set up database connection properties in server.xml or context.xml

I am trying to set up the database connection properties using JNDI for a Spring web application.
I am considering two approaches as below:
Approach 1:
In your Spring configuration you may have something like:
<jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/facs"/>
Then in your webapp /META-INF/context.xml file you should have something similar too:
<?xml version='1.0' encoding='utf-8'?>
<!-- antiResourceLocking="true" -->
<Context path="/podd-apn"
reloadable="true"
cachingAllowed="false"
antiResourceLocking="true"
>
<Resource name="jdbc/facs"
type="javax.sql.DataSource" username="${database.username}" password="${database.password}"
driverClassName="org.postgresql.Driver"
url="${database.url}"
maxActive="8" maxIdle="4"
global="jdbc/facs"
/>
</Context>
And in your web.xml you should something like:
<!-- JNDI -->
<resource-ref>
<description>FACs Datasource</description>
<res-ref-name>jdbc/facs</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
Approach 2:
Setup in the Spring context like this:
<jee:jndi-lookup id="dbDataSource"
jndi-name="jdbc/DatabaseName"
expected-type="javax.sql.DataSource" />
You can declare the JNDI resource in Tomcat's server.xml using something like this:
<GlobalNamingResources>
<Resource name="jdbc/DatabaseName" auth="Container" type="javax.sql.DataSource"
username="dbUsername" password="dbPasswd"
url="jdbc:postgresql://localhost/dbname"
driverClassName="org.postgresql.Driver"
initialSize="5" maxWait="5000"
maxActive="120" maxIdle="5"
validationQuery="select 1"
poolPreparedStatements="true"/>
</GlobalNamingResources/>
And reference the JNDI resource from Tomcat's web context.xml like this:
<ResourceLink name="jdbc/DatabaseName"
global="jdbc/DatabaseName"
type="javax.sql.DataSource"/>
My question is where is the best place to keep database properties? Should they be placed in server.xml or context.xml?
Also, if I have 2 databases, should I use two configs?
Also, is it best practice to directly place them in either server.xml or context.xml? Or do I need to configure through Tomcat Manager GUI console?
Thanks!

I prefer a third approach that takes the best from
Approach 1 and Approach 2 described by user1016403.
Approach 3
Save database properties on the server.xml
reference the server.xml database properties from the web application META-INF/context.xml
Approach 3 benefits
While the first point is useful for security reasons the second point is useful for referencing server properties value from the web application, even if server properties values will change.
Moreover decoupling resource definitions on the server from their use by the web application makes such configuration scalable across organizations with various complexity where different teams work on different tiers/layers: the server administrators team can work without conflicting with developers team if the administrator shares the same JNDI name with the developer for each resource.
Approach 3 implementation
Define the JNDI name jdbc/ApplicationContext_DatabaseName.
Declare the jdbc/ApplicationContext_DatabaseName's various properties and values in Tomcat's server.xml using something like this:
<GlobalNamingResources>
<Resource name="jdbc/ApplicationContext_DatabaseName" auth="Container" type="javax.sql.DataSource"
username="dbUsername" password="dbPasswd"
url="jdbc:postgresql://localhost/dbname"
driverClassName="org.postgresql.Driver"
initialSize="5" maxWait="5000"
maxActive="120" maxIdle="5"
validationQuery="select 1"
poolPreparedStatements="true"/>
</GlobalNamingResources/>
Link the jdbc/ApplicationContext_DatabaseName's properties from web application META-INF/context.xml by an application-private JNDI context java:comp/env/ specified in the name attribute:
<Context path="/ApplicationContext" ... >
<!--
"global" attribute links to GlobalNamingResources in the ${catalina.base}/conf/server.xml (server administrator team)
"name" attribute is relative to the application-private JNDI context java:comp/env/ and is looked up from the java web application (application developer team)
-->
<ResourceLink global="jdbc/ApplicationContext_DatabaseName" name="jdbc/DatabaseName" type="javax.sql.DataSource"/>
</Context>
Finally, in order to use the JNDI resource, specify the JNDI name jdbc/DatabaseName in web application's deployment descriptor:
<resource-ref>
<description>DatabaseName's Datasource</description>
<res-ref-name>jdbc/DatabaseName</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
and in Spring context:
<jee:jndi-lookup id="DatabaseNameDataSource"
jndi-name="jdbc/DatabaseName"
expected-type="javax.sql.DataSource" />
Approach 3 drawbacks
If the JNDI name gets changed then both the server.xml and the META-INF/context.xml will have to be edited and a deploy would be necessary; nevertheless this scenario is rare.
Approach 3 variations
Many data sources used by one web application
Simply add configurations to Tomcat's server.xml:
<GlobalNamingResources>
<Resource name="jdbc/ApplicationContext_DatabaseName1" ... />
<Resource name="jdbc/ApplicationContext_DatabaseName2" ... />
...
</GlobalNamingResources/>
Add link web application META-INF/context.xml by an application-private JNDI context java:comp/env/ specified in the name attribute:
<Context path="/ApplicationContext" ... >
<ResourceLink global="jdbc/ApplicationContext_DatabaseName1" name="jdbc/DatabaseName1" ... />
<ResourceLink global="jdbc/ApplicationContext_DatabaseName2" name="jdbc/DatabaseName2" ... />
...
</Context>
Finally add JNDI resources usage in web application's deployment descriptor:
<resource-ref>
<description>DatabaseName1's Datasource</description>
<res-ref-name>jdbc/DatabaseName1</res-ref-name> ...
</resource-ref>
<resource-ref>
<description>DatabaseName2's Datasource</description>
<res-ref-name>jdbc/DatabaseName2</res-ref-name> ...
</resource-ref>
...
and in Spring context:
<jee:jndi-lookup id="DatabaseName1DataSource"
jndi-name="jdbc/DatabaseName1" ... />
<jee:jndi-lookup id="DatabaseName2DataSource"
jndi-name="jdbc/DatabaseName2" ... />
...
Many data sources used by many web application on the same server
Simply add configuration to Tomcat's server.xml:
<GlobalNamingResources>
<Resource name="jdbc/ApplicationContextX_DatabaseName1" ... />
<Resource name="jdbc/ApplicationContextX_DatabaseName2" ... />
<Resource name="jdbc/ApplicationContextY_DatabaseName1" ... />
<Resource name="jdbc/ApplicationContextY_DatabaseName2" ... />
...
</GlobalNamingResources/>
the others configuration should be deducible from previous variation case.
Many data sources to the same database used by many web application on the same server
In such case a Tomcat's server.xml configurations like:
<GlobalNamingResources>
<Resource name="jdbc/ApplicationContextX_DatabaseName" ... />
<Resource name="jdbc/ApplicationContextY_DatabaseName" ... />
ends up in two different web applications META-INF/context.xml like:
<Context path="/ApplicationContextX" ... >
<ResourceLink global="jdbc/ApplicationContextX_DatabaseName" name="jdbc/DatabaseName" ... />
</Context>
and like:
<Context path="/ApplicationContextY" ... >
<ResourceLink global="jdbc/ApplicationContextY_DatabaseName" name="jdbc/DatabaseName" ... />
</Context>
so someone might be worried about the fact that the same name="jdbc/DatabaseName" is looked up, and then used, by two different applications deployed on the same server: this is not a problem because the jdbc/DatabaseName is an application-private JNDI context java:comp/env/, so ApplicationContextX by using java:comp/env/ can't (by design) look up the resource linked to global="jdbc/ApplicationContextY_DatabaseName".
Of course if you felt more relaxed without this worry you might use a different naming strategy like:
<Context path="/ApplicationContextX" ... >
<ResourceLink global="jdbc/ApplicationContextX_DatabaseName" name="jdbc/applicationXprivateDatabaseName" ... />
</Context>
and like:
<Context path="/ApplicationContextY" ... >
<ResourceLink global="jdbc/ApplicationContextY_DatabaseName" name="jdbc/applicationYprivateDatabaseName" ... />
</Context>

YOUR_APP.xml file
I prefer Approach 2 (put everything (not only some attribute in the config), but instead of placing them in the global server.xml or global context.xml you should place it in the application-specific context.xml.default YOUR_APP.xml file in your Tomcat.
The YOUR_APP.xml file is located in $catalinaHome/conf/<engine>/<host> (for example conf/Catalina/localhost/YOUR_APP.xml).
The configuration in application specific YOUR_APP.xml is only available for the specific application.
See the guide published by MuleSoft. And see the official documentation, Tomcat Configuration Reference, page for The Context Container
Version 9
Version 8
To quote that documentation:
Individual Context elements may be explicitly defined:
• …
• In individual files (with a ".xml" extension) in the $CATALINA_BASE/conf/[enginename]/[hostname]/ directory. The context path and version will be derived from the base name of the file (the file name less the .xml extension).
• …

Approach 4
Instead of using JNDI I work with .properties files and build complex object during program initialization instead on configuration time.
You already use Spring and it is easy construct DataSource by:
<context:property-placeholder location="classpath:app.properties"/>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="oracle.jdbc.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:#${db.host}:${db.port}:${db.user}"/>
<property name="username" value="${db.user}"/>
<property name="password" value="${db.pass}"/>
</bean>
I completely agree with Ralph with using deployment descriptor in $CATALINA_BASE/conf/[enginename]/[hostname]/$APP.xmlbut instead JNDI I like plain key-value file!
With Spring injecting above properties into bean fields are easy:
#Value("${db.user}") String defaultSchema;
instead of JNDI:
#Inject ApplicationContext context;
Enviroment env = context.getEnvironment();
String defaultSchema = env.getProperty("db.user");
Note also that EL allow this (default values and deep recursive substitution):
#Value('${db.user:testdb}') private String dbUserName;
<property name='username' value='${db.user.${env}}'/>
To externalize .properties file I use modern Tomcat 7 that has org.apache.catalina.loader.VirtualWebappLoader:
<Loader className="org.apache.catalina.loader.VirtualWebappLoader"
virtualClasspath="/srv/web/app/"/>
So your devops fill virtualClasspath with local external full paths which is separate per application and put local app.propertiesto that dir.
See also:
Adding a directory to tomcat classpath
Can I create a custom classpath on a per application basis in Tomcat
Externalizing Tomcat webapp config from .war file
How to read a properties file outside my webapp context in Tomcat
Configure Tomcat to use properties file to load DB connection information
Externalize Tomcat configuration

step 1: context.xml
<Context path="/projectname">
<Resource auth="Container"
driverClassName="com.mysql.jdbc.Driver"
logAbandoned="true"
maxActive="100" ``
maxIdle="30"
maxWait="10000"
name="refname"
removeAbandoned="true"
removeAbandonedTimeout="60"
type="javax.sql.DataSource"
url="jdbc:mysql://localhost:8080/dbname"
username="root"
password="root"/>
</Context>
Step 2 : web.xml
<resource-ref>
<description>DB Connection</description>
<res-ref-name>refname</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
Step 3 : create a class to get connection
Connection connection = null;
Context context = (Context) new InitialContext().lookup("java:comp/env");
DataSource ds = (DataSource) context.lookup("refname");
connection = ds.getConnection();
Everything is set

You also can use JNDI URL support for different application configuration for test, integration test, production.
<Context>
...
<Resource auth="Container" factory="com.benasmussen.jndi.url.URLFactory"
name="url/MyUrl" type="java.net.URL" url="file:///your/path/to/file"/>
...
</Context>
<jee:jndi-lookup id="myUrl" jndi-name="java:comp/env/url/MyUrl" expected-type="java.net.URL" />
Check out the GitHub project Tomcat JNDI URL Support to enable JNDI URL support for Tomcat servers.

Placing the Resource tag inside conf/context.xml gets an exception but is okay when I place the same inside META-INF/context.xml : Why is that?

To connect to derby database using tomcat as the server initially I added the following to conf/context.xml of Tomcat :
<Resource name="jdbc/PollDatasource" auth="Container" type="javax.sql.DataSource"
driverClassName="org.apache.derby.jdbc.ClientDriver"
url="jdbc:derby://localhost:1527/poll database;create=true"
username="suhail" password="suhail"
maxActive="20" maxIdle="10" maxWait="-1" />
and the Resource-ref tag in web.xml of the WEB-INF/web.xml of the project.
<resource-ref>
<description>my connection</description>
<res-ref-name>jdbc/PollDatasource</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
But when I ran a servlet that had to connect to the database,the statement :
connection = dataSource.getConnection();
caused an exception :
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
I haven't understood the reason for this exception yet.
After the exception I removed the Resource tag from the conf/context.xml of the Tomcat and placed it in the META-INF/context.xml of my project.
When I tried the servlet again,it worked without any exception !
What could be the reason I am getting the exception when I place the Resource tag inside the global context.xml file (i.e inside conf/context.xml) but do not get the exception when I place it inside the context.xml specific to my application ?. (i.e inside META-INF/context.xml)

Adding <Resource> to conf/context.xml will make a copy of that resource available for every webapp you deploy on your server -- probably not what you want to do. If you want a <Resource> to be globally available, it's more appropriate to put it into conf/server.xml under <GlobalNamiongResources>.
I would expect that the error you are getting is because you don't have your JDBC driver in the right place. Defining the <Resource> in conf/context.xml may result in a different ClassLoader being used to load your <Resource>.