This project builds on the openSUSE Java 11 image here to build a pre-configured Tomcat Docker image.
It can be used as a base image for hosting web projects which use Java technologies such as Java Servlets or JavaServer Pages.
Here is an example Dockerfile which uses this image as a base:
FROM cafapi/opensuse-tomcat-jre11:latest
COPY demowebapp/ $CATALINA_HOME/webapps/demowebapp/
COPY demowebapp-admin/ $CATALINA_HOME/adminapps/ROOT/
The derived image is expected to supply the web application being deployed, which should be copied into Tomcat's default webapps directory, and it is also expected to supply an administration application, which should be copied into the adminapps directory. The administration application must supply a /healthcheck endpoint which can be used by Docker, or the container orchestrator, to check on the health of the service when it is running. The administration application may optionally supply other administration or operations functionality, to assist with debugging for example, but it is required to supply a healthcheck endpoint.
Tini is pre-installed in the container. If the image entrypoint is not overwritten then it will be automatically used.
PostgreSQL Client is pre-installed in the container. psql is a terminal-based front-end to PostgreSQL. It enables you to type in queries interactively, issue them to PostgreSQL, and see the query results. Alternatively, input can be from a file or from command line arguments. In addition, psql provides a number of meta-commands and various shell-like features to facilitate writing scripts and automating a wide variety of tasks.
Any executable scripts added to the /startup/startup.d/ directory will be automatically run each time the container is started (assuming the image entrypoint is not overwritten).
The image comes pre-installed with a startup script which provides a mechanism to extend the CA certificates which should be trusted.
The image comes pre-installed with a script that configures the Tomcat log level with the level set in the provided environment variable CAF_LOG_LEVEL. The levels available are mapped to Tomcat log levels as follows:
| CAF_LOG_LEVEL | Tomcat Log Level |
|---|---|
| FATAL | SEVERE |
| ERROR | SEVERE |
| WARN | WARNING |
| INFO | INFO |
| DEBUG | FINE |
| TRACE | FINEST |
This image comes pre-installed with a utility script which can be used to setup a SSL certificate for use with Tomcat.
If the SSL_TOMCAT_CA_CERT_LOCATION environment variable is present then the script will be executed and the following environment variables are read:
| Environment Variable | Required | Description |
|---|---|---|
| SSL_TOMCAT_CA_CERT_LOCATION | Yes | Location of the SSL certificate to be setup. Note: this replaces the location of the default keystore. |
| SSL_TOMCAT_CA_CERT_KEYSTORE_PASS | No | Replaces the default keystore password. |
| SSL_TOMCAT_CA_CERT_KEY_PASS | No | Replaces the default key password. |
| SSL_TOMCAT_CA_CERT_KEYSTORE_ALIAS | No | Replaces the default keystore alias. |
The image comes pre-installed with a utility script which can be used to check if a PostgreSQL database exists and to create it if it does not.
When the script is called it must be passed an environment variable prefix for the service:
/scripts/check-create-pgdb.sh SERVICE_
The script then reads the database details from a set of environment variables with the specified prefix:
| Environment Variable | Description |
|---|---|
SERVICE_DATABASE_HOST |
The host name of the machine on which the PostgreSQL server is running. |
SERVICE_DATABASE_PORT |
The TCP port on which the PostgreSQL server is listening for connections. |
SERVICE_DATABASE_USERNAME |
The username to use when establishing the connection to the PostgreSQL server. |
SERVICE_DATABASE_PASSWORD |
The password to use when establishing the connection to the PostgreSQL server. |
SERVICE_DATABASE_APPNAME |
The application name that PostgreSQL should associate with the connection for logging and monitoring. |
SERVICE_DATABASE_NAME |
The name of the PostgreSQL database to be created. |