Building the Docker Image for an API Gateway Instance

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About this task

The API Gateway Docker image provides an API Gateway installation. Depending on the existing installation, the API Gateway Docker image provides a standard API Gateway or an advanced API Gateway instance. When running the image, the API Gateway is started. The API Gateway image is created on top of an Integration Server image.

To build a Docker image for an API Gateway instance

Procedure

  1. Create a docker file for the Integration Server (IS) instance by running the following command: 
    ./is_container.sh createDockerfile [optional arguments]
    Argument Description
    -Dimage.name Optional. Name of base image upon which the new image is built.

    Default: centos:7

    -Dinstance.name Optional. IS instance name to include in the image.

    Default: default

    -Dport.list Optional. Comma-separated list of the ports on the instance to expose in the image.

    Default: 5555,9999

    -Dpackage.list Optional. Comma-separated list of Wm packages on the instance to include in the image.

    Default: all (this includes all the Wm packages and the Default package)

    -Dinclude.jdk Optional. Whether to include the Integration Server JDK (true) or JRE (false) in the image.

    Default: true

    -Dfile.name Optional. File name for the generated docker file.

    Default: Dockerfile_IS

  2. Build the IS Docker image using the Docker file Dockerfile_IS by running the following command: 
    ./is_container.sh build [optional arguments]
    Argument Description
    -Dfile.name Optional. File name of the Docker file to use to build the Docker image.

    Default: Dockerfile_IS

    -Dimage.name Optional. Name of the generated Docker image.

    Default: is:micro

  3. Create a Docker file for the API Gateway instance from the IS image is:micro by running the following command: 
    ./apigw_container.sh createDockerfile [optional arguments]
    Argument Description
    --instance.name Optional. API Gateway instance to include in the image.

    Default: default

    --port.list Comma-separated list of the ports on the instance to expose in the image.

    Default: 9072

    --base.image Name of the base Integration Server image upon which this image should be built.

    Default: is:micro

    --file.name Optional. File name for the generated Docker file.

    Default: Dockerfile_IS_APIGW

    --target.configuration Optional. Target configuration for which Dockerfile is created.

    Not specifying any value builds a Dockerfile for the Docker and Kubernetes environments.

    Specifying the value OpenShift builds a Dockerfile for an OpenShift environment.

    Note: If you specify the --target.configuration option, the Integration Server image specified by the --base.image option should be available before you create the API Gateway Dockerfile. The Integration Server Docker image is analyzed with docker inspect in order to extract some information necessary for the API Gateway Dockerfile.
    --os.image Optional. Name of the base operating system image upon which this image is built if the --target.configuration is set to OpenShift.

    Default: centos:7

    Note: The value of this parameter has to be aligned with the one specified for -Dimage.name in Step 1.
    The Docker file is created under the packages directory of the specified Integration Server instance. In a default installation, the Docker file is created in the folder SAG_Root/IntegrationServer/instances/default/packages/Dockerfile_IS_APIGW.
  4. Build the API Gateway Docker image using the core Docker file Dockerfile_IS_APIGW by running the following command: 
    ./apigw_container.sh build [optional arguments]
    Argument Description
    instance.name Optional. API Gateway instance to include in the image.

    Default: default

    file.name File name of the Docker file to use to build the Docker image.

    Default: Dockerfile_IS_APIGW

    image.name Optional. Name for the generated Docker image that contains the custom packages.

    Default: is:apigw

    The image is stored in the local registry of the Docker host. To check the image, run the following command: 
    $ docker images

Example

A sample shell script for creating an API Gateway Docker image looks as follows: 

echo "is createDockerfile ======================================================="
./is_container.sh createDockerfile
status=$?
 
if [ $status -ne 0 ]
then
    echo "Failed! status: $status"
    exit $status
fi
 
echo "is build =================================================================="
./is_container.sh build
status=$?
 
if [ $status -ne 0 ]
then
    echo "Failed! status: $status"
    exit $status
fi
 
echo "apigw createDockerfile =================================================="
./apigw_container.sh createDockerfile    
status=$?
 
if [ $status -ne 0 ]
then
    echo "Failed! status: $status"
    exit $status
fi
 
echo "apigw build ============================================================="
./apigw_container.sh build
status=$?
 
if [ $status -ne 0 ]
then
    echo "Failed! status: $status"
    exit $status
fi
After running the steps, the created images can be listed using the command docker images. The following sample result shows the base image centos:7, the Integration Server image is:micro, and the API Gateway image is:apigw. 
REPOSITORY          TAG       IMAGEID            CREATED             SIZE
is                  apigw     af29373fc98a        15 hours ago        1.3GB
is                  micro     06e7c0de4807        15 hours ago        1.1GB
centos              7         36540f359ca3        12 days ago         193MB
Note: The is:micro and therefore, the is:apigw images are based on the centos:7 image, which is available from the official CentOS repository

The Docker images resulting from Docker files created using the createDockerFile command feature the following:

  • Docker logging.

    API Gateway Docker containers log to stdout and stderr. The API Gateway logs can be fetched with Docker logs.

  • Docker health check.

    API Gateway Docker containers perform health checks. You can use wget request against the API Gateway REST API to check the health status of API Gateway.

    The following wget request shows a curl invocation sending a request against the HTTP port. If API Gateway exposes an HTTPS port, only the wget is created accordingly. The option --no-check-certificate is used to avoid any failure due to certificate problems. 

    HEALTHCHECK CMD curl  --no-check-certificate 
http://localhost:5555/rest/apigateway/health

    The wget checks the API Gateway availability by sending requests to the API Gateway REST health resource. If the wget is successful, API Gateway is considered healthy.

  • Graceful shutdown.

    Docker stop issues a SIGTERM to the running API Gateway.