Getting Started

Make sure you have first read the Introduction so you understand what CLAM is and what its architecture is like.

You start a new CLAM webservice project using the clamnewproject tool. The tool generates all the necessary files, which you have to edit. The tool takes one argument: an identifier for your system. This identifier is for internal use, possibly for use in URLs, paths, and filenames. It may not not contain any spaces or other special characters. Mind that this ID is case sensitive, so it is strongly recommended to keep it all lower case. Example:

$ clamnewproject myfirstproject

The tool will create a directory named after the identifier, in which various template files are created which are named after the chosen identifier. You are expected to edit the service configuration file, a Python script, as well as a host-specific configuration file and one of the two system wrapper scripts (choose Python or shell script, or write one from scratch in your favourite language). The scripts are heavily commented to help you along, along with the documentation you are reading, this should provide you with all knowledge necessary to make a webservice.

  • myfirstproject/ - Service Configuration File

  • myfirstproject/myfirstproject.config.yml - A more generic external configution file which is automatically

included from the service configuration file unless a more host specific variant is found (myfirstproject.$HOSTNAME.yml). This will be addressed in External Configuration Files.

  • myfirstproject/ - System Wrapper Script in Python (this is recommended over the shell version as it is suited for more complex webservices)

  • myfirstproject/ - System Wrapper Script in shell script (only suggested for simple webservices)

  • myfirstproject/myfirstproject.wsgi - WSGI script, you probably don’t need to edit this

  • - Installation script (edit the metadata in here), run pip install . for installation in production environments or pip install -e for installation during development. (the start scripts mentioned below do this automatically for you)

  • Dockerfile - OCI Container build script. You may need to adapt this to add extra dependencies your system may need.

  • - Lists files to include in installation by

  • INSTRUCTIONS.rst - Automatically generated instructions. They complement/reiterate most of waht is said here.

Moreover, some scripts and sample configurations are generated:

  • - Start your webservice using the built-in development server.

  • - Start your webservice using the production server using uwsgi. To use this you will need to configure your webservice (e.g. Apache or nginx).

These template files need to be edited for your particular application. They are heavily commented to guide you. The INSTRUCTIONS.rst file will be created in your project directory and provides instructions on what files to edit and how to start the clam service for your specific project. Starting your webservice is as easy as running, the script will inform you to what URL to direct your browser once the webservice is running.

You can choose not to make use of one of the two generated system wrapper scripts and instead either write one from scratch in another language of your choice, or directly let CLAM invoke your application. Moreover, a wrapper is only intended for CLAM’s project paradigm, the action paradigm (Actions) does not make use of it at all.

Starting Your webservice

You can start your webservice in development mode with the included script, but not before you first read how to construct your webservice. Read the Service configuration documentation, and afterwards the wrapperscript documentation.

The start script simply installs your webservice and runs clamservice to run it, passing the module name of your webservice configuration. Make sure you first activated your Python virtual environment (if used) when calling the start script.

For production environments, read the documentation on Deployment in production.

Overriding host, port and urlprefix (advanced)

The HOST, PORT and URLPREFIX are configured in the service configuration file or the host-specific external configuration file it includes, CLAM will attempt to automatically guess them when they are not explicitly set. If you run behind a reverse proxy (common in production environments), you will need to set USE_FORWARDED_HOST = True so CLAM can automatically detect where the original request was coming from.

It is possible, however, to override these when launching or deploying the webserver, without changing the service configuration itself. If you use the development server, using clamservice, then you can pass the -u flag with the full URL CLAM should use. You can also set an environment variable CLAMFORCEURL, which has the same effect. This latter option also works when deploying CLAM through WSGI. The use of USE_FORWARDED_HOST is preferred though.