Resources¶

A Resource is a pre-requisite for a command in a Step.

Resource is a term used to describe an external requirement that is needed before a step can be executed successfully, e.g. source code which needs to be continuously integrated and delivered.

To denote that a particular step needs a resource:

{
    "cmd": "sbt test",
    "needs_resource": "my-scala-src"
}

This resource must be declared in the resources section of the Pipeline definition.

Each entry consists of the following keys:

name: String, Required: The unique name of the resource by which its to be referred in the needs_resource key of a step.
type: String, Required: This can either be internal or external. External resources are to be fetched from a Resource Provider, whereas Internal ones are outputs of another pipeline in the system. Resources are loaded lazily when required, so if a declared resource isn’t used in a step, it will not be fetched and if fetched will be cached for the remainder of the steps.

Conditional keys:

If type is external:

params: Map[String, Any], Required: This are the params that are to be sent to the Resource Provider when requesting the resource. These are a property of that particular provider and helps in customizing the kind of resource fetched.

If type is internal:

params: Map[String, Any], Required: This are the params that are to be sent to the Artifact Store when requesting the resource. Since Bob is going to request an artifact from a previous build, it simply calls the corresponding Artifact Store with the group, name, run_id of the artifact that was produced. The name of the artifact must be same as the name of the resource.
provider: In this case this becomes the name of the registered Artifact Store.

Example:

[
    {
        "name": "my-source",
        "type": "external",
        "provider": "github-provider",
        "params": {
            "repo": "https://github.com/bob-cd/bob",
            "branch": "main"
        }
    },
    {
        "name": "my-ml-model",
        "type": "internal",
        "provider": "s3",
        "params": {
            "group": "dev",
            "name": "make-model",
            "run_id": "r-0ef66ba9-e397-461b-a6d9-f52f91889264"
        }
    }
]

A Resource can be used fetch any external items which may be needed in a build. This is provided to Bob via a Resource Provider.

Resource Provider¶

A Resource Provider is Bob's way of abstracting itself from knowing about how to fetch various resources.

The most general use case for a resource provider is to clone source code that is to be continuously integrated and delivered.

A Resource Provider is any system which has the following properties:

It is a web server.
It is reachable from the network that Bob is in.
Exposes an endpoint at /bob_resource upon which when a GET request is made, a tar archive is sent back. The rationale for using the tar format is:
- Its quite ubiquitous and can be implemented with relative ease as its part of the stdlib of various languages.
- Generally resources tend to be source code and have multiple files/folders and using an archive makes it easy to send multiple things.
- Bob uses Podman as its orchestrator and follows its design decision of using tar files to send things over.

A reference resource provider which handles simple Github pulls can be found

This gives the following advantages:

Bob doesn't have to care about how to fetch a particular Resource nor does it have to care about what the resource is.
Using a resource provider details like auth, permissions and in cases like source control, things pertaining to private repositories, user access etc can be offloaded outside of Bob.
Multiple instances of Bob can share a resource provider.
Pretty much any source of data can be abstracted specially the various Version Control Systems.
The Resource Provider can be written in any language, can scale independently of Bob and be registered at runtime with Bob.

A resource provider must be registered with Bob prior to the execution of a Step that needs a resource.

To register a Resource provider with Bob:

Make a POST request on the end point /resource-providers/<name> with the body:
```
{
    "url": "https://my-awesome-resources.bob.io"
}
```
A 202 response from Bob indicates success. Here name is the unique name with which Bob identifies this. The url must be reachable from Bob.

Conversely a DELETE request on /resource-providers/<name> un-registers it from Bob.

To list registered resource providers make a GET request on /resource-providers.