Backend setup

First and most important thing is, SkyWalking backend startup behaviours are driven by config/application.yml. Understood the setting file will help you to read this document.

Startup script

The default startup scripts are /bin/oapService.sh(.bat). Read start up mode document to know other options of starting backend.

application.yml

The core concept behind this setting file is, SkyWalking collector is based on pure modulization design. End user can switch or assemble the collector features by their own requirements.

So, in application.yml, there are three levels.

1. Level 1, module name. Meaning this module is active in running mode.
2. Level 2, provider name. Set the provider of the module.
3. Level 3. settings of the provider.

Example:

core:
  default:
    restHost: 0.0.0.0
    restPort: 12800
    restContextPath: /
    gRPCHost: 0.0.0.0
    gRPCPort: 11800

1. core is the module.
2. default is the default implementor of core module.
3. restHost, restPort, ... gRPCHost are all setting items of the implementor.

At the same time, modules includes required and optional, the required modules provide the skeleton of backend, even modulization supported pluggable, remove those modules are meanless. We highly recommend you don't try to change APIs of those modules, unless you understand SkyWalking project and its codes very well.

List the required modules here

1. Core. Do basic and major skeleton of all data analysis and stream dispatch.
2. Cluster. Manage multiple backend instances in a cluster, which could provide high throughputs process capabilities.
3. Storage. Make the analysis result persistence.
4. Query. Provide query interfaces to UI.

For Cluster and Storage have provided multiple implementors(providers), see Cluster management and Choose storage documents in the link list.

Also, several receiver modules are provided. Receiver is the module in charge of accepting incoming data requests to backend. Most(all) provide service by some network(RPC) protocol, such as gRPC, HTTPRestful.
The receivers have many different module names, you could read Set receivers document in the link list.

Advanced feature document link list

After understand the setting file structure, you could choose your interesting feature document. We recommend you to read the feature documents in our following order.

1. Overriding settings in application.yml is supported
2. IP and port setting. Introduce how IP and port set and be used.
3. Backend init mode startup. How to init the environment and exit graciously. Read this before you try to initial a new cluster.
4. Cluster management. Guide you to set backend server in cluster mode.
5. Deploy in kubernetes. Guide you to build and use SkyWalking image, and deploy in k8s.
6. Choose storage. As we know, in default quick start, backend is running with H2 DB. But clearly, it doesn't fit the product env. In here, you could find what other choices do you have. Choose the one you like, we are also welcome anyone to contribute new storage implementor,
7. Set receivers. You could choose receivers by your requirements, most receivers are harmless, at least our default receivers are. You would set and active all receivers provided.
8. Do trace sampling at backend. This sample keep the metric accurate, only don't save some of traces in storage based on rate.
9. Official OAL scripts. As you known from our OAL introduction, most of backend analysis capabilities based on the scripts. Here is the description of official scripts, which helps you to understand which metric data are in process, also could be used in alarm.
10. Alarm. Alarm provides a time-series based check mechanism. You could set alarm rules targeting the analysis oal metric objects.

Telemetry for backend

OAP backend cluster itself underlying is a distributed streaming process system. For helping the Ops team, we provide the telemetry for OAP backend itself. Follow document to use it.