> For the complete documentation index, see [llms.txt](https://hanfak.gitbook.io/workspace/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hanfak.gitbook.io/workspace/general-paradigms/architecture/cloud/sidecar.md). # Sidecar * Problem * Peripheral tasks such as Monitoring, Logging etc are critical to most applications and often integrated within them. * However, these tasks run alongside the same process as the application which is potentially inefficient and points to improper separation of concerns. * Plus, outages caused in these monitoring and logging components could severely impact the entire application functions. * Solution * Co-locate as Sidecar * Uses * PRoxy * Egress traffic using https * Internal service traffic using https * How it works * Co-locate the set of tasks along with the application but place them in their process or container as a Sidecar * Sidecars are typically small/pluggable components and can be written in different languages * Both application and sidecar are deployed as a single unit, therefore latency is low * The sidecar can be used for modifying how the application container works without having to make any changes to the code * The sidecar is bolted to the application and its lifecycle is dependent on the application * If the sidecar container logic gets complex or tightly coupled with the main application, it may better be integrated with the main application’s code instead * example * A common example of the sidecar is the literal sidecar attached to a motorcycle — working as a single unit * The sidecar enhances the usability of the motorcycle by increasing passenger capacity * The sidecar could be made by another company and need not be bought from the motorcycle manufacturer — providing modularity and flexibility of choice * It does not have an engine of its own but relies on the engine of the actual motorcycle. If the motorcycle stops, the sidecar stops ## Sidecar patterns * Sidecar * Adapter * Ambassador *