在支援Overlay Network與Shared Volume之Docker Swarm叢集上提供高可用性軟體容器服務

黃泓霖 ； 陳劭睿 ； 何敏煌 ； 王尉任

《TANET2016 臺灣網際網路研討會》 2016 (2016/11) Pp. 685-690-123

https://doi.org/10.6679/TANET.2016.123

摘要

在近幾年來的IT 產業裡，作業系統容器化(OS Containerization)的概念正逐漸被重視，這種概念就是在作業系統層級開啟虛擬而且獨立的作業環境，亦即軟體容器(Software Container) ，並讓應用程式在軟體容器執行。這種方式與虛擬機器相較而言，具有較輕量的額外效能負擔，因此逐漸受到企業所青睞。在軟體容器平台的管理與建置工具中，Docker是目前最被廣泛重視與應用的開源專案。DockerSwarm 則是一個用來建立Docker 容器運算叢集的開源專案。在本文研究中發現，目前Docker Swarm的版本(1.2.0)對於Docker 容器的高可用性(High Availability, HA)功能並未非常完善，故本研究將專注於Docker Swarm 中的HA 議題。本文提出一個輕量型的HA 架構，並於Docker Swarm 上實作高可用性Docker 容器叢集之功能。這個HA 架構利用Docker 容器共享數據卷(shared Docker volume)來確保資料不會在軟體容器復原後遺失，並使用Docker層疊網路(Overlay Network)動態配置容器位址讓軟體容器間可以彼此溝通。此HA 架構中最重要的是本研究所提出的容器錯誤監測與回復機制，讓軟體容器可以在發生錯誤後快速重啟。從實驗結果指出，本研究所提出的HA 機制可以大幅降低Docker Container 的服務停止時間(Downtime)，並提升以容器運行的應用程式或服務之可用性。

關鍵字

高可用性 ； 作業系統容器化 ； 作業系統虛擬化 ； 軟體容器 ； Docker ； Docker Swarm

並列摘要

In recent years, a similar light-weight technology, usually called OS containerization (or OS-level virtualization), has gradually become a hot issue in IT industry. The OS containerization technology provides a logical compute instance, known as the software container, as the fundamental compute unit to host applications or services. A software container is emulated by the host OS. Therefore, it has light-weight overheads in terms of instance creation/deletion time and consumed memory space, when compared with hardware virtualization. Docker is one of the popular open-source projects for OS containerization. It allows people to create and to manage software containers on a host OS. Docker Swarm is another open-source project for building a compute pool of Docker containers. Based on our study, Docker Swarm does not well support the high availability (HA) feature for its Docker containers in the current version 1.2.0. To this end, this research focuses on the HA issue of Docker Swarm. In this paper, we present a light-weight HA architecture as well as its implementation based on Docker Swarm. The HA architecture uses shared Docker volume to prevent data loss. It also uses Docker overlay networks to enable communication among software containers on different hosts. We also implement a light-weight monitoring mechanism to detect whether a software container fails, as well as a recovery mechanism to recover a failed software container in a second. With the proposed mechanisms, we can reduce the downtime of any failed software container on Docker Swarm, and improve the ability of the applications/services running on the software containers consequently.

並列關鍵字

High availability ； OS containerization ； OS-level virtualization ； Software container ； Docker ； Docker Swarm