A Penalty-Aware Cloud Monitoring System based on Blockchains Christian Dienbauer Benedikt Pittl [email protected] [email protected] University of Vienna University of Vienna Vienna, Austria Vienna, Austria Werner Mach Erich Schikuta [email protected] [email protected] University of Vienna University of Vienna Vienna, Austria Vienna, Austria ABSTRACT Applications & Services (iiWAS ’20), November 30-December 2, 2020, Chiang Today, traded cloud services are described by service level agree- Mai, Thailand. ACM, New York, NY, USA, 9 pages. https://doi.org/10.1145/ 3428757.3429130 ments that specify the obligations of providers such as availability or reliability. Violations of service level agreements lead to penalty payments. The recent development of prominent cloud platforms 1 INTRODUCTION such as the re-design of Amazon’s spot marketspace underpins a Cloud providers such as Amazon and Azure sell their datacenter trend towards dynamic cloud markets where consumers migrate resources in the form of services. For the description of the services, their services continuously to different marketspaces and providers so-called Service Level Agreements (SLAs) are used [17]. They are to reach a cost-optimum. This leads to a heterogeneous IT infrastruc- specifications that define, inter alia, details about the offered service ture and consequently aggravates the monitoring of the delivered such as availability and reliability. Violations of SLAs lead to penalty service quality. Hence, there is a need for a transparent penalty payments, and so consumers are interested in monitoring the ser- management system, which ensures that consumers automatically vice performance. Therefore, cloud providers such as Amazons offer get penalty payments from providers in case of service violations. monitoring platforms like Amazon Cloudwatch that provide APIs to In the paper at hand, we present a cloud monitoring system that query the performance metrics of the service. Besides, several third- is able to execute penalty payments autonomously. In this regard, party cloud monitoring platforms are existing such as dynatrace1, we revert to smart contracts hosted on blockchains. They contin- datadog2 or AppDynamics3. The vision of a monitoring platform uously monitor cloud services and trigger penalty payments to that also manages penalty payments is still unrivaled [13]. For the consumers in case of service violations. We implemented the pre- establishment of such a platform in industry not only machine- sented approach with the IBM Hyperledger Fabric framework and readable SLAs such as described in [13] are necessary, but also the created a use case with Amazon’s cloud services as well as Azures transparent management of penalty payments has to be ensured. cloud services to illustrate the universal design of the introduced Hence, in the last years, neutral third parties were introduced that approach. are responsible for confirming service violations and transferring penalty payments to consumers [11, 28]. Even such neutral third CCS CONCEPTS party approaches have structural weaknesses as Robert Sams sum- • Information systems ! Information systems applications; marizes with three sins [12]: sin of commission, sin of deletion and • Computer systems organization ! Architectures. sin of omission. Nowadays, the scientific community reverts to neu- tral consensus finding approaches among untrusted participants KEYWORDS which are technically realized by the blockchain technology. For Cloud Monitoring, Smart Contracts, Cloud Computing example, the authors of [21] introduced an approach for managing and modifying SLA terms with blockchains - penalty management ACM Reference Format: for SLA violations was neglected. Christian Dienbauer, Benedikt Pittl, Werner Mach, and Erich Schikuta. 2020. The paper at hand focuses on the development of a blockchain- A Penalty-Aware Cloud Monitoring System based on Blockchains. In The based, penalty-aware cloud monitoring platform. Thereby we apply 22nd International Conference on Information Integration and Web-based so-called smart contracts, which are programs executed on the Permission to make digital or hard copies of all or part of this work for personal or blockchain. A first step towards such systems was introduced in classroom use is granted without fee provided that copies are not made or distributed the short paper [15] where a pure provider-centric smart contract for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM was introduced - see related work. In contrast to that, the approach must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, introduced in that paper treats a smart contract as a bilateral agree- to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from [email protected]. ment between consumers and providers. Therefore, consumers and iiWAS ’20, November 30-December 2, 2020, Chiang Mai, Thailand © 2020 Association for Computing Machinery. 1https://www.dynatrace.com ACM ISBN 978-1-4503-8922-8/20/11...$15.00 2https://www.datadoghq.com/ https://doi.org/10.1145/3428757.3429130 3https://www.appdynamics.com/ iiWAS ’20, November 30-December 2, 2020, Chiang Mai, Thailand Dienbauer et al. providers have to register the SLAs of the traded cloud services in is queried and regardless of time, the results need to be the same to a smart contract, including corresponding commonly trusted cloud ensure a deterministic behavior of the blockchain. monitoring authorities. The smart contract uses them to monitor Today, most of the monitoring platforms are cloud provider- the performance of the cloud services and automatically transfers specific, limiting the monitoring of heterogeneous IT infrastruc- penalties to the consumer in case of SLA violations. This ensures tures, as can be found in smart city architectures and industry 4.0 [4]. that consumers get penalties immediately for service violations This can enable data-driven applications that require reliable com- while providers can profit from a clear and transparent monitoring munication models to operate more efficiently [9]. Complex cloud approach. The technical feasibility of our approach is demonstrated service compositions are currently hard to monitor with existing by a smart contract deployed on the Hyperledger Fabric Blockchain4 monitoring platforms, and so in [16] a generic framework to moni- that uses arbitrary monitoring services for detecting SLA violations tor the performance of services deployed on different providers is and consequently executing penalty payments. Within this paper, presented. To collect data from the services, the framework suggests we use cloud services as well as monitoring APIs both from Amazon a client-server approach, where agents are deployed together with and from Azure. the service that should be monitored: Those agents can be accessed The remainder of the paper is structured as follows: Founda- by a centralized monitoring platform to retrieve data of a monitored tions and related work are introduced in Section 2. The concept service. A similar approach in the context of edge computing is of the penalty-aware cloud monitoring platform is presented in presented in [4]. There, an architecture divided into management Section 3, followed by an introduction of our implementation with and worker layer is suggested. The management layer provides the IBM Hyperledger Fabric Blockchain, Amazon EC2, and Azure functionalities to measure the activities of the edge nodes in the in Section 4. A discussion about the presented concept is given in network to distribute workloads based on different algorithms. Section 5. The paper closes with a conclusion in Section 6. An approach for monitoring data streams in distributed systems with the focus on communication-efficiency and data privacy can 2 FOUNDATIONS AND RELATED WORK be found in [19]. The system collects information about different This section is structured along two parts. The first part describes components and sets the granularity based on a given threshold by foundations of the blockchain technology. In the second part, re- a centralized monitoring unit. Such centralized monitoring systems lated cloud monitoring approaches are introduced. suffer from a single point of failure and therefore a distributed With the rising popularity of the Bitcoin in mid-2017, the under- agent-based monitoring system to handle multi-tenant service- lying blockchain technology gained in attraction. This technology based systems can be used [27]. As a challenge of service monitoring is not limited to cryptocurrencies and so organizations from various is the system overhead of monitoring tools and so that the collection domains started to identify reliable business models enabled by the of data should be done in a resource-effective manner [23]. blockchain [5]. A typology of emerging blockchain applications To foster the quality of services and the reliability business pro- with regards to the domains where they are applied is presented cesses that are based on those, Service Level Agreements (SLAs) in [8, 29]. Due to the decentralized nature with no need for inter- between a service provider and consumer are defined [7]. As SLAs mediaries, the blockchain technology can handle transactions in are legally binding contracts, they should be audited by an in- different