Glance (OpenStack)

Glance (OpenStack)
Name	Glance
Developer	OpenStack Foundation
Released	2010
Programming language	Python
Operating system	Cross-platform
License	Apache License 2.0

Glance (OpenStack) Glance is an image service for cloud platforms providing discovery, registration and delivery of virtual machine images for Amazon Web Services, Google Cloud Platform, Microsoft Azure, Red Hat, Canonical, SUSE, IBM, Intel, NVIDIA and other Linux and Unix vendors. It integrates with virtualization and orchestration systems such as KVM, QEMU, Xen Project, VMware ESXi, Hyper-V and container platforms like Docker and Kubernetes to serve bootable images, snapshots and volume-backed images. Originating within the OpenStack ecosystem and governed by the Open Infrastructure Foundation, Glance plays a central role in provisioning workflows for projects including Nova (OpenStack), Cinder (OpenStack), Neutron (OpenStack), Keystone (OpenStack), and Horizon (OpenStack).

Overview

Glance functions as an image registry and image delivery service used by cloud operators such as Rackspace, DreamHost, HP Enterprise, Mirantis, Canonical Ltd., Red Hat, Inc., SUSE Linux GmbH and research institutions like CERN, NASA, Lawrence Berkeley National Laboratory and Los Alamos National Laboratory. It stores metadata and payloads, supports multiple storage backends including OpenStack Swift, Ceph, Amazon S3, Google Cloud Storage, Microsoft Azure Blob Storage and POSIX file systems. Glance originated in early 2010s OpenStack development drives and has evolved across OpenStack releases like Austin, Bexar, Cactus, Diablo, Essex, Folsom, Grizzly, Havana, Icehouse, Juno, Kilo, Liberty, Mitaka, Newton, Ocata, Pike, Queens, Rocky, Stein, Train, Ussuri, Victoria, Wallaby, Xena, and beyond.

Architecture

Glance implements a client-server architecture with RESTful APIs influenced by Representational State Transfer patterns and HTTP semantics used by services such as OpenStack Identity API and OpenStack Image API. Core components include the API server, registry (historically), image storage backends, and image conversion and import/export services. It interacts with compute services like OpenStack Compute and storage services such as OpenStack Block Storage and object stores like Ceph Object Gateway and Swift Object Storage. Integration points and middleware align with Keystone, Panko, Gnocchi and telemetry stacks. Glance supports image formats including QCOW2, VMDK, VHD, raw and ISO image standards used in virtualization across vendors like VMware, Inc. and Microsoft Corporation.

Features

Glance provides image discovery, metadata tagging, versioning and copy-on-write delivery, with optional image caching and streaming to reduce boot latency for services like OpenStack Nova and orchestration tools such as OpenStack Heat and Ansible. It offers image import/export, image conversion plugins compatible with libguestfs, qemu-img, and integration with ImageMagick for ancillary tasks. Policy-driven access integrates with Keystone Identity Service and supports image visibility flags, image member management and multi-tenant catalogs used by cloud providers including OVH, DigitalOcean, Alibaba Group, Tencent Cloud and Hetzner Online GmbH. Administrative features include image lifecycle management, image signing, store-to-store copy via backends like RADOS, GlusterFS, HDFS and cloud gateways.

Deployment and Integration

Operators deploy Glance within distributions and platforms from Canonical Ubuntu, Red Hat OpenStack Platform, SUSE OpenStack Cloud and third-party distributions from Mirantis Fuel and SUSE Manager. It is commonly deployed on orchestration layers including Kubernetes with operators and Helm charts, on virtualized infrastructure managed by oVirt and Proxmox VE, and on bare-metal provisioning tools like MAAS and iPXE. Integration with CI/CD pipelines involves tools such as Jenkins, GitLab CI/CD, Zuul CI, Travis CI and configuration management from Puppet, Chef, SaltStack and Ansible. Monitoring and logging typically use Prometheus, Grafana, ELK Stack, Fluentd and Zabbix.

Security and Access Control

Glance uses Keystone (OpenStack) for authentication and authorization, supports role-based access control aligned with Open Policy Agent and policy frameworks, and can be configured for TLS via OpenSSL and Let's Encrypt certificates. It supports image signing via formats like PEM, X.509 and integration with hardware security modules from Thales Group, Gemalto, and cloud KMS services from AWS KMS, Google Cloud KMS and Azure Key Vault. Auditing and compliance workflows integrate with OpenStack Audit, OSCAP, and enterprise tools from Splunk, IBM QRadar, McAfee and Trend Micro.

Development and Community

Glance development is coordinated by contributors from companies such as Red Hat, Canonical, SUSE, IBM, Intel Corporation, Wind River Systems, Mirantis, Rackspace, Huawei Technologies, Cisco Systems, Nokia, Orange S.A., Verizon, Bloomberg L.P., BlackBerry Limited, Sony, Samsung Electronics, Facebook, Twitter, and community members affiliated with research centers like Fermilab and Argonne National Laboratory. The project follows OpenStack governance, release cycles, and code review practices on platforms like Gerrit, GitHub, and issue tracking on Launchpad and StoryBoard. Contribution guidelines reference Apache License norms and continuous integration across test frameworks including Tempest, Zuul and unit test suites.

Use Cases and Adoption

Glance is used for VM image cataloging and delivery in public clouds like Amazon EC2, private clouds in financial institutions such as Deutsche Bank, JPMorgan Chase, healthcare providers like Mayo Clinic and Cleveland Clinic, research grids such as European Grid Infrastructure and PRACE, and telecommunications NFV deployments by Ericsson, Nokia Networks and Cisco. It supports imaging workflows for HPC centers including Oak Ridge National Laboratory and hybrid cloud scenarios involving OpenStack-Ansible, Kolla-Ansible, and managed services by HPE GreenLake and IBM Cloud. Operators leverage Glance for disaster recovery, image distribution across regions, and immutable infrastructure practices used in DevOps toolchains.

Category:OpenStack