Openstack之路（三）镜像服务Glance
Glance的概述Glance是为虚拟机的创建提供镜像的服务，我们基于Openstack是构建基本的IaaS平台对外提供虚拟机，而虚拟机在创建时必须为选择需要安装的操作系统，Glance服务就是为该选择提供不同的操作系统镜像。
Glance的组件
[*]Glance-API
主要用来响应各种REST请求然后通过其它模块（主要是glance-registry组件和后端存储接口）完成镜像的上传、删除、查询等操作。可以简单的再分为两部分：一层中间件，它主要是做一些对请求的解析工作（如分析出版本号）， 另外一部分提供实际的服务（如与镜像上传下载的后端存储接×××互）。默认绑定端口是9292。
[*]Glance-Registry
镜像注册服务用于提供镜像元数据的REST接口。主要工作是存储或者获取镜像的元数据，与MySQL数据库进行交互。也可以简单的再细分为两部分，API和具体的Server。元数据是指镜像相关的一些信息（如id，size， status，location，checksum，min_disk，min_ram，owner等）真正的镜像数据保存在实际所使用的后端存储里（如Swift，S3，Filesystem等）。默认绑定的端口是9191。
[*]Image Store
严格来说Image Store不属于Glance的组件，这里把它单独分出来只是为了方便理解，它只是一个接口层，提供镜像存储和查询的接口。具体的实现则需要外部存储（Swift，S3）的支持。
Glance的工作流程
Glance安装配置
Glance的安装
[*]创建一个数据库、服务凭证和API端点
MariaDB [(none)]> create database glance;
Query OK, 1 row affected (0.00 sec)
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| glance |
| information_schema |
| keystone |
| mysql |
| performance_schema |
+--------------------+
5 rows in set (0.00 sec)
MariaDB [(none)]> grant all on glance.* to 'glance'@'localhost' identified by 'glance';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> grant all on glance.* to 'glance'@'%' identified by 'glance';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> exit
Bye
[*]获得admin凭证来获取只有管理员能执行的命令的访问权限
# source admin-openrc
[*]要创建服务证书，完成这些步骤
创建glance用户
# openstack user create --domain default --password-prompt glance
User Password:
Repeat User Password:
+---------------------+----------------------------------+
| Field | Value |
+---------------------+----------------------------------+
| domain_id | default |
| enabled | True |
| id | bd7a2a0f75384a33a4abb349c6840bc8 |
| name | glance |
| password_expires_at | None |
+---------------------+----------------------------------+
添加admin角色到glance用户和service项目上
# openstack role add --project service --user glance admin
[*]创建glance服务实体
# openstack service create --name glance \
--description "OpenStack Image" image
+-------------+----------------------------------+
| Field | Value |
+-------------+----------------------------------+
| description | OpenStack Image |
| enabled | True |
| id | 8188d497252d44f59cb2e8e0c4017055 |
| name | glance |
| type | image |
+-------------+----------------------------------+
[*]创建镜像服务的API端点
# openstack endpoint create --region RegionOne \
image public http://192.168.56.11:9292
+--------------+----------------------------------+
| Field | Value |
+--------------+----------------------------------+
| enabled | True |
| id | d52e57b312ab4fadb2f84222660f01a8 |
| interface | public |
| region | RegionOne |
| region_id | RegionOne |
| service_id | 8188d497252d44f59cb2e8e0c4017055 |
| service_name | glance |
| service_type | image |
| url | http://192.168.56.11:9292 |
+--------------+----------------------------------+
# openstack endpoint create --region RegionOne \
image internal http://192.168.56.11:9292
+--------------+----------------------------------+
| Field | Value |
+--------------+----------------------------------+
| enabled | True |
| id | f44c4a6fb1d64140bded5f220cbad948 |
| interface | internal |
| region | RegionOne |
| region_id | RegionOne |
| service_id | 8188d497252d44f59cb2e8e0c4017055 |
| service_name | glance |
| service_type | image |
| url | http://192.168.56.11:9292 |
+--------------+----------------------------------+
# openstack endpoint create --region RegionOne \
image admin http://192.168.56.11:9292
+--------------+----------------------------------+
| Field | Value |
+--------------+----------------------------------+
| enabled | True |
| id | f1b9538274f54cae8b0349bfbf17dca0 |
| interface | admin |
| region | RegionOne |
| region_id | RegionOne |
| service_id | 8188d497252d44f59cb2e8e0c4017055 |
| service_name | glance |
| service_type | image |
| url | http://192.168.56.11:9292 |
+--------------+----------------------------------+
[*]安装Glance相关软件包
# yum -y install openstack-glance
# rpm -qa openstack-glance
openstack-glance-13.0.0-1.el7.noarch
Glance的配置
[*]编辑/etc/glance/glance-api.conf文件，并完成如下更改
# cp -a /etc/glance/glance-api.conf /etc/glance/glance-api.conf_$(date +%F)
# vim /etc/glance/glance-api.conf
在部分，配置数据库访问
......
1748 connection = mysql+pymysql://glance:glance@192.168.56.11/glance
在和部分，配置认证服务访问
3179 auth_uri = http://192.168.56.11:5000
3180 auth_url = http://192.168.56.11:35357
3181 memcached_servers = 192.168.56.11:11211
3182 auth_type = password
3183 project_domain_name = Default
3184 user_domain_name = Default
3185 project_name = service
3186 username = glance
3187 password = glance
......
3990 flavor = keystone
在部分，配置本地文件系统存储和镜像文件位置
......
1864 stores = file,http
1896 default_store = file
2196 filesystem_store_datadir = /var/lib/glance/images
[*]编辑/etc/glance/glance-registry.conf文件，并完成如下更改
# cp -a /etc/glance/glance-registry.conf /etc/glance/glance-registry.conf_$(date +%F)
# vim /etc/glance/glance-registry.conf
在部分，配置数据库访问
......
1038 connection = mysql+pymysql://glance:glance@192.168.56.11/glance
在和部分，配置认证服务访问
1128 auth_uri = http://192.168.56.11:5000
1129 auth_url = http://192.168.56.11:35357
1130 memcached_servers = 192.168.56.11:11211
1131 auth_type = password
1132 project_domain_name = Default
1133 user_domain_name = Default
1134 project_name = service
1135 username = glance
1136 password = glance
......
1910 flavor = keystone
[*]写入镜像服务数据库，可以忽略警告信息
# su -s /bin/sh -c "glance-manage db_sync" glance
#mysql -uglance -pglance -e "use glance;show tables;"|wc -l
21
[*]启动镜像服务，并配置为开机自启
# systemctl enable openstack-glance-api.service openstack-glance-registry.service
# systemctl start openstack-glance-api.service openstack-glance-registry.service
# systemctl status openstack-glance-api.service openstack-glance-registry.service
Glance验证操作
使用CirrOS对镜像服务进行验证，CirrOS是一个小型的Linux镜像可以用来帮助你进行Openstack部署测试。
[*]获得admin凭证来获取只有管理员能执行的命令的访问权限
# source admin-openrc
[*]下载CirrOS源镜像
# wget http://download.cirros-cloud.net/0.3.4/cirros-0.3.4-x86_64-disk.img
# ls -l cirros-0.3.4-x86_64-disk.img
-rw-r--r-- 1 root root 13287936 May82015 cirros-0.3.4-x86_64-disk.img
[*]使用qcow2磁盘格式，bare容器格式上传镜像到镜像服务并设置公共可见，这样所有的项目都可以访问它
# openstack image create "cirros" \
--file cirros-0.3.4-x86_64-disk.img \
--disk-format qcow2 --container-format bare \
--public
+------------------+------------------------------------------------------+
| Field | Value |
+------------------+------------------------------------------------------+
| checksum | ee1eca47dc88f4879d8a229cc70a07c6 |
| container_format | bare |
| created_at | 2018-01-20T04:35:25Z |
| disk_format | qcow2 |
| file | /v2/images/cd96090c-87ca-4eb3-b964-a7457639bc1e/file |
| id | cd96090c-87ca-4eb3-b964-a7457639bc1e |
| min_disk | 0 |
| min_ram | 0 |
| name | cirros |
| owner | 14055178975d417987c5a94f030c7acf |
| protected | False |
| schema | /v2/schemas/image |
| size | 13287936 |
| status | active |
| tags | |
| updated_at | 2018-01-20T04:35:26Z |
| virtual_size | None |
| visibility | public |
+------------------+------------------------------------------------------+
[*]确认镜像的上传并验证属性
# openstack image list
+--------------------------------------+--------+--------+
| ID | Name | Status |
+--------------------------------------+--------+--------+
| b4223969-0add-4641-8317-18e2b1d25b54 | cirros | active |
+--------------------------------------+--------+--------+
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