linux du jour
DESCRIPTION
A short overview of current technologies plucked from the Texas Linux Fest schedule for 2014. Includes overviews of systemd, popular configuration management tools, docker, distributed log collection, and openstack.TRANSCRIPT
Austin Linux Meetup
Linux Du JourA tour of Texas Linux Fest
in 5 little talks
I’m MatthewDevOps Engineer at RetailMeNot
We’re a Linux shop
systemd
DockerConfiguration Management
Distributed Log CollectionOpenStack
Topics
I’m not an expert in these technologies Mostly learned about them in the last few days
systemdsystem and service manager
(first program started by the kernel)
systemd
• Replaces init
• Dependency-based
• Also replaces inetd
starts programs at boot programs are started only when needed by other programs • parallel startup can start programs in response to TCP connections, but also via DBUS
systemd
• units, not scripts
!
versus traditional init
Lines 77 - 162 /etc/init.d/ssh
Debian Squeeze
case "$1" in start) [...] ;; ! stop) [...] ;; ! reload|force-reload) [...] ;; ! restart) [...] ;; ! try-restart) [...] ;; ! status) [...] ;; ! *) [...] esac
Hard to see, important thing is the case statement that responds to start, stop, etc. 86 lines, less than half the init script for ssh
[Unit] Description=OpenSSH server daemon After=syslog.target network.target auditd.service ![Service] EnvironmentFile=/etc/sysconfig/sshd ExecStartPre=/usr/sbin/sshd-keygen ExecStart=/usr/sbin/sshd -D $OPTIONS ExecReload=/bin/kill -HUP $MAINPID KillMode=process Restart=on-failure RestartSec=42s ![Install] WantedBy=multi-user.target
/usr/lib/systemd/system/sshd.service Fedora 2015 Lines
Contrast 15 lines!
systemd
• units, not scripts
• dependencies, not ordering
versus traditional init
# Provides: sshd # Required-Start: $remote_fs $syslog # Required-Stop: $remote_fs $syslog # Default-Start: 2 3 4 5 # Default-Stop: # Short-Description: OpenBSD Secure Shell server
lrwxrwxrwx 1 root root 17 Mar 26 02:05 S01vboxadd -> ../init.d/vboxadd lrwxrwxrwx 1 root root 25 Mar 26 02:05 S02vboxadd-service -> ../init.d/vboxadd-service lrwxrwxrwx 1 root root 17 Mar 26 02:06 S16portmap -> ../init.d/portmap lrwxrwxrwx 1 root root 20 Mar 26 02:06 S17nfs-common -> ../init.d/nfs-common lrwxrwxrwx 1 root root 23 Mar 27 04:28 S19apt-cacher-ng -> ../init.d/apt-cacher-ng lrwxrwxrwx 1 root root 20 Mar 27 04:33 S19fancontrol -> ../init.d/fancontrol lrwxrwxrwx 1 root root 17 Mar 26 02:06 S19rsyslog -> ../init.d/rsyslog lrwxrwxrwx 1 root root 14 Mar 26 02:06 S19sudo -> ../init.d/sudo lrwxrwxrwx 1 root root 17 Mar 27 04:25 S20apache2 -> ../init.d/apache2 lrwxrwxrwx 1 root root 15 Mar 27 04:25 S21acpid -> ../init.d/acpid lrwxrwxrwx 1 root root 13 Mar 27 04:25 S21atd -> ../init.d/atd lrwxrwxrwx 1 root root 14 Mar 27 04:25 S21cron -> ../init.d/cron lrwxrwxrwx 1 root root 13 Mar 27 04:25 S21ntp -> ../init.d/ntp lrwxrwxrwx 1 root root 20 Mar 27 04:33 S21postgresql -> ../init.d/postgresql lrwxrwxrwx 1 root root 16 Mar 27 04:25 S21puppet -> ../init.d/puppet lrwxrwxrwx 1 root root 18 Mar 27 04:34 S21puppetdb -> ../init.d/puppetdb lrwxrwxrwx 1 root root 22 Mar 27 04:28 S21puppetmaster -> ../init.d/puppetmaster lrwxrwxrwx 1 root root 18 Mar 27 04:28 S21puppetqd -> ../init.d/puppetqd lrwxrwxrwx 1 root root 15 Mar 27 04:25 S21rsync -> ../init.d/rsync lrwxrwxrwx 1 root root 15 Mar 27 04:33 S21snmpd -> ../init.d/snmpd lrwxrwxrwx 1 root root 13 Mar 27 04:25 S21ssh -> ../init.d/ssh lrwxrwxrwx 1 root root 17 Mar 27 04:34 S21sysstat -> ../init.d/sysstat lrwxrwxrwx 1 root root 15 Mar 27 04:33 S22exim4 -> ../init.d/exim4 lrwxrwxrwx 1 root root 18 Mar 27 04:25 S23bootlogs -> ../init.d/bootlogs lrwxrwxrwx 1 root root 18 Mar 27 04:25 S24rc.local -> ../init.d/rc.local lrwxrwxrwx 1 root root 19 Mar 27 04:25 S24rmnologin -> ../init.d/rmnologin lrwxrwxrwx 1 root root 23 Mar 27 04:25 S24stop-bootlogd -> ../init.d/stop-bootlogd
Metadata at the top of init scripts Helps maintains run level link madness
[Unit] Description=OpenSSH server daemon After=syslog.target network.target auditd.service ![Service] EnvironmentFile=/etc/sysconfig/sshd ExecStartPre=/usr/sbin/sshd-keygen ExecStart=/usr/sbin/sshd -D $OPTIONS ExecReload=/bin/kill -HUP $MAINPID KillMode=process Restart=on-failure RestartSec=42s ![Install] WantedBy=multi-user.target
Requirements Target: runlevel equivalent
systemd
• units, not scripts
• dependencies, not ordering
• systemctl, not service
versus traditional init
root@box-sol-aus-eop-pup-aio-000-i-simulate:~# service --status-all [ + ] acpid [ + ] apache2 [ ? ] apt-cacher-ng [ + ] atd [ - ] bootlogd [ - ] bootlogs [ ? ] bootmisc.sh [ ? ] checkfs.sh [ - ] checkroot.sh [ ? ] console-setup [ ? ] cron [ - ] exim4 [ - ] fancontrol [ - ] hostname.sh ...
service(8) System Manager's Manual service(8) ![...] !DESCRIPTION [...] The SCRIPT parameter specifies a System V init script, located in /etc/init.d/SCRIPT. The supported values of COMMAND depend on the invoked script, service passes COMMAND and OPTIONS it to the init script unmodified. All scripts should support at least the start
UNIT LOAD ACTIVE SUB DESCRIPTION [...] chronyd.service loaded active running NTP client/server crond.service loaded active running Command Scheduler cryptsetup.target loaded active active Encrypted Volumes dbus.service loaded active running D-Bus System Message Bus dbus.socket loaded active running D-Bus System Message Bus So dev-dm\x2d0.swap loaded active active /dev/dm-0 dev-hugepages.mount loaded active mounted Huge Pages File System dev-mqueue.mount loaded active mounted POSIX Message Queue File Sy dm-event.socket loaded active listening Device-mapper event daemon docker.service loaded active running Docker Application Containe fedora-readonly.service loaded active exited Configure read-only root su firewalld.service loaded active running firewalld - dynamic firewal getty.target loaded active active Login Prompts [email protected] loaded active running Getty on tty1 kmod-static-nodes.service loaded active exited Create list of required sta local-fs-pre.target loaded active active Local File Systems (Pre) local-fs.target loaded active active Local File Systems lvm2-lvmetad.service loaded active running LVM2 metadata daemon lvm2-lvmetad.socket loaded active running LVM2 metadata daemon socket lvm2-monitor.service loaded active exited Monitoring of LVM2 mirrors, lvm2-pvscan@8:2.service loaded active exited LVM2 PV scan on device 8:2 multi-user.target loaded active active Multi-User System network.target loaded active active Network paths.target loaded active active Paths polkit.service loaded active running Authorization Manager proc-sys...t_misc.automount loaded active waiting Arbitrary Executable File F remote-fs.target loaded active active Remote File Systems session-3.scope loaded active running Session 3 of user vagrant slices.target loaded active active Slices sockets.target loaded active active Sockets sound.target loaded active active Sound Card sshd.service loaded active running OpenSSH server daemon [...]
Tracks state automatically
Unit Commands: list-units List loaded units list-sockets List loaded sockets ordered by address start [NAME...] Start (activate) one or more units stop [NAME...] Stop (deactivate) one or more units reload [NAME...] Reload one or more units restart [NAME...] Start or restart one or more units try-restart [NAME...] Restart one or more units if active reload-or-restart [NAME...] Reload one or more units if possible, otherwise start or restart reload-or-try-restart [NAME...] Reload one or more units if possible, otherwise restart if active isolate [NAME] Start one unit and stop all others kill [NAME...] Send signal to processes of a unit is-active [NAME...] Check whether units are active is-failed [NAME...] Check whether units are failed status [NAME...|PID...] Show runtime status of one or more units show [NAME...|JOB...] Show properties of one or more units/jobs or the manager set-property [NAME] [ASSIGNMENT...] Sets one or more properties of a unit help [NAME...|PID...] Show manual for one or more units reset-failed [NAME...] Reset failed state for all, one, or more units list-dependencies [NAME] Recursively show units which are required or wanted by this unit or by which this unit is required or wanted
Standard set of commands for all services
learning systemdhttp://0pointer.de/blog/projects/inetd.html
(includes links to 10 predecessors)
Configuration Management
tracking system changes i.e. ansible, cfengine, chef, puppet, saltstack
Configuration Management
• Declarative, not imperative
• Extensible
• Master-client or standalone
Some are less declarative than others All are extensible All can run master-client or standalone
Architecture
master
client
config repo
disc. agent
ansible chef puppet salt
repo module/playbook
recipe/cookbook
module/repo state/pillar
server ansible chef master master
client N/A client agent minion
discovery agent
ansible facts ohai facter salt grains
remote commands (built in) knife mcollective (built in)
GUI Tower Chef Manage
Puppet Enterprise
Halite (alpha)
Ansible
• Python-based (2.X)
• Push-based (no server)
• Works over SSH
• Config format: YAML
• Modules: Any language
Emphasis on virtual infrastructure integration
Chef
• Ruby-based
• Config format: Ruby
• Modules: Ruby
Emphasis on developer-friendly, agile experience
Puppet
• Ruby-based
• Config format: Puppet DSL
• Modules: Puppet DSL, Ruby (for extensions)
Emphasis on declaration, not process
SaltStack
• Python-based
• Config format: YAML
• Modules: Python/Cython
Emphasis on speed, scalability
Installing Apache… with ansible
/etc/ansible/hostslocalhost ansible_connection=local
local-apache.yml (playbook)--- - hosts: localhost tasks: - name: install apache apt: name=apache2 - name: ensure apache is running service: name=apache2 state=started
# ansible-playbook local-apache.yml
# mkdir cache # chef-solo --override-runlist \ "recipe[apache::install]" -c config.rb
Installing Apache… with chef
config.rbbase_dir Dir.pwd + "/" file_cache_path base_dir + "cache/" cookbook_path base_dir + "cookbooks/"
cookbooks/apache/recipes/install.rbpackage 'apache2' do action :install end service 'apache2' do action [ :enable, :start ] end
# puppet apply apache-install.pp
Installing Apache… with puppet
apache-install.pppackage {'apache2': ensure => 'installed', } !service {'apache2': ensure => 'running', enable => true, require => Package['apache2'], }
Installing Apache… with saltstack
/etc/salt/minionfile_client: local
/srv/salt/top.slsbase: '*': - apache
# salt-call --local state.highstate
/srv/salt/top.slsapache2: pkg: - installed service: - running - require: - pkg: apache2
learn moreansible
http://docs.ansible.com/
chef http://docs.opscode.com/
puppet http://docs.puppetlabs.com/
saltstack http://docs.saltstack.com/
dockercontainer deployment and management
Containers
• lightweight virtual machine
• chroot on steroids
Lighter than a VM • Same kernel • Little or no boot time • As little as one process Mightier than chroot • resource constraints (memory, CPU) • separate pids, users, groups, networking
Docker
• layered filesystem templates
• container build and run automation
• expose network services
Docker
• installation
• first docker container
• dockerfiles
Demo: Install • yum install -y docker-io • systemctl start docker • systemctl enable docker • docker pull ubuntu:14.04 • docker images Demo: Run • docker run -i -t —name demo ubuntu:14.04 /bin/bash • dpkg -l • lsb_release -d • exit • docker ps -a • docker start demo • docker attach demo • ps awfux
learning dockerhttp://docs.docker.io/introduction/working-with-docker/
https://www.stgraber.org (LXC itself)
Distributed Log Collection
Architecture
client
client
client
aggregator
files
database
search index
Aggregators
• Accept
• Transform
• Filter
• Forward
Accept • native formats like system logs, message queues, snmp • via client agents Transform • Add structure (json, etc) • Extract data into fields (hostname, message, time, etc) Filter • Remove or combine entries • combine multi-line • criteria matching Forward • Send logs to their destination • storage, notifications/alerts, message queues
What’s available?
logstash
fluentd
flume
http://logstash.net
http://fluentd.org
https://flume.apache.org/
Logstash - Aimed at flexibility • includes tons of inputs, filters, and outputs FluentD - Aimed at robustness • built-in support for high availability, delivery assurance Flume - Part of the Hadoop ecosystem • stores data in HDFS
ElasticSearch + Kibana• Auto-balancing, auto-scaling search index, REST API
• Pretty GUI for searching logs
Works with any of these aggregators Great replacement for Splunk Missing the alerting component, but easy to work around
learn morehttp://jasonwilder.com/blog/2012/01/03/centralized-logging/ http://jasonwilder.com/blog/2013/11/19/fluentd-vs-logstash/
OpenStackopen source virtualization platform
OpenStack Capabilities
• Virtual Machines
• Storage (Object and Block)
• Database (MySQL-compatible)
• Networking
• REST API
AWS EquivalentsOpenStack AWS
Compute Nova EC2
Networking Neutron Classic + VPC
Database Trove RDS
Storage (Block) Cinder EBS
Storage (Object) Swift S3
Identity Keystone IAM
Monitoring Celiometer CloudWatch
Orchestration Heat CloudFormation
Dashboard Horizon AWS Console
Some are similar, but not direct equivalents (e.g. Keystone) !OpenStack-based providers usually provide several other services like DNS, CDN, or message queues (Amazon does too)
Public OpenStack Clouds
The Competition
• Apache CloudStack
• VMware vCloud
• Eucalyptus
Setting Up Your Own
• DevStack (http://devstack.org/)
• OpenStack Guides
• http://docs.openstack.org/icehouse/
• Ubuntu Cloud Installerhttp://www.ubuntu.com/download/cloud/install-ubuntu-cloud
DevStack is installable on a VM, even Vagrant Guides for CentOS, Debian Wheezy, Fedora, RedHat, SuSE, Ubuntu Cloud Installer requires six hosts (can be VMs)
learn morehttp://docs.openstack.org/
puppet
chef
saltstackansible openstack
fluentd
flume
logstash
docker
systemd
configuration management
distributed logging linux containers
elasticsearch
kibana