linux du jour

Austin Linux Meetup

Linux Du JourA tour of Texas Linux Fest

in 5 little talks

Texas Linux Fest June 13 - 14

Austin texaslinuxfest.org

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 getty@tty1.service 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