Introduction to the Container-Technologie Docker such as the Graph-Database Neo4j.

1. MoreCloudTechnologies
Docker,Neo4j

2. Docker

3. What is Docker?

4. • Docker Engine +
• Docker Hub

5. Docker Engine
=
Portable, lightweight
runtime and packing tool

6. Docker Hub
=
Cloud service for sharing
application and automation
workflows

7. Why is Docker relevant?

8. Receives a lot of attention.

9. Docker is not a Cloud but
it’s an interesting
building block technology.

10. How does Docker work?

11. Docker Architecture

12. << VM / Physical >>
Host
Container 1
Container 2
Container 3
…
Docker Client
$> docker run …
Docker Daemon

13. Docker Images

14. • Read-only (filesystem) templates
• OS + Software, e.g. Ubuntu + Nginx
• Used to create Docker containers
• Docker makes image handling easy

15. Unions FS

16. • Stackable unification file system
• Can merge contents of several
directories (branches) while keeping
them physically dedicated
• Allows to mix read-only and writable
branches
• Branches can be inserted/deleted
anywhere in the tree

17. • Handles
• elimination of duplicates
• partial-error conditions

18. Stack files and directories
(branches) of several
filesystems together to form
a single coherent filesystem.

19. Docker Registries

20. • A Docker registry holds Docker images
• You upload / download images
• Can be public or private
• Docker hub is a public Docker registry
• Access images of other Docker users
(Community)

21. Docker Containers

22. • Contains what an app needs to run
• Created from a Docker image
• States: run, started, stopped, moved,
deleted
• Isolated runtime environment
(~= OS level virtualized VM)

23. • Docker containers use Union FS to add
layers to „version“ your container’s
filesystem
• Copy-on-write (COW) approach

24. • Starting with a base image, a container
can be developed step by step
• The „Dockerfile“ contains these steps
• Image + Docker Image = Final Image

25. Docker Container
=
OS (image) + user files +
meta-data

26. Running a Docker Container

27. docker run -i -t ubuntu /bin/bash

28. • Docker Client command is run
• Talking to the Docker daemon
• Start a container from the „ubuntu“
image
• Inside the container run the command
„/bin/bash“

29. • Pulls the ubuntu image
• Creates a new container
• Allocates fs and mounts rw-layer
• Allocates a net / bridge interface
• Setup IP address
• Executes process (/bin/bash)
• Captures and provides app output

30. Docker Container Isolation

31. • Namespaces
• Control Groups
• Union fs
• Container format

32. Namespaces

33. Namespaces are
a linux feature.

34. „A namespace wraps a global system resource in an
abstraction that makes it appear to the processes within
the namespace that they have their own isolated
instance of the global resource. Changes to the global
resource are visible to other processes that are members
of the namespace, but are invisible to other processes.
One use of namespaces is to implement containers.“
- http://man7.org/linux/man-pages/man7/namespaces.7.html

35. Namespace Isolates
IPC System V IPC, POSIX message queues
Network Network devices, stacks, ports, etc.
Mount Mount points
PID Process IDs
User User and group IDs
UTS Hostname and NIS domain name

36. Control Groups

37. Control Groups are a feature
of the linux kernel.

38. „Control Groups provide a mechanism
for aggregating/partitioning sets of
tasks, and all their future children, into
hierarchical groups with
specialized behaviour.“
- https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt

39. Union FS

40. Container Format

41. • container format =
Namespaces + Control Groups
+ Union fs
• Libcontainer = default container format
• https://github.com/docker/
libcontainer

42. • Alternative container format
• LXC
• BSD Jails (future)
• Solaris Zones (future)

43. What do I need Docker for?

44. • Build your own application platform /
PaaS.
• Want to stay in control of what happens
inside your containers (in contrast to
Cloud Foundry where you delegate this).

45. Show me a Docker demo!

46. https://www.docker.com/tryit/

47. Neo4j

48. What is Neo4j?

49. Neo4j is a graph database.

50. • Stores data in a graph rather than tables.
• A graph contains nodes.
• Nodes have key, value properties.
• Nodes can be labeled to group them

51. • Relations = links between nodes
• Relations can be traversed bi-
directionally (even when being directed)
• Relation can have properties, too

52. http://neo4j.com/docs/stable/what-is-a-graphdb.html

53. • Graphs can be queried (traversed)
• Indexes look-up nodes or relationships
• Find nodes with specific properties
faster than traversing the graph.

55. Why is Neo4j relevant?

56. • Because graphes are
• Think of Facebook’s social graph with its
social search

57. How does Neo4j work?

58. Nodes

59. • Fundamental unit to form a graph
• Can have properties
• Often used to represent entities
(although - depending on the domain
model - also relations could be
meaningful to do so)
• Can have 0..* labels

60. Relationships

61. • Fundamental unit to form a graph
• Link nodes
• Can have properties
• Relations can be traversed bi-
directionally (even when being directed)
• Reflexive relations are allowed
• Relation can be typed > similar to labels
for Nodes

62. Properties

63. • Properties = key, value pairs
• Key = string
• Value = primitive || array
• Types: boolean, byte, short, int, long,
float, double, char, String

64. Labels

65. • Labels are used to group nodes
• Nodes with the same label belong to the
same set > Can be used in queries
• A node may have 0..* labels
• Used when defining constraints/indices.

66. Paths

67. • A path is one or more nodes connected
by relations
• Typically retrieved as a query or
traversal result

68. Traversals

69. • Traversing
• = visiting a graph’s nodes
• = following nodes according to specific
rules
• Most likely only a sub-graph is traversed

70. • Cypher = declarative way to query a
graph by traversal and other techniques
• Traversal Framework Java API
• http://neo4j.com/docs/stable/tutorial-
traversal-java-api.html
• Explicit graph traversal

71. Schema

72. • Neo4j is a schema-optional graph
database
• Can be used without a schema
• Schemas can produce performance
and modelling benefits

73. • Indices
• Performance increase > Nodes can be
lookup up faster
• Are eventually available > indices are
being populated in the background

74. • Contraints
• Rules how data should look like
• Violations will cause Neo4j deny the
concerning changes

75. Querying Data
The Cypher Query Language

76. • = Declarative, SQL-inspired language to
describe graph patterns
• Describe what to select (e.g. sub-
graphs), insert, update or delete
• without the need on how exactly this
happens (graph theory ninja magic)

77. (a) - [:LIKES] - (b)A B
LIKES

78. What do I need Neo4j for?

79. When you need to apply
graph theory on large data
sets.

80. Show me a Neo4j demo!

81. http://neo4j.com/docs/
stable/cypherdoc-linked-
lists.html

82. Thank you.
@fischerjulian
j@avtq.de

83. Links & Sources

84. • neo4j.com
• docker.com
• http://unionfs.filesystems.org/
• mesos.apache.org
• spark.apache.org