1
00:00:06,690 --> 00:00:08,520
- In this video we are going to explore

2
00:00:08,520 --> 00:00:11,020
multi-valued variables.

3
00:00:11,020 --> 00:00:12,540
So what is going on?

4
00:00:12,540 --> 00:00:15,210
Well, there are two
ways to store variables

5
00:00:15,210 --> 00:00:18,410
with multiple values, the
dictionary and the array.

6
00:00:18,410 --> 00:00:21,050
And you need to understand the difference.

7
00:00:21,050 --> 00:00:23,310
Dictionaries and arrays
and Ansible are based

8
00:00:23,310 --> 00:00:25,740
on Python dictionaries and arrays.

9
00:00:25,740 --> 00:00:28,250
An array which is also known as a list

10
00:00:28,250 --> 00:00:30,760
is an ordered list of
values where each value

11
00:00:30,760 --> 00:00:33,260
can be addressed individually.

12
00:00:33,260 --> 00:00:35,150
It looks like list is, and then

13
00:00:35,150 --> 00:00:37,560
between square brackets
and every single value

14
00:00:37,560 --> 00:00:40,163
between double quotes,
you have the values.

15
00:00:41,380 --> 00:00:43,270
And if you use a command

16
00:00:43,270 --> 00:00:46,290
in Python like print on the variable list,

17
00:00:46,290 --> 00:00:50,730
value zero then you print array index zero

18
00:00:50,730 --> 00:00:52,533
which will return to value one.

19
00:00:53,520 --> 00:00:57,580
A dictionary or a hash is an
unordered collection of values,

20
00:00:57,580 --> 00:00:59,453
which is stored as a key-value pair.

21
00:01:00,470 --> 00:01:04,660
You would write it as
dictionary equals one, colon,

22
00:01:04,660 --> 00:01:08,100
text one, two colon,
text two, three colon,

23
00:01:08,100 --> 00:01:11,740
text three, and you can use print Dict

24
00:01:11,740 --> 00:01:14,770
to print the actual dictionary value.

25
00:01:14,770 --> 00:01:17,160
Notice that the dictionary
itself to make it even

26
00:01:17,160 --> 00:01:20,980
a little bit more confusing
can be presented in a list.

27
00:01:20,980 --> 00:01:22,820
We'll talk about that later.

28
00:01:22,820 --> 00:01:25,700
Before we continue, you should
also notice that an array

29
00:01:25,700 --> 00:01:26,800
is the same as a list

30
00:01:26,800 --> 00:01:29,820
and a dictionary is the same as a hash.

31
00:01:29,820 --> 00:01:33,160
Now let's try to understand
array and dictionaries.

32
00:01:33,160 --> 00:01:36,380
So multi-valued variables
can be used in playbooks.

33
00:01:36,380 --> 00:01:38,490
And when using a multi-valued variable,

34
00:01:38,490 --> 00:01:42,260
it can be written as an array
or a list or as a dictionary.

35
00:01:42,260 --> 00:01:45,670
And each of these has their
own specific use cases.

36
00:01:45,670 --> 00:01:49,520
Dictionaries are the default
to use in Ansible facts

37
00:01:49,520 --> 00:01:52,470
and arrays are common for
multi-valued variables.

38
00:01:52,470 --> 00:01:55,763
And the big benefit is that
they easily support loops.

39
00:01:56,860 --> 00:01:59,740
You are going to learn about
loops in the next lesson

40
00:01:59,740 --> 00:02:02,350
which is about using conditionals,

41
00:02:02,350 --> 00:02:03,850
but already I need to tell you

42
00:02:03,850 --> 00:02:06,600
that loops are not supported
on dictionaries directly,

43
00:02:06,600 --> 00:02:09,990
only by using the dict2items filter.

44
00:02:09,990 --> 00:02:13,350
We'll talk about filters
later in lesson 10.

45
00:02:13,350 --> 00:02:15,340
Now let's focus on dictionary.

46
00:02:15,340 --> 00:02:17,720
Dictionaries can be written in two ways,

47
00:02:17,720 --> 00:02:21,660
so you can write them
in the yamal notation,

48
00:02:21,660 --> 00:02:23,440
which should be the preferred way

49
00:02:23,440 --> 00:02:25,890
because the indentation
is nicely indicating

50
00:02:25,890 --> 00:02:27,050
what you are doing.

51
00:02:27,050 --> 00:02:30,540
So we have users, two
users, Linda and Lisa

52
00:02:30,540 --> 00:02:32,850
and every user has their own property.

53
00:02:32,850 --> 00:02:35,510
And you can also write it this way.

54
00:02:35,510 --> 00:02:40,510
And if you use a dictionary,
there are two notations.

55
00:02:40,630 --> 00:02:42,740
There is a notation that
we have already seen

56
00:02:42,740 --> 00:02:45,980
in a multi-valued variable,
which is variable name

57
00:02:45,980 --> 00:02:47,400
in between square brackets.

58
00:02:47,400 --> 00:02:52,400
You use the specific value
that you want to address

59
00:02:52,520 --> 00:02:54,520
as in users, Linda shell,

60
00:02:54,520 --> 00:02:58,310
which will print the
shell for you. So Linda.

61
00:02:58,310 --> 00:03:01,140
You can also use the dotted format

62
00:03:01,140 --> 00:03:02,650
which we have talked about before.

63
00:03:02,650 --> 00:03:04,840
This is basically what we've already seen

64
00:03:04,840 --> 00:03:06,563
when we were talking about facts.

65
00:03:07,640 --> 00:03:09,840
So dictionaries are used in facts.

66
00:03:09,840 --> 00:03:12,560
Arrays are used in conditionals.

67
00:03:12,560 --> 00:03:16,160
And again, notice that dictionaries
can be a part of a list

68
00:03:16,160 --> 00:03:19,680
which is used in Ansible facts.

69
00:03:19,680 --> 00:03:21,640
Now let's talk about arrays.

70
00:03:21,640 --> 00:03:23,730
An array provides a list of item

71
00:03:23,730 --> 00:03:26,520
where each item can be
addressed separately.

72
00:03:26,520 --> 00:03:29,870
You can easily recognize the
array because in an array

73
00:03:29,870 --> 00:03:32,420
every item starts with a hyphen.

74
00:03:32,420 --> 00:03:35,530
So we have username, Linda, username, Lisa

75
00:03:35,530 --> 00:03:39,810
and the array has different
properties for these users.

76
00:03:39,810 --> 00:03:42,440
The nice thing about an array
is that individual items

77
00:03:42,440 --> 00:03:44,480
in the array can be addressed

78
00:03:44,480 --> 00:03:48,150
by using var_ name, square
bracket, zero, for instance

79
00:03:48,150 --> 00:03:50,470
where zero is the array offset

80
00:03:50,470 --> 00:03:53,801
and print the first value in the array.

81
00:03:53,801 --> 00:03:55,480
And you can use arrays for looping

82
00:03:55,480 --> 00:03:58,270
and looping as said before
is not what you should do

83
00:03:58,270 --> 00:04:01,850
on dictionaries and to
access all of the variables

84
00:04:01,850 --> 00:04:04,560
in an array you can
use with items or loop.

85
00:04:04,560 --> 00:04:07,230
This also is something that
we are going to discover

86
00:04:07,230 --> 00:04:09,593
in the next lesson about conditionals.

87
00:04:10,650 --> 00:04:13,550
Now, how do we recognize
list and dictionaries?

88
00:04:13,550 --> 00:04:15,600
If you're an experienced
Phython programmer

89
00:04:15,600 --> 00:04:19,630
that might be easy if you're
not, it's not that obvious.

90
00:04:19,630 --> 00:04:21,530
Now the thing is in output like facts,

91
00:04:21,530 --> 00:04:25,540
a list is always written
between square brackets

92
00:04:25,540 --> 00:04:29,450
and dictionaries are written
between curly brackets.

93
00:04:29,450 --> 00:04:32,910
And if the output is just
showing double quotes

94
00:04:32,910 --> 00:04:34,530
then it's a string.

95
00:04:34,530 --> 00:04:37,340
A nice way to show that
is by having a look

96
00:04:37,340 --> 00:04:41,220
at ansible_mounts in the facts,
because in ansible_mounts

97
00:04:41,220 --> 00:04:44,173
you will actually see
a list of dictionaries.

98
00:04:45,090 --> 00:04:46,350
Let's go check this out.

99
00:04:46,350 --> 00:04:49,163
And also let's have a look
at a couple of examples.

100
00:04:51,080 --> 00:04:54,783
So first I would like to talk
about recognizing this stuff.

101
00:04:56,440 --> 00:05:00,480
We've created the Ubuntu
fax textel earlier

102
00:05:00,480 --> 00:05:04,630
and I would like to show
you in this fax textel

103
00:05:04,630 --> 00:05:06,690
what we can see.

104
00:05:06,690 --> 00:05:08,640
So what already starts here,

105
00:05:08,640 --> 00:05:11,350
Ansible all IP four addresses.

106
00:05:11,350 --> 00:05:12,650
We can see the square brackets.

107
00:05:12,650 --> 00:05:16,120
So the square brackets, that
means that this is an array

108
00:05:16,120 --> 00:05:19,513
an array that has one specific value only.

109
00:05:20,720 --> 00:05:23,710
Then we can see a dictionary like here in

110
00:05:23,710 --> 00:05:24,780
Ansible commands line.

111
00:05:24,780 --> 00:05:27,460
So Ansible commands line is a dictionary.

112
00:05:27,460 --> 00:05:29,530
And in this dictionary

113
00:05:29,530 --> 00:05:33,320
we have these multiple key value pairs

114
00:05:33,320 --> 00:05:35,340
and notice that Ansible effects itself

115
00:05:35,340 --> 00:05:38,480
is a dictionary, a dictionary
containing dictionaries

116
00:05:38,480 --> 00:05:40,053
which may contain arrays.

117
00:05:41,000 --> 00:05:44,170
Here we have examples of just strings.

118
00:05:44,170 --> 00:05:47,600
So if you just see the double
quotes, then this is a string.

119
00:05:47,600 --> 00:05:50,380
Now how about the Ansible mounts?

120
00:05:50,380 --> 00:05:51,900
Well, if you have a look at that,

121
00:05:51,900 --> 00:05:53,630
there you can see Ansible mounts

122
00:05:53,630 --> 00:05:55,330
starting with a square bracket

123
00:05:55,330 --> 00:05:59,320
which means that the
contents really is an array.

124
00:05:59,320 --> 00:06:02,380
And in the array we have dictionaries.

125
00:06:02,380 --> 00:06:05,480
So it's an array of dictionaries and yes

126
00:06:05,480 --> 00:06:08,590
that is how you can mix
the two of them together.

127
00:06:08,590 --> 00:06:11,960
Now, at this point, that
might not make total sense,

128
00:06:11,960 --> 00:06:14,600
but by the time we've
talked about conditionals,

129
00:06:14,600 --> 00:06:16,983
you will try, you will
start to understand.

130
00:06:17,850 --> 00:06:20,340
Let's have a look at some quick examples,

131
00:06:20,340 --> 00:06:22,330
which are in the sub-directory,

132
00:06:22,330 --> 00:06:25,803
arrays in the basics directory
and of course get repository.

133
00:06:26,720 --> 00:06:28,760
So we have variables

134
00:06:28,760 --> 00:06:33,680
and I'm going to show you
vars users dictionary.

135
00:06:37,000 --> 00:06:39,810
And there we go, we
can see the dictionary.

136
00:06:39,810 --> 00:06:42,240
Now, how do you recognize
this as a dictionary?

137
00:06:42,240 --> 00:06:44,030
You recognize it as a dictionary

138
00:06:44,030 --> 00:06:46,290
mainly because there are no hyphens.

139
00:06:46,290 --> 00:06:47,930
If you define an array

140
00:06:47,930 --> 00:06:51,430
every item in the array
starts with a hyphen.

141
00:06:51,430 --> 00:06:56,430
If you compare that to users
list the other example,

142
00:06:57,290 --> 00:06:58,810
there you can see the clear difference

143
00:06:58,810 --> 00:07:01,923
between the dictionary and the array.

144
00:07:03,090 --> 00:07:05,750
Now, how are we going to use them?

145
00:07:05,750 --> 00:07:10,050
Well, there is multi-list dot YAML

146
00:07:10,050 --> 00:07:11,830
and in multi-list dot YAML.

147
00:07:11,830 --> 00:07:12,870
What do we see?

148
00:07:12,870 --> 00:07:16,650
We see that we are
including the variable fell

149
00:07:16,650 --> 00:07:21,060
and in this variable fell,
we are addressing the items

150
00:07:21,060 --> 00:07:23,690
in the array by looping over users.

151
00:07:23,690 --> 00:07:26,060
Now we haven't really seen loop yet.

152
00:07:26,060 --> 00:07:27,960
Loop is something that you can use

153
00:07:27,960 --> 00:07:30,820
on an array and loop will
work on every single item

154
00:07:30,820 --> 00:07:32,670
that is encountered on the array.

155
00:07:32,670 --> 00:07:34,310
So we have item, dot, username

156
00:07:34,310 --> 00:07:37,040
and item dot home there,
and item dot shell.

157
00:07:37,040 --> 00:07:38,120
Now, how does that work?

158
00:07:38,120 --> 00:07:40,710
If you get back to the user's list

159
00:07:40,710 --> 00:07:43,940
the item is the thing that
you can see right here

160
00:07:43,940 --> 00:07:45,580
starting with a hyphen.

161
00:07:45,580 --> 00:07:47,710
So item dot username is going

162
00:07:47,710 --> 00:07:51,530
for the first item for the
second item for the third item.

163
00:07:51,530 --> 00:07:55,920
So every item is individually explored.

164
00:07:55,920 --> 00:08:00,710
And if you run it,
ansible-playbook on multi list,

165
00:08:00,710 --> 00:08:02,533
then this is what you get.

166
00:08:03,950 --> 00:08:08,510
So one line for every
single item in the array.

167
00:08:08,510 --> 00:08:10,740
Now how about the dictionary?

168
00:08:10,740 --> 00:08:12,970
What can we do with the dictionary?

169
00:08:12,970 --> 00:08:17,760
Well, dictionaries are
honestly not as spectacular,

170
00:08:17,760 --> 00:08:20,220
but in a dictionary you can address

171
00:08:20,220 --> 00:08:22,200
the dictionary value specifically.

172
00:08:22,200 --> 00:08:24,077
So users dot Linda dot username

173
00:08:24,077 --> 00:08:29,077
and users dot Linda dot
homedir is what you can use

174
00:08:29,130 --> 00:08:33,380
but there is no way to
easily loop over the values

175
00:08:33,380 --> 00:08:35,570
in a dictionary.

176
00:08:35,570 --> 00:08:39,820
So let's have a look and
there, we can see the result.

177
00:08:39,820 --> 00:08:43,840
So two different ways of
using multi-valued variables.

178
00:08:43,840 --> 00:08:46,200
And that is really something
that you need to be aware of.

179
00:08:46,200 --> 00:08:49,630
So that you use the right
approach when encountering

180
00:08:49,630 --> 00:08:51,240
the right variable type.

181
00:08:51,240 --> 00:08:55,110
Most important the ansible facts by nature

182
00:08:55,110 --> 00:08:58,420
is a huge collection of dictionaries

183
00:08:58,420 --> 00:09:01,820
and arrays that is what
you can use to loop over.

184
00:09:01,820 --> 00:09:05,133
We'll see more of this
later throughout the scores.