1
00:00:06,690 --> 00:00:09,390
- So while working with
system D in many cases

2
00:00:09,390 --> 00:00:12,240
you will just use the
default service configuration

3
00:00:12,240 --> 00:00:14,370
but I want to show you how you can modify

4
00:00:14,370 --> 00:00:16,230
service configuration.

5
00:00:16,230 --> 00:00:19,230
You should always start
using system CTL Cat on the

6
00:00:19,230 --> 00:00:23,640
service. That will show you
the current unit configuration.

7
00:00:23,640 --> 00:00:26,250
Of course, there's a
configuration fell behind it.

8
00:00:26,250 --> 00:00:27,630
But the thing in system D is

9
00:00:27,630 --> 00:00:31,260
that there can be multiple
configuration fells behind it.

10
00:00:31,260 --> 00:00:33,360
And if you use system CTL cat

11
00:00:33,360 --> 00:00:36,870
now you are just going to get
all the configuration fells

12
00:00:36,870 --> 00:00:38,763
that this service is using.

13
00:00:40,050 --> 00:00:40,883
You wanna know

14
00:00:40,883 --> 00:00:44,850
about configurable parameters,
your system, CTL show.

15
00:00:44,850 --> 00:00:47,760
And once you have found
your configurable parameter

16
00:00:47,760 --> 00:00:51,900
you can use system CTL
edit on your service.

17
00:00:51,900 --> 00:00:54,730
And after modifying your
service configuration

18
00:00:54,730 --> 00:00:58,830
it is good to tell system D
to reload its configuration

19
00:00:58,830 --> 00:01:01,440
system CTL daemon reload

20
00:01:01,440 --> 00:01:04,680
that will force system D to
reload its configuration.

21
00:01:04,680 --> 00:01:06,450
You will notice that in modern versions

22
00:01:06,450 --> 00:01:09,330
of system D that's not
always necessary anymore

23
00:01:09,330 --> 00:01:11,338
but especially in older versions

24
00:01:11,338 --> 00:01:14,430
this might be something that you wanna do.

25
00:01:14,430 --> 00:01:19,410
And system CTR restart
on your service is what

26
00:01:19,410 --> 00:01:21,600
you want to do to restart the service

27
00:01:21,600 --> 00:01:23,490
if it was already running.

28
00:01:23,490 --> 00:01:24,393
Let me show you.

29
00:01:27,720 --> 00:01:30,960
So I'm going to start using system CTL Cat

30
00:01:30,960 --> 00:01:34,233
on SS H D dot service.

31
00:01:35,790 --> 00:01:40,470
This is a sent OS system and
SSH is running by default.

32
00:01:40,470 --> 00:01:41,790
So what do we see?

33
00:01:41,790 --> 00:01:44,580
We see that SSH is using user lip system D

34
00:01:44,580 --> 00:01:46,350
system SSHD dot service.

35
00:01:46,350 --> 00:01:48,360
That's the configuration file.

36
00:01:48,360 --> 00:01:50,280
We have the unit configuration

37
00:01:50,280 --> 00:01:51,810
and in the unit configuration

38
00:01:51,810 --> 00:01:54,840
you have generic stuff,
including the dependencies.

39
00:01:54,840 --> 00:01:57,000
And now we have the service configuration

40
00:01:57,000 --> 00:02:01,620
in which you specify exactly
what should be happening.

41
00:02:01,620 --> 00:02:02,700
Now, what I'm interested

42
00:02:02,700 --> 00:02:06,000
in is this restart on and restart sec.

43
00:02:06,000 --> 00:02:07,560
And I'm going to copy that

44
00:02:07,560 --> 00:02:11,970
and let me use sudo systems CTL edit

45
00:02:11,970 --> 00:02:15,990
on httpd dot service, well dot service

46
00:02:15,990 --> 00:02:18,810
you don't even have to type dot service.

47
00:02:18,810 --> 00:02:22,500
If you just type system
CTL edit httpd, it'll

48
00:02:22,500 --> 00:02:25,830
automatically assume that
you want to edit a service.

49
00:02:25,830 --> 00:02:26,700
And here we go.

50
00:02:26,700 --> 00:02:27,780
And we are

51
00:02:27,780 --> 00:02:32,780
in the default system D editor,
which is, which is nano.

52
00:02:34,500 --> 00:02:36,272
Now read carefully.

53
00:02:36,272 --> 00:02:37,350
What do we see?

54
00:02:37,350 --> 00:02:39,930
We see anything between
here and a comment below

55
00:02:39,930 --> 00:02:41,790
will become the new contents of the valve.

56
00:02:41,790 --> 00:02:43,488
That's exactly what I need.

57
00:02:43,488 --> 00:02:46,950
So we can see right here

58
00:02:46,950 --> 00:02:50,160
lines below the comment will be discarded.

59
00:02:50,160 --> 00:02:51,360
Then why are they there?

60
00:02:51,360 --> 00:02:53,400
Well, because they allow you to see

61
00:02:53,400 --> 00:02:56,280
what you currently have
in your configuration.

62
00:02:56,280 --> 00:02:59,040
Now I'm going to paste and in my paste

63
00:02:59,040 --> 00:03:04,040
I'm using restart on failure
and restart sec is 42 seconds.

64
00:03:04,560 --> 00:03:08,193
And I want to put that
in the service section.

65
00:03:09,840 --> 00:03:11,490
Now I'm going to use cultural X

66
00:03:11,490 --> 00:03:13,230
to write the modified buffer.

67
00:03:13,230 --> 00:03:14,640
And there we go.

68
00:03:14,640 --> 00:03:17,820
And I am going to use system CTL cat

69
00:03:17,820 --> 00:03:19,500
on httpd.

70
00:03:19,500 --> 00:03:22,410
And what is system Key CTL cat showing?

71
00:03:22,410 --> 00:03:25,590
It's showing the context
of httpd dot service.

72
00:03:25,590 --> 00:03:28,170
That's the default configuration.

73
00:03:28,170 --> 00:03:31,260
And to the end, it is
also showing my additions

74
00:03:31,260 --> 00:03:34,920
and my additions have been
added in ETC system D system

75
00:03:34,920 --> 00:03:38,580
in a sub directory and
in their override.com.

76
00:03:38,580 --> 00:03:41,400
So this override.com is
automatically applied

77
00:03:41,400 --> 00:03:43,830
to the httpd dot service.

78
00:03:43,830 --> 00:03:45,240
So I have my researchers

79
00:03:45,240 --> 00:03:48,513
on failure and the
research sec is 42 seconds.

80
00:03:49,500 --> 00:03:50,333
Is that okay?

81
00:03:50,333 --> 00:03:52,560
Well, I can live with that

82
00:03:52,560 --> 00:03:57,383
and let me do a sudo
system CTL start on httpd.

83
00:03:58,650 --> 00:04:03,063
And now let me do sudo kill all httpd.

84
00:04:04,200 --> 00:04:08,490
and sudo system CTL status on httpd.

85
00:04:08,490 --> 00:04:11,940
And then we need to figure
out what is happening.

86
00:04:11,940 --> 00:04:12,840
So what do we see?

87
00:04:12,840 --> 00:04:16,260
We see that the service is
inactive in that, and oh

88
00:04:16,260 --> 00:04:17,400
that is not good.

89
00:04:17,400 --> 00:04:20,370
Hey, you know what system D doesn't know

90
00:04:20,370 --> 00:04:22,410
about its new option, apparently.

91
00:04:22,410 --> 00:04:24,300
So let's tell it about it.

92
00:04:24,300 --> 00:04:28,801
I'm first going to use system
CTL, start on httpd again

93
00:04:28,801 --> 00:04:31,530
and this looks like one
of these cases where

94
00:04:31,530 --> 00:04:35,880
we need sudo system CTL daemon reload

95
00:04:35,880 --> 00:04:37,380
which is their system D

96
00:04:37,380 --> 00:04:40,950
can you please reload your configuration?

97
00:04:40,950 --> 00:04:44,580
Now I'm using system CTL
status, and I'm looking

98
00:04:44,580 --> 00:04:49,580
at PID4938, and I'm going
to sudo kill minus nine.

99
00:04:50,250 --> 00:04:52,770
That's a command that I
will explain later in much

100
00:04:52,770 --> 00:04:57,633
more detail, but I'm killing
minus nine, the process 4938.

101
00:04:58,620 --> 00:05:01,350
And now I'm going to
use my status again to

102
00:05:01,350 --> 00:05:04,110
see what is going on.

103
00:05:04,110 --> 00:05:06,300
And now we can see it's working.

104
00:05:06,300 --> 00:05:07,380
Do you see that

105
00:05:07,380 --> 00:05:08,880
active is now set

106
00:05:08,880 --> 00:05:11,940
to activating auto restart?

107
00:05:11,940 --> 00:05:13,140
So what does that mean?

108
00:05:13,140 --> 00:05:14,940
That means that the
option that I have just

109
00:05:14,940 --> 00:05:19,470
applied is adding
protection to the service.

110
00:05:19,470 --> 00:05:22,230
If something bad happens
to the service system

111
00:05:22,230 --> 00:05:23,340
D can make sure

112
00:05:23,340 --> 00:05:26,280
that the service is
automatically started again.

113
00:05:26,280 --> 00:05:30,210
And this is one of the most
awesome features in system D

114
00:05:30,210 --> 00:05:33,210
because before system D if
you wanted to add protection

115
00:05:33,210 --> 00:05:37,050
like this to a service, then
you really only had one choice

116
00:05:37,050 --> 00:05:40,200
and that is to install a
high availability closer.

117
00:05:40,200 --> 00:05:41,246
Now, you don't have to do

118
00:05:41,246 --> 00:05:44,070
a high availability closer anymore.

119
00:05:44,070 --> 00:05:48,240
You just use the system D restart equals

120
00:05:48,240 --> 00:05:51,900
on failure and restart number of seconds

121
00:05:51,900 --> 00:05:54,360
and it'll automatically get back.

122
00:05:54,360 --> 00:05:55,680
Do we already have it?

123
00:05:55,680 --> 00:05:56,513
There we go.

124
00:05:56,513 --> 00:05:58,110
We already have it.

125
00:05:58,110 --> 00:06:01,530
So system D made sure it's
automatically started again

126
00:06:01,530 --> 00:06:03,960
and this is just one of
the many nice features

127
00:06:03,960 --> 00:06:07,680
of system D. I can talk
about system D for hours.

128
00:06:07,680 --> 00:06:09,390
That's not my intention here

129
00:06:09,390 --> 00:06:11,643
so let's continue with the next video.