Canonical Juju

Specific machine placement by hostname in bundle

Bug #1882025 reported by Vern Hart on 2020-06-04

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	Canonical Juju	Triaged	Wishlist	Unassigned

Bug Description

From the command line we can specify:

juju deploy graylog --to graylog-1.maas

But there isn't an equivalent for bundles.

We commonly tag individual machines with their name and use those tags as a constraint in the machines section and use the machine id in an application's "to:" directive:

    machines:
      "0":
        constraints: tags=graylog
    applications:
      graylog:
        charm: cs:graylog
        to:
        - "0"

It could potentially simplify and make things a bit clearer if we could specify the machine name directly in the to directive:

    applications:
      graylog:
      charm: cs:graylog
      to:
      - "graylog-1.maas"

Is this technically feasible?

Tags:

Revision history for this message

Ian Booth (wallyworld) wrote on 2020-06-05:

It is feasible but some work is needed since in bundles, the "to" is interpreted as follows:

(<containertype>:)?(<unit>|<machine>|new)

So we'd need to figure out a syntax to use to support the new semantics.

Changed in juju:
milestone:	none → 2.9-beta1
status:	New → Triaged

Revision history for this message

Vern Hart (vern) wrote on 2020-06-09:

containertype is [none|kvm|lxd] (or lxc which gets interpreted as lxd)
unit is <application>/<unitid>
application is [-a-z0-9]+ (except no double dashes "--" or groups of only numbers)
unitid and machine are both [0-9]+
new is just "new"

Currently it's not valid to have a period (.) in the bundle's "to" directive.

So it seems to me that a check to see if it has a period would be sufficient to try the string as a hostname or IP address.

Now that I have found the resolveMachine function in cmd/juju/application/bundle.go I see that it's not quite that simple. But it does seem possible.

Canonical Juju QA Bot (juju-qa-bot) on 2020-10-16

Changed in juju:
milestone:	2.9-beta1 → 2.9-rc1

Revision history for this message

John A Meinel (jameinel) wrote on 2020-10-26:

If we implement support for this, we should qualify it with a prefix (like zone=, or subnet=, we could support hostname= or name=)
I don't want to have a heuristic of whether or not a '.' is present to treat the content differently.

Revision history for this message

Ian Booth (wallyworld) wrote on 2020-10-27:

The scope of the change to support extending the bundle placement syntax to allow compatibility with the single charm deployment placement syntax is non-trivial. Not only does the bundle parsing code need to be changed and new semantics wired through, so too does the bundle diff handling which compares a bundle with what's been deployed already to generate a set of changes.

Moving to 2.9.1 milestone given it is unlikely to be able to be done prior to 2.9.0

Changed in juju:
milestone:	2.9-rc1 → 2.9.1

Ian Booth (wallyworld) on 2021-04-30

Changed in juju:
milestone:	2.9.1 → 2.9.2

Canonical Juju QA Bot (juju-qa-bot) on 2021-05-19

Changed in juju:
milestone:	2.9.2 → 2.9.3

Canonical Juju QA Bot (juju-qa-bot) on 2021-05-25

Changed in juju:
milestone:	2.9.3 → 2.9.4

Canonical Juju QA Bot (juju-qa-bot) on 2021-06-02

Changed in juju:
milestone:	2.9.4 → 2.9.5

Canonical Juju QA Bot (juju-qa-bot) on 2021-06-16

Changed in juju:
milestone:	2.9.5 → 2.9.6

Canonical Juju QA Bot (juju-qa-bot) on 2021-06-21

Changed in juju:
milestone:	2.9.6 → 2.9.7

Canonical Juju QA Bot (juju-qa-bot) on 2021-06-30

Changed in juju:
milestone:	2.9.7 → 2.9.8

Canonical Juju QA Bot (juju-qa-bot) on 2021-07-08

Changed in juju:
milestone:	2.9.8 → 2.9.9

Canonical Juju QA Bot (juju-qa-bot) on 2021-07-15

Changed in juju:
milestone:	2.9.9 → 2.9.10

Canonical Juju QA Bot (juju-qa-bot) on 2021-07-30

Changed in juju:
milestone:	2.9.10 → 2.9.11

Canonical Juju QA Bot (juju-qa-bot) on 2021-08-11

Changed in juju:
milestone:	2.9.11 → 2.9.12

Canonical Juju QA Bot (juju-qa-bot) on 2021-08-25

Changed in juju:
milestone:	2.9.12 → 2.9.13

Canonical Juju QA Bot (juju-qa-bot) on 2021-09-08

Changed in juju:
milestone:	2.9.13 → 2.9.14

Canonical Juju QA Bot (juju-qa-bot) on 2021-09-10

Changed in juju:
milestone:	2.9.14 → 2.9.15

Canonical Juju QA Bot (juju-qa-bot) on 2021-09-24

Changed in juju:
milestone:	2.9.15 → 2.9.16

Canonical Juju QA Bot (juju-qa-bot) on 2021-10-07

Changed in juju:
milestone:	2.9.16 → 2.9.17

Canonical Juju QA Bot (juju-qa-bot) on 2021-10-22

Changed in juju:
milestone:	2.9.17 → 2.9.18

Canonical Juju QA Bot (juju-qa-bot) on 2021-11-04

Changed in juju:
milestone:	2.9.18 → 2.9.19

Canonical Juju QA Bot (juju-qa-bot) on 2021-11-17

Changed in juju:
milestone:	2.9.19 → 2.9.20

Canonical Juju QA Bot (juju-qa-bot) on 2021-11-26

Changed in juju:
milestone:	2.9.20 → 2.9.21

Canonical Juju QA Bot (juju-qa-bot) on 2021-12-01

Changed in juju:
milestone:	2.9.21 → 2.9.22

Canonical Juju QA Bot (juju-qa-bot) on 2021-12-10

Changed in juju:
milestone:	2.9.22 → 2.9.23

Canonical Juju QA Bot (juju-qa-bot) on 2022-01-12

Changed in juju:
milestone:	2.9.23 → 2.9.24

Canonical Juju QA Bot (juju-qa-bot) on 2022-02-01

Changed in juju:
milestone:	2.9.24 → 2.9.25

Canonical Juju QA Bot (juju-qa-bot) on 2022-02-15

Changed in juju:
milestone:	2.9.25 → 2.9.26

Canonical Juju QA Bot (juju-qa-bot) on 2022-03-09

Changed in juju:
milestone:	2.9.26 → 2.9.27

Canonical Juju QA Bot (juju-qa-bot) on 2022-03-18

Changed in juju:
milestone:	2.9.27 → 2.9.28

Canonical Juju QA Bot (juju-qa-bot) on 2022-03-30

Changed in juju:
milestone:	2.9.28 → 2.9.29

John A Meinel (jameinel) on 2022-04-26

Changed in juju:
milestone:	2.9.29 → none
tags:	added: bundles

Revision history for this message

Vern Hart (vern) wrote on 2022-08-25:

It occurs to me that this might be done with constraints.

I have not tested using tags in application constraints but if that works, it would accomplish the idea of simplifying the bundle.

Even better would be to implement a hostname constraint that would have a similar effect.

While this wouldn’t fulfill the exact original request, it seems like it’d be more in line with how juju currently works.

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